Advanced to version 1.0.1.

.gitignore

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/27
 
 #  Copyright (c) 2022 imacat.
@@ -38,3 +38,4 @@ excludes
 *.mo
 zh_Hans
 test_temp.py
+dummy.js

.readthedocs.yaml

@@ -0,0 +1,40 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/4/5
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+# Build documentation in the docs/ directory with Sphinx
+
+# If using Sphinx, optionally build your docs in additional formats such as PDF
+formats: all
+
+# Optionally declare the Python requirements required to build your docs
+python:
+   install:
+   - method: pip
+     path: .

MANIFEST.in

@@ -1,4 +1,4 @@
-# The Mia! Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2022/8/21
 
 #  Copyright (c) 2022-2023 imacat.
@@ -15,14 +15,14 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-include src/accounting/translations/*
-include src/accounting/translations/*/LC_MESSAGES/*
-include docs/*
-include docs/source/*
-include docs/source/_static/*
-include docs/source/_templates/*
-include tests/*
-include tests/test_site/*
-include tests/test_site/templates/*
-include tests/test_site/translations/*
-include tests/test_site/translations/*/LC_MESSAGES/*
+recursive-include src/accounting/static *
+exclude src/accounting/static/js/dummy.js
+recursive-include src/accounting/templates *
+recursive-include src/accounting/translations *
+recursive-include src/accounting/data *
+recursive-include docs *
+recursive-exclude docs/build *
+recursive-include tests *
+exclude tests/test_temp.py
+recursive-exclude tests *.pyc
+recursive-exclude tests/instance *

README.rst

@@ -1,24 +1,178 @@
-=====================
-Mia! Accounting Flask
-=====================
+===============
+Mia! Accounting
+===============
 
 
 Description
 ===========
 
-This is the Mia! Accounting Flask project.  It is an accounting
-module for the Flask_ applications.
+*Mia! Accounting* is an accounting module for Flask_ applications.
+It implements `double-entry bookkeeping`_, and generates the following
+accounting reports:
+
+* Trial balance
+* Income statement
+* Balance sheet
+
+In addition, *Mia! Accounting* tracks offsets for unpaid payables and
+receivables.
+
+You may try the `live demonstration`_.
 
 
-Install
-=======
+Installation
+============
 
-Install the latest source from the
-`Mia! Accounting Flask repository`_.
+Install *Mia! Accounting* with ``pip``:
 
 ::
 
-    pip install git+https://gitea.imacat.idv.tw/imacat/mia-accounting-flask.git
+    pip install mia-accounting
+
+You may also download the from the `PyPI project page`_ or the
+`release page`_ on the `Git repository`_.
+
+
+Prerequisites
+=============
+
+You need a running Flask application with database user login.
+The primary key of the user data model must be integer.
+
+The following front-end JavaScript libraries must be loaded.  You may
+download it locally or use CDN_.
+
+* Bootstrap_ 5.2.3 or above
+* FontAwesome_ 6.2.1 or above
+* `Decimal.js`_ 6.4.3 or above
+* `Tempus-Dominus`_ 6.4.3 or above
+
+
+Configuration
+=============
+
+You need to pass the Flask *app* and an implementation of
+`UserUtilityInterface`_ to the `init_app`_ function.
+``UserUtilityInterface`` contains everything *Mia! Accounting* needs.
+
+The following is an example configuration for *Mia! Accounting*.
+
+::
+
+    from flask import Response, redirect
+    from .auth import current_user()
+    from .modules import User
+
+    def create_app(test_config=None) -> Flask:
+        app: Flask = Flask(__name__)
+
+        ... (Configuration of SQLAlchemy, CSRF, Babel_JS, ... etc) ...
+
+        import accounting
+
+        class UserUtils(accounting.UserUtilityInterface[User]):
+
+            def can_view(self) -> bool:
+                return True
+
+            def can_edit(self) -> bool:
+                return "editor" in current_user().roles
+
+            def can_admin(self) -> bool:
+                return current_user().is_admin
+
+            def unauthorized(self) -> Response:
+                return redirect("/login")
+
+            @property
+            def cls(self) -> t.Type[User]:
+                return User
+
+            @property
+            def pk_column(self) -> Column:
+                return User.id
+
+            @property
+            def current_user(self) -> User | None:
+                return current_user()
+
+            def get_by_username(self, username: str) -> User | None:
+                return User.query.filter(User.username == username).first()
+
+            def get_pk(self, user: User) -> int:
+                return user.id
+
+        accounting.init_app(app, UserUtils())
+
+        ... (Any other configuration) ...
+
+        return app
+
+
+Database Initialization
+=======================
+
+After the configuration, you need to run
+`flask_sqlalchemy.SQLAlchemy.create_all`_ to create the
+database tables that *Mia! Accounting* uses.
+
+*Mia! Accounting* adds three console commands:
+
+* ``accounting-init-base``
+* ``accounting-init-accounts``
+* ``accounting-init-currencies``
+
+After database tables are created, run
+``accounting-init-base`` first, and then the other two commands.
+
+::
+
+    % flask --app myapp accounting-init-base
+    % flask --app myapp accounting-init-accounts
+    % flask --app myapp accounting-init-currencies
+
+
+Navigation Menu
+===============
+
+Include the navigation menu in the `Bootstrap navigation bar`_ in your
+base template:
+
+::
+
+    <nav class="navbar navbar-expand-lg bg-body-tertiary bg-dark navbar-dark">
+      <div class="container-fluid">
+        ...
+        <div id="collapsible-navbar" class="collapse navbar-collapse">
+          <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+            ...
+            {% include "accounting/include/nav.html" %}
+            ...
+          </ul>
+          ...
+        </div>
+      </div>
+    </nav>
+
+Check your Flask application and see how it works.
+
+
+Test Site and Live Demonstration
+================================
+
+You may find a working example in the `test site`_ in the
+`source distribution`_.  It is the simplest website that works with
+*Mia! Accounting*.  It is used in the automatic tests.  It is the same
+code run for `live demonstration`_.
+
+If you do not have a running Flask application, you may start with the
+test site.
+
+
+Documentation
+=============
+
+Refer to the `documentation on Read the Docs`_.
 
 
 Copyright
@@ -46,5 +200,22 @@ Authors
 | imacat@mail.imacat.idv.tw
 | 2023/1/27
 
+
 .. _Flask: https://flask.palletsprojects.com
-.. _Mia! Accounting Flask repository: https://gitea.imacat.idv.tw/imacat/mia-accounting-flask
+.. _double-entry bookkeeping: https://en.wikipedia.org/wiki/Double-entry_bookkeeping
+.. _live demonstration: https://accounting.imacat.idv.tw
+.. _PyPI project page: https://pypi.org/project/mia-accounting
+.. _release page: https://github.com/imacat/mia-accounting/releases
+.. _Git repository: https://github.com/imacat/mia-accounting
+.. _CDN: https://en.wikipedia.org/wiki/Content_delivery_network
+.. _Bootstrap: https://getbootstrap.com
+.. _FontAwesome: https://fontawesome.com
+.. _Decimal.js: https://mikemcl.github.io/decimal.js
+.. _Tempus-Dominus: https://getdatepicker.com
+.. _UserUtilityInterface: https://mia-accounting.readthedocs.io/en/latest/accounting.utils.html#accounting.utils.user.UserUtilityInterface
+.. _init_app: https://mia-accounting.readthedocs.io/en/latest/accounting.html#accounting.init_app
+.. _flask_sqlalchemy.SQLAlchemy.create_all: https://flask-sqlalchemy.palletsprojects.com/en/3.0.x/api/#flask_sqlalchemy.SQLAlchemy.create_all
+.. _Bootstrap navigation bar: https://getbootstrap.com/docs/5.3/components/navbar/
+.. _test site: https://github.com/imacat/mia-accounting/tree/main/tests/test_site
+.. _source distribution: https://pypi.org/project/mia-accounting/#files
+.. _documentation on Read the Docs: https://mia-accounting.readthedocs.io

docs/source/accounting.account.rst

@@ -28,10 +28,10 @@ accounting.account.forms module
    :undoc-members:
    :show-inheritance:
 
-accounting.account.query module
--------------------------------
+accounting.account.queries module
+---------------------------------
 
-.. automodule:: accounting.account.query
+.. automodule:: accounting.account.queries
    :members:
    :undoc-members:
    :show-inheritance:

docs/source/accounting.base_account.rst

@@ -20,10 +20,10 @@ accounting.base\_account.converters module
    :undoc-members:
    :show-inheritance:
 
-accounting.base\_account.query module
--------------------------------------
+accounting.base\_account.queries module
+---------------------------------------
 
-.. automodule:: accounting.base_account.query
+.. automodule:: accounting.base_account.queries
    :members:
    :undoc-members:
    :show-inheritance:

docs/source/accounting.currency.rst

@@ -28,10 +28,10 @@ accounting.currency.forms module
    :undoc-members:
    :show-inheritance:
 
-accounting.currency.query module
---------------------------------
+accounting.currency.queries module
+----------------------------------
 
-.. automodule:: accounting.currency.query
+.. automodule:: accounting.currency.queries
    :members:
    :undoc-members:
    :show-inheritance:

docs/source/accounting.journal_entry.forms.rst

@@ -0,0 +1,45 @@
+accounting.journal\_entry.forms package
+=======================================
+
+Submodules
+----------
+
+accounting.journal\_entry.forms.currency module
+-----------------------------------------------
+
+.. automodule:: accounting.journal_entry.forms.currency
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.forms.journal\_entry module
+-----------------------------------------------------
+
+.. automodule:: accounting.journal_entry.forms.journal_entry
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.forms.line\_item module
+-------------------------------------------------
+
+.. automodule:: accounting.journal_entry.forms.line_item
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.forms.reorder module
+----------------------------------------------
+
+.. automodule:: accounting.journal_entry.forms.reorder
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.journal_entry.forms
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.journal_entry.rst

@@ -0,0 +1,46 @@
+accounting.journal\_entry package
+=================================
+
+Subpackages
+-----------
+
+.. toctree::
+   :maxdepth: 4
+
+   accounting.journal_entry.forms
+   accounting.journal_entry.utils
+
+Submodules
+----------
+
+accounting.journal\_entry.converters module
+-------------------------------------------
+
+.. automodule:: accounting.journal_entry.converters
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.template\_filters module
+--------------------------------------------------
+
+.. automodule:: accounting.journal_entry.template_filters
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.views module
+--------------------------------------
+
+.. automodule:: accounting.journal_entry.views
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.journal_entry
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.journal_entry.utils.rst

@@ -0,0 +1,53 @@
+accounting.journal\_entry.utils package
+=======================================
+
+Submodules
+----------
+
+accounting.journal\_entry.utils.account\_option module
+------------------------------------------------------
+
+.. automodule:: accounting.journal_entry.utils.account_option
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.utils.description\_editor module
+----------------------------------------------------------
+
+.. automodule:: accounting.journal_entry.utils.description_editor
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.utils.offset\_alias module
+----------------------------------------------------
+
+.. automodule:: accounting.journal_entry.utils.offset_alias
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.utils.operators module
+------------------------------------------------
+
+.. automodule:: accounting.journal_entry.utils.operators
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.journal\_entry.utils.original\_line\_items module
+------------------------------------------------------------
+
+.. automodule:: accounting.journal_entry.utils.original_line_items
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.journal_entry.utils
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.option.rst

@@ -0,0 +1,29 @@
+accounting.option package
+=========================
+
+Submodules
+----------
+
+accounting.option.forms module
+------------------------------
+
+.. automodule:: accounting.option.forms
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.option.views module
+------------------------------
+
+.. automodule:: accounting.option.views
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.option
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.report.period.rst

@@ -0,0 +1,69 @@
+accounting.report.period package
+================================
+
+Submodules
+----------
+
+accounting.report.period.chooser module
+---------------------------------------
+
+.. automodule:: accounting.report.period.chooser
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.description module
+-------------------------------------------
+
+.. automodule:: accounting.report.period.description
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.month\_end module
+------------------------------------------
+
+.. automodule:: accounting.report.period.month_end
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.parser module
+--------------------------------------
+
+.. automodule:: accounting.report.period.parser
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.period module
+--------------------------------------
+
+.. automodule:: accounting.report.period.period
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.shortcuts module
+-----------------------------------------
+
+.. automodule:: accounting.report.period.shortcuts
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.period.specification module
+---------------------------------------------
+
+.. automodule:: accounting.report.period.specification
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.report.period
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.report.reports.rst

@@ -0,0 +1,69 @@
+accounting.report.reports package
+=================================
+
+Submodules
+----------
+
+accounting.report.reports.balance\_sheet module
+-----------------------------------------------
+
+.. automodule:: accounting.report.reports.balance_sheet
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.income\_expenses module
+-------------------------------------------------
+
+.. automodule:: accounting.report.reports.income_expenses
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.income\_statement module
+--------------------------------------------------
+
+.. automodule:: accounting.report.reports.income_statement
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.journal module
+----------------------------------------
+
+.. automodule:: accounting.report.reports.journal
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.ledger module
+---------------------------------------
+
+.. automodule:: accounting.report.reports.ledger
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.search module
+---------------------------------------
+
+.. automodule:: accounting.report.reports.search
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.reports.trial\_balance module
+-----------------------------------------------
+
+.. automodule:: accounting.report.reports.trial_balance
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.report.reports
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.report.rst

@@ -0,0 +1,47 @@
+accounting.report package
+=========================
+
+Subpackages
+-----------
+
+.. toctree::
+   :maxdepth: 4
+
+   accounting.report.period
+   accounting.report.reports
+   accounting.report.utils
+
+Submodules
+----------
+
+accounting.report.converters module
+-----------------------------------
+
+.. automodule:: accounting.report.converters
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.template\_filters module
+------------------------------------------
+
+.. automodule:: accounting.report.template_filters
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.views module
+------------------------------
+
+.. automodule:: accounting.report.views
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.report
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.report.utils.rst

@@ -0,0 +1,69 @@
+accounting.report.utils package
+===============================
+
+Submodules
+----------
+
+accounting.report.utils.base\_page\_params module
+-------------------------------------------------
+
+.. automodule:: accounting.report.utils.base_page_params
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.base\_report module
+-------------------------------------------
+
+.. automodule:: accounting.report.utils.base_report
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.csv\_export module
+------------------------------------------
+
+.. automodule:: accounting.report.utils.csv_export
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.option\_link module
+-------------------------------------------
+
+.. automodule:: accounting.report.utils.option_link
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.report\_chooser module
+----------------------------------------------
+
+.. automodule:: accounting.report.utils.report_chooser
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.report\_type module
+-------------------------------------------
+
+.. automodule:: accounting.report.utils.report_type
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.report.utils.urls module
+-----------------------------------
+
+.. automodule:: accounting.report.utils.urls
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+Module contents
+---------------
+
+.. automodule:: accounting.report.utils
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/source/accounting.rst

@@ -10,12 +10,22 @@ Subpackages
    accounting.account
    accounting.base_account
    accounting.currency
-   accounting.transaction
+   accounting.journal_entry
+   accounting.option
+   accounting.report
    accounting.utils
 
 Submodules
 ----------
 
+accounting.forms module
+-----------------------
+
+.. automodule:: accounting.forms
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
 accounting.locale module
 ------------------------
 
@@ -32,6 +42,22 @@ accounting.models module
    :undoc-members:
    :show-inheritance:
 
+accounting.template\_filters module
+-----------------------------------
+
+.. automodule:: accounting.template_filters
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.template\_globals module
+-----------------------------------
+
+.. automodule:: accounting.template_globals
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
 Module contents
 ---------------
 

docs/source/accounting.transaction.rst

@@ -1,61 +0,0 @@
-accounting.transaction package
-==============================
-
-Submodules
-----------
-
-accounting.transaction.converters module
-----------------------------------------
-
-.. automodule:: accounting.transaction.converters
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-accounting.transaction.dispatcher module
-----------------------------------------
-
-.. automodule:: accounting.transaction.dispatcher
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-accounting.transaction.forms module
------------------------------------
-
-.. automodule:: accounting.transaction.forms
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-accounting.transaction.query module
------------------------------------
-
-.. automodule:: accounting.transaction.query
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-accounting.transaction.template module
---------------------------------------
-
-.. automodule:: accounting.transaction.template
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-accounting.transaction.views module
------------------------------------
-
-.. automodule:: accounting.transaction.views
-   :members:
-   :undoc-members:
-   :show-inheritance:
-
-Module contents
----------------
-
-.. automodule:: accounting.transaction
-   :members:
-   :undoc-members:
-   :show-inheritance:

docs/source/accounting.utils.rst

@@ -4,6 +4,22 @@ accounting.utils package
 Submodules
 ----------
 
+accounting.utils.cast module
+----------------------------
+
+.. automodule:: accounting.utils.cast
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+accounting.utils.current\_account module
+----------------------------------------
+
+.. automodule:: accounting.utils.current_account
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
 accounting.utils.flash\_errors module
 -------------------------------------
 
@@ -12,6 +28,14 @@ accounting.utils.flash\_errors module
    :undoc-members:
    :show-inheritance:
 
+accounting.utils.journal\_entry\_types module
+---------------------------------------------
+
+.. automodule:: accounting.utils.journal_entry_types
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
 accounting.utils.next\_uri module
 ---------------------------------
 
@@ -20,6 +44,14 @@ accounting.utils.next\_uri module
    :undoc-members:
    :show-inheritance:
 
+accounting.utils.options module
+-------------------------------
+
+.. automodule:: accounting.utils.options
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
 accounting.utils.pagination module
 ----------------------------------
 

docs/source/conf.py

@@ -10,10 +10,10 @@ sys.path.insert(0, os.path.abspath('../../src/'))
 # -- Project information -----------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
-project = 'Mia! Accounting Flask'
+project = 'Mia! Accounting'
 copyright = '2023, imacat'
 author = 'imacat'
-release = '0.0.0'
+release = '1.0.1'
 
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
@@ -28,5 +28,5 @@ exclude_patterns = []
 # -- Options for HTML output -------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
 
-html_theme = 'nature'
+html_theme = 'sphinx_rtd_theme'
 html_static_path = ['_static']

docs/source/examples.rst

@@ -0,0 +1,61 @@
+Examples
+========
+
+
+.. _example-userutils:
+
+An Example Configuration
+------------------------
+
+The following is an example configuration for *Mia! Accounting*.
+
+::
+
+    from flask import Response, redirect
+    from .auth import current_user()
+    from .modules import User
+
+    def create_app(test_config=None) -> Flask:
+        app: Flask = Flask(__name__)
+
+        ... (Configuration of SQLAlchemy, CSRF, Babel_JS, ... etc) ...
+
+        import accounting
+
+        class UserUtils(accounting.UserUtilityInterface[User]):
+
+            def can_view(self) -> bool:
+                return True
+
+            def can_edit(self) -> bool:
+                return "editor" in current_user().roles
+
+            def can_admin(self) -> bool:
+                return current_user().is_admin
+
+            def unauthorized(self) -> Response:
+                return redirect("/login")
+
+            @property
+            def cls(self) -> t.Type[User]:
+                return User
+
+            @property
+            def pk_column(self) -> Column:
+                return User.id
+
+            @property
+            def current_user(self) -> User | None:
+                return current_user()
+
+            def get_by_username(self, username: str) -> User | None:
+                return User.query.filter(User.username == username).first()
+
+            def get_pk(self, user: User) -> int:
+                return user.id
+
+        accounting.init_app(app, UserUtils())
+
+        ... (Any other configuration) ...
+
+        return app

docs/source/history.rst

@@ -0,0 +1,57 @@
+History
+=======
+
+I created my own private accounting application in Perl_/mod_perl_ in
+2007, as part of my personal website.  The first revision was made
+using Perl/Mojolicious_ in 2019, with the aim of making it
+mobile-friendly using Bootstrap_, and with modern back-end and
+front-end technologies such as jQuery.
+
+The second revision was done in Python_/Django_ in 2020, as I was
+looking to change my career from PHP_/Laravel_ to Python, but lacked
+experience with large Python projects.  I needed something in my
+portfolio and decided to work on the somewhat outdated Mojolicious
+project.
+
+Despite having no prior experience with Django, I spent two months
+working late nights to create the `Mia! Accounting Django`_
+application.  It took me another 1.5 months to make it an independent
+module, which I later released as an open source project on PyPI.
+
+The application worked nicely for my household bookkeeping for two
+years.  However, new demands arose over time, especially with tracking
+payables and receivables.  This was critical `during the pandemic`_ as
+more payments were made online with credit cards.
+
+The biggest issue I encountered was with
+`Django's MTV architectural pattern`_.  Django takes over the control
+flow.  I had to override several parts of the `class-based views`_ for
+different but yet simple control flow logic.  In the end, it became
+very difficult to track whether things went wrong because I overrode
+something or because it just wouldn't work with the basic assumption
+of the class-based views.  By the time I realized it, it was too late
+for me to drop Django's MTV and rewrite everything from class-based
+views to function-based views.
+
+Therefore, I decided to turn to microframeworks_ like Flask_.   After
+working with modularized Flask and FastAPI_ applications for two
+years, I returned to the project and wrote its third revision using
+Flask in 2023.
+
+
+.. _Perl: https://www.perl.org
+.. _mod_perl: https://perl.apache.org
+.. _Mojolicious: https://mojolicious.org
+.. _Bootstrap: https://getbootstrap.com
+.. _jQuery: https://jquery.com
+.. _Python: https://www.python.org
+.. _Django: https://www.djangoproject.com
+.. _PHP: https://www.php.net
+.. _Laravel: https://laravel.com
+.. _Mia! Accounting Django: https://github.com/imacat/mia-accounting-django
+.. _during the pandemic: https://en.wikipedia.org/wiki/COVID-19_pandemic
+.. _FastAPI: https://fastapi.tiangolo.com
+.. _Django's MTV architectural pattern: https://docs.djangoproject.com/en/dev/faq/general/#django-appears-to-be-a-mvc-framework-but-you-call-the-controller-the-view-and-the-view-the-template-how-come-you-don-t-use-the-standard-names
+.. _class-based views: https://docs.djangoproject.com/en/4.2/topics/class-based-views/
+.. _microframeworks: https://en.wikipedia.org/wiki/Microframework
+.. _Flask: https://flask.palletsprojects.com

docs/source/index.rst

@@ -1,15 +1,20 @@
-.. Mia! Accounting Flask documentation master file, created by
+.. Mia! Accounting documentation master file, created by
    sphinx-quickstart on Fri Jan 27 12:20:04 2023.
    You can adapt this file completely to your liking, but it should at least
    contain the root `toctree` directive.
 
-Welcome to Mia! Accounting Flask's documentation!
-=================================================
+Welcome to Mia! Accounting's documentation!
+===========================================
 
 .. toctree::
    :maxdepth: 2
    :caption: Contents:
 
+   intro
+   accounting
+   examples
+   history
+
 
 
 Indices and tables

docs/source/intro.rst

@@ -0,0 +1,138 @@
+Introduction
+============
+
+*Mia! Accounting* is an accounting module for Flask_ applications.
+It implements `double-entry bookkeeping`_, and generates the following
+accounting reports:
+
+* Trial balance
+* Income statement
+* Balance sheet
+
+In addition, *Mia! Accounting* tracks offsets for unpaid payables and
+receivables.
+
+You may try the `live demonstration`_.
+
+
+Installation
+------------
+
+Install *Mia! Accounting* with ``pip``:
+
+::
+
+    pip install mia-accounting
+
+You may also download the from the `PyPI project page`_ or the
+`release page`_ on the `Git repository`_.
+
+
+Prerequisites
+-------------
+
+You need a running Flask application with database user login.
+The primary key of the user data model must be integer.
+
+The following front-end JavaScript libraries must be loaded.  You may
+download it locally or use CDN_.
+
+* Bootstrap_ 5.2.3 or above
+* FontAwesome_ 6.2.1 or above
+* `Decimal.js`_ 6.4.3 or above
+* `Tempus-Dominus`_ 6.4.3 or above
+
+
+Configuration
+-------------
+
+You need to pass the Flask *app* and an implementation of
+:py:class:`accounting.utils.user.UserUtilityInterface` to the
+:py:func:`accounting.init_app` function.  ``UserUtilityInterface``
+contains everything *Mia! Accounting* needs.
+
+See an example in :ref:`example-userutils`.
+
+
+Database Initialization
+-----------------------
+
+After the configuration, you need to run
+`flask_sqlalchemy.SQLAlchemy.create_all`_ to create the
+database tables that *Mia! Accounting* uses.
+
+*Mia! Accounting* adds three console commands:
+
+* ``accounting-init-base``
+* ``accounting-init-accounts``
+* ``accounting-init-currencies``
+
+After database tables are created, run
+``accounting-init-base`` first, and then the other two commands.
+
+::
+
+    % flask --app myapp accounting-init-base
+    % flask --app myapp accounting-init-accounts
+    % flask --app myapp accounting-init-currencies
+
+
+Navigation Menu
+---------------
+
+Include the navigation menu in the `Bootstrap navigation bar`_ in your
+base template:
+
+::
+
+    <nav class="navbar navbar-expand-lg bg-body-tertiary bg-dark navbar-dark">
+      <div class="container-fluid">
+        ...
+        <div id="collapsible-navbar" class="collapse navbar-collapse">
+          <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+            ...
+            {% include "accounting/include/nav.html" %}
+            ...
+          </ul>
+          ...
+        </div>
+      </div>
+    </nav>
+
+Check your Flask application and see how it works.
+
+
+Test Site and Live Demonstration
+--------------------------------
+
+You may find a working example in the `test site`_ in the
+`source distribution`_.  It is the simplest website that works with
+*Mia! Accounting*.  It is used in the automatic tests.  It is the same
+code run for `live demonstration`_.
+
+If you do not have a running Flask application, you may start with the
+test site.
+
+
+Documentation
+-------------
+
+Refer to the `documentation on Read the Docs`_.
+
+
+.. _Flask: https://flask.palletsprojects.com
+.. _double-entry bookkeeping: https://en.wikipedia.org/wiki/Double-entry_bookkeeping
+.. _live demonstration: https://accounting.imacat.idv.tw
+.. _PyPI project page: https://pypi.org/project/mia-accounting
+.. _release page: https://github.com/imacat/mia-accounting/releases
+.. _Git repository: https://github.com/imacat/mia-accounting
+.. _CDN: https://en.wikipedia.org/wiki/Content_delivery_network
+.. _Bootstrap: https://getbootstrap.com
+.. _FontAwesome: https://fontawesome.com
+.. _Decimal.js: https://mikemcl.github.io/decimal.js
+.. _Tempus-Dominus: https://getdatepicker.com
+.. _flask_sqlalchemy.SQLAlchemy.create_all: https://flask-sqlalchemy.palletsprojects.com/en/3.0.x/api/#flask_sqlalchemy.SQLAlchemy.create_all
+.. _Bootstrap navigation bar: https://getbootstrap.com/docs/5.3/components/navbar/
+.. _test site: https://github.com/imacat/mia-accounting/tree/main/tests/test_site
+.. _source distribution: https://pypi.org/project/mia-accounting/#files
+.. _documentation on Read the Docs: https://mia-accounting.readthedocs.io

pyproject.toml

@@ -1,7 +1,7 @@
-# The Mia! Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2022/8/21
 
-#  Copyright (c) 2022 imacat.
+#  Copyright (c) 2022-2023 imacat.
 #
 #  Licensed under the Apache License, Version 2.0 (the "License");
 #  you may not use this file except in compliance with the License.
@@ -15,6 +15,51 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+[project]
+name = "mia-accounting"
+version = "1.0.1"
+description = "A Flask accounting module."
+readme = "README.rst"
+requires-python = ">=3.11"
+authors = [
+    {name = "imacat", email = "imacat@mail.imacat.idv.tw"},
+]
+keywords = ["mia", "accounting", "flask"]
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: Apache Software License",
+    "Operating System :: OS Independent",
+    "Framework :: Flask",
+    "Topic :: Office/Business :: Financial :: Accounting",
+]
+dependencies = [
+    "flask",
+    "Flask-SQLAlchemy",
+    "Flask-WTF",
+    "Flask-Babel >= 3",
+    "Flask-Babel-JS",
+]
+
+[project.optional-dependencies]
+test = [
+    "unittest",
+    "httpx",
+    "OpenCC",
+]
+
+[project.urls]
+"Documentation" = "https://mia-accounting.readthedocs.io"
+"Repository" = "https://github.com/imacat/mia-accounting"
+"Bug Tracker" = "https://github.com/imacat/mia-accounting/issues"
+"Demonstration" = "https://accounting.imacat.idv.tw"
+
 [build-system]
 requires = ["setuptools>=42"]
 build-backend = "setuptools.build_meta"
+
+[tool.setuptools.exclude-package-data]
+"*" = [
+    "babel.cfg",
+    "*.pot",
+    "*.po",
+]

setup.cfg

@@ -1,56 +0,0 @@
-# The Mia! Flask Project.
-# Author: imacat@mail.imacat.idv.tw (imacat), 2022/8/21
-
-#  Copyright (c) 2022-2023 imacat.
-#
-#  Licensed under the Apache License, Version 2.0 (the "License");
-#  you may not use this file except in compliance with the License.
-#  You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-#  Unless required by applicable law or agreed to in writing, software
-#  distributed under the License is distributed on an "AS IS" BASIS,
-#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-#  See the License for the specific language governing permissions and
-#  limitations under the License.
-
-[metadata]
-name = mia-accounting-flask
-version = 0.3.0
-author = imacat
-author_email = imacat@mail.imacat.idv.tw
-description = The Mia! Accounting Flask project.
-long_description = file: README.rst
-long_description_content_type = text/x-rst
-url = https://github.com/imacat/mia-accounting-flask
-project_urls =
-    Bug Tracker = https://github.com/imacat/mia-accounting-flask/issues
-classifiers =
-    Programming Language :: Python :: 3
-    License :: OSI Approved :: Apache Software License
-    Operating System :: OS Independent
-    Framework :: Flask
-    Topic :: Office/Business :: Financial :: Accounting
-
-[options]
-package_dir =
-    = src
-python_requires = >=3.11
-install_requires =
-  flask
-  Flask-SQLAlchemy
-  Flask-WTF
-  Flask-Babel >= 3
-  Flask-Babel-JS
-tests_require =
-  unittest
-  httpx
-  OpenCC
-
-[options.package_data]
-accounting =
-  static/**
-  templates/**
-  translations/*/LC_MESSAGES/*.mo
-  data/**

src/accounting/__init__.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/25
 
 #  Copyright (c) 2023 imacat.
@@ -17,13 +17,12 @@
 """The accounting application.
 
 """
-import typing as t
 from pathlib import Path
 
 from flask import Flask, Blueprint
 from flask_sqlalchemy import SQLAlchemy
 
-from accounting.utils.user import AbstractUserUtils
+from accounting.utils.user import UserUtilityInterface
 
 db: SQLAlchemy = SQLAlchemy()
 """The database instance."""
@@ -31,19 +30,13 @@ data_dir: Path = Path(__file__).parent / "data"
 """The data directory."""
 
 
-def init_app(app: Flask, user_utils: AbstractUserUtils,
-             url_prefix: str = "/accounting",
-             can_view_func: t.Callable[[], bool] | None = None,
-             can_edit_func: t.Callable[[], bool] | None = None) -> None:
+def init_app(app: Flask, user_utils: UserUtilityInterface,
+             url_prefix: str = "/accounting") -> None:
     """Initialize the application.
 
     :param app: The Flask application.
     :param user_utils: The user utilities.
     :param url_prefix: The URL prefix of the accounting application.
-    :param can_view_func: A callback that returns whether the current user can
-        view the accounting data.
-    :param can_edit_func: A callback that returns whether the current user can
-        edit the accounting data.
     :return: None.
     """
     # The database instance must be set before loading everything
@@ -54,15 +47,28 @@ def init_app(app: Flask, user_utils: AbstractUserUtils,
     init_user_utils(user_utils)
 
     bp: Blueprint = Blueprint("accounting", __name__,
-                              url_prefix=url_prefix,
                               template_folder="templates",
                               static_folder="static")
 
+    from .template_filters import format_amount, format_date, default
+    bp.add_app_template_filter(format_amount, "accounting_format_amount")
+    bp.add_app_template_filter(format_date, "accounting_format_date")
+    bp.add_app_template_filter(default, "accounting_default")
+
+    from .template_globals import currency_options, default_currency_code
+    bp.add_app_template_global(currency_options,
+                               "accounting_currency_options")
+    bp.add_app_template_global(default_currency_code,
+                               "accounting_default_currency_code")
+
     from . import locale
     locale.init_app(app, bp)
 
     from .utils import permission
-    permission.init_app(bp, can_view_func, can_edit_func)
+    permission.init_app(bp, user_utils)
+
+    from .utils import next_uri
+    next_uri.init_app(bp)
 
     from . import base_account
     base_account.init_app(app, bp)
@@ -73,10 +79,13 @@ def init_app(app: Flask, user_utils: AbstractUserUtils,
     from . import currency
     currency.init_app(app, bp)
 
-    from . import transaction
-    transaction.init_app(app, bp)
+    from . import journal_entry
+    journal_entry.init_app(app, bp)
 
-    from .utils import next_uri
-    next_uri.init_app(bp)
+    from . import report
+    report.init_app(app, url_prefix)
 
-    app.register_blueprint(bp)
+    from . import option
+    option.init_app(bp)
+
+    app.register_blueprint(bp, url_prefix=url_prefix)

src/accounting/account/__init__.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/30
 
 #  Copyright (c) 2023 imacat.

src/accounting/account/commands.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/30
 
 #  Copyright (c) 2023 imacat.
@@ -18,7 +18,6 @@
 
 """
 import os
-import re
 from secrets import randbelow
 
 import click
@@ -30,7 +29,7 @@ from accounting.utils.user import has_user, get_user_pk
 
 AccountData = tuple[int, str, int, str, str, str, bool]
 """The format of the account data, as a list of (ID, base account code, number,
-English, Traditional Chinese, Simplified Chinese, is-pay-off-needed) tuples."""
+English, Traditional Chinese, Simplified Chinese, is-need-offset) tuples."""
 
 
 def __validate_username(ctx: click.core.Context, param: click.core.Option,
@@ -93,14 +92,37 @@ def init_accounts_command(username: str) -> None:
     data: list[AccountData] = []
     for base in bases_to_add:
         l10n: dict[str, str] = {x.locale: x.title for x in base.l10n}
-        is_pay_off_needed: bool = True if re.match("^[12]1[34]", base.code) \
-            else False
+        is_need_offset: bool = __is_need_offset(base.code)
         data.append((get_new_id(), base.code, 1, base.title_l10n,
-                     l10n["zh_Hant"], l10n["zh_Hans"], is_pay_off_needed))
+                     l10n["zh_Hant"], l10n["zh_Hans"], is_need_offset))
     __add_accounting_accounts(data, creator_pk)
     click.echo(F"{len(data)} added.  Accounting accounts initialized.")
 
 
+def __is_need_offset(base_code: str) -> bool:
+    """Checks that whether journal entry line items in the account need offset.
+
+    :param base_code: The code of the base account.
+    :return: True if journal entry line items in the account need offset, or
+        False otherwise.
+    """
+    # Assets
+    if base_code[0] == "1":
+        if base_code[:3] in {"113", "114", "118", "184"}:
+            return True
+        if base_code in {"1411", "1421", "1431", "1441", "1511", "1521",
+                         "1581", "1611", "1851", ""}:
+            return True
+        return False
+    # Liabilities
+    if base_code[0] == "2":
+        if base_code in {"2111", "2114", "2284", "2293"}:
+            return False
+        return True
+    # Only assets and liabilities need offset
+    return False
+
+
 def __add_accounting_accounts(data: list[AccountData], creator_pk: int)\
         -> None:
     """Adds the accounts.
@@ -113,7 +135,7 @@ def __add_accounting_accounts(data: list[AccountData], creator_pk: int)\
                                        base_code=x[1],
                                        no=x[2],
                                        title_l10n=x[3],
-                                       is_pay_off_needed=x[6],
+                                       is_need_offset=x[6],
                                        created_by_id=creator_pk,
                                        updated_by_id=creator_pk)
                                for x in data]

src/accounting/account/converters.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/31
 
 #  Copyright (c) 2023 imacat.

src/accounting/account/forms.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/1
 
 #  Copyright (c) 2023 imacat.
@@ -53,6 +53,20 @@ class BaseAccountAvailable:
                 "The base account is not available."))
 
 
+class NoOffsetNominalAccount:
+    """The validator to check nominal account is not to be offset."""
+
+    def __call__(self, form: FlaskForm, field: BooleanField) -> None:
+        assert isinstance(form, AccountForm)
+        if not field.data:
+            return
+        if form.base_code.data is None:
+            return
+        if form.base_code.data[0] not in {"1", "2", "3"}:
+            raise ValidationError(lazy_gettext(
+                "A nominal account does not need offset."))
+
+
 class AccountForm(FlaskForm):
     """The form to create or edit an account."""
     base_code = StringField(
@@ -66,8 +80,9 @@ class AccountForm(FlaskForm):
         filters=[strip_text],
         validators=[DataRequired(lazy_gettext("Please fill in the title"))])
     """The title."""
-    is_pay_off_needed = BooleanField()
-    """Whether the the entries of this account need pay-off."""
+    is_need_offset = BooleanField(
+        validators=[NoOffsetNominalAccount()])
+    """Whether the the journal entry line items of this account need offset."""
 
     def populate_obj(self, obj: Account) -> None:
         """Populates the form data into an account object.
@@ -87,7 +102,10 @@ class AccountForm(FlaskForm):
             obj.base_code = self.base_code.data
             obj.no = count + 1
         obj.title = self.title.data
-        obj.is_pay_off_needed = self.is_pay_off_needed.data
+        if self.base_code.data[0] in {"1", "2", "3"}:
+            obj.is_need_offset = self.is_need_offset.data
+        else:
+            obj.is_need_offset = False
         if is_new:
             current_user_pk: int = get_current_user_pk()
             obj.created_by_id = current_user_pk

src/accounting/account/queries.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/30
 
 #  Copyright (c) 2023 imacat.
@@ -14,7 +14,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-"""The account query.
+"""The queries for the account management.
 
 """
 import sqlalchemy as sa
@@ -40,15 +40,15 @@ def get_account_query() -> list[Account]:
     conditions: list[sa.BinaryExpression] = []
     for k in keywords:
         l10n: list[AccountL10n] = AccountL10n.query\
-            .filter(AccountL10n.title.contains(k)).all()
+            .filter(AccountL10n.title.icontains(k)).all()
         l10n_matches: set[str] = {x.account_id for x in l10n}
         sub_conditions: list[sa.BinaryExpression] \
             = [Account.base_code.contains(k),
-               Account.title_l10n.contains(k),
+               Account.title_l10n.icontains(k),
                code.contains(k),
                Account.id.in_(l10n_matches)]
-        if k in gettext("Pay-off needed"):
-            sub_conditions.append(Account.is_pay_off_needed)
+        if k in gettext("Needs Offset"):
+            sub_conditions.append(Account.is_need_offset)
         conditions.append(sa.or_(*sub_conditions))
 
     return Account.query.filter(*conditions)\

src/accounting/account/views.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/30
 
 #  Copyright (c) 2023 imacat.
@@ -27,13 +27,14 @@ from werkzeug.datastructures import ImmutableMultiDict
 from accounting import db
 from accounting.locale import lazy_gettext
 from accounting.models import Account, BaseAccount
+from accounting.utils.cast import s
 from accounting.utils.flash_errors import flash_form_errors
 from accounting.utils.next_uri import inherit_next, or_next
 from accounting.utils.pagination import Pagination
 from accounting.utils.permission import can_view, has_permission, can_edit
 from accounting.utils.user import get_current_user_pk
 from .forms import AccountForm, sort_accounts_in, AccountReorderForm
-from .query import get_account_query
+from .queries import get_account_query
 
 bp: Blueprint = Blueprint("account", __name__)
 """The view blueprint for the account management."""
@@ -86,7 +87,7 @@ def add_account() -> redirect:
     form.populate_obj(account)
     db.session.add(account)
     db.session.commit()
-    flash(lazy_gettext("The account is added successfully"), "success")
+    flash(s(lazy_gettext("The account is added successfully")), "success")
     return redirect(inherit_next(__get_detail_uri(account)))
 
 
@@ -138,12 +139,12 @@ def update_account(account: Account) -> redirect:
     with db.session.no_autoflush:
         form.populate_obj(account)
     if not account.is_modified:
-        flash(lazy_gettext("The account was not modified."), "success")
+        flash(s(lazy_gettext("The account was not modified.")), "success")
         return redirect(inherit_next(__get_detail_uri(account)))
     account.updated_by_id = get_current_user_pk()
     account.updated_at = sa.func.now()
     db.session.commit()
-    flash(lazy_gettext("The account is updated successfully."), "success")
+    flash(s(lazy_gettext("The account is updated successfully.")), "success")
     return redirect(inherit_next(__get_detail_uri(account)))
 
 
@@ -156,10 +157,13 @@ def delete_account(account: Account) -> redirect:
     :return: The redirection to the account list on success, or the account
         detail on error.
     """
+    if not account.can_delete:
+        flash(s(lazy_gettext("The account cannot be deleted.")), "error")
+        return redirect(inherit_next(__get_detail_uri(account)))
     account.delete()
     sort_accounts_in(account.base_code, account.id)
     db.session.commit()
-    flash(lazy_gettext("The account is deleted successfully."), "success")
+    flash(s(lazy_gettext("The account is deleted successfully.")), "success")
     return redirect(or_next(__get_list_uri()))
 
 
@@ -186,10 +190,10 @@ def sort_accounts(base: BaseAccount) -> redirect:
     form: AccountReorderForm = AccountReorderForm(base)
     form.save_order()
     if not form.is_modified:
-        flash(lazy_gettext("The order was not modified."), "success")
+        flash(s(lazy_gettext("The order was not modified.")), "success")
         return redirect(or_next(__get_list_uri()))
     db.session.commit()
-    flash(lazy_gettext("The order is updated successfully."), "success")
+    flash(s(lazy_gettext("The order is updated successfully.")), "success")
     return redirect(or_next(__get_list_uri()))
 
 

src/accounting/base_account/__init__.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/25
 
 #  Copyright (c) 2023 imacat.

src/accounting/base_account/commands.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/25
 
 #  Copyright (c) 2023 imacat.

src/accounting/base_account/converters.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/1
 
 #  Copyright (c) 2023 imacat.

src/accounting/base_account/queries.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/26
 
 #  Copyright (c) 2023 imacat.
@@ -14,7 +14,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-"""The base account query.
+"""The queries for the base account management.
 
 """
 import sqlalchemy as sa
@@ -35,10 +35,10 @@ def get_base_account_query() -> list[BaseAccount]:
     conditions: list[sa.BinaryExpression] = []
     for k in keywords:
         l10n: list[BaseAccountL10n] = BaseAccountL10n.query\
-            .filter(BaseAccountL10n.title.contains(k)).all()
+            .filter(BaseAccountL10n.title.icontains(k)).all()
         l10n_matches: set[str] = {x.account_code for x in l10n}
         conditions.append(sa.or_(BaseAccount.code.contains(k),
-                                 BaseAccount.title_l10n.contains(k),
+                                 BaseAccount.title_l10n.icontains(k),
                                  BaseAccount.code.in_(l10n_matches)))
     return BaseAccount.query.filter(*conditions)\
         .order_by(BaseAccount.code).all()

src/accounting/base_account/views.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/26
 
 #  Copyright (c) 2023 imacat.
@@ -34,7 +34,7 @@ def list_accounts() -> str:
 
     :return: The account list.
     """
-    from .query import get_base_account_query
+    from .queries import get_base_account_query
     accounts: list[BaseAccount] = get_base_account_query()
     pagination: Pagination = Pagination[BaseAccount](accounts)
     return render_template("accounting/base-account/list.html",

src/accounting/currency/__init__.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.

src/accounting/currency/commands.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.

src/accounting/currency/converters.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.

src/accounting/currency/forms.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.
@@ -17,8 +17,6 @@
 """The forms for the currency management.
 
 """
-from __future__ import annotations
-
 from flask_wtf import FlaskForm
 from wtforms import StringField, ValidationError
 from wtforms.validators import DataRequired, Regexp, NoneOf
@@ -30,14 +28,11 @@ from accounting.utils.strip_text import strip_text
 from accounting.utils.user import get_current_user_pk
 
 
-class CurrencyForm(FlaskForm):
-    """The form to create or edit a currency."""
-    CODE_BLOCKLIST: list[str] = ["create", "store", "exists-code"]
-    """The reserved codes that are not available."""
-
-    class CodeUnique:
+class CodeUnique:
     """The validator to check if the code is unique."""
-        def __call__(self, form: CurrencyForm, field: StringField) -> None:
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, CurrencyForm)
         if field.data == "":
             return
         if form.obj_code is not None and form.obj_code == field.data:
@@ -46,6 +41,11 @@ class CurrencyForm(FlaskForm):
             raise ValidationError(lazy_gettext(
                 "Code conflicts with another currency."))
 
+
+class CurrencyForm(FlaskForm):
+    """The form to create or edit a currency."""
+    CODE_BLOCKLIST: list[str] = ["create", "store", "exists-code"]
+    """The reserved codes that are not available."""
     code = StringField(
         filters=[strip_text],
         validators=[DataRequired(lazy_gettext("Please fill in the code.")),

src/accounting/currency/queries.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.
@@ -14,7 +14,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-"""The currency query.
+"""The queries for the currency management.
 
 """
 import sqlalchemy as sa
@@ -35,10 +35,10 @@ def get_currency_query() -> list[Currency]:
     conditions: list[sa.BinaryExpression] = []
     for k in keywords:
         l10n: list[CurrencyL10n] = CurrencyL10n.query\
-            .filter(CurrencyL10n.name.contains(k)).all()
+            .filter(CurrencyL10n.name.icontains(k)).all()
         l10n_matches: set[str] = {x.account_code for x in l10n}
-        conditions.append(sa.or_(Currency.code.contains(k),
-                                 Currency.name_l10n.contains(k),
+        conditions.append(sa.or_(Currency.code.icontains(k),
+                                 Currency.name_l10n.icontains(k),
                                  Currency.code.in_(l10n_matches)))
     return Currency.query.filter(*conditions)\
         .order_by(Currency.code).all()

src/accounting/currency/views.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
 
 #  Copyright (c) 2023 imacat.
@@ -27,6 +27,7 @@ from werkzeug.datastructures import ImmutableMultiDict
 from accounting import db
 from accounting.locale import lazy_gettext
 from accounting.models import Currency
+from accounting.utils.cast import s
 from accounting.utils.flash_errors import flash_form_errors
 from accounting.utils.next_uri import inherit_next, or_next
 from accounting.utils.pagination import Pagination
@@ -47,7 +48,7 @@ def list_currencies() -> str:
 
     :return: The currency list.
     """
-    from .query import get_currency_query
+    from .queries import get_currency_query
     currencies: list[Currency] = get_currency_query()
     pagination: Pagination = Pagination[Currency](currencies)
     return render_template("accounting/currency/list.html",
@@ -88,7 +89,7 @@ def add_currency() -> redirect:
     form.populate_obj(currency)
     db.session.add(currency)
     db.session.commit()
-    flash(lazy_gettext("The currency is added successfully"), "success")
+    flash(s(lazy_gettext("The currency is added successfully.")), "success")
     return redirect(inherit_next(__get_detail_uri(currency)))
 
 
@@ -141,12 +142,12 @@ def update_currency(currency: Currency) -> redirect:
     with db.session.no_autoflush:
         form.populate_obj(currency)
     if not currency.is_modified:
-        flash(lazy_gettext("The currency was not modified."), "success")
+        flash(s(lazy_gettext("The currency was not modified.")), "success")
         return redirect(inherit_next(__get_detail_uri(currency)))
     currency.updated_by_id = get_current_user_pk()
     currency.updated_at = sa.func.now()
     db.session.commit()
-    flash(lazy_gettext("The currency is updated successfully."), "success")
+    flash(s(lazy_gettext("The currency is updated successfully.")), "success")
     return redirect(inherit_next(__get_detail_uri(currency)))
 
 
@@ -159,9 +160,12 @@ def delete_currency(currency: Currency) -> redirect:
     :return: The redirection to the currency list on success, or the currency
         detail on error.
     """
+    if not currency.can_delete:
+        flash(s(lazy_gettext("The currency cannot be deleted.")), "error")
+        return redirect(inherit_next(__get_detail_uri(currency)))
     currency.delete()
     db.session.commit()
-    flash(lazy_gettext("The currency is deleted successfully."), "success")
+    flash(s(lazy_gettext("The currency is deleted successfully.")), "success")
     return redirect(or_next(url_for("accounting.currency.list")))
 
 
@@ -182,4 +186,3 @@ def __get_detail_uri(currency: Currency) -> str:
     :return: The detail URI of the currency.
     """
     return url_for("accounting.currency.detail", currency=currency)
-

src/accounting/forms.py

@@ -0,0 +1,96 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/22
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The forms.
+
+"""
+import re
+
+from flask_babel import LazyString
+from flask_wtf import FlaskForm
+from wtforms import StringField, ValidationError
+from wtforms.validators import DataRequired
+
+from accounting import db
+from accounting.locale import lazy_gettext
+from accounting.models import Currency, Account
+
+
+ACCOUNT_REQUIRED: DataRequired = DataRequired(
+    lazy_gettext("Please select the account."))
+"""The validator to check if the account code is empty."""
+
+
+class CurrencyExists:
+    """The validator to check if the account exists."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None:
+            return
+        if db.session.get(Currency, field.data) is None:
+            raise ValidationError(lazy_gettext(
+                "The currency does not exist."))
+
+
+class AccountExists:
+    """The validator to check if the account exists."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None:
+            return
+        if Account.find_by_code(field.data) is None:
+            raise ValidationError(lazy_gettext(
+                "The account does not exist."))
+
+
+class IsDebitAccount:
+    """The validator to check if the account is for debit line items."""
+
+    def __init__(self, message: str | LazyString):
+        """Constructs the validator.
+
+        :param message: The error message.
+        """
+        self.__message: str | LazyString = message
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None:
+            return
+        if re.match(r"^(?:[1235689]|7[5678])", field.data) \
+                and not field.data.startswith("3351-") \
+                and not field.data.startswith("3353-"):
+            return
+        raise ValidationError(self.__message)
+
+
+class IsCreditAccount:
+    """The validator to check if the account is for credit line items."""
+
+    def __init__(self, message: str | LazyString):
+        """Constructs the validator.
+
+        :param message: The error message.
+        """
+        self.__message: str | LazyString = message
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None:
+            return
+        if re.match(r"^(?:[123489]|7[1234])", field.data) \
+                and not field.data.startswith("3351-") \
+                and not field.data.startswith("3353-"):
+            return
+        raise ValidationError(self.__message)

src/accounting/journal_entry/__init__.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/18
 
 #  Copyright (c) 2023 imacat.
@@ -14,7 +14,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-"""The transaction management.
+"""The journal entry management.
 
 """
 from flask import Flask, Blueprint
@@ -27,11 +27,11 @@ def init_app(app: Flask, bp: Blueprint) -> None:
     :param bp: The blueprint of the accounting application.
     :return: None.
     """
-    from .converters import TransactionConverter, TransactionTypeConverter, \
+    from .converters import JournalEntryConverter, JournalEntryTypeConverter, \
         DateConverter
-    app.url_map.converters["transaction"] = TransactionConverter
-    app.url_map.converters["transactionType"] = TransactionTypeConverter
+    app.url_map.converters["journalEntry"] = JournalEntryConverter
+    app.url_map.converters["journalEntryType"] = JournalEntryTypeConverter
     app.url_map.converters["date"] = DateConverter
 
-    from .views import bp as transaction_bp
-    bp.register_blueprint(transaction_bp, url_prefix="/transactions")
+    from .views import bp as journal_entry_bp
+    bp.register_blueprint(journal_entry_bp, url_prefix="/journal-entries")

src/accounting/journal_entry/converters.py

@@ -0,0 +1,107 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/19
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The path converters for the journal entry management.
+
+"""
+from datetime import date
+
+from flask import abort
+from sqlalchemy.orm import selectinload
+from werkzeug.routing import BaseConverter
+
+from accounting.models import JournalEntry, JournalEntryLineItem
+from accounting.utils.journal_entry_types import JournalEntryType
+
+
+class JournalEntryConverter(BaseConverter):
+    """The journal entry converter to convert the journal entry ID from and to
+    the corresponding journal entry in the routes."""
+
+    def to_python(self, value: str) -> JournalEntry:
+        """Converts a journal entry ID to a journal entry.
+
+        :param value: The journal entry ID.
+        :return: The corresponding journal entry.
+        """
+        journal_entry: JournalEntry | None = JournalEntry.query\
+            .join(JournalEntryLineItem)\
+            .filter(JournalEntry.id == value)\
+            .options(selectinload(JournalEntry.line_items)
+                     .selectinload(JournalEntryLineItem.offsets)
+                     .selectinload(JournalEntryLineItem.journal_entry))\
+            .first()
+        if journal_entry is None:
+            abort(404)
+        return journal_entry
+
+    def to_url(self, value: JournalEntry) -> str:
+        """Converts a journal entry to its ID.
+
+        :param value: The journal entry.
+        :return: The ID.
+        """
+        return str(value.id)
+
+
+class JournalEntryTypeConverter(BaseConverter):
+    """The journal entry converter to convert the journal entry type ID from
+    and to the corresponding journal entry type in the routes."""
+
+    def to_python(self, value: str) -> JournalEntryType:
+        """Converts a journal entry ID to a journal entry.
+
+        :param value: The journal entry ID.
+        :return: The corresponding journal entry type.
+        """
+        type_dict: dict[str, JournalEntryType] \
+            = {x.value: x for x in JournalEntryType}
+        journal_entry_type: JournalEntryType | None = type_dict.get(value)
+        if journal_entry_type is None:
+            abort(404)
+        return journal_entry_type
+
+    def to_url(self, value: JournalEntryType) -> str:
+        """Converts a journal entry type to its ID.
+
+        :param value: The journal entry type.
+        :return: The ID.
+        """
+        return str(value.value)
+
+
+class DateConverter(BaseConverter):
+    """The date converter to convert the ISO date from and to the
+    corresponding date in the routes."""
+
+    def to_python(self, value: str) -> date:
+        """Converts an ISO date to a date.
+
+        :param value: The ISO date.
+        :return: The corresponding date.
+        """
+        try:
+            return date.fromisoformat(value)
+        except ValueError:
+            abort(404)
+
+    def to_url(self, value: date) -> str:
+        """Converts a date to its ISO date.
+
+        :param value: The date.
+        :return: The ISO date.
+        """
+        return value.isoformat()

src/accounting/journal_entry/forms/__init__.py

@@ -0,0 +1,22 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The forms for the journal entry management.
+
+"""
+from .reorder import sort_journal_entries_in, JournalEntryReorderForm
+from .journal_entry import JournalEntryForm, CashReceiptJournalEntryForm, \
+    CashDisbursementJournalEntryForm, TransferJournalEntryForm

src/accounting/journal_entry/forms/currency.py

@@ -0,0 +1,294 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The currency sub-forms for the journal entry management.
+
+"""
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask_babel import LazyString
+from flask_wtf import FlaskForm
+from wtforms import StringField, ValidationError, FieldList, IntegerField, \
+    BooleanField, FormField
+from wtforms.validators import DataRequired
+
+from accounting import db
+from accounting.forms import CurrencyExists
+from accounting.journal_entry.utils.offset_alias import offset_alias
+from accounting.locale import lazy_gettext
+from accounting.models import JournalEntryLineItem
+from accounting.utils.cast import be
+from accounting.utils.strip_text import strip_text
+from .line_item import LineItemForm, CreditLineItemForm, DebitLineItemForm
+
+
+CURRENCY_REQUIRED: DataRequired = DataRequired(
+    lazy_gettext("Please select the currency."))
+"""The validator to check if the currency code is empty."""
+
+
+class SameCurrencyAsOriginalLineItems:
+    """The validator to check if the currency is the same as the
+    original line items."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, CurrencyForm)
+        if field.data is None:
+            return
+        original_line_item_id: set[int] \
+            = {x.original_line_item_id.data
+               for x in form.line_items
+               if x.original_line_item_id.data is not None}
+        if len(original_line_item_id) == 0:
+            return
+        original_line_item_currency_codes: set[str] = set(db.session.scalars(
+            sa.select(JournalEntryLineItem.currency_code)
+            .filter(JournalEntryLineItem.id.in_(original_line_item_id))).all())
+        for currency_code in original_line_item_currency_codes:
+            if field.data != currency_code:
+                raise ValidationError(lazy_gettext(
+                    "The currency must be the same as the"
+                    " original line item."))
+
+
+class KeepCurrencyWhenHavingOffset:
+    """The validator to check if the currency is the same when there is
+    offset."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, CurrencyForm)
+        if field.data is None:
+            return
+        offset: sa.Alias = offset_alias()
+        original_line_items: list[JournalEntryLineItem]\
+            = JournalEntryLineItem.query\
+            .join(offset, be(JournalEntryLineItem.id
+                             == offset.c.original_line_item_id),
+                  isouter=True)\
+            .filter(JournalEntryLineItem.id
+                    .in_({x.id.data for x in form.line_items
+                          if x.id.data is not None}))\
+            .group_by(JournalEntryLineItem.id,
+                      JournalEntryLineItem.currency_code)\
+            .having(sa.func.count(offset.c.id) > 0).all()
+        for original_line_item in original_line_items:
+            if original_line_item.currency_code != field.data:
+                raise ValidationError(lazy_gettext(
+                    "The currency must not be changed when there is offset."))
+
+
+class NeedSomeLineItems:
+    """The validator to check if there is any line item sub-form."""
+
+    def __call__(self, form: FlaskForm, field: FieldList) -> None:
+        if len(field) == 0:
+            raise ValidationError(lazy_gettext(
+                "Please add some line items."))
+
+
+class IsBalanced:
+    """The validator to check that the total amount of the debit and credit
+    line items are equal."""
+
+    def __call__(self, form: FlaskForm, field: BooleanField) -> None:
+        assert isinstance(form, TransferCurrencyForm)
+        if len(form.debit) == 0 or len(form.credit) == 0:
+            return
+        if form.debit_total != form.credit_total:
+            raise ValidationError(lazy_gettext(
+                "The totals of the debit and credit amounts do not match."))
+
+
+class CurrencyForm(FlaskForm):
+    """The form to create or edit a currency in a journal entry."""
+    no = IntegerField()
+    """The order in the journal entry."""
+    code = StringField()
+    """The currency code."""
+    whole_form = BooleanField()
+    """The pseudo field for the whole form validators."""
+
+    @property
+    def line_items(self) -> list[LineItemForm]:
+        """Returns the line item sub-forms.
+
+        :return: The line item sub-forms.
+        """
+        line_item_forms: list[LineItemForm] = []
+        if isinstance(self, CashReceiptCurrencyForm):
+            line_item_forms.extend([x.form for x in self.credit])
+        elif isinstance(self, CashDisbursementCurrencyForm):
+            line_item_forms.extend([x.form for x in self.debit])
+        elif isinstance(self, TransferCurrencyForm):
+            line_item_forms.extend([x.form for x in self.debit])
+            line_item_forms.extend([x.form for x in self.credit])
+        return line_item_forms
+
+    @property
+    def is_code_locked(self) -> bool:
+        """Returns whether the currency code should not be changed.
+
+        :return: True if the currency code should not be changed, or False
+            otherwise
+        """
+        line_item_forms: list[LineItemForm] = self.line_items
+        original_line_item_id: set[int] \
+            = {x.original_line_item_id.data for x in line_item_forms
+               if x.original_line_item_id.data is not None}
+        if len(original_line_item_id) > 0:
+            return True
+        line_item_id: set[int] = {x.id.data for x in line_item_forms
+                                  if x.id.data is not None}
+        select: sa.Select = sa.select(sa.func.count(JournalEntryLineItem.id))\
+            .filter(JournalEntryLineItem.original_line_item_id
+                    .in_(line_item_id))
+        return db.session.scalar(select) > 0
+
+
+class CashReceiptCurrencyForm(CurrencyForm):
+    """The form to create or edit a currency in a
+    cash receipt journal entry."""
+    no = IntegerField()
+    """The order in the journal entry."""
+    code = StringField(
+        filters=[strip_text],
+        validators=[CURRENCY_REQUIRED,
+                    CurrencyExists(),
+                    SameCurrencyAsOriginalLineItems(),
+                    KeepCurrencyWhenHavingOffset()])
+    """The currency code."""
+    credit = FieldList(FormField(CreditLineItemForm),
+                       validators=[NeedSomeLineItems()])
+    """The credit line items."""
+    whole_form = BooleanField()
+    """The pseudo field for the whole form validators."""
+
+    @property
+    def credit_total(self) -> Decimal:
+        """Returns the total amount of the credit line items.
+
+        :return: The total amount of the credit line items.
+        """
+        return sum([x.amount.data for x in self.credit
+                    if x.amount.data is not None])
+
+    @property
+    def credit_errors(self) -> list[str | LazyString]:
+        """Returns the credit line item errors, without the errors in their
+        sub-forms.
+
+        :return:
+        """
+        return [x for x in self.credit.errors
+                if isinstance(x, str) or isinstance(x, LazyString)]
+
+
+class CashDisbursementCurrencyForm(CurrencyForm):
+    """The form to create or edit a currency in a
+    cash disbursement journal entry."""
+    no = IntegerField()
+    """The order in the journal entry."""
+    code = StringField(
+        filters=[strip_text],
+        validators=[CURRENCY_REQUIRED,
+                    CurrencyExists(),
+                    SameCurrencyAsOriginalLineItems(),
+                    KeepCurrencyWhenHavingOffset()])
+    """The currency code."""
+    debit = FieldList(FormField(DebitLineItemForm),
+                      validators=[NeedSomeLineItems()])
+    """The debit line items."""
+    whole_form = BooleanField()
+    """The pseudo field for the whole form validators."""
+
+    @property
+    def debit_total(self) -> Decimal:
+        """Returns the total amount of the debit line items.
+
+        :return: The total amount of the debit line items.
+        """
+        return sum([x.amount.data for x in self.debit
+                    if x.amount.data is not None])
+
+    @property
+    def debit_errors(self) -> list[str | LazyString]:
+        """Returns the debit line item errors, without the errors in their
+        sub-forms.
+
+        :return:
+        """
+        return [x for x in self.debit.errors
+                if isinstance(x, str) or isinstance(x, LazyString)]
+
+
+class TransferCurrencyForm(CurrencyForm):
+    """The form to create or edit a currency in a transfer journal entry."""
+    no = IntegerField()
+    """The order in the journal entry."""
+    code = StringField(
+        filters=[strip_text],
+        validators=[CURRENCY_REQUIRED,
+                    CurrencyExists(),
+                    SameCurrencyAsOriginalLineItems(),
+                    KeepCurrencyWhenHavingOffset()])
+    """The currency code."""
+    debit = FieldList(FormField(DebitLineItemForm),
+                      validators=[NeedSomeLineItems()])
+    """The debit line items."""
+    credit = FieldList(FormField(CreditLineItemForm),
+                       validators=[NeedSomeLineItems()])
+    """The credit line items."""
+    whole_form = BooleanField(validators=[IsBalanced()])
+    """The pseudo field for the whole form validators."""
+
+    @property
+    def debit_total(self) -> Decimal:
+        """Returns the total amount of the debit line items.
+
+        :return: The total amount of the debit line items.
+        """
+        return sum([x.amount.data for x in self.debit
+                    if x.amount.data is not None])
+
+    @property
+    def credit_total(self) -> Decimal:
+        """Returns the total amount of the credit line items.
+
+        :return: The total amount of the credit line items.
+        """
+        return sum([x.amount.data for x in self.credit
+                    if x.amount.data is not None])
+
+    @property
+    def debit_errors(self) -> list[str | LazyString]:
+        """Returns the debit line item errors, without the errors in their
+        sub-forms.
+
+        :return:
+        """
+        return [x for x in self.debit.errors
+                if isinstance(x, str) or isinstance(x, LazyString)]
+
+    @property
+    def credit_errors(self) -> list[str | LazyString]:
+        """Returns the credit line item errors, without the errors in their
+        sub-forms.
+
+        :return:
+        """
+        return [x for x in self.credit.errors
+                if isinstance(x, str) or isinstance(x, LazyString)]

src/accounting/journal_entry/forms/journal_entry.py

@@ -0,0 +1,593 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/18
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The journal entry forms for the journal entry management.
+
+"""
+import datetime as dt
+import typing as t
+from abc import ABC, abstractmethod
+
+import sqlalchemy as sa
+from flask_babel import LazyString
+from flask_wtf import FlaskForm
+from wtforms import DateField, FieldList, FormField, TextAreaField, \
+    BooleanField
+from wtforms.validators import DataRequired, ValidationError
+
+from accounting import db
+from accounting.locale import lazy_gettext
+from accounting.models import JournalEntry, Account, JournalEntryLineItem, \
+    JournalEntryCurrency
+from accounting.journal_entry.utils.account_option import AccountOption
+from accounting.journal_entry.utils.original_line_items import \
+    get_selectable_original_line_items
+from accounting.journal_entry.utils.description_editor import DescriptionEditor
+from accounting.utils.random_id import new_id
+from accounting.utils.strip_text import strip_multiline_text
+from accounting.utils.user import get_current_user_pk
+from .currency import CurrencyForm, CashReceiptCurrencyForm, \
+    CashDisbursementCurrencyForm, TransferCurrencyForm
+from .line_item import LineItemForm, DebitLineItemForm, CreditLineItemForm
+from .reorder import sort_journal_entries_in
+
+DATE_REQUIRED: DataRequired = DataRequired(
+    lazy_gettext("Please fill in the date."))
+"""The validator to check if the date is empty."""
+
+
+class NotBeforeOriginalLineItems:
+    """The validator to check if the date is not before the
+    original line items."""
+
+    def __call__(self, form: FlaskForm, field: DateField) -> None:
+        assert isinstance(form, JournalEntryForm)
+        if field.data is None:
+            return
+        min_date: dt.date | None = form.min_date
+        if min_date is None:
+            return
+        if field.data < min_date:
+            raise ValidationError(lazy_gettext(
+                "The date cannot be earlier than the original line items."))
+
+
+class NotAfterOffsetItems:
+    """The validator to check if the date is not after the offset items."""
+
+    def __call__(self, form: FlaskForm, field: DateField) -> None:
+        assert isinstance(form, JournalEntryForm)
+        if field.data is None:
+            return
+        max_date: dt.date | None = form.max_date
+        if max_date is None:
+            return
+        if field.data > max_date:
+            raise ValidationError(lazy_gettext(
+                "The date cannot be later than the offset items."))
+
+
+class NeedSomeCurrencies:
+    """The validator to check if there is any currency sub-form."""
+
+    def __call__(self, form: FlaskForm, field: FieldList) -> None:
+        if len(field) == 0:
+            raise ValidationError(lazy_gettext("Please add some currencies."))
+
+
+class CannotDeleteOriginalLineItemsWithOffset:
+    """The validator to check the original line items with offset."""
+
+    def __call__(self, form: FlaskForm, field: FieldList) -> None:
+        assert isinstance(form, JournalEntryForm)
+        if form.obj is None:
+            return
+        existing_matched_original_line_item_id: set[int] \
+            = {x.id for x in form.obj.line_items if len(x.offsets) > 0}
+        line_item_id_in_form: set[int] \
+            = {x.id.data for x in form.line_items if x.id.data is not None}
+        for line_item_id in existing_matched_original_line_item_id:
+            if line_item_id not in line_item_id_in_form:
+                raise ValidationError(lazy_gettext(
+                    "Line items with offset cannot be deleted."))
+
+
+class JournalEntryForm(FlaskForm):
+    """The base form to create or edit a journal entry."""
+    date = DateField()
+    """The date."""
+    currencies = FieldList(FormField(CurrencyForm))
+    """The line items categorized by their currencies."""
+    note = TextAreaField()
+    """The note."""
+
+    def __init__(self, *args, **kwargs):
+        """Constructs a base journal entry form.
+
+        :param args: The arguments.
+        :param kwargs: The keyword arguments.
+        """
+        super().__init__(*args, **kwargs)
+        self.is_modified: bool = False
+        """Whether the journal entry is modified during populate_obj()."""
+        self.collector: t.Type[LineItemCollector] = LineItemCollector
+        """The line item collector.  The default is the base abstract
+        collector only to provide the correct type.  The subclass forms should
+        provide their own collectors."""
+        self.obj: JournalEntry | None = kwargs.get("obj")
+        """The journal entry, when editing an existing one."""
+        self._is_need_payable: bool = False
+        """Whether we need the payable original line items."""
+        self._is_need_receivable: bool = False
+        """Whether we need the receivable original line items."""
+        self.__original_line_item_options: list[JournalEntryLineItem] | None \
+            = None
+        """The options of the original line items."""
+        self.__net_balance_exceeded: dict[int, LazyString] | None = None
+        """The original line items whose net balances were exceeded by the
+        amounts in the line item sub-forms."""
+        for line_item in self.line_items:
+            line_item.journal_entry_form = self
+
+    def populate_obj(self, obj: JournalEntry) -> None:
+        """Populates the form data into a journal entry object.
+
+        :param obj: The journal entry object.
+        :return: None.
+        """
+        is_new: bool = obj.id is None
+        if is_new:
+            obj.id = new_id(JournalEntry)
+        self.date: DateField
+        self.__set_date(obj, self.date.data)
+        obj.note = self.note.data
+
+        collector_cls: t.Type[LineItemCollector] = self.collector
+        collector: collector_cls = collector_cls(self, obj)
+        collector.collect()
+
+        to_delete: set[int] = {x.id for x in obj.line_items
+                               if x.id not in collector.to_keep}
+        if len(to_delete) > 0:
+            JournalEntryLineItem.query\
+                .filter(JournalEntryLineItem.id.in_(to_delete)).delete()
+            self.is_modified = True
+
+        if is_new or db.session.is_modified(obj):
+            self.is_modified = True
+
+        if is_new:
+            current_user_pk: int = get_current_user_pk()
+            obj.created_by_id = current_user_pk
+            obj.updated_by_id = current_user_pk
+
+    @property
+    def line_items(self) -> list[LineItemForm]:
+        """Collects and returns the line item sub-forms.
+
+        :return: The line item sub-forms.
+        """
+        line_items: list[LineItemForm] = []
+        for currency in self.currencies:
+            line_items.extend(currency.line_items)
+        return line_items
+
+    def __set_date(self, obj: JournalEntry, new_date: dt.date) -> None:
+        """Sets the journal entry date and number.
+
+        :param obj: The journal entry object.
+        :param new_date: The new date.
+        :return: None.
+        """
+        if obj.date is None or obj.date != new_date:
+            if obj.date is not None:
+                sort_journal_entries_in(obj.date, obj.id)
+            if self.max_date is not None and new_date == self.max_date:
+                db_min_no: int | None = db.session.scalar(
+                    sa.select(sa.func.min(JournalEntry.no))
+                    .filter(JournalEntry.date == new_date))
+                if db_min_no is None:
+                    obj.date = new_date
+                    obj.no = 1
+                else:
+                    obj.date = new_date
+                    obj.no = db_min_no - 1
+                    sort_journal_entries_in(new_date)
+            else:
+                sort_journal_entries_in(new_date, obj.id)
+                count: int = JournalEntry.query\
+                    .filter(JournalEntry.date == new_date).count()
+                obj.date = new_date
+                obj.no = count + 1
+
+    @property
+    def debit_account_options(self) -> list[AccountOption]:
+        """The selectable debit accounts.
+
+        :return: The selectable debit accounts.
+        """
+        accounts: list[AccountOption] \
+            = [AccountOption(x) for x in Account.selectable_debit()
+               if not (x.code[0] == "2" and x.is_need_offset)]
+        in_use: set[int] = set(db.session.scalars(
+            sa.select(JournalEntryLineItem.account_id)
+            .filter(JournalEntryLineItem.is_debit)
+            .group_by(JournalEntryLineItem.account_id)).all())
+        for account in accounts:
+            account.is_in_use = account.id in in_use
+        return accounts
+
+    @property
+    def credit_account_options(self) -> list[AccountOption]:
+        """The selectable credit accounts.
+
+        :return: The selectable credit accounts.
+        """
+        accounts: list[AccountOption] \
+            = [AccountOption(x) for x in Account.selectable_credit()
+               if not (x.code[0] == "1" and x.is_need_offset)]
+        in_use: set[int] = set(db.session.scalars(
+            sa.select(JournalEntryLineItem.account_id)
+            .filter(sa.not_(JournalEntryLineItem.is_debit))
+            .group_by(JournalEntryLineItem.account_id)).all())
+        for account in accounts:
+            account.is_in_use = account.id in in_use
+        return accounts
+
+    @property
+    def currencies_errors(self) -> list[str | LazyString]:
+        """Returns the currency errors, without the errors in their sub-forms.
+
+        :return: The currency errors, without the errors in their sub-forms.
+        """
+        return [x for x in self.currencies.errors
+                if isinstance(x, str) or isinstance(x, LazyString)]
+
+    @property
+    def description_editor(self) -> DescriptionEditor:
+        """Returns the description editor.
+
+        :return: The description editor.
+        """
+        return DescriptionEditor()
+
+    @property
+    def original_line_item_options(self) -> list[JournalEntryLineItem]:
+        """Returns the selectable original line items.
+
+        :return: The selectable original line items.
+        """
+        if self.__original_line_item_options is None:
+            self.__original_line_item_options \
+                = get_selectable_original_line_items(
+                    {x.id.data for x in self.line_items
+                     if x.id.data is not None},
+                    self._is_need_payable, self._is_need_receivable)
+        return self.__original_line_item_options
+
+    @property
+    def min_date(self) -> dt.date | None:
+        """Returns the minimal available date.
+
+        :return: The minimal available date.
+        """
+        original_line_item_id: set[int] \
+            = {x.original_line_item_id.data for x in self.line_items
+               if x.original_line_item_id.data is not None}
+        if len(original_line_item_id) == 0:
+            return None
+        select: sa.Select = sa.select(sa.func.max(JournalEntry.date))\
+            .join(JournalEntryLineItem)\
+            .filter(JournalEntryLineItem.id.in_(original_line_item_id))
+        return db.session.scalar(select)
+
+    @property
+    def max_date(self) -> dt.date | None:
+        """Returns the maximum available date.
+
+        :return: The maximum available date.
+        """
+        line_item_id: set[int] = {x.id.data for x in self.line_items
+                                  if x.id.data is not None}
+        select: sa.Select = sa.select(sa.func.min(JournalEntry.date))\
+            .join(JournalEntryLineItem)\
+            .filter(JournalEntryLineItem.original_line_item_id
+                    .in_(line_item_id))
+        return db.session.scalar(select)
+
+
+T = t.TypeVar("T", bound=JournalEntryForm)
+"""A journal entry form variant."""
+
+
+class LineItemCollector(t.Generic[T], ABC):
+    """The line item collector."""
+
+    def __init__(self, form: T, obj: JournalEntry):
+        """Constructs the line item collector.
+
+        :param form: The journal entry form.
+        :param obj: The journal entry.
+        """
+        self.form: T = form
+        """The journal entry form."""
+        self.__obj: JournalEntry = obj
+        """The journal entry object."""
+        self.__line_items: list[JournalEntryLineItem] = list(obj.line_items)
+        """The existing line items."""
+        self.__line_items_by_id: dict[int, JournalEntryLineItem] \
+            = {x.id: x for x in self.__line_items}
+        """A dictionary from the line item ID to their line items."""
+        self.__no_by_id: dict[int, int] \
+            = {x.id: x.no for x in self.__line_items}
+        """A dictionary from the line item number to their line items."""
+        self.__currencies: list[JournalEntryCurrency] = obj.currencies
+        """The currencies in the journal entry."""
+        self._debit_no: int = 1
+        """The number index for the debit line items."""
+        self._credit_no: int = 1
+        """The number index for the credit line items."""
+        self.to_keep: set[int] = set()
+        """The ID of the existing line items to keep."""
+
+    @abstractmethod
+    def collect(self) -> set[int]:
+        """Collects the line items.
+
+        :return: The ID of the line items to keep.
+        """
+
+    def _add_line_item(self, form: LineItemForm, currency_code: str, no: int) \
+            -> None:
+        """Composes a line item from the form.
+
+        :param form: The line item form.
+        :param currency_code: The code of the currency.
+        :param no: The number of the line item.
+        :return: None.
+        """
+        line_item: JournalEntryLineItem | None \
+            = self.__line_items_by_id.get(form.id.data)
+        if line_item is not None:
+            line_item.currency_code = currency_code
+            form.populate_obj(line_item)
+            line_item.no = no
+            if db.session.is_modified(line_item):
+                self.form.is_modified = True
+        else:
+            line_item = JournalEntryLineItem()
+            line_item.currency_code = currency_code
+            form.populate_obj(line_item)
+            line_item.no = no
+            self.__obj.line_items.append(line_item)
+            self.form.is_modified = True
+        self.to_keep.add(line_item.id)
+
+    def _make_cash_line_item(self, forms: list[LineItemForm], is_debit: bool,
+                             currency_code: str, no: int) -> None:
+        """Composes the cash line item at the other debit or credit of the
+        cash journal entry.
+
+        :param forms: The line item forms in the same currency.
+        :param is_debit: True for a cash receipt journal entry, or False for a
+            cash disbursement journal entry.
+        :param currency_code: The code of the currency.
+        :param no: The number of the line item.
+        :return: None.
+        """
+        candidates: list[JournalEntryLineItem] \
+            = [x for x in self.__line_items
+               if x.is_debit == is_debit and x.currency_code == currency_code]
+        line_item: JournalEntryLineItem
+        if len(candidates) > 0:
+            candidates.sort(key=lambda x: x.no)
+            line_item = candidates[0]
+            line_item.account_id = Account.cash().id
+            line_item.description = None
+            line_item.amount = sum([x.amount.data for x in forms])
+            line_item.no = no
+            if db.session.is_modified(line_item):
+                self.form.is_modified = True
+        else:
+            line_item = JournalEntryLineItem()
+            line_item.id = new_id(JournalEntryLineItem)
+            line_item.is_debit = is_debit
+            line_item.currency_code = currency_code
+            line_item.account_id = Account.cash().id
+            line_item.description = None
+            line_item.amount = sum([x.amount.data for x in forms])
+            line_item.no = no
+            self.__obj.line_items.append(line_item)
+            self.form.is_modified = True
+        self.to_keep.add(line_item.id)
+
+    def _sort_line_item_forms(self, forms: list[LineItemForm]) -> None:
+        """Sorts the line item sub-forms.
+
+        :param forms: The line item sub-forms.
+        :return: None.
+        """
+        missing_no: int = 100 if len(self.__no_by_id) == 0 \
+            else max(self.__no_by_id.values()) + 100
+        ord_by_form: dict[LineItemForm, int] \
+            = {forms[i]: i for i in range(len(forms))}
+        recv_no: set[int] = {x.no.data for x in forms if x.no.data is not None}
+        missing_recv_no: int = 100 if len(recv_no) == 0 else max(recv_no) + 100
+        forms.sort(key=lambda x: (x.no.data or missing_recv_no,
+                                  missing_no if x.id.data is None else
+                                  self.__no_by_id.get(x.id.data, missing_no),
+                                  ord_by_form.get(x)))
+
+    def _sort_currency_forms(self, forms: list[CurrencyForm]) -> None:
+        """Sorts the currency forms.
+
+        :param forms: The currency forms.
+        :return: None.
+        """
+        missing_no: int = len(self.__currencies) + 100
+        no_by_code: dict[str, int] = {self.__currencies[i].code: i
+                                      for i in range(len(self.__currencies))}
+        ord_by_form: dict[CurrencyForm, int] \
+            = {forms[i]: i for i in range(len(forms))}
+        recv_no: set[int] = {x.no.data for x in forms if x.no.data is not None}
+        missing_recv_no: int = 100 if len(recv_no) == 0 else max(recv_no) + 100
+        forms.sort(key=lambda x: (x.no.data or missing_recv_no,
+                                  no_by_code.get(x.code.data, missing_no),
+                                  ord_by_form.get(x)))
+
+
+class CashReceiptJournalEntryForm(JournalEntryForm):
+    """The form to create or edit a cash receipt journal entry."""
+    date = DateField(
+        validators=[DATE_REQUIRED,
+                    NotBeforeOriginalLineItems(),
+                    NotAfterOffsetItems()])
+    """The date."""
+    currencies = FieldList(FormField(CashReceiptCurrencyForm), name="currency",
+                           validators=[NeedSomeCurrencies()])
+    """The line items categorized by their currencies."""
+    note = TextAreaField(filters=[strip_multiline_text])
+    """The note."""
+    whole_form = BooleanField(
+        validators=[CannotDeleteOriginalLineItemsWithOffset()])
+    """The pseudo field for the whole form validators."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._is_need_receivable = True
+
+        class Collector(LineItemCollector[CashReceiptJournalEntryForm]):
+            """The line item collector for the cash receipt journal entries."""
+
+            def collect(self) -> None:
+                currencies: list[CashReceiptCurrencyForm] \
+                    = [x.form for x in self.form.currencies]
+                self._sort_currency_forms(currencies)
+                for currency in currencies:
+                    # The debit cash line item
+                    self._make_cash_line_item(list(currency.credit), True,
+                                              currency.code.data,
+                                              self._debit_no)
+                    self._debit_no = self._debit_no + 1
+
+                    # The credit forms
+                    credit_forms: list[CreditLineItemForm] \
+                        = [x.form for x in currency.credit]
+                    self._sort_line_item_forms(credit_forms)
+                    for credit_form in credit_forms:
+                        self._add_line_item(credit_form, currency.code.data,
+                                            self._credit_no)
+                        self._credit_no = self._credit_no + 1
+
+        self.collector = Collector
+
+
+class CashDisbursementJournalEntryForm(JournalEntryForm):
+    """The form to create or edit a cash disbursement journal entry."""
+    date = DateField(
+        validators=[DATE_REQUIRED,
+                    NotBeforeOriginalLineItems(),
+                    NotAfterOffsetItems()])
+    """The date."""
+    currencies = FieldList(FormField(CashDisbursementCurrencyForm),
+                           name="currency",
+                           validators=[NeedSomeCurrencies()])
+    """The line items categorized by their currencies."""
+    note = TextAreaField(filters=[strip_multiline_text])
+    """The note."""
+    whole_form = BooleanField(
+        validators=[CannotDeleteOriginalLineItemsWithOffset()])
+    """The pseudo field for the whole form validators."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._is_need_payable = True
+
+        class Collector(LineItemCollector[CashDisbursementJournalEntryForm]):
+            """The line item collector for the cash disbursement journal
+            entries."""
+
+            def collect(self) -> None:
+                currencies: list[CashDisbursementCurrencyForm] \
+                    = [x.form for x in self.form.currencies]
+                self._sort_currency_forms(currencies)
+                for currency in currencies:
+                    # The debit forms
+                    debit_forms: list[DebitLineItemForm] \
+                        = [x.form for x in currency.debit]
+                    self._sort_line_item_forms(debit_forms)
+                    for debit_form in debit_forms:
+                        self._add_line_item(debit_form, currency.code.data,
+                                            self._debit_no)
+                        self._debit_no = self._debit_no + 1
+
+                    # The credit forms
+                    self._make_cash_line_item(list(currency.debit), False,
+                                              currency.code.data,
+                                              self._credit_no)
+                    self._credit_no = self._credit_no + 1
+
+        self.collector = Collector
+
+
+class TransferJournalEntryForm(JournalEntryForm):
+    """The form to create or edit a transfer journal entry."""
+    date = DateField(
+        validators=[DATE_REQUIRED,
+                    NotBeforeOriginalLineItems(),
+                    NotAfterOffsetItems()])
+    """The date."""
+    currencies = FieldList(FormField(TransferCurrencyForm), name="currency",
+                           validators=[NeedSomeCurrencies()])
+    """The line items categorized by their currencies."""
+    note = TextAreaField(filters=[strip_multiline_text])
+    """The note."""
+    whole_form = BooleanField(
+        validators=[CannotDeleteOriginalLineItemsWithOffset()])
+    """The pseudo field for the whole form validators."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._is_need_payable = True
+        self._is_need_receivable = True
+
+        class Collector(LineItemCollector[TransferJournalEntryForm]):
+            """The line item collector for the transfer journal entries."""
+
+            def collect(self) -> None:
+                currencies: list[TransferCurrencyForm] \
+                    = [x.form for x in self.form.currencies]
+                self._sort_currency_forms(currencies)
+                for currency in currencies:
+                    # The debit forms
+                    debit_forms: list[DebitLineItemForm] \
+                        = [x.form for x in currency.debit]
+                    self._sort_line_item_forms(debit_forms)
+                    for debit_form in debit_forms:
+                        self._add_line_item(debit_form, currency.code.data,
+                                            self._debit_no)
+                        self._debit_no = self._debit_no + 1
+
+                    # The credit forms
+                    credit_forms: list[CreditLineItemForm] \
+                        = [x.form for x in currency.credit]
+                    self._sort_line_item_forms(credit_forms)
+                    for credit_form in credit_forms:
+                        self._add_line_item(credit_form, currency.code.data,
+                                            self._credit_no)
+                        self._credit_no = self._credit_no + 1
+
+        self.collector = Collector

src/accounting/journal_entry/forms/line_item.py

@@ -0,0 +1,499 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The line item sub-forms for the journal entry management.
+
+"""
+from datetime import date
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask_babel import LazyString
+from flask_wtf import FlaskForm
+from sqlalchemy.orm import selectinload
+from wtforms import StringField, ValidationError, DecimalField, IntegerField
+from wtforms.validators import Optional
+
+from accounting import db
+from accounting.forms import ACCOUNT_REQUIRED, AccountExists, IsDebitAccount, \
+    IsCreditAccount
+from accounting.locale import lazy_gettext
+from accounting.models import Account, JournalEntryLineItem
+from accounting.template_filters import format_amount
+from accounting.utils.cast import be
+from accounting.utils.random_id import new_id
+from accounting.utils.strip_text import strip_text
+from accounting.utils.user import get_current_user_pk
+
+
+class OriginalLineItemExists:
+    """The validator to check if the original line item exists."""
+
+    def __call__(self, form: FlaskForm, field: IntegerField) -> None:
+        if field.data is None:
+            return
+        if db.session.get(JournalEntryLineItem, field.data) is None:
+            raise ValidationError(lazy_gettext(
+                "The original line item does not exist."))
+
+
+class OriginalLineItemOppositeDebitCredit:
+    """The validator to check if the original line item is on the opposite
+    debit or credit."""
+
+    def __call__(self, form: FlaskForm, field: IntegerField) -> None:
+        if field.data is None:
+            return
+        original_line_item: JournalEntryLineItem | None \
+            = db.session.get(JournalEntryLineItem, field.data)
+        if original_line_item is None:
+            return
+        if isinstance(form, CreditLineItemForm) \
+                and original_line_item.is_debit:
+            return
+        if isinstance(form, DebitLineItemForm) \
+                and not original_line_item.is_debit:
+            return
+        raise ValidationError(lazy_gettext(
+            "The original line item is on the same debit or credit."))
+
+
+class OriginalLineItemNeedOffset:
+    """The validator to check if the original line item needs offset."""
+
+    def __call__(self, form: FlaskForm, field: IntegerField) -> None:
+        if field.data is None:
+            return
+        original_line_item: JournalEntryLineItem | None \
+            = db.session.get(JournalEntryLineItem, field.data)
+        if original_line_item is None:
+            return
+        if not original_line_item.account.is_need_offset:
+            raise ValidationError(lazy_gettext(
+                "The original line item does not need offset."))
+
+
+class OriginalLineItemNotOffset:
+    """The validator to check if the original line item is not itself an
+    offset item."""
+
+    def __call__(self, form: FlaskForm, field: IntegerField) -> None:
+        if field.data is None:
+            return
+        original_line_item: JournalEntryLineItem | None \
+            = db.session.get(JournalEntryLineItem, field.data)
+        if original_line_item is None:
+            return
+        if original_line_item.original_line_item_id is not None:
+            raise ValidationError(lazy_gettext(
+                "The original line item cannot be an offset item."))
+
+
+class SameAccountAsOriginalLineItem:
+    """The validator to check if the account is the same as the
+    original line item."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, LineItemForm)
+        if field.data is None or form.original_line_item_id.data is None:
+            return
+        original_line_item: JournalEntryLineItem | None \
+            = db.session.get(JournalEntryLineItem,
+                             form.original_line_item_id.data)
+        if original_line_item is None:
+            return
+        if field.data != original_line_item.account_code:
+            raise ValidationError(lazy_gettext(
+                "The account must be the same as the original line item."))
+
+
+class KeepAccountWhenHavingOffset:
+    """The validator to check if the account is the same when having offset."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, LineItemForm)
+        if field.data is None or form.id.data is None:
+            return
+        line_item: JournalEntryLineItem | None = db.session\
+            .query(JournalEntryLineItem)\
+            .filter(JournalEntryLineItem.id == form.id.data)\
+            .options(selectinload(JournalEntryLineItem.offsets)).first()
+        if line_item is None or len(line_item.offsets) == 0:
+            return
+        if field.data != line_item.account_code:
+            raise ValidationError(lazy_gettext(
+                "The account must not be changed when there is offset."))
+
+
+class NotStartPayableFromDebit:
+    """The validator to check that a payable line item does not start from
+    debit."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, DebitLineItemForm)
+        if field.data is None \
+                or field.data[0] != "2" \
+                or form.original_line_item_id.data is not None:
+            return
+        account: Account | None = Account.find_by_code(field.data)
+        if account is not None and account.is_need_offset:
+            raise ValidationError(lazy_gettext(
+                "A payable line item cannot start from debit."))
+
+
+class NotStartReceivableFromCredit:
+    """The validator to check that a receivable line item does not start
+    from credit."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        assert isinstance(form, CreditLineItemForm)
+        if field.data is None \
+                or field.data[0] != "1" \
+                or form.original_line_item_id.data is not None:
+            return
+        account: Account | None = Account.find_by_code(field.data)
+        if account is not None and account.is_need_offset:
+            raise ValidationError(lazy_gettext(
+                "A receivable line item cannot start from credit."))
+
+
+class PositiveAmount:
+    """The validator to check if the amount is positive."""
+
+    def __call__(self, form: FlaskForm, field: DecimalField) -> None:
+        if field.data is None:
+            return
+        if field.data <= 0:
+            raise ValidationError(lazy_gettext(
+                "Please fill in a positive amount."))
+
+
+class NotExceedingOriginalLineItemNetBalance:
+    """The validator to check if the amount exceeds the net balance of the
+    original line item."""
+
+    def __call__(self, form: FlaskForm, field: DecimalField) -> None:
+        assert isinstance(form, LineItemForm)
+        if field.data is None or form.original_line_item_id.data is None:
+            return
+        original_line_item: JournalEntryLineItem | None \
+            = db.session.get(JournalEntryLineItem,
+                             form.original_line_item_id.data)
+        if original_line_item is None:
+            return
+        is_debit: bool = isinstance(form, DebitLineItemForm)
+        existing_line_item_id: set[int] = set()
+        if form.journal_entry_form.obj is not None:
+            existing_line_item_id \
+                = {x.id for x in form.journal_entry_form.obj.line_items}
+        offset_total_func: sa.Function = sa.func.sum(sa.case(
+            (be(JournalEntryLineItem.is_debit == is_debit),
+             JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount))
+        offset_total_but_form: Decimal | None = db.session.scalar(
+            sa.select(offset_total_func)
+            .filter(be(JournalEntryLineItem.original_line_item_id
+                       == original_line_item.id),
+                    JournalEntryLineItem.id.not_in(existing_line_item_id)))
+        if offset_total_but_form is None:
+            offset_total_but_form = Decimal("0")
+        offset_total_on_form: Decimal = sum(
+            [x.amount.data for x in form.journal_entry_form.line_items
+             if x.original_line_item_id.data == original_line_item.id
+             and x.amount != field and x.amount.data is not None])
+        net_balance: Decimal = original_line_item.amount \
+            - offset_total_but_form - offset_total_on_form
+        if field.data > net_balance:
+            raise ValidationError(lazy_gettext(
+                "The amount must not exceed the net balance %(balance)s of the"
+                " original line item.", balance=format_amount(net_balance)))
+
+
+class NotLessThanOffsetTotal:
+    """The validator to check if the amount is less than the offset total."""
+
+    def __call__(self, form: FlaskForm, field: DecimalField) -> None:
+        assert isinstance(form, LineItemForm)
+        if field.data is None or form.id.data is None:
+            return
+        is_debit: bool = isinstance(form, DebitLineItemForm)
+        select_offset_total: sa.Select = sa.select(sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit != is_debit,
+             JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount)))\
+            .filter(be(JournalEntryLineItem.original_line_item_id
+                       == form.id.data))
+        offset_total: Decimal | None = db.session.scalar(select_offset_total)
+        if offset_total is not None and field.data < offset_total:
+            raise ValidationError(lazy_gettext(
+                "The amount must not be less than the offset total %(total)s.",
+                total=format_amount(offset_total)))
+
+
+class LineItemForm(FlaskForm):
+    """The base form to create or edit a line item."""
+    id = IntegerField()
+    """The existing line item ID."""
+    no = IntegerField()
+    """The order in the currency."""
+    original_line_item_id = IntegerField()
+    """The Id of the original line item."""
+    account_code = StringField()
+    """The account code."""
+    description = StringField()
+    """The description."""
+    amount = DecimalField()
+    """The amount."""
+
+    def __init__(self, *args, **kwargs):
+        """Constructs a base line item form.
+
+        :param args: The arguments.
+        :param kwargs: The keyword arguments.
+        """
+        super().__init__(*args, **kwargs)
+        from .journal_entry import JournalEntryForm
+        self.journal_entry_form: JournalEntryForm | None = None
+        """The source journal entry form."""
+
+    @property
+    def account_text(self) -> str:
+        """Returns the text representation of the account.
+
+        :return: The text representation of the account.
+        """
+        if self.account_code.data is None:
+            return ""
+        account: Account | None = Account.find_by_code(self.account_code.data)
+        if account is None:
+            return ""
+        return str(account)
+
+    @property
+    def __original_line_item(self) -> JournalEntryLineItem | None:
+        """Returns the original line item.
+
+        :return: The original line item.
+        """
+        if not hasattr(self, "____original_line_item"):
+            def get_line_item() -> JournalEntryLineItem | None:
+                if self.original_line_item_id.data is None:
+                    return None
+                return db.session.get(JournalEntryLineItem,
+                                      self.original_line_item_id.data)
+            setattr(self, "____original_line_item", get_line_item())
+        return getattr(self, "____original_line_item")
+
+    @property
+    def original_line_item_date(self) -> date | None:
+        """Returns the text representation of the original line item.
+
+        :return: The text representation of the original line item.
+        """
+        return None if self.__original_line_item is None \
+            else self.__original_line_item.journal_entry.date
+
+    @property
+    def original_line_item_text(self) -> str | None:
+        """Returns the text representation of the original line item.
+
+        :return: The text representation of the original line item.
+        """
+        return None if self.__original_line_item is None \
+            else str(self.__original_line_item)
+
+    @property
+    def is_need_offset(self) -> bool:
+        """Returns whether the line item needs offset.
+
+        :return: True if the line item needs offset, or False otherwise.
+        """
+        if self.account_code.data is None:
+            return False
+        if self.account_code.data[0] == "1":
+            if isinstance(self, CreditLineItemForm):
+                return False
+        elif self.account_code.data[0] == "2":
+            if isinstance(self, DebitLineItemForm):
+                return False
+        else:
+            return False
+        account: Account | None = Account.find_by_code(self.account_code.data)
+        return account is not None and account.is_need_offset
+
+    @property
+    def offsets(self) -> list[JournalEntryLineItem]:
+        """Returns the offsets.
+
+        :return: The offsets.
+        """
+        if not hasattr(self, "__offsets"):
+            def get_offsets() -> list[JournalEntryLineItem]:
+                if not self.is_need_offset or self.id.data is None:
+                    return []
+                return JournalEntryLineItem.query\
+                    .filter(JournalEntryLineItem.original_line_item_id
+                            == self.id.data)\
+                    .options(selectinload(JournalEntryLineItem.journal_entry),
+                             selectinload(JournalEntryLineItem.account),
+                             selectinload(JournalEntryLineItem.offsets)
+                             .selectinload(
+                                 JournalEntryLineItem.journal_entry)).all()
+            setattr(self, "__offsets", get_offsets())
+        return getattr(self, "__offsets")
+
+    @property
+    def offset_total(self) -> Decimal | None:
+        """Returns the total amount of the offsets.
+
+        :return: The total amount of the offsets.
+        """
+        if not hasattr(self, "__offset_total"):
+            def get_offset_total():
+                if not self.is_need_offset or self.id.data is None:
+                    return None
+                is_debit: bool = isinstance(self, DebitLineItemForm)
+                return sum([x.amount if x.is_debit != is_debit else -x.amount
+                            for x in self.offsets])
+            setattr(self, "__offset_total", get_offset_total())
+        return getattr(self, "__offset_total")
+
+    @property
+    def net_balance(self) -> Decimal | None:
+        """Returns the net balance.
+
+        :return: The net balance.
+        """
+        if not self.is_need_offset or self.id.data is None \
+                or self.amount.data is None:
+            return None
+        return self.amount.data - self.offset_total
+
+    @property
+    def all_errors(self) -> list[str | LazyString]:
+        """Returns all the errors of the form.
+
+        :return: All the errors of the form.
+        """
+        all_errors: list[str | LazyString] = []
+        for key in self.errors:
+            if key != "csrf_token":
+                all_errors.extend(self.errors[key])
+        return all_errors
+
+
+class DebitLineItemForm(LineItemForm):
+    """The form to create or edit a debit line item."""
+    id = IntegerField()
+    """The existing line item ID."""
+    no = IntegerField()
+    """The order in the currency."""
+    original_line_item_id = IntegerField(
+        validators=[Optional(),
+                    OriginalLineItemExists(),
+                    OriginalLineItemOppositeDebitCredit(),
+                    OriginalLineItemNeedOffset(),
+                    OriginalLineItemNotOffset()])
+    """The ID of the original line item."""
+    account_code = StringField(
+        filters=[strip_text],
+        validators=[
+            ACCOUNT_REQUIRED,
+            AccountExists(),
+            IsDebitAccount(lazy_gettext(
+                "This account is not for debit line items.")),
+            SameAccountAsOriginalLineItem(),
+            KeepAccountWhenHavingOffset(),
+            NotStartPayableFromDebit()])
+    """The account code."""
+    description = StringField(filters=[strip_text])
+    """The description."""
+    amount = DecimalField(
+        validators=[PositiveAmount(),
+                    NotExceedingOriginalLineItemNetBalance(),
+                    NotLessThanOffsetTotal()])
+    """The amount."""
+
+    def populate_obj(self, obj: JournalEntryLineItem) -> None:
+        """Populates the form data into a line item object.
+
+        :param obj: The line item object.
+        :return: None.
+        """
+        is_new: bool = obj.id is None
+        if is_new:
+            obj.id = new_id(JournalEntryLineItem)
+        obj.original_line_item_id = self.original_line_item_id.data
+        obj.account_id = Account.find_by_code(self.account_code.data).id
+        obj.description = self.description.data
+        obj.is_debit = True
+        obj.amount = self.amount.data
+        if is_new:
+            current_user_pk: int = get_current_user_pk()
+            obj.created_by_id = current_user_pk
+            obj.updated_by_id = current_user_pk
+
+
+class CreditLineItemForm(LineItemForm):
+    """The form to create or edit a credit line item."""
+    id = IntegerField()
+    """The existing line item ID."""
+    no = IntegerField()
+    """The order in the currency."""
+    original_line_item_id = IntegerField(
+        validators=[Optional(),
+                    OriginalLineItemExists(),
+                    OriginalLineItemOppositeDebitCredit(),
+                    OriginalLineItemNeedOffset(),
+                    OriginalLineItemNotOffset()])
+    """The ID of the original line item."""
+    account_code = StringField(
+        filters=[strip_text],
+        validators=[
+            ACCOUNT_REQUIRED,
+            AccountExists(),
+            IsCreditAccount(lazy_gettext(
+                "This account is not for credit line items.")),
+            SameAccountAsOriginalLineItem(),
+            KeepAccountWhenHavingOffset(),
+            NotStartReceivableFromCredit()])
+    """The account code."""
+    description = StringField(filters=[strip_text])
+    """The description."""
+    amount = DecimalField(
+        validators=[PositiveAmount(),
+                    NotExceedingOriginalLineItemNetBalance(),
+                    NotLessThanOffsetTotal()])
+    """The amount."""
+
+    def populate_obj(self, obj: JournalEntryLineItem) -> None:
+        """Populates the form data into a line item object.
+
+        :param obj: The line item object.
+        :return: None.
+        """
+        is_new: bool = obj.id is None
+        if is_new:
+            obj.id = new_id(JournalEntryLineItem)
+        obj.original_line_item_id = self.original_line_item_id.data
+        obj.account_id = Account.find_by_code(self.account_code.data).id
+        obj.description = self.description.data
+        obj.is_debit = False
+        obj.amount = self.amount.data
+        if is_new:
+            current_user_pk: int = get_current_user_pk()
+            obj.created_by_id = current_user_pk
+            obj.updated_by_id = current_user_pk

src/accounting/journal_entry/forms/reorder.py

@@ -0,0 +1,95 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The reorder forms for the journal entry management.
+
+"""
+from datetime import date
+
+import sqlalchemy as sa
+from flask import request
+
+from accounting import db
+from accounting.models import JournalEntry
+
+
+def sort_journal_entries_in(journal_entry_date: date,
+                            exclude: int | None = None) -> None:
+    """Sorts the journal entries under a date after changing the date or
+    deleting a journal entry.
+
+    :param journal_entry_date: The date of the journal entry.
+    :param exclude: The journal entry ID to exclude.
+    :return: None.
+    """
+    conditions: list[sa.BinaryExpression] \
+        = [JournalEntry.date == journal_entry_date]
+    if exclude is not None:
+        conditions.append(JournalEntry.id != exclude)
+    journal_entries: list[JournalEntry] = JournalEntry.query\
+        .filter(*conditions)\
+        .order_by(JournalEntry.no).all()
+    for i in range(len(journal_entries)):
+        if journal_entries[i].no != i + 1:
+            journal_entries[i].no = i + 1
+
+
+class JournalEntryReorderForm:
+    """The form to reorder the journal entries."""
+
+    def __init__(self, journal_entry_date: date):
+        """Constructs the form to reorder the journal entries in a day.
+
+        :param journal_entry_date: The date.
+        """
+        self.date: date = journal_entry_date
+        self.is_modified: bool = False
+
+    def save_order(self) -> None:
+        """Saves the order of the account.
+
+        :return:
+        """
+        journal_entries: list[JournalEntry] = JournalEntry.query\
+            .filter(JournalEntry.date == self.date).all()
+
+        # Collects the specified order.
+        orders: dict[JournalEntry, int] = {}
+        for journal_entry in journal_entries:
+            if f"{journal_entry.id}-no" in request.form:
+                try:
+                    orders[journal_entry] \
+                        = int(request.form[f"{journal_entry.id}-no"])
+                except ValueError:
+                    pass
+
+        # Missing and invalid orders are appended to the end.
+        missing: list[JournalEntry] \
+            = [x for x in journal_entries if x not in orders]
+        if len(missing) > 0:
+            next_no: int = 1 if len(orders) == 0 else max(orders.values()) + 1
+            for journal_entry in missing:
+                orders[journal_entry] = next_no
+
+        # Sort by the specified order first, and their original order.
+        journal_entries.sort(key=lambda x: (orders[x], x.no))
+
+        # Update the orders.
+        with db.session.no_autoflush:
+            for i in range(len(journal_entries)):
+                if journal_entries[i].no != i + 1:
+                    journal_entries[i].no = i + 1
+                    self.is_modified = True

src/accounting/journal_entry/template_filters.py

@@ -0,0 +1,82 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/25
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The template filters for the journal entry management.
+
+"""
+from decimal import Decimal
+from html import escape
+from urllib.parse import ParseResult, urlparse, parse_qsl, urlencode, \
+    urlunparse
+
+from flask import request
+
+
+def with_type(uri: str) -> str:
+    """Adds the journal entry type to the URI, if it is specified.
+
+    :param uri: The URI.
+    :return: The result URL, optionally with the journal entry type added.
+    """
+    if "as" not in request.args:
+        return uri
+    uri_p: ParseResult = urlparse(uri)
+    params: list[tuple[str, str]] = parse_qsl(uri_p.query)
+    params = [x for x in params if x[0] != "as"]
+    params.append(("as", request.args["as"]))
+    parts: list[str] = list(uri_p)
+    parts[4] = urlencode(params)
+    return urlunparse(parts)
+
+
+def to_transfer(uri: str) -> str:
+    """Adds the transfer journal entry type to the URI.
+
+    :param uri: The URI.
+    :return: The result URL, with the transfer journal entry type added.
+    """
+    uri_p: ParseResult = urlparse(uri)
+    params: list[tuple[str, str]] = parse_qsl(uri_p.query)
+    params = [x for x in params if x[0] != "as"]
+    params.append(("as", "transfer"))
+    parts: list[str] = list(uri_p)
+    parts[4] = urlencode(params)
+    return urlunparse(parts)
+
+
+def format_amount_input(value: Decimal | None) -> str:
+    """Format an amount for an input value.
+
+    :param value: The amount.
+    :return: The formatted amount text for an input value.
+    """
+    if value is None:
+        return ""
+    whole: int = int(value)
+    frac: Decimal = (value - whole).normalize()
+    return str(whole) + str(frac)[1:]
+
+
+def text2html(value: str) -> str:
+    """Converts plain text into HTML.
+
+    :param value: The plain text.
+    :return: The HTML.
+    """
+    s: str = escape(value)
+    s = s.replace("\n", "<br>")
+    s = s.replace("  ", " &nbsp;")
+    return s

src/accounting/journal_entry/utils/__init__.py

@@ -0,0 +1,19 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The utilities for the journal entry management.
+
+"""

src/accounting/journal_entry/utils/account_option.py

@@ -0,0 +1,49 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The account option for the journal entry management.
+
+"""
+from accounting.models import Account
+
+
+class AccountOption:
+    """An account option."""
+
+    def __init__(self, account: Account):
+        """Constructs an account option.
+
+        :param account: The account.
+        """
+        self.id: str = account.id
+        """The account ID."""
+        self.code: str = account.code
+        """The account code."""
+        self.query_values: list[str] = account.query_values
+        """The values to be queried."""
+        self.__str: str = str(account)
+        """The string representation of the account option."""
+        self.is_in_use: bool = False
+        """True if this account is in use, or False otherwise."""
+        self.is_need_offset: bool = account.is_need_offset
+        """True if this account needs offset, or False otherwise."""
+
+    def __str__(self) -> str:
+        """Returns the string representation of the account option.
+
+        :return: The string representation of the account option.
+        """
+        return self.__str

src/accounting/journal_entry/utils/description_editor.py

@@ -0,0 +1,346 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/27
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The description editor.
+
+"""
+import re
+import typing as t
+
+import sqlalchemy as sa
+
+from accounting import db
+from accounting.models import Account, JournalEntryLineItem
+from accounting.utils.options import options, Recurring
+
+
+class DescriptionAccount:
+    """An account for a description tag."""
+
+    def __init__(self, account: Account, freq: int):
+        """Constructs an account for a description tag.
+
+        :param account: The account.
+        :param freq: The frequency of the tag with the account.
+        """
+        self.__account: Account = account
+        """The account."""
+        self.id: int = account.id
+        """The account ID."""
+        self.code: str = account.code
+        """The account code."""
+        self.is_need_offset: bool = account.is_need_offset
+        """Whether the journal entry line items of this account need offset."""
+        self.freq: int = freq
+        """The frequency of the tag with the account."""
+
+    def __str__(self) -> str:
+        """Returns the string representation of the account.
+
+        :return: The string representation of the account.
+        """
+        return str(self.__account)
+
+    def add_freq(self, freq: int) -> None:
+        """Adds the frequency of an account.
+
+        :param freq: The frequency of the tag name with the account.
+        :return: None.
+        """
+        self.freq = self.freq + freq
+
+
+class DescriptionTag:
+    """A description tag."""
+
+    def __init__(self, name: str):
+        """Constructs a description tag.
+
+        :param name: The tag name.
+        """
+        self.name: str = name
+        """The tag name."""
+        self.__account_dict: dict[int, DescriptionAccount] = {}
+        """The accounts that come with the tag, in the order of their
+        frequency."""
+        self.freq: int = 0
+        """The frequency of the tag."""
+
+    def __str__(self) -> str:
+        """Returns the string representation of the tag.
+
+        :return: The string representation of the tag.
+        """
+        return self.name
+
+    def add_account(self, account: Account, freq: int):
+        """Adds an account.
+
+        :param account: The associated account.
+        :param freq: The frequency of the tag name with the account.
+        :return: None.
+        """
+        self.__account_dict[account.id] = DescriptionAccount(account, freq)
+        self.freq = self.freq + freq
+
+    @property
+    def accounts(self) -> list[DescriptionAccount]:
+        """Returns the accounts by the order of their frequencies.
+
+        :return: The accounts by the order of their frequencies.
+        """
+        return sorted(self.__account_dict.values(), key=lambda x: -x.freq)
+
+    @property
+    def account_codes(self) -> list[str]:
+        """Returns the account codes by the order of their frequencies.
+
+        :return: The account codes by the order of their frequencies.
+        """
+        return [x.code for x in self.accounts]
+
+
+class DescriptionType:
+    """A description type"""
+
+    def __init__(self, type_id: t.Literal["general", "travel", "bus"]):
+        """Constructs a description type.
+
+        :param type_id: The type ID, either "general", "travel", or "bus".
+        """
+        self.id: t.Literal["general", "travel", "bus"] = type_id
+        """The type ID."""
+        self.__tag_dict: dict[str, DescriptionTag] = {}
+        """A dictionary from the tag name to their corresponding tag."""
+
+    def add_tag(self, name: str, account: Account, freq: int) -> None:
+        """Adds a tag.
+
+        :param name: The tag name.
+        :param account: The associated account.
+        :param freq: The frequency of the tag name with the account.
+        :return: None.
+        """
+        if name not in self.__tag_dict:
+            self.__tag_dict[name] = DescriptionTag(name)
+        self.__tag_dict[name].add_account(account, freq)
+
+    @property
+    def tags(self) -> list[DescriptionTag]:
+        """Returns the tags by the order of their frequencies.
+
+        :return: The tags by the order of their frequencies.
+        """
+        return sorted(self.__tag_dict.values(), key=lambda x: -x.freq)
+
+
+class DescriptionRecurring:
+    """A recurring transaction."""
+
+    def __init__(self, name: str, account: Account, description_template: str):
+        """Constructs a recurring transaction.
+
+        :param name: The name.
+        :param description_template: The description template.
+        :param account: The account.
+        """
+        self.name: str = name
+        self.account: DescriptionAccount = DescriptionAccount(account, 0)
+        self.description_template: str = description_template
+
+    @property
+    def account_codes(self) -> list[str]:
+        """Returns the account codes by the order of their frequencies.
+
+        :return: The account codes by the order of their frequencies.
+        """
+        return [self.account.code]
+
+
+class DescriptionDebitCredit:
+    """The description on debit or credit."""
+
+    def __init__(self, debit_credit: t.Literal["debit", "credit"]):
+        """Constructs the description on debit or credit.
+
+        :param debit_credit: Either "debit" or "credit".
+        """
+        self.debit_credit: t.Literal["debit", "credit"] = debit_credit
+        """Either debit or credit."""
+        self.general: DescriptionType = DescriptionType("general")
+        """The general tags."""
+        self.travel: DescriptionType = DescriptionType("travel")
+        """The travel tags."""
+        self.bus: DescriptionType = DescriptionType("bus")
+        """The bus tags."""
+        self.__type_dict: dict[t.Literal["general", "travel", "bus"],
+                               DescriptionType] \
+            = {x.id: x for x in {self.general, self.travel, self.bus}}
+        """A dictionary from the type ID to the corresponding tags."""
+        self.recurring: list[DescriptionRecurring] = []
+        """The recurring transactions."""
+
+    def add_tag(self, tag_type: t.Literal["general", "travel", "bus"],
+                name: str, account: Account, freq: int) -> None:
+        """Adds a tag.
+
+        :param tag_type: The tag type, either "general", "travel", or "bus".
+        :param name: The name.
+        :param account: The associated account.
+        :param freq: The frequency of the tag name with the account.
+        :return: None.
+        """
+        self.__type_dict[tag_type].add_tag(name, account, freq)
+
+    @property
+    def accounts(self) -> list[DescriptionAccount]:
+        """Returns the suggested accounts of all tags in the description editor
+        in debit or credit, in their frequency order.
+
+        :return: The suggested accounts of all tags, in their frequency order.
+        """
+        accounts: dict[int, DescriptionAccount] = {}
+        freq: dict[int, int] = {}
+        for tag_type in self.__type_dict.values():
+            for tag in tag_type.tags:
+                for account in tag.accounts:
+                    accounts[account.id] = account
+                    if account.id not in freq:
+                        freq[account.id] = 0
+                    freq[account.id] \
+                        = freq[account.id] + account.freq
+        for recurring in self.recurring:
+            accounts[recurring.account.id] = recurring.account
+            if recurring.account.id not in freq:
+                freq[recurring.account.id] = 0
+        return [accounts[y] for y in sorted(freq.keys(),
+                                            key=lambda x: -freq[x])]
+
+
+class DescriptionEditor:
+    """The description editor."""
+
+    def __init__(self):
+        """Constructs the description editor."""
+        self.debit: DescriptionDebitCredit = DescriptionDebitCredit("debit")
+        """The debit tags."""
+        self.credit: DescriptionDebitCredit = DescriptionDebitCredit("credit")
+        """The credit tags."""
+        self.__init_tags()
+        self.__init_recurring()
+
+    def __init_tags(self):
+        """Initializes the tags.
+
+        :return: None.
+        """
+        debit_credit: sa.Label = sa.case(
+            (JournalEntryLineItem.is_debit, "debit"),
+            else_="credit").label("debit_credit")
+        tag_type: sa.Label = sa.case(
+            (JournalEntryLineItem.description.like("_%—_%—_%→_%"), "bus"),
+            (sa.or_(JournalEntryLineItem.description.like("_%—_%→_%"),
+                    JournalEntryLineItem.description.like("_%—_%↔_%")),
+             "travel"),
+            else_="general").label("tag_type")
+        tag: sa.Label = get_prefix(JournalEntryLineItem.description, "—")\
+            .label("tag")
+        select: sa.Select = sa.Select(debit_credit, tag_type, tag,
+                                      JournalEntryLineItem.account_id,
+                                      sa.func.count().label("freq"))\
+            .filter(JournalEntryLineItem.description.is_not(None),
+                    JournalEntryLineItem.description.like("_%—_%"),
+                    JournalEntryLineItem.original_line_item_id.is_(None))\
+            .group_by(debit_credit, tag_type, tag,
+                      JournalEntryLineItem.account_id)
+        result: list[sa.Row] = db.session.execute(select).all()
+        accounts: dict[int, Account] \
+            = {x.id: x for x in Account.query
+               .filter(Account.id.in_({x.account_id for x in result})).all()}
+        debit_credit_dict: dict[t.Literal["debit", "credit"],
+                                DescriptionDebitCredit] \
+            = {x.debit_credit: x for x in {self.debit, self.credit}}
+        for row in result:
+            debit_credit_dict[row.debit_credit].add_tag(
+                row.tag_type, row.tag, accounts[row.account_id], row.freq)
+
+    def __init_recurring(self) -> None:
+        """Initializes the recurring transactions.
+
+        :return: None.
+        """
+        recurring: Recurring = options.recurring
+        accounts: dict[str, Account] \
+            = self.__get_accounts(recurring.codes)
+        self.debit.recurring \
+            = [DescriptionRecurring(x.name, accounts[x.account_code],
+                                    x.description_template)
+               for x in recurring.expenses]
+        self.credit.recurring \
+            = [DescriptionRecurring(x.name, accounts[x.account_code],
+                                    x.description_template)
+               for x in recurring.incomes]
+
+    @staticmethod
+    def __get_accounts(codes: set[str]) -> dict[str, Account]:
+        """Finds and returns the accounts by codes.
+
+        :param codes: The account codes.
+        :return: The account.
+        """
+        if len(codes) == 0:
+            return {}
+
+        def get_condition(code0: str) -> sa.BinaryExpression:
+            m: re.Match = re.match(r"^(\d{4})-(\d{3})$", code0)
+            assert m is not None,\
+                f"Malformed account code \"{code0}\" for regular transactions."
+            return sa.and_(Account.base_code == m.group(1),
+                           Account.no == int(m.group(2)))
+
+        conditions: list[sa.BinaryExpression] \
+            = [get_condition(x) for x in codes]
+        accounts: dict[str, Account] \
+            = {x.code: x for x in
+               Account.query.filter(sa.or_(*conditions)).all()}
+        for code in codes:
+            assert code in accounts,\
+                f"Unknown account \"{code}\" for regular transactions."
+        return accounts
+
+
+def get_prefix(string: str | sa.Column, separator: str | sa.Column) \
+        -> sa.Function:
+    """Returns the SQL function to find the prefix of a string.
+
+    :param string: The string.
+    :param separator: The separator.
+    :return: The position of the substring, starting from 1.
+    """
+    return sa.func.substr(string, 0, get_position(string, separator))
+
+
+def get_position(string: str | sa.Column, substring: str | sa.Column) \
+        -> sa.Function:
+    """Returns the SQL function to find the position of a substring.
+
+    :param string: The string.
+    :param substring: The substring.
+    :return: The position of the substring, starting from 1.
+    """
+    if db.engine.name == "postgresql":
+        return sa.func.strpos(string, substring)
+    return sa.func.instr(string, substring)

src/accounting/journal_entry/utils/offset_alias.py

@@ -0,0 +1,39 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/15
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The SQLAlchemy alias for the offset items.
+
+"""
+import typing as t
+
+import sqlalchemy as sa
+
+from accounting.models import JournalEntryLineItem
+
+
+def offset_alias() -> sa.Alias:
+    """Returns the SQLAlchemy alias for the offset items.
+
+    :return: The SQLAlchemy alias for the offset items.
+    """
+
+    def as_from(model_cls: t.Any) -> sa.FromClause:
+        return model_cls
+
+    def as_alias(alias: t.Any) -> sa.Alias:
+        return alias
+
+    return as_alias(sa.alias(as_from(JournalEntryLineItem), name="offset"))

src/accounting/journal_entry/utils/operators.py

@@ -0,0 +1,336 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/19
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The operators for different journal entry types.
+
+"""
+import typing as t
+from abc import ABC, abstractmethod
+
+from flask import render_template, request, abort
+from flask_wtf import FlaskForm
+
+from accounting.models import JournalEntry
+from accounting.template_globals import default_currency_code
+from accounting.utils.journal_entry_types import JournalEntryType
+from accounting.journal_entry.forms import JournalEntryForm, \
+    CashReceiptJournalEntryForm, CashDisbursementJournalEntryForm, \
+    TransferJournalEntryForm
+from accounting.journal_entry.forms.line_item import LineItemForm
+
+
+class JournalEntryOperator(ABC):
+    """The base journal entry operator."""
+    CHECK_ORDER: int = -1
+    """The order when checking the journal entry operator."""
+
+    @property
+    @abstractmethod
+    def form(self) -> t.Type[JournalEntryForm]:
+        """Returns the form class.
+
+        :return: The form class.
+        """
+
+    @abstractmethod
+    def render_create_template(self, form: FlaskForm) -> str:
+        """Renders the template for the form to create a journal entry.
+
+        :param form: The journal entry form.
+        :return: the form to create a journal entry.
+        """
+
+    @abstractmethod
+    def render_detail_template(self, journal_entry: JournalEntry) -> str:
+        """Renders the template for the detail page.
+
+        :param journal_entry: The journal entry.
+        :return: the detail page.
+        """
+
+    @abstractmethod
+    def render_edit_template(self, journal_entry: JournalEntry,
+                             form: FlaskForm) -> str:
+        """Renders the template for the form to edit a journal entry.
+
+        :param journal_entry: The journal entry.
+        :param form: The form.
+        :return: the form to edit a journal entry.
+        """
+
+    @abstractmethod
+    def is_my_type(self, journal_entry: JournalEntry) -> bool:
+        """Checks and returns whether the journal entry belongs to the type.
+
+        :param journal_entry: The journal entry.
+        :return: True if the journal entry belongs to the type, or False
+            otherwise.
+        """
+
+    @property
+    def _line_item_template(self) -> str:
+        """Renders and returns the template for the line item sub-form.
+
+        :return: The template for the line item sub-form.
+        """
+        return render_template(
+            "accounting/journal-entry/include/form-line-item.html",
+            currency_index="CURRENCY_INDEX",
+            debit_credit="DEBIT_CREDIT",
+            line_item_index="LINE_ITEM_INDEX",
+            form=LineItemForm())
+
+
+class CashReceiptJournalEntry(JournalEntryOperator):
+    """A cash receipt journal entry."""
+    CHECK_ORDER: int = 2
+    """The order when checking the journal entry operator."""
+
+    @property
+    def form(self) -> t.Type[JournalEntryForm]:
+        """Returns the form class.
+
+        :return: The form class.
+        """
+        return CashReceiptJournalEntryForm
+
+    def render_create_template(self, form: CashReceiptJournalEntryForm) -> str:
+        """Renders the template for the form to create a journal entry.
+
+        :param form: The journal entry form.
+        :return: the form to create a journal entry.
+        """
+        return render_template(
+            "accounting/journal-entry/receipt/create.html",
+            form=form,
+            journal_entry_type=JournalEntryType.CASH_RECEIPT,
+            currency_template=self.__currency_template,
+            line_item_template=self._line_item_template)
+
+    def render_detail_template(self, journal_entry: JournalEntry) -> str:
+        """Renders the template for the detail page.
+
+        :param journal_entry: The journal entry.
+        :return: the detail page.
+        """
+        return render_template("accounting/journal-entry/receipt/detail.html",
+                               obj=journal_entry)
+
+    def render_edit_template(self, journal_entry: JournalEntry,
+                             form: CashReceiptJournalEntryForm) -> str:
+        """Renders the template for the form to edit a journal entry.
+
+        :param journal_entry: The journal entry.
+        :param form: The form.
+        :return: the form to edit a journal entry.
+        """
+        return render_template("accounting/journal-entry/receipt/edit.html",
+                               journal_entry=journal_entry, form=form,
+                               currency_template=self.__currency_template,
+                               line_item_template=self._line_item_template)
+
+    def is_my_type(self, journal_entry: JournalEntry) -> bool:
+        """Checks and returns whether the journal entry belongs to the type.
+
+        :param journal_entry: The journal entry.
+        :return: True if the journal entry belongs to the type, or False
+            otherwise.
+        """
+        return journal_entry.is_cash_receipt
+
+    @property
+    def __currency_template(self) -> str:
+        """Renders and returns the template for the currency sub-form.
+
+        :return: The template for the currency sub-form.
+        """
+        return render_template(
+            "accounting/journal-entry/receipt/include/form-currency.html",
+            currency_index="CURRENCY_INDEX",
+            currency_code_data=default_currency_code(),
+            credit_total="-")
+
+
+class CashDisbursementJournalEntry(JournalEntryOperator):
+    """A cash disbursement journal entry."""
+    CHECK_ORDER: int = 1
+    """The order when checking the journal entry operator."""
+
+    @property
+    def form(self) -> t.Type[JournalEntryForm]:
+        """Returns the form class.
+
+        :return: The form class.
+        """
+        return CashDisbursementJournalEntryForm
+
+    def render_create_template(self, form: CashDisbursementJournalEntryForm) \
+            -> str:
+        """Renders the template for the form to create a journal entry.
+
+        :param form: The journal entry form.
+        :return: the form to create a journal entry.
+        """
+        return render_template(
+            "accounting/journal-entry/disbursement/create.html",
+            form=form,
+            journal_entry_type=JournalEntryType.CASH_DISBURSEMENT,
+            currency_template=self.__currency_template,
+            line_item_template=self._line_item_template)
+
+    def render_detail_template(self, journal_entry: JournalEntry) -> str:
+        """Renders the template for the detail page.
+
+        :param journal_entry: The journal entry.
+        :return: the detail page.
+        """
+        return render_template(
+            "accounting/journal-entry/disbursement/detail.html",
+            obj=journal_entry)
+
+    def render_edit_template(self, journal_entry: JournalEntry,
+                             form: CashDisbursementJournalEntryForm) -> str:
+        """Renders the template for the form to edit a journal entry.
+
+        :param journal_entry: The journal entry.
+        :param form: The form.
+        :return: the form to edit a journal entry.
+        """
+        return render_template(
+            "accounting/journal-entry/disbursement/edit.html",
+            journal_entry=journal_entry, form=form,
+            currency_template=self.__currency_template,
+            line_item_template=self._line_item_template)
+
+    def is_my_type(self, journal_entry: JournalEntry) -> bool:
+        """Checks and returns whether the journal entry belongs to the type.
+
+        :param journal_entry: The journal entry.
+        :return: True if the journal entry belongs to the type, or False
+            otherwise.
+        """
+        return journal_entry.is_cash_disbursement
+
+    @property
+    def __currency_template(self) -> str:
+        """Renders and returns the template for the currency sub-form.
+
+        :return: The template for the currency sub-form.
+        """
+        return render_template(
+            "accounting/journal-entry/disbursement/include/form-currency.html",
+            currency_index="CURRENCY_INDEX",
+            currency_code_data=default_currency_code(),
+            debit_total="-")
+
+
+class TransferJournalEntry(JournalEntryOperator):
+    """A transfer journal entry."""
+    CHECK_ORDER: int = 3
+    """The order when checking the journal entry operator."""
+
+    @property
+    def form(self) -> t.Type[JournalEntryForm]:
+        """Returns the form class.
+
+        :return: The form class.
+        """
+        return TransferJournalEntryForm
+
+    def render_create_template(self, form: TransferJournalEntryForm) -> str:
+        """Renders the template for the form to create a journal entry.
+
+        :param form: The journal entry form.
+        :return: the form to create a journal entry.
+        """
+        return render_template(
+            "accounting/journal-entry/transfer/create.html",
+            form=form,
+            journal_entry_type=JournalEntryType.TRANSFER,
+            currency_template=self.__currency_template,
+            line_item_template=self._line_item_template)
+
+    def render_detail_template(self, journal_entry: JournalEntry) -> str:
+        """Renders the template for the detail page.
+
+        :param journal_entry: The journal entry.
+        :return: the detail page.
+        """
+        return render_template("accounting/journal-entry/transfer/detail.html",
+                               obj=journal_entry)
+
+    def render_edit_template(self, journal_entry: JournalEntry,
+                             form: TransferJournalEntryForm) -> str:
+        """Renders the template for the form to edit a journal entry.
+
+        :param journal_entry: The journal entry.
+        :param form: The form.
+        :return: the form to edit a journal entry.
+        """
+        return render_template("accounting/journal-entry/transfer/edit.html",
+                               journal_entry=journal_entry, form=form,
+                               currency_template=self.__currency_template,
+                               line_item_template=self._line_item_template)
+
+    def is_my_type(self, journal_entry: JournalEntry) -> bool:
+        """Checks and returns whether the journal entry belongs to the type.
+
+        :param journal_entry: The journal entry.
+        :return: True if the journal entry belongs to the type, or False
+            otherwise.
+        """
+        return True
+
+    @property
+    def __currency_template(self) -> str:
+        """Renders and returns the template for the currency sub-form.
+
+        :return: The template for the currency sub-form.
+        """
+        return render_template(
+            "accounting/journal-entry/transfer/include/form-currency.html",
+            currency_index="CURRENCY_INDEX",
+            currency_code_data=default_currency_code(),
+            debit_total="-", credit_total="-")
+
+
+JOURNAL_ENTRY_TYPE_TO_OP: dict[JournalEntryType, JournalEntryOperator] \
+    = {JournalEntryType.CASH_RECEIPT: CashReceiptJournalEntry(),
+       JournalEntryType.CASH_DISBURSEMENT: CashDisbursementJournalEntry(),
+       JournalEntryType.TRANSFER: TransferJournalEntry()}
+"""The map from the journal entry types to their operators."""
+
+
+def get_journal_entry_op(journal_entry: JournalEntry,
+                         is_check_as: bool = False) -> JournalEntryOperator:
+    """Returns the journal entry operator that may be specified in the "as"
+    query parameter.  If it is not specified, check the journal entry type from
+    the journal entry.
+
+    :param journal_entry: The journal entry.
+    :param is_check_as: True to check the "as" parameter, or False otherwise.
+    :return: None.
+    """
+    if is_check_as and "as" in request.args:
+        type_dict: dict[str, JournalEntryType] \
+            = {x.value: x for x in JournalEntryType}
+        if request.args["as"] not in type_dict:
+            abort(404)
+        return JOURNAL_ENTRY_TYPE_TO_OP[type_dict[request.args["as"]]]
+    for journal_entry_type in sorted(JOURNAL_ENTRY_TYPE_TO_OP.values(),
+                                     key=lambda x: x.CHECK_ORDER):
+        if journal_entry_type.is_my_type(journal_entry):
+            return journal_entry_type

src/accounting/journal_entry/utils/original_line_items.py

@@ -0,0 +1,85 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/10
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The selectable original line items.
+
+"""
+from decimal import Decimal
+
+import sqlalchemy as sa
+from sqlalchemy.orm import selectinload
+
+from accounting import db
+from accounting.models import Account, JournalEntry, JournalEntryLineItem
+from accounting.utils.cast import be
+from .offset_alias import offset_alias
+
+
+def get_selectable_original_line_items(
+        line_item_id_on_form: set[int], is_payable: bool,
+        is_receivable: bool) -> list[JournalEntryLineItem]:
+    """Queries and returns the selectable original line items, with their net
+    balances.  The offset amounts of the form is excluded.
+
+    :param line_item_id_on_form: The ID of the line items on the form.
+    :param is_payable: True to check the payable original line items, or False
+        otherwise.
+    :param is_receivable: True to check the receivable original line items, or
+        False otherwise.
+    :return: The selectable original line items, with their net balances.
+    """
+    assert is_payable or is_receivable
+    offset: sa.Alias = offset_alias()
+    net_balance: sa.Label = (JournalEntryLineItem.amount + sa.func.sum(sa.case(
+        (offset.c.id.in_(line_item_id_on_form), 0),
+        (be(offset.c.is_debit == JournalEntryLineItem.is_debit),
+         offset.c.amount),
+        else_=-offset.c.amount))).label("net_balance")
+    conditions: list[sa.BinaryExpression] = [Account.is_need_offset]
+    sub_conditions: list[sa.BinaryExpression] = []
+    if is_payable:
+        sub_conditions.append(sa.and_(Account.base_code.startswith("2"),
+                                      sa.not_(JournalEntryLineItem.is_debit)))
+    if is_receivable:
+        sub_conditions.append(sa.and_(Account.base_code.startswith("1"),
+                                      JournalEntryLineItem.is_debit))
+    conditions.append(sa.or_(*sub_conditions))
+    select_net_balances: sa.Select \
+        = sa.select(JournalEntryLineItem.id, net_balance)\
+        .join(Account)\
+        .join(offset, be(JournalEntryLineItem.id
+                         == offset.c.original_line_item_id),
+              isouter=True)\
+        .filter(*conditions)\
+        .group_by(JournalEntryLineItem.id)\
+        .having(sa.or_(sa.func.count(offset.c.id) == 0, net_balance != 0))
+    net_balances: dict[int, Decimal] \
+        = {x.id: x.net_balance
+           for x in db.session.execute(select_net_balances).all()}
+    line_items: list[JournalEntryLineItem] = JournalEntryLineItem.query\
+        .filter(JournalEntryLineItem.id.in_({x for x in net_balances}))\
+        .join(JournalEntry)\
+        .order_by(JournalEntry.date, JournalEntry.no,
+                  JournalEntryLineItem.is_debit, JournalEntryLineItem.no)\
+        .options(selectinload(JournalEntryLineItem.currency),
+                 selectinload(JournalEntryLineItem.account),
+                 selectinload(JournalEntryLineItem.journal_entry)).all()
+    line_items.reverse()
+    for line_item in line_items:
+        line_item.net_balance = line_item.amount \
+            if net_balances[line_item.id] is None \
+            else net_balances[line_item.id]
+    return line_items

src/accounting/journal_entry/views.py

@@ -0,0 +1,238 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/18
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The views for the journal entry management.
+
+"""
+from datetime import date
+from urllib.parse import parse_qsl, urlencode
+
+import sqlalchemy as sa
+from flask import Blueprint, render_template, session, redirect, request, \
+    flash, url_for
+from werkzeug.datastructures import ImmutableMultiDict
+
+from accounting import db
+from accounting.locale import lazy_gettext
+from accounting.models import JournalEntry
+from accounting.utils.cast import s
+from accounting.utils.flash_errors import flash_form_errors
+from accounting.utils.next_uri import inherit_next, or_next
+from accounting.utils.permission import has_permission, can_view, can_edit
+from accounting.utils.journal_entry_types import JournalEntryType
+from accounting.utils.user import get_current_user_pk
+from .forms import sort_journal_entries_in, JournalEntryReorderForm
+from .template_filters import with_type, to_transfer, format_amount_input, \
+    text2html
+from .utils.operators import JournalEntryOperator, JOURNAL_ENTRY_TYPE_TO_OP, \
+    get_journal_entry_op
+
+bp: Blueprint = Blueprint("journal-entry", __name__)
+"""The view blueprint for the journal entry management."""
+bp.add_app_template_filter(with_type, "accounting_journal_entry_with_type")
+bp.add_app_template_filter(to_transfer, "accounting_journal_entry_to_transfer")
+bp.add_app_template_filter(format_amount_input,
+                           "accounting_journal_entry_format_amount_input")
+bp.add_app_template_filter(text2html, "accounting_journal_entry_text2html")
+
+
+@bp.get("/create/<journalEntryType:journal_entry_type>", endpoint="create")
+@has_permission(can_edit)
+def show_add_journal_entry_form(journal_entry_type: JournalEntryType) -> str:
+    """Shows the form to add a journal entry.
+
+    :param journal_entry_type: The journal entry type.
+    :return: The form to add a journal entry.
+    """
+    journal_entry_op: JournalEntryOperator \
+        = JOURNAL_ENTRY_TYPE_TO_OP[journal_entry_type]
+    form: journal_entry_op.form
+    if "form" in session:
+        form = journal_entry_op.form(
+            ImmutableMultiDict(parse_qsl(session["form"])))
+        del session["form"]
+        form.validate()
+    else:
+        form = journal_entry_op.form()
+        form.date.data = date.today()
+    return journal_entry_op.render_create_template(form)
+
+
+@bp.post("/store/<journalEntryType:journal_entry_type>", endpoint="store")
+@has_permission(can_edit)
+def add_journal_entry(journal_entry_type: JournalEntryType) -> redirect:
+    """Adds a journal entry.
+
+    :param journal_entry_type: The journal entry type.
+    :return: The redirection to the journal entry detail on success, or the
+        journal entry creation form on error.
+    """
+    journal_entry_op: JournalEntryOperator \
+        = JOURNAL_ENTRY_TYPE_TO_OP[journal_entry_type]
+    form: journal_entry_op.form = journal_entry_op.form(request.form)
+    if not form.validate():
+        flash_form_errors(form)
+        session["form"] = urlencode(list(request.form.items()))
+        return redirect(inherit_next(with_type(
+            url_for("accounting.journal-entry.create",
+                    journal_entry_type=journal_entry_type))))
+    journal_entry: JournalEntry = JournalEntry()
+    form.populate_obj(journal_entry)
+    db.session.add(journal_entry)
+    db.session.commit()
+    flash(s(lazy_gettext("The journal entry is added successfully.")),
+          "success")
+    return redirect(inherit_next(__get_detail_uri(journal_entry)))
+
+
+@bp.get("/<journalEntry:journal_entry>", endpoint="detail")
+@has_permission(can_view)
+def show_journal_entry_detail(journal_entry: JournalEntry) -> str:
+    """Shows the journal entry detail.
+
+    :param journal_entry: The journal entry.
+    :return: The detail.
+    """
+    journal_entry_op: JournalEntryOperator \
+        = get_journal_entry_op(journal_entry)
+    return journal_entry_op.render_detail_template(journal_entry)
+
+
+@bp.get("/<journalEntry:journal_entry>/edit", endpoint="edit")
+@has_permission(can_edit)
+def show_journal_entry_edit_form(journal_entry: JournalEntry) -> str:
+    """Shows the form to edit a journal entry.
+
+    :param journal_entry: The journal entry.
+    :return: The form to edit the journal entry.
+    """
+    journal_entry_op: JournalEntryOperator \
+        = get_journal_entry_op(journal_entry, is_check_as=True)
+    form: journal_entry_op.form
+    if "form" in session:
+        form = journal_entry_op.form(
+            ImmutableMultiDict(parse_qsl(session["form"])))
+        del session["form"]
+        form.obj = journal_entry
+        form.validate()
+    else:
+        form = journal_entry_op.form(obj=journal_entry)
+    return journal_entry_op.render_edit_template(journal_entry, form)
+
+
+@bp.post("/<journalEntry:journal_entry>/update", endpoint="update")
+@has_permission(can_edit)
+def update_journal_entry(journal_entry: JournalEntry) -> redirect:
+    """Updates a journal entry.
+
+    :param journal_entry: The journal entry.
+    :return: The redirection to the journal entry detail on success, or the
+        journal entry edit form on error.
+    """
+    journal_entry_op: JournalEntryOperator \
+        = get_journal_entry_op(journal_entry, is_check_as=True)
+    form: journal_entry_op.form = journal_entry_op.form(request.form)
+    form.obj = journal_entry
+    if not form.validate():
+        flash_form_errors(form)
+        session["form"] = urlencode(list(request.form.items()))
+        return redirect(inherit_next(with_type(
+            url_for("accounting.journal-entry.edit",
+                    journal_entry=journal_entry))))
+    with db.session.no_autoflush:
+        form.populate_obj(journal_entry)
+    if not form.is_modified:
+        flash(s(lazy_gettext("The journal entry was not modified.")),
+              "success")
+        return redirect(inherit_next(__get_detail_uri(journal_entry)))
+    journal_entry.updated_by_id = get_current_user_pk()
+    journal_entry.updated_at = sa.func.now()
+    db.session.commit()
+    flash(s(lazy_gettext("The journal entry is updated successfully.")),
+          "success")
+    return redirect(inherit_next(__get_detail_uri(journal_entry)))
+
+
+@bp.post("/<journalEntry:journal_entry>/delete", endpoint="delete")
+@has_permission(can_edit)
+def delete_journal_entry(journal_entry: JournalEntry) -> redirect:
+    """Deletes a journal entry.
+
+    :param journal_entry: The journal entry.
+    :return: The redirection to the journal entry list on success, or the
+        journal entry detail on error.
+    """
+    if not journal_entry.can_delete:
+        flash(s(lazy_gettext("The journal entry cannot be deleted.")), "error")
+        return redirect(inherit_next(__get_detail_uri(journal_entry)))
+    journal_entry.delete()
+    sort_journal_entries_in(journal_entry.date, journal_entry.id)
+    db.session.commit()
+    flash(s(lazy_gettext("The journal entry is deleted successfully.")),
+          "success")
+    return redirect(or_next(__get_default_page_uri()))
+
+
+@bp.get("/dates/<date:journal_entry_date>", endpoint="order")
+@has_permission(can_view)
+def show_journal_entry_order(journal_entry_date: date) -> str:
+    """Shows the order of the journal entries in a same date.
+
+    :param journal_entry_date: The date.
+    :return: The order of the journal entries in the date.
+    """
+    journal_entries: list[JournalEntry] = JournalEntry.query \
+        .filter(JournalEntry.date == journal_entry_date) \
+        .order_by(JournalEntry.no).all()
+    return render_template("accounting/journal-entry/order.html",
+                           date=journal_entry_date, list=journal_entries)
+
+
+@bp.post("/dates/<date:journal_entry_date>", endpoint="sort")
+@has_permission(can_edit)
+def sort_journal_entries(journal_entry_date: date) -> redirect:
+    """Reorders the journal entries in a date.
+
+    :param journal_entry_date: The date.
+    :return: The redirection to the incoming account or the account list.  The
+        reordering operation does not fail.
+    """
+    form: JournalEntryReorderForm = JournalEntryReorderForm(journal_entry_date)
+    form.save_order()
+    if not form.is_modified:
+        flash(s(lazy_gettext("The order was not modified.")), "success")
+        return redirect(or_next(__get_default_page_uri()))
+    db.session.commit()
+    flash(s(lazy_gettext("The order is updated successfully.")), "success")
+    return redirect(or_next(__get_default_page_uri()))
+
+
+def __get_detail_uri(journal_entry: JournalEntry) -> str:
+    """Returns the detail URI of a journal entry.
+
+    :param journal_entry: The journal entry.
+    :return: The detail URI of the journal entry.
+    """
+    return url_for("accounting.journal-entry.detail",
+                   journal_entry=journal_entry)
+
+
+def __get_default_page_uri() -> str:
+    """Returns the URI for the default page.
+
+    :return: The URI for the default page.
+    """
+    return url_for("accounting-report.default")

src/accounting/locale.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/25
 
 #  Copyright (c) 2023 imacat.

src/accounting/models.py

@@ -1,4 +1,4 @@
-# The Mia! Accounting Flask Project.
+# The Mia! Accounting Project.
 # Author: imacat@mail.imacat.idv.tw (imacat), 2023/1/25
 
 #  Copyright (c) 2023 imacat.
@@ -24,8 +24,8 @@ import typing as t
 from decimal import Decimal
 
 import sqlalchemy as sa
-from flask import current_app
-from flask_babel import get_locale
+from babel import Locale
+from flask_babel import get_locale, get_babel
 from sqlalchemy import text
 
 from accounting import db
@@ -52,7 +52,7 @@ class BaseAccount(db.Model):
 
         :return: The string representation of the base account.
         """
-        return F"{self.code} {self.title}"
+        return f"{self.code} {self.title.title()}"
 
     @property
     def title(self) -> str:
@@ -60,11 +60,11 @@ class BaseAccount(db.Model):
 
         :return: The title in the current locale.
         """
-        current_locale = str(get_locale())
-        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+        current_locale: Locale = get_locale()
+        if current_locale == get_babel().instance.default_locale:
             return self.title_l10n
         for l10n in self.l10n:
-            if l10n.locale == current_locale:
+            if l10n.locale == str(current_locale):
                 return l10n.title
         return self.title_l10n
 
@@ -113,8 +113,8 @@ class Account(db.Model):
     """The account number under the base account."""
     title_l10n = db.Column("title", db.String, nullable=False)
     """The title."""
-    is_pay_off_needed = db.Column(db.Boolean, nullable=False, default=False)
-    """Whether the entries of this account need pay-off."""
+    is_need_offset = db.Column(db.Boolean, nullable=False, default=False)
+    """Whether the journal entry line items of this account need offset."""
     created_at = db.Column(db.DateTime(timezone=True), nullable=False,
                            server_default=db.func.now())
     """The time of creation."""
@@ -138,20 +138,15 @@ class Account(db.Model):
     l10n = db.relationship("AccountL10n", back_populates="account",
                            lazy=False)
     """The localized titles."""
-    entries = db.relationship("JournalEntry", back_populates="account")
-    """The journal entries."""
+    line_items = db.relationship("JournalEntryLineItem",
+                                 back_populates="account")
+    """The journal entry line items."""
 
-    __CASH = "1111-001"
+    CASH_CODE: str = "1111-001"
     """The code of the cash account,"""
-    __RECEIVABLE = "1141-001"
-    """The code of the receivable account,"""
-    __PAYABLE = "2141-001"
-    """The code of the payable account,"""
-    __ACCUMULATED_CHANGE = "3351-001"
+    ACCUMULATED_CHANGE_CODE: str = "3351-001"
     """The code of the accumulated-change account,"""
-    __BROUGHT_FORWARD = "3352-001"
-    """The code of the brought-forward account,"""
-    __NET_CHANGE = "3353-001"
+    NET_CHANGE_CODE: str = "3353-001"
     """The code of the net-change account,"""
 
     def __str__(self) -> str:
@@ -159,7 +154,7 @@ class Account(db.Model):
 
         :return: The string representation of this account.
         """
-        return F"{self.base_code}-{self.no:03d} {self.title}"
+        return f"{self.base_code}-{self.no:03d} {self.title.title()}"
 
     @property
     def code(self) -> str:
@@ -167,7 +162,7 @@ class Account(db.Model):
 
         :return: The code.
         """
-        return F"{self.base_code}-{self.no:03d}"
+        return f"{self.base_code}-{self.no:03d}"
 
     @property
     def title(self) -> str:
@@ -175,11 +170,11 @@ class Account(db.Model):
 
         :return: The title in the current locale.
         """
-        current_locale = str(get_locale())
-        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+        current_locale: Locale = get_locale()
+        if current_locale == get_babel().instance.default_locale:
             return self.title_l10n
         for l10n in self.l10n:
-            if l10n.locale == current_locale:
+            if l10n.locale == str(current_locale):
                 return l10n.title
         return self.title_l10n
 
@@ -193,34 +188,71 @@ class Account(db.Model):
         if self.title_l10n is None:
             self.title_l10n = value
             return
-        current_locale = str(get_locale())
-        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+        current_locale: Locale = get_locale()
+        if current_locale == get_babel().instance.default_locale:
             self.title_l10n = value
             return
         for l10n in self.l10n:
-            if l10n.locale == current_locale:
+            if l10n.locale == str(current_locale):
                 l10n.title = value
                 return
-        self.l10n.append(AccountL10n(locale=current_locale, title=value))
+        self.l10n.append(AccountL10n(locale=str(current_locale), title=value))
 
     @property
-    def is_in_use(self) -> bool:
-        """Returns whether the account is in use.
+    def is_real(self) -> bool:
+        """Returns whether the account is a real account.
 
-        :return: True if the account is in use, or False otherwise.
+        :return: True if the account is a real account, or False otherwise.
         """
-        if not hasattr(self, "__is_in_use"):
-            setattr(self, "__is_in_use", len(self.entries) > 0)
-        return getattr(self, "__is_in_use")
+        return self.base_code[0] in {"1", "2", "3"}
 
-    @is_in_use.setter
-    def is_in_use(self, is_in_use: bool) -> None:
-        """Sets whether the account is in use.
+    @property
+    def is_nominal(self) -> bool:
+        """Returns whether the account is a nominal account.
+
+        :return: True if the account is a nominal account, or False otherwise.
+        """
+        return not self.is_real
+
+    @property
+    def query_values(self) -> list[str]:
+        """Returns the values to be queried.
+
+        :return: The values to be queried.
+        """
+        return [self.code, self.title_l10n] + [x.title for x in self.l10n]
+
+    @property
+    def is_modified(self) -> bool:
+        """Returns whether a product account was modified.
+
+        :return: True if modified, or False otherwise.
+        """
+        if db.session.is_modified(self):
+            return True
+        for l10n in self.l10n:
+            if db.session.is_modified(l10n):
+                return True
+        return False
+
+    @property
+    def can_delete(self) -> bool:
+        """Returns whether the account can be deleted.
+
+        :return: True if the account can be deleted, or False otherwise.
+        """
+        if self.code in {"1111-001", "3351-001", "3353-001"}:
+            return False
+        return len(self.line_items) == 0
+
+    def delete(self) -> None:
+        """Deletes this account.
 
-        :param is_in_use: True if the account is in use, or False otherwise.
         :return: None.
         """
-        setattr(self, "__is_in_use", is_in_use)
+        AccountL10n.query.filter(AccountL10n.account == self).delete()
+        cls: t.Type[t.Self] = self.__class__
+        cls.query.filter(cls.id == self.id).delete()
 
     @classmethod
     def find_by_code(cls, code: str) -> t.Self | None:
@@ -236,13 +268,15 @@ class Account(db.Model):
                                 cls.no == int(m.group(2))).first()
 
     @classmethod
-    def debit(cls) -> list[t.Self]:
-        """Returns the debit accounts.
+    def selectable_debit(cls) -> list[t.Self]:
+        """Returns the selectable debit accounts.
+        Payable line items can not start from debit.
 
-        :return: The debit accounts.
+        :return: The selectable debit accounts.
         """
         return cls.query.filter(sa.or_(cls.base_code.startswith("1"),
-                                       cls.base_code.startswith("2"),
+                                       sa.and_(cls.base_code.startswith("2"),
+                                               sa.not_(cls.is_need_offset)),
                                        cls.base_code.startswith("3"),
                                        cls.base_code.startswith("5"),
                                        cls.base_code.startswith("6"),
@@ -257,12 +291,14 @@ class Account(db.Model):
             .order_by(cls.base_code, cls.no).all()
 
     @classmethod
-    def credit(cls) -> list[t.Self]:
-        """Returns the debit accounts.
+    def selectable_credit(cls) -> list[t.Self]:
+        """Returns the selectable debit accounts.
+        Receivable line items can not start from credit.
 
-        :return: The debit accounts.
+        :return: The selectable debit accounts.
         """
-        return cls.query.filter(sa.or_(cls.base_code.startswith("1"),
+        return cls.query.filter(sa.or_(sa.and_(cls.base_code.startswith("1"),
+                                               sa.not_(cls.is_need_offset)),
                                        cls.base_code.startswith("2"),
                                        cls.base_code.startswith("3"),
                                        cls.base_code.startswith("4"),
@@ -276,37 +312,13 @@ class Account(db.Model):
                                 cls.base_code != "3353")\
             .order_by(cls.base_code, cls.no).all()
 
-    @property
-    def query_values(self) -> list[str]:
-        """Returns the values to be queried.
-
-        :return: The values to be queried.
-        """
-        return [self.code, self.title_l10n] + [x.title for x in self.l10n]
-
     @classmethod
     def cash(cls) -> t.Self:
         """Returns the cash account.
 
         :return: The cash account
         """
-        return cls.find_by_code(cls.__CASH)
-
-    @classmethod
-    def receivable(cls) -> t.Self:
-        """Returns the receivable account.
-
-        :return: The receivable account
-        """
-        return cls.find_by_code(cls.__RECEIVABLE)
-
-    @classmethod
-    def payable(cls) -> t.Self:
-        """Returns the payable account.
-
-        :return: The payable account
-        """
-        return cls.find_by_code(cls.__PAYABLE)
+        return cls.find_by_code(cls.CASH_CODE)
 
     @classmethod
     def accumulated_change(cls) -> t.Self:
@@ -314,45 +326,7 @@ class Account(db.Model):
 
         :return: The accumulated-change account
         """
-        return cls.find_by_code(cls.__ACCUMULATED_CHANGE)
-
-    @classmethod
-    def brought_forward(cls) -> t.Self:
-        """Returns the brought-forward account.
-
-        :return: The brought-forward account
-        """
-        return cls.find_by_code(cls.__BROUGHT_FORWARD)
-
-    @classmethod
-    def net_change(cls) -> t.Self:
-        """Returns the net-change account.
-
-        :return: The net-change account
-        """
-        return cls.find_by_code(cls.__NET_CHANGE)
-
-    @property
-    def is_modified(self) -> bool:
-        """Returns whether a product account was modified.
-
-        :return: True if modified, or False otherwise.
-        """
-        if db.session.is_modified(self):
-            return True
-        for l10n in self.l10n:
-            if db.session.is_modified(l10n):
-                return True
-        return False
-
-    def delete(self) -> None:
-        """Deletes this account.
-
-        :return: None.
-        """
-        AccountL10n.query.filter(AccountL10n.account == self).delete()
-        cls: t.Type[t.Self] = self.__class__
-        cls.query.filter(cls.id == self.id).delete()
+        return cls.find_by_code(cls.ACCUMULATED_CHANGE_CODE)
 
 
 class AccountL10n(db.Model):
@@ -403,15 +377,16 @@ class Currency(db.Model):
     l10n = db.relationship("CurrencyL10n", back_populates="currency",
                            lazy=False)
     """The localized names."""
-    entries = db.relationship("JournalEntry", back_populates="currency")
-    """The journal entries."""
+    line_items = db.relationship("JournalEntryLineItem",
+                                 back_populates="currency")
+    """The journal entry line items."""
 
     def __str__(self) -> str:
         """Returns the string representation of the currency.
 
         :return: The string representation of the currency.
         """
-        return F"{self.name} ({self.code})"
+        return f"{self.name.title()} ({self.code})"
 
     @property
     def name(self) -> str:
@@ -419,11 +394,11 @@ class Currency(db.Model):
 
         :return: The name in the current locale.
         """
-        current_locale = str(get_locale())
-        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+        current_locale: Locale = get_locale()
+        if current_locale == get_babel().instance.default_locale:
             return self.name_l10n
         for l10n in self.l10n:
-            if l10n.locale == current_locale:
+            if l10n.locale == str(current_locale):
                 return l10n.name
         return self.name_l10n
 
@@ -437,15 +412,15 @@ class Currency(db.Model):
         if self.name_l10n is None:
             self.name_l10n = value
             return
-        current_locale = str(get_locale())
-        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+        current_locale: Locale = get_locale()
+        if current_locale == get_babel().instance.default_locale:
             self.name_l10n = value
             return
         for l10n in self.l10n:
-            if l10n.locale == current_locale:
+            if l10n.locale == str(current_locale):
                 l10n.name = value
                 return
-        self.l10n.append(CurrencyL10n(locale=current_locale, name=value))
+        self.l10n.append(CurrencyL10n(locale=str(current_locale), name=value))
 
     @property
     def is_modified(self) -> bool:
@@ -460,6 +435,17 @@ class Currency(db.Model):
                 return True
         return False
 
+    @property
+    def can_delete(self) -> bool:
+        """Returns whether the currency can be deleted.
+
+        :return: True if the currency can be deleted, or False otherwise.
+        """
+        from accounting.template_globals import default_currency_code
+        if self.code == default_currency_code():
+            return False
+        return len(self.line_items) == 0
+
     def delete(self) -> None:
         """Deletes the currency.
 
@@ -487,23 +473,23 @@ class CurrencyL10n(db.Model):
     """The localized name."""
 
 
-class TransactionCurrency:
-    """A currency in a transaction."""
+class JournalEntryCurrency:
+    """A currency in a journal entry."""
 
-    def __init__(self, code: str, debit: list[JournalEntry],
-                 credit: list[JournalEntry]):
-        """Constructs the currency in the transaction.
+    def __init__(self, code: str, debit: list[JournalEntryLineItem],
+                 credit: list[JournalEntryLineItem]):
+        """Constructs the currency in the journal entry.
 
         :param code: The currency code.
-        :param debit: The debit entries.
-        :param credit: The credit entries.
+        :param debit: The debit line items.
+        :param credit: The credit line items.
         """
         self.code: str = code
         """The currency code."""
-        self.debit: list[JournalEntry] = debit
-        """The debit entries."""
-        self.credit: list[JournalEntry] = credit
-        """The credit entries."""
+        self.debit: list[JournalEntryLineItem] = debit
+        """The debit line items."""
+        self.credit: list[JournalEntryLineItem] = credit
+        """The credit line items."""
 
     @property
     def name(self) -> str:
@@ -515,28 +501,28 @@ class TransactionCurrency:
 
     @property
     def debit_total(self) -> Decimal:
-        """Returns the total amount of the debit journal entries.
+        """Returns the total amount of the debit line items.
 
-        :return: The total amount of the debit journal entries.
+        :return: The total amount of the debit line items.
         """
         return sum([x.amount for x in self.debit])
 
     @property
     def credit_total(self) -> str:
-        """Returns the total amount of the credit journal entries.
+        """Returns the total amount of the credit line items.
 
-        :return: The total amount of the credit journal entries.
+        :return: The total amount of the credit line items.
         """
         return sum([x.amount for x in self.credit])
 
 
-class Transaction(db.Model):
-    """A transaction."""
-    __tablename__ = "accounting_transactions"
+class JournalEntry(db.Model):
+    """A journal entry."""
+    __tablename__ = "accounting_journal_entries"
     """The table name."""
     id = db.Column(db.Integer, nullable=False, primary_key=True,
                    autoincrement=False)
-    """The transaction ID."""
+    """The journal entry ID."""
     date = db.Column(db.Date, nullable=False)
     """The date."""
     no = db.Column(db.Integer, nullable=False, default=text("1"))
@@ -563,35 +549,38 @@ class Transaction(db.Model):
     """The ID of the updator."""
     updated_by = db.relationship(user_cls, foreign_keys=updated_by_id)
     """The updator."""
-    entries = db.relationship("JournalEntry", back_populates="transaction")
-    """The journal entries."""
+    line_items = db.relationship("JournalEntryLineItem",
+                                 back_populates="journal_entry")
+    """The line items."""
 
     def __str__(self) -> str:
-        """Returns the string representation of this transaction.
+        """Returns the string representation of this journal entry.
 
-        :return: The string representation of this transaction.
+        :return: The string representation of this journal entry.
         """
-        if self.is_cash_expense:
-            return gettext("Cash Expense Transaction#%(id)s", id=self.id)
-        if self.is_cash_income:
-            return gettext("Cash Income Transaction#%(id)s", id=self.id)
-        return gettext("Transfer Transaction#%(id)s", id=self.id)
+        if self.is_cash_disbursement:
+            return gettext("Cash Disbursement Journal Entry#%(id)s",
+                           id=self.id)
+        if self.is_cash_receipt:
+            return gettext("Cash Receipt Journal Entry#%(id)s", id=self.id)
+        return gettext("Transfer Journal Entry#%(id)s", id=self.id)
 
     @property
-    def currencies(self) -> list[TransactionCurrency]:
-        """Returns the journal entries categorized by their currencies.
+    def currencies(self) -> list[JournalEntryCurrency]:
+        """Returns the line items categorized by their currencies.
 
         :return: The currency categories.
         """
-        entries: list[JournalEntry] = sorted(self.entries, key=lambda x: x.no)
+        line_items: list[JournalEntryLineItem] = sorted(self.line_items,
+                                                        key=lambda x: x.no)
         codes: list[str] = []
-        by_currency: dict[str, list[JournalEntry]] = {}
-        for entry in entries:
-            if entry.currency_code not in by_currency:
-                codes.append(entry.currency_code)
-                by_currency[entry.currency_code] = []
-            by_currency[entry.currency_code].append(entry)
-        return [TransactionCurrency(code=x,
+        by_currency: dict[str, list[JournalEntryLineItem]] = {}
+        for line_item in line_items:
+            if line_item.currency_code not in by_currency:
+                codes.append(line_item.currency_code)
+                by_currency[line_item.currency_code] = []
+            by_currency[line_item.currency_code].append(line_item)
+        return [JournalEntryCurrency(code=x,
                                      debit=[y for y in by_currency[x]
                                             if y.is_debit],
                                      credit=[y for y in by_currency[x]
@@ -599,96 +588,116 @@ class Transaction(db.Model):
                 for x in codes]
 
     @property
-    def is_cash_income(self) -> bool:
-        """Returns whether this is a cash income transaction.
+    def is_cash_receipt(self) -> bool:
+        """Returns whether this is a cash receipt journal entry.
 
-        :return: True if this is a cash income transaction, or False otherwise.
+        :return: True if this is a cash receipt journal entry, or False
+            otherwise.
         """
         for currency in self.currencies:
             if len(currency.debit) > 1:
                 return False
-            if currency.debit[0].account.code != "1111-001":
+            if currency.debit[0].account.code != Account.CASH_CODE:
                 return False
         return True
 
     @property
-    def is_cash_expense(self) -> bool:
-        """Returns whether this is a cash expense transaction.
+    def is_cash_disbursement(self) -> bool:
+        """Returns whether this is a cash disbursement journal entry.
 
-        :return: True if this is a cash expense transaction, or False
+        :return: True if this is a cash disbursement journal entry, or False
             otherwise.
         """
         for currency in self.currencies:
             if len(currency.credit) > 1:
                 return False
-            if currency.credit[0].account.code != "1111-001":
+            if currency.credit[0].account.code != Account.CASH_CODE:
+                return False
+        return True
+
+    @property
+    def can_delete(self) -> bool:
+        """Returns whether the journal entry can be deleted.
+
+        :return: True if the journal entry can be deleted, or False otherwise.
+        """
+        for line_item in self.line_items:
+            if len(line_item.offsets) > 0:
                 return False
         return True
 
     def delete(self) -> None:
-        """Deletes the transaction.
+        """Deletes the journal entry.
 
         :return: None.
         """
-        JournalEntry.query\
-            .filter(JournalEntry.transaction_id == self.id).delete()
+        JournalEntryLineItem.query\
+            .filter(JournalEntryLineItem.journal_entry_id == self.id).delete()
         db.session.delete(self)
 
 
-class JournalEntry(db.Model):
-    """An accounting journal entry."""
-    __tablename__ = "accounting_journal_entries"
+class JournalEntryLineItem(db.Model):
+    """A line item in the journal entry."""
+    __tablename__ = "accounting_journal_entry_line_items"
     """The table name."""
     id = db.Column(db.Integer, nullable=False, primary_key=True,
                    autoincrement=False)
-    """The entry ID."""
-    transaction_id = db.Column(db.Integer,
-                               db.ForeignKey(Transaction.id,
+    """The line item ID."""
+    journal_entry_id = db.Column(db.Integer,
+                                 db.ForeignKey(JournalEntry.id,
                                                onupdate="CASCADE",
                                                ondelete="CASCADE"),
                                  nullable=False)
-    """The transaction ID."""
-    transaction = db.relationship(Transaction, back_populates="entries")
-    """The transaction."""
+    """The journal entry ID."""
+    journal_entry = db.relationship(JournalEntry, back_populates="line_items")
+    """The journal entry."""
     is_debit = db.Column(db.Boolean, nullable=False)
-    """True for a debit entry, or False for a credit entry."""
+    """True for a debit line item, or False for a credit line item."""
     no = db.Column(db.Integer, nullable=False)
-    """The entry number under the transaction and debit or credit."""
-    pay_off_target_id = db.Column(db.Integer,
+    """The line item number under the journal entry and debit or credit."""
+    original_line_item_id = db.Column(db.Integer,
                                       db.ForeignKey(id, onupdate="CASCADE"),
                                       nullable=True)
-    """The ID of the pay-off target entry."""
-    pay_off_target = db.relationship("JournalEntry", back_populates="pay_off",
+    """The ID of the original line item."""
+    original_line_item = db.relationship("JournalEntryLineItem",
+                                         back_populates="offsets",
                                          remote_side=id, passive_deletes=True)
-    """The pay-off target entry."""
-    pay_off = db.relationship("JournalEntry", back_populates="pay_off_target")
-    """The pay-off entries."""
+    """The original line item."""
+    offsets = db.relationship("JournalEntryLineItem",
+                              back_populates="original_line_item")
+    """The offset items."""
     currency_code = db.Column(db.String,
                               db.ForeignKey(Currency.code, onupdate="CASCADE"),
                               nullable=False)
     """The currency code."""
-    currency = db.relationship(Currency, back_populates="entries")
+    currency = db.relationship(Currency, back_populates="line_items")
     """The currency."""
     account_id = db.Column(db.Integer,
                            db.ForeignKey(Account.id,
                                          onupdate="CASCADE"),
                            nullable=False)
     """The account ID."""
-    account = db.relationship(Account, back_populates="entries", lazy=False)
+    account = db.relationship(Account, back_populates="line_items", lazy=False)
     """The account."""
-    summary = db.Column(db.String, nullable=True)
-    """The summary."""
+    description = db.Column(db.String, nullable=True)
+    """The description."""
     amount = db.Column(db.Numeric(14, 2), nullable=False)
     """The amount."""
 
-    @property
-    def eid(self) -> int | None:
-        """Returns the journal entry ID.  This is the alternative name of the
-        ID field, to work with WTForms.
+    def __str__(self) -> str:
+        """Returns the string representation of the line item.
 
-        :return: The journal entry ID.
+        :return: The string representation of the line item.
         """
-        return self.id
+        if not hasattr(self, "__str"):
+            from accounting.template_filters import format_date, format_amount
+            setattr(self, "__str",
+                    gettext("%(date)s %(description)s %(amount)s",
+                            date=format_date(self.journal_entry.date),
+                            description="" if self.description is None
+                            else self.description,
+                            amount=format_amount(self.amount)))
+        return getattr(self, "__str")
 
     @property
     def account_code(self) -> str:
@@ -697,3 +706,101 @@ class JournalEntry(db.Model):
         :return: The account code.
         """
         return self.account.code
+
+    @property
+    def debit(self) -> Decimal | None:
+        """Returns the debit amount.
+
+        :return: The debit amount, or None if this is not a debit line item.
+        """
+        return self.amount if self.is_debit else None
+
+    @property
+    def is_need_offset(self) -> bool:
+        """Returns whether the line item needs offset.
+
+        :return: True if the line item needs offset, or False otherwise.
+        """
+        if not self.account.is_need_offset:
+            return False
+        if self.account.base_code[0] == "1" and not self.is_debit:
+            return False
+        if self.account.base_code[0] == "2" and self.is_debit:
+            return False
+        return True
+
+    @property
+    def credit(self) -> Decimal | None:
+        """Returns the credit amount.
+
+        :return: The credit amount, or None if this is not a credit line item.
+        """
+        return None if self.is_debit else self.amount
+
+    @property
+    def net_balance(self) -> Decimal:
+        """Returns the net balance.
+
+        :return: The net balance.
+        """
+        if not hasattr(self, "__net_balance"):
+            setattr(self, "__net_balance", self.amount + sum(
+                [x.amount if x.is_debit == self.is_debit else -x.amount
+                 for x in self.offsets]))
+        return getattr(self, "__net_balance")
+
+    @net_balance.setter
+    def net_balance(self, net_balance: Decimal) -> None:
+        """Sets the net balance.
+
+        :param net_balance: The net balance.
+        :return: None.
+        """
+        setattr(self, "__net_balance", net_balance)
+
+    @property
+    def query_values(self) -> list[str]:
+        """Returns the values to be queried.
+
+        :return: The values to be queried.
+        """
+        def format_amount(value: Decimal) -> str:
+            whole: int = int(value)
+            frac: Decimal = (value - whole).normalize()
+            return str(whole) + str(abs(frac))[1:]
+
+        return ["{}/{}/{}".format(self.journal_entry.date.year,
+                                  self.journal_entry.date.month,
+                                  self.journal_entry.date.day),
+                "" if self.description is None else self.description,
+                format_amount(self.amount)]
+
+
+class Option(db.Model):
+    """An option."""
+    __tablename__ = "accounting_options"
+    """The table name."""
+    name = db.Column(db.String, nullable=False, primary_key=True)
+    """The name."""
+    value = db.Column(db.Text, nullable=False)
+    """The option value."""
+    created_at = db.Column(db.DateTime(timezone=True), nullable=False,
+                           server_default=db.func.now())
+    """The time of creation."""
+    created_by_id = db.Column(db.Integer,
+                              db.ForeignKey(user_pk_column,
+                                            onupdate="CASCADE"),
+                              nullable=False)
+    """The ID of the creator."""
+    created_by = db.relationship(user_cls, foreign_keys=created_by_id)
+    """The creator."""
+    updated_at = db.Column(db.DateTime(timezone=True), nullable=False,
+                           server_default=db.func.now())
+    """The time of last update."""
+    updated_by_id = db.Column(db.Integer,
+                              db.ForeignKey(user_pk_column,
+                                            onupdate="CASCADE"),
+                              nullable=False)
+    """The ID of the updator."""
+    updated_by = db.relationship(user_cls, foreign_keys=updated_by_id)
+    """The updator."""

src/accounting/option/__init__.py

@@ -0,0 +1,30 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/22
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The option management.
+
+"""
+from flask import Blueprint
+
+
+def init_app(bp: Blueprint) -> None:
+    """Initialize the application.
+
+    :param bp: The blueprint of the accounting application.
+    :return: None.
+    """
+    from .views import bp as option_bp
+    bp.register_blueprint(option_bp, url_prefix="/options")

src/accounting/option/forms.py

@@ -0,0 +1,269 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/22
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The forms for the option management.
+
+"""
+from flask import render_template
+from flask_babel import LazyString
+from flask_wtf import FlaskForm
+from wtforms import StringField, FieldList, FormField, IntegerField
+from wtforms.validators import DataRequired, ValidationError
+
+from accounting.forms import ACCOUNT_REQUIRED, CurrencyExists, AccountExists, \
+    IsDebitAccount, IsCreditAccount
+from accounting.locale import lazy_gettext
+from accounting.models import Account
+from accounting.utils.current_account import CurrentAccount
+from accounting.utils.options import Options
+from accounting.utils.strip_text import strip_text
+
+
+class CurrentAccountExists:
+    """The validator to check that the current account exists."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None or field.data == CurrentAccount.CURRENT_AL_CODE:
+            return
+        if Account.find_by_code(field.data) is None:
+            raise ValidationError(lazy_gettext(
+                "The account does not exist."))
+
+
+class AccountNotCurrent:
+    """The validator to check that the account is a current account."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None or field.data == CurrentAccount.CURRENT_AL_CODE:
+            return
+        if field.data[:2] not in {"11", "12", "21", "22"}:
+            raise ValidationError(lazy_gettext(
+                "This is not a current account."))
+
+
+class NotStartPayableFromExpense:
+    """The validator to check that a payable line item does not start from
+    expense."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None or field.data[0] != "2":
+            return
+        account: Account | None = Account.find_by_code(field.data)
+        if account is not None and account.is_need_offset:
+            raise ValidationError(lazy_gettext(
+                "You cannot select a payable account as expense."))
+
+
+class NotStartReceivableFromIncome:
+    """The validator to check that a receivable line item does not start
+    from income."""
+
+    def __call__(self, form: FlaskForm, field: StringField) -> None:
+        if field.data is None or field.data[0] != "1":
+            return
+        account: Account | None = Account.find_by_code(field.data)
+        if account is not None and account.is_need_offset:
+            raise ValidationError(lazy_gettext(
+                "You cannot select a receivable account as income."))
+
+
+class RecurringItemForm(FlaskForm):
+    """The base sub-form to add or update the recurring item."""
+    no = IntegerField()
+    """The order number of this recurring item."""
+    name = StringField()
+    """The name of the recurring item."""
+    account_code = StringField()
+    """The account code."""
+    description_template = StringField()
+    """The description template."""
+
+    @property
+    def account_text(self) -> str | None:
+        """Returns the account text.
+
+        :return: The account text.
+        """
+        if self.account_code.data is None:
+            return None
+        account: Account | None = Account.find_by_code(self.account_code.data)
+        return None if account is None else str(account)
+
+    @property
+    def all_errors(self) -> list[str | LazyString]:
+        """Returns all the errors of the form.
+
+        :return: All the errors of the form.
+        """
+        all_errors: list[str | LazyString] = []
+        for key in self.errors:
+            if key != "csrf_token":
+                all_errors.extend(self.errors[key])
+        return all_errors
+
+
+class RecurringExpenseForm(RecurringItemForm):
+    """The sub-form to add or update the recurring expenses."""
+    no = IntegerField()
+    """The order number of this recurring item."""
+    name = StringField(
+        filters=[strip_text],
+        validators=[DataRequired(lazy_gettext("Please fill in the name."))])
+    """The name of the recurring item."""
+    account_code = StringField(
+        filters=[strip_text],
+        validators=[
+            ACCOUNT_REQUIRED,
+            AccountExists(),
+            IsDebitAccount(lazy_gettext("This account is not for expense.")),
+            NotStartPayableFromExpense()])
+    """The account code."""
+    description_template = StringField(
+        filters=[strip_text],
+        validators=[
+            DataRequired(lazy_gettext(
+                "Please fill in the description template."))])
+    """The template for the line item description."""
+
+
+class RecurringIncomeForm(RecurringItemForm):
+    """The sub-form to add or update the recurring incomes."""
+    no = IntegerField()
+    """The order number of this recurring item."""
+    name = StringField(
+        filters=[strip_text],
+        validators=[DataRequired(lazy_gettext("Please fill in the name."))])
+    """The name of the recurring item."""
+    account_code = StringField(
+        filters=[strip_text],
+        validators=[
+            ACCOUNT_REQUIRED,
+            AccountExists(),
+            IsCreditAccount(lazy_gettext("This account is not for income.")),
+            NotStartReceivableFromIncome()])
+    """The account code."""
+    description_template = StringField(
+        filters=[strip_text],
+        validators=[
+            DataRequired(lazy_gettext(
+                "Please fill in the description template."))])
+    """The description template."""
+
+
+class RecurringForm(RecurringItemForm):
+    """The sub-form for the recurring expenses and incomes."""
+    expenses = FieldList(FormField(RecurringExpenseForm), name="expense")
+    """The recurring expenses."""
+    incomes = FieldList(FormField(RecurringIncomeForm), name="income")
+    """The recurring incomes."""
+
+    @property
+    def item_template(self) -> str:
+        """Returns the template of a recurring item.
+
+        :return: The template of a recurring item.
+        """
+        return render_template(
+            "accounting/option/include/form-recurring-item.html",
+            expense_income="EXPENSE_INCOME",
+            item_index="ITEM_INDEX",
+            form=RecurringItemForm())
+
+    @property
+    def expense_accounts(self) -> list[Account]:
+        """The expense accounts.
+
+        :return: None.
+        """
+        return Account.selectable_debit()
+
+    @property
+    def income_accounts(self) -> list[Account]:
+        """The income accounts.
+
+        :return: None.
+        """
+        return Account.selectable_credit()
+
+    @property
+    def as_data(self) -> dict[str, list[tuple[str, str, str]]]:
+        """Returns the form data.
+
+        :return: The form data.
+        """
+        def as_tuple(item: RecurringItemForm) -> tuple[str, str, str]:
+            return (item.name.data, item.account_code.data,
+                    item.description_template.data)
+
+        expenses: list[RecurringItemForm] = [x.form for x in self.expenses]
+        self.__sort_item_forms(expenses)
+        incomes: list[RecurringItemForm] = [x.form for x in self.incomes]
+        self.__sort_item_forms(incomes)
+        return {"expense": [as_tuple(x) for x in expenses],
+                "income": [as_tuple(x) for x in incomes]}
+
+    @staticmethod
+    def __sort_item_forms(forms: list[RecurringItemForm]) -> None:
+        """Sorts the recurring item sub-forms.
+
+        :param forms: The recurring item sub-forms.
+        :return: None.
+        """
+        ord_by_form: dict[RecurringItemForm, int] \
+            = {forms[i]: i for i in range(len(forms))}
+        recv_no: set[int] = {x.no.data for x in forms if x.no.data is not None}
+        missing_recv_no: int = 100 if len(recv_no) == 0 else max(recv_no) + 100
+        forms.sort(key=lambda x: (x.no.data or missing_recv_no,
+                                  ord_by_form.get(x)))
+
+
+class OptionForm(FlaskForm):
+    """The form to update the options."""
+    default_currency_code = StringField(
+        filters=[strip_text],
+        validators=[
+            DataRequired(lazy_gettext("Please select the default currency.")),
+            CurrencyExists()])
+    """The default currency code."""
+    default_ie_account_code = StringField(
+        filters=[strip_text],
+        validators=[
+            DataRequired(lazy_gettext(
+                "Please select the default account"
+                " for the income and expenses log.")),
+            CurrentAccountExists(),
+            AccountNotCurrent()])
+    """The default account code for the income and expenses log."""
+    recurring = FormField(RecurringForm)
+    """The recurring expenses and incomes."""
+
+    def populate_obj(self, obj: Options) -> None:
+        """Populates the form data into a currency object.
+
+        :param obj: The currency object.
+        :return: None.
+        """
+        obj.default_currency_code = self.default_currency_code.data
+        obj.default_ie_account_code = self.default_ie_account_code.data
+        obj.recurring_data = self.recurring.form.as_data
+
+    @property
+    def current_accounts(self) -> list[CurrentAccount]:
+        """Returns the current accounts.
+
+        :return: The current accounts.
+        """
+        return CurrentAccount.accounts()

src/accounting/option/views.py

@@ -0,0 +1,83 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/22
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The views for the option management.
+
+"""
+from urllib.parse import parse_qsl, urlencode
+
+from flask import Blueprint, render_template, redirect, session, request, \
+    flash, url_for
+from werkzeug.datastructures import ImmutableMultiDict
+
+from accounting.locale import lazy_gettext
+from accounting.utils.cast import s
+from accounting.utils.flash_errors import flash_form_errors
+from accounting.utils.next_uri import inherit_next
+from accounting.utils.options import options
+from accounting.utils.permission import has_permission, can_admin
+from .forms import OptionForm
+
+bp: Blueprint = Blueprint("option", __name__)
+"""The view blueprint for the currency management."""
+
+
+@bp.get("", endpoint="detail")
+@has_permission(can_admin)
+def show_options() -> str:
+    """Shows the options.
+
+    :return: The options.
+    """
+    return render_template("accounting/option/detail.html", obj=options)
+
+
+@bp.get("edit", endpoint="edit")
+@has_permission(can_admin)
+def show_option_form() -> str:
+    """Shows the option form.
+
+    :return: The option form.
+    """
+    form: OptionForm
+    if "form" in session:
+        form = OptionForm(ImmutableMultiDict(parse_qsl(session["form"])))
+        del session["form"]
+        form.validate()
+    else:
+        form = OptionForm(obj=options)
+    return render_template("accounting/option/form.html", form=form)
+
+
+@bp.post("update", endpoint="update")
+@has_permission(can_admin)
+def update_options() -> redirect:
+    """Updates the options.
+
+    :return: The redirection to the option form.
+    """
+    form = OptionForm(request.form)
+    if not form.validate():
+        flash_form_errors(form)
+        session["form"] = urlencode(list(request.form.items()))
+        return redirect(inherit_next(url_for("accounting.option.edit")))
+    form.populate_obj(options)
+    if not options.is_modified:
+        flash(s(lazy_gettext("The settings were not modified.")), "success")
+        return redirect(inherit_next(url_for("accounting.option.detail")))
+    options.commit()
+    flash(s(lazy_gettext("The settings are saved successfully.")), "success")
+    return redirect(inherit_next(url_for("accounting.option.detail")))

src/accounting/report/__init__.py

@@ -0,0 +1,35 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/3
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The report management.
+
+"""
+from flask import Flask
+
+
+def init_app(app: Flask, url_prefix: str) -> None:
+    """Initialize the application.
+
+    :param app: The Flask application.
+    :param url_prefix: The URL prefix of the accounting application.
+    :return: None.
+    """
+    from .converters import PeriodConverter, IncomeExpensesAccountConverter
+    app.url_map.converters["period"] = PeriodConverter
+    app.url_map.converters["ieAccount"] = IncomeExpensesAccountConverter
+
+    from .views import bp as report_bp
+    app.register_blueprint(report_bp, url_prefix=url_prefix)

src/accounting/report/converters.py

@@ -0,0 +1,79 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/3
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The path converters for the report management.
+
+"""
+import re
+
+from flask import abort
+from werkzeug.routing import BaseConverter
+
+from accounting.models import Account
+from accounting.utils.current_account import CurrentAccount
+from .period import Period, get_period
+
+
+class PeriodConverter(BaseConverter):
+    """The supplier converter to convert the period specification from and to
+    the corresponding period in the routes."""
+
+    def to_python(self, value: str) -> Period:
+        """Converts a period specification to a period.
+
+        :param value: The period specification.
+        :return: The corresponding period.
+        """
+        try:
+            return get_period(value)
+        except ValueError:
+            abort(404)
+
+    def to_url(self, value: Period) -> str:
+        """Converts a period to its specification.
+
+        :param value: The period.
+        :return: Its specification.
+        """
+        return value.spec
+
+
+class IncomeExpensesAccountConverter(BaseConverter):
+    """The supplier converter to convert the income and expenses log pseudo
+    account code from and to the corresponding pseudo account in the routes."""
+
+    def to_python(self, value: str) -> CurrentAccount:
+        """Converts an account code to an account.
+
+        :param value: The account code.
+        :return: The corresponding account.
+        """
+        if value == CurrentAccount.CURRENT_AL_CODE:
+            return CurrentAccount.current_assets_and_liabilities()
+        if not re.match("^[12][12]", value):
+            abort(404)
+        account: Account | None = Account.find_by_code(value)
+        if account is None:
+            abort(404)
+        return CurrentAccount(account)
+
+    def to_url(self, value: CurrentAccount) -> str:
+        """Converts an account to account code.
+
+        :param value: The account.
+        :return: Its code.
+        """
+        return value.code

src/accounting/report/period/__init__.py

@@ -0,0 +1,22 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/9
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period utility.
+
+"""
+from .chooser import PeriodChooser
+from .parser import get_period
+from .period import Period

src/accounting/report/period/chooser.py

@@ -0,0 +1,97 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period chooser.
+
+This file is largely taken from the NanoParma ERP project, first written in
+2021/9/16 by imacat (imacat@nanoparma.com).
+
+"""
+import typing as t
+from datetime import date
+
+from accounting.models import JournalEntry
+from .period import Period
+from .shortcuts import ThisMonth, LastMonth, SinceLastMonth, ThisYear, \
+    LastYear, Today, Yesterday, AllTime, TemplatePeriod, YearPeriod
+
+
+class PeriodChooser:
+    """The period chooser."""
+
+    def __init__(self, get_url: t.Callable[[Period], str]):
+        """Constructs a period chooser.
+
+        :param get_url: The callback to return the URL of the current report in
+            a period.
+        """
+        self.__get_url: t.Callable[[Period], str] = get_url
+        """The callback to return the URL of the current report in a period."""
+
+        # Shortcut periods
+        self.this_month_url: str = get_url(ThisMonth())
+        """The URL for this month."""
+        self.last_month_url: str = get_url(LastMonth())
+        """The URL for last month."""
+        self.since_last_month_url: str = get_url(SinceLastMonth())
+        """The URL since last mint."""
+        self.this_year_url: str = get_url(ThisYear())
+        """The URL for this year."""
+        self.last_year_url: str = get_url(LastYear())
+        """The URL for last year."""
+        self.today_url: str = get_url(Today())
+        """The URL for today."""
+        self.yesterday_url: str = get_url(Yesterday())
+        """The URL for yesterday."""
+        self.all_url: str = get_url(AllTime())
+        """The URL for all period."""
+        self.url_template: str = get_url(TemplatePeriod())
+        """The URL template."""
+
+        first: JournalEntry | None \
+            = JournalEntry.query.order_by(JournalEntry.date).first()
+        start: date | None = None if first is None else first.date
+
+        # Attributes
+        self.data_start: date | None = start
+        """The start of the data."""
+        self.has_data: bool = start is not None
+        """Whether there is any data."""
+        self.has_last_month: bool = False
+        """Where there is data in last month."""
+        self.has_last_year: bool = False
+        """Whether there is data in last year."""
+        self.has_yesterday: bool = False
+        """Whether there is data in yesterday."""
+        self.available_years: list[int] = []
+        """The available years."""
+
+        if self.has_data:
+            today: date = date.today()
+            self.has_last_month = start < date(today.year, today.month, 1)
+            self.has_last_year = start.year < today.year
+            self.has_yesterday = start < today
+            if start.year < today.year - 1:
+                self.available_years \
+                    = reversed(range(start.year, today.year - 1))
+
+    def year_url(self, year: int) -> str:
+        """Returns the period URL of a year.
+
+        :param year: The year
+        :return: The period URL of the year.
+        """
+        return self.__get_url(YearPeriod(year))

src/accounting/report/period/description.py

@@ -0,0 +1,179 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period description composer.
+
+"""
+from datetime import date, timedelta
+
+from accounting.locale import gettext
+
+
+def get_desc(start: date | None, end: date | None) -> str:
+    """Returns the period description.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The period description.
+    """
+    if start is None and end is None:
+        return gettext("for all time")
+    if start is None:
+        return __get_until_desc(end)
+    if end is None:
+        return __get_since_desc(start)
+    try:
+        return __get_year_desc(start, end)
+    except ValueError:
+        pass
+    try:
+        return __get_month_desc(start, end)
+    except ValueError:
+        pass
+    return __get_day_desc(start, end)
+
+
+def __get_since_desc(start: date) -> str:
+    """Returns the description without the end day.
+
+    :param start: The start of the period.
+    :return: The description without the end day.
+    """
+
+    def get_start_desc() -> str:
+        """Returns the description of the start day.
+
+        :return: The description of the start day.
+        """
+        if start.month == 1 and start.day == 1:
+            return str(start.year)
+        if start.day == 1:
+            return __format_month(start)
+        return __format_day(start)
+
+    return gettext("since %(start)s", start=get_start_desc())
+
+
+def __get_until_desc(end: date) -> str:
+    """Returns the description without the start day.
+
+    :param end: The end of the period.
+    :return: The description without the start day.
+    """
+
+    def get_end_desc() -> str:
+        """Returns the description of the end day.
+
+        :return: The description of the end day.
+        """
+        if end.month == 12 and end.day == 31:
+            return str(end.year)
+        if (end + timedelta(days=1)).day == 1:
+            return __format_month(end)
+        return __format_day(end)
+
+    return gettext("until %(end)s", end=get_end_desc())
+
+
+def __get_year_desc(start: date, end: date) -> str:
+    """Returns the description as a year range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The description as a year range.
+    :raise ValueError: The period is not a year range.
+    """
+    if start.month != 1 or start.day != 1 \
+            or end.month != 12 or end.day != 31:
+        raise ValueError
+    start_text: str = str(start.year)
+    if start.year == end.year:
+        return __get_in_desc(start_text)
+    return __get_from_to_desc(start_text, str(end.year))
+
+
+def __get_month_desc(start: date, end: date) -> str:
+    """Returns the description as a month range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The description as a month range.
+    :raise ValueError: The period is not a month range.
+    """
+    if start.day != 1 or (end + timedelta(days=1)).day != 1:
+        raise ValueError
+    start_text: str = __format_month(start)
+    if start.year == end.year and start.month == end.month:
+        return __get_in_desc(start_text)
+    if start.year == end.year:
+        return __get_from_to_desc(start_text, str(end.month))
+    return __get_from_to_desc(start_text, __format_month(end))
+
+
+def __get_day_desc(start: date, end: date) -> str:
+    """Returns the description as a day range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The description as a day range.
+    :raise ValueError: The period is a month or year range.
+    """
+    start_text: str = __format_day(start)
+    if start == end:
+        return __get_in_desc(start_text)
+    if start.year == end.year and start.month == end.month:
+        return __get_from_to_desc(start_text, str(end.day))
+    if start.year == end.year:
+        end_month_day: str = f"{end.month}/{end.day}"
+        return __get_from_to_desc(start_text, end_month_day)
+    return __get_from_to_desc(start_text, __format_day(end))
+
+
+def __format_month(month: date) -> str:
+    """Formats a month.
+
+    :param month: The month.
+    :return: The formatted month.
+    """
+    return f"{month.year}/{month.month}"
+
+
+def __format_day(day: date) -> str:
+    """Formats a day.
+
+    :param day: The day.
+    :return: The formatted day.
+    """
+    return f"{day.year}/{day.month}/{day.day}"
+
+
+def __get_in_desc(period: str) -> str:
+    """Returns the description of a whole year, month, or day.
+
+    :param period: The time period.
+    :return: The description of a whole year, month, or day.
+    """
+    return gettext("in %(period)s", period=period)
+
+
+def __get_from_to_desc(start: str, end: str) -> str:
+    """Returns the description of a separated start and end.
+
+    :param start: The start.
+    :param end: The end.
+    :return: The description of the separated start and end.
+    """
+    return gettext("in %(start)s-%(end)s", start=start, end=end)

src/accounting/report/period/month_end.py

@@ -0,0 +1,31 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The utility to return the end of a month.
+
+"""
+import calendar
+from datetime import date
+
+
+def month_end(day: date) -> date:
+    """Returns the end day of month for a date.
+
+    :param day: The date.
+    :return: The end day of the month of that day.
+    """
+    last_day: int = calendar.monthrange(day.year, day.month)[1]
+    return date(day.year, day.month, last_day)

src/accounting/report/period/parser.py

@@ -0,0 +1,119 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period specification parser.
+
+"""
+import calendar
+import re
+import typing as t
+from datetime import date
+
+from .period import Period
+from .shortcuts import ThisMonth, LastMonth, SinceLastMonth, ThisYear, \
+    LastYear, Today, Yesterday, AllTime
+
+DATE_SPEC_RE: str = r"(\d{4})(?:-(\d{2})(?:-(\d{2}))?)?"
+"""The regular expression of a date specification."""
+
+
+def get_period(spec: str | None = None) -> Period:
+    """Returns a period instance.
+
+    :param spec: The period specification, or omit for the default.
+    :return: The period instance.
+    :raise ValueError: When the period specification is invalid.
+    """
+    if spec is None:
+        return ThisMonth()
+    named_periods: dict[str, t.Type[t.Callable[[], Period]]] = {
+        "this-month": lambda: ThisMonth(),
+        "last-month": lambda: LastMonth(),
+        "since-last-month": lambda: SinceLastMonth(),
+        "this-year": lambda: ThisYear(),
+        "last-year": lambda: LastYear(),
+        "today": lambda: Today(),
+        "yesterday": lambda: Yesterday(),
+        "all-time": lambda: AllTime(),
+    }
+    if spec in named_periods:
+        return named_periods[spec]()
+    start, end = __parse_spec(spec)
+    if start is not None and end is not None and start > end:
+        raise ValueError
+    return Period(start, end)
+
+
+def __parse_spec(text: str) -> tuple[date | None, date | None]:
+    """Parses the period specification.
+
+    :param text: The period specification.
+    :return: The start and end day of the period.  The start and end day
+        may be None.
+    :raise ValueError: When the date is invalid.
+    """
+    if text == "-":
+        return None, None
+    m = re.match(f"^{DATE_SPEC_RE}$", text)
+    if m is not None:
+        return __get_start(m[1], m[2], m[3]), \
+               __get_end(m[1], m[2], m[3])
+    m = re.match(f"^{DATE_SPEC_RE}-$", text)
+    if m is not None:
+        return __get_start(m[1], m[2], m[3]), None
+    m = re.match(f"-{DATE_SPEC_RE}$", text)
+    if m is not None:
+        return None, __get_end(m[1], m[2], m[3])
+    m = re.match(f"^{DATE_SPEC_RE}-{DATE_SPEC_RE}$", text)
+    if m is not None:
+        return __get_start(m[1], m[2], m[3]), \
+               __get_end(m[4], m[5], m[6])
+    raise ValueError
+
+
+def __get_start(year: str, month: str | None, day: str | None) -> date:
+    """Returns the start of the period from the date representation.
+
+    :param year: The year.
+    :param month: The month, if any.
+    :param day: The day, if any.
+    :return: The start of the period.
+    :raise ValueError: When the date is invalid.
+    """
+    if day is not None:
+        return date(int(year), int(month), int(day))
+    if month is not None:
+        return date(int(year), int(month), 1)
+    return date(int(year), 1, 1)
+
+
+def __get_end(year: str, month: str | None, day: str | None) -> date:
+    """Returns the end of the period from the date representation.
+
+    :param year: The year.
+    :param month: The month, if any.
+    :param day: The day, if any.
+    :return: The end of the period.
+    :raise ValueError: When the date is invalid.
+    """
+    if day is not None:
+        return date(int(year), int(month), int(day))
+    if month is not None:
+        year_n: int = int(year)
+        month_n: int = int(month)
+        day_n: int = calendar.monthrange(year_n, month_n)[1]
+        return date(year_n, month_n, day_n)
+    return date(int(year), 12, 31)

src/accounting/report/period/period.py

@@ -0,0 +1,129 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The date period.
+
+This file is largely taken from the NanoParma ERP project, first written in
+2021/9/16 by imacat (imacat@nanoparma.com).
+
+"""
+import typing as t
+from datetime import date, timedelta
+
+from .description import get_desc
+from .month_end import month_end
+from .specification import get_spec
+
+
+class Period:
+    """A date period."""
+
+    def __init__(self, start: date | None, end: date | None):
+        """Constructs a new date period.
+
+        :param start: The start date, or None from the very beginning.
+        :param end: The end date, or None till no end.
+        """
+        self.start: date | None = start
+        """The start of the period."""
+        self.end: date | None = end
+        """The end of the period."""
+        self.is_default: bool = False
+        """Whether the is the default period."""
+        self.is_this_month: bool = False
+        """Whether the period is this month."""
+        self.is_last_month: bool = False
+        """Whether the period is last month."""
+        self.is_since_last_month: bool = False
+        """Whether the period is since last month."""
+        self.is_this_year: bool = False
+        """Whether the period is this year."""
+        self.is_last_year: bool = False
+        """Whether the period is last year."""
+        self.is_today: bool = False
+        """Whether the period is today."""
+        self.is_yesterday: bool = False
+        """Whether the period is yesterday."""
+        self.is_all: bool = start is None and end is None
+        """Whether the period is all time."""
+        self.spec: str = ""
+        """The period specification."""
+        self.desc: str = ""
+        """The text description."""
+        self.is_a_month: bool = False
+        """Whether the period is a whole month."""
+        self.is_type_month: bool = False
+        """Whether the period is for the month chooser."""
+        self.is_a_year: bool = False
+        """Whether the period is a whole year."""
+        self.is_a_day: bool = False
+        """Whether the period is a single day."""
+        self._set_properties()
+
+    def _set_properties(self) -> None:
+        """Sets the following properties.
+
+        * self.spec
+        * self.desc
+        * self.is_a_month
+        * self.is_type_month
+        * self.is_a_year
+        * self.is_a_day
+
+        Override this method to set the properties in the subclasses, to skip
+        the calculation.
+
+        :return: None.
+        """
+        self.spec = get_spec(self.start, self.end)
+        self.desc = get_desc(self.start, self.end)
+        if self.start is None or self.end is None:
+            return
+        self.is_a_month = self.start.day == 1 \
+            and self.end == month_end(self.start)
+        self.is_type_month = self.is_a_month
+        self.is_a_year = self.start == date(self.start.year, 1, 1) \
+            and self.end == date(self.start.year, 12, 31)
+        self.is_a_day = self.start == self.end
+
+    def is_year(self, year: int) -> bool:
+        """Returns whether the period is the specific year period.
+
+        :param year: The year.
+        :return: True if the period is the year period, or False otherwise.
+        """
+        if not self.is_a_year:
+            return False
+        return self.start.year == year
+
+    @property
+    def is_type_arbitrary(self) -> bool:
+        """Returns whether this period is an arbitrary period.
+
+        :return: True if this is an arbitrary period, or False otherwise.
+        """
+        return not self.is_type_month and not self.is_a_year \
+            and not self.is_a_day
+
+    @property
+    def before(self) -> t.Self | None:
+        """Returns the period before this period.
+
+        :return: The period before this period.
+        """
+        if self.start is None:
+            return None
+        return Period(None, self.start - timedelta(days=1))

src/accounting/report/period/shortcuts.py

@@ -0,0 +1,168 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The named shortcut periods.
+
+"""
+from datetime import date, timedelta
+
+from accounting.locale import gettext
+from .month_end import month_end
+from .period import Period
+
+
+class ThisMonth(Period):
+    """The period of this month."""
+    def __init__(self):
+        today: date = date.today()
+        this_month_start: date = date(today.year, today.month, 1)
+        super().__init__(this_month_start, month_end(today))
+        self.is_default = True
+        self.is_this_month = True
+
+    def _set_properties(self) -> None:
+        self.spec = "this-month"
+        self.desc = gettext("This Month")
+        self.is_a_month = True
+        self.is_type_month = True
+
+
+class LastMonth(Period):
+    """The period of this month."""
+    def __init__(self):
+        today: date = date.today()
+        year: int = today.year
+        month: int = today.month - 1
+        if month < 1:
+            year = year - 1
+            month = 12
+        start: date = date(year, month, 1)
+        super().__init__(start, month_end(start))
+        self.is_last_month = True
+
+    def _set_properties(self) -> None:
+        self.spec = "last-month"
+        self.desc = gettext("Last Month")
+        self.is_a_month = True
+        self.is_type_month = True
+
+
+class SinceLastMonth(Period):
+    """The period of this month."""
+    def __init__(self):
+        today: date = date.today()
+        year: int = today.year
+        month: int = today.month - 1
+        if month < 1:
+            year = year - 1
+            month = 12
+        start: date = date(year, month, 1)
+        super().__init__(start, None)
+        self.is_since_last_month = True
+
+    def _set_properties(self) -> None:
+        self.spec = "since-last-month"
+        self.desc = gettext("Since Last Month")
+        self.is_type_month = True
+
+
+class ThisYear(Period):
+    """The period of this year."""
+    def __init__(self):
+        year: int = date.today().year
+        start: date = date(year, 1, 1)
+        end: date = date(year, 12, 31)
+        super().__init__(start, end)
+        self.is_this_year = True
+
+    def _set_properties(self) -> None:
+        self.spec = "this-year"
+        self.desc = gettext("This Year")
+        self.is_a_year = True
+
+
+class LastYear(Period):
+    """The period of last year."""
+    def __init__(self):
+        year: int = date.today().year
+        start: date = date(year - 1, 1, 1)
+        end: date = date(year - 1, 12, 31)
+        super().__init__(start, end)
+        self.is_last_year = True
+
+    def _set_properties(self) -> None:
+        self.spec = "last-year"
+        self.desc = gettext("Last Year")
+        self.is_a_year = True
+
+
+class Today(Period):
+    """The period of today."""
+    def __init__(self):
+        today: date = date.today()
+        super().__init__(today, today)
+        self.is_today = True
+
+    def _set_properties(self) -> None:
+        self.spec = "today"
+        self.desc = gettext("Today")
+        self.is_a_day = True
+
+
+class Yesterday(Period):
+    """The period of yesterday."""
+    def __init__(self):
+        yesterday: date = date.today() - timedelta(days=1)
+        super().__init__(yesterday, yesterday)
+        self.is_yesterday = True
+
+    def _set_properties(self) -> None:
+        self.spec = "yesterday"
+        self.desc = gettext("Yesterday")
+        self.is_a_day = True
+
+
+class AllTime(Period):
+    """The period of all time."""
+    def __init__(self):
+        super().__init__(None, None)
+        self.is_all = True
+
+    def _set_properties(self) -> None:
+        self.spec = "all-time"
+        self.desc = gettext("All")
+
+
+class TemplatePeriod(Period):
+    """The period template."""
+    def __init__(self):
+        super().__init__(None, None)
+
+    def _set_properties(self) -> None:
+        self.spec = "PERIOD"
+
+
+class YearPeriod(Period):
+    """A year period."""
+
+    def __init__(self, year: int):
+        """Constructs a year period.
+
+        :param year: The year.
+        """
+        start: date = date(year, 1, 1)
+        end: date = date(year, 12, 31)
+        super().__init__(start, end)

src/accounting/report/period/specification.py

@@ -0,0 +1,120 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The period specification composer.
+
+"""
+from datetime import date, timedelta
+
+
+def get_spec(start: date | None, end: date | None) -> str:
+    """Returns the period specification.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The period specification.
+    """
+    if start is None and end is None:
+        return "-"
+    if end is None:
+        return __get_since_spec(start)
+    if start is None:
+        return __get_until_spec(end)
+    try:
+        return __get_year_spec(start, end)
+    except ValueError:
+        pass
+    try:
+        return __get_month_spec(start, end)
+    except ValueError:
+        pass
+    return __get_day_spec(start, end)
+
+
+def __get_since_spec(start: date) -> str:
+    """Returns the period specification without the end day.
+
+    :param start: The start of the period.
+    :return: The period specification without the end day
+    """
+    if start.month == 1 and start.day == 1:
+        return start.strftime("%Y-")
+    if start.day == 1:
+        return start.strftime("%Y-%m-")
+    return start.strftime("%Y-%m-%d-")
+
+
+def __get_until_spec(end: date) -> str:
+    """Returns the period specification without the start day.
+
+    :param end: The end of the period.
+    :return: The period specification without the start day
+    """
+    if end.month == 12 and end.day == 31:
+        return end.strftime("-%Y")
+    if (end + timedelta(days=1)).day == 1:
+        return end.strftime("-%Y-%m")
+    return end.strftime("-%Y-%m-%d")
+
+
+def __get_year_spec(start: date, end: date) -> str:
+    """Returns the period specification as a year range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The period specification as a year range.
+    :raise ValueError: The period is not a year range.
+    """
+    if start.month != 1 or start.day != 1 \
+            or end.month != 12 or end.day != 31:
+        raise ValueError
+    start_spec: str = start.strftime("%Y")
+    if start.year == end.year:
+        return start_spec
+    end_spec: str = end.strftime("%Y")
+    return f"{start_spec}-{end_spec}"
+
+
+def __get_month_spec(start: date, end: date) -> str:
+    """Returns the period specification as a month range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The period specification as a month range.
+    :raise ValueError: The period is not a month range.
+    """
+    if start.day != 1 or (end + timedelta(days=1)).day != 1:
+        raise ValueError
+    start_spec: str = start.strftime("%Y-%m")
+    if start.year == end.year and start.month == end.month:
+        return start_spec
+    end_spec: str = end.strftime("%Y-%m")
+    return f"{start_spec}-{end_spec}"
+
+
+def __get_day_spec(start: date, end: date) -> str:
+    """Returns the period specification as a day range.
+
+    :param start: The start of the period.
+    :param end: The end of the period.
+    :return: The period specification as a day range.
+    :raise ValueError: The period is a month or year range.
+    """
+    start_spec: str = start.strftime("%Y-%m-%d")
+    if start == end:
+        return start_spec
+    end_spec: str = end.strftime("%Y-%m-%d")
+    return f"{start_spec}-{end_spec}"

src/accounting/report/reports/__init__.py

@@ -0,0 +1,26 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The reports.
+
+"""
+from .balance_sheet import BalanceSheet
+from .income_expenses import IncomeExpenses
+from .income_statement import IncomeStatement
+from .journal import Journal
+from .ledger import Ledger
+from .search import Search
+from .trial_balance import TrialBalance

src/accounting/report/reports/balance_sheet.py

@@ -0,0 +1,475 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The balance sheet.
+
+"""
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import render_template, Response
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, BaseAccount, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.option_link import OptionLink
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import ledger_url, balance_sheet_url, \
+    income_statement_url
+
+
+class ReportAccount:
+    """An account in the report."""
+
+    def __init__(self, account: Account, amount: Decimal, url: str):
+        """Constructs an account in the report.
+
+        :param account: The account.
+        :param amount: The amount.
+        :param url: The URL to the ledger of the account.
+        """
+        self.account: Account = account
+        """The account."""
+        self.amount: Decimal = amount
+        """The amount of the account."""
+        self.url: str = url
+        """The URL to the ledger of the account."""
+
+
+class Subsection:
+    """A subsection."""
+
+    def __init__(self, title: BaseAccount):
+        """Constructs a subsection.
+
+        :param title: The title account.
+        """
+        self.title: BaseAccount = title
+        """The title account."""
+        self.accounts: list[ReportAccount] = []
+        """The accounts in the subsection."""
+
+    @property
+    def total(self) -> Decimal:
+        """Returns the total of the subsection.
+
+        :return: The total of the subsection.
+        """
+        return sum([x.amount for x in self.accounts])
+
+
+class Section:
+    """A section."""
+
+    def __init__(self, title: BaseAccount):
+        """Constructs a section.
+
+        :param title: The title account.
+        """
+        self.title: BaseAccount = title
+        """The title account."""
+        self.subsections: list[Subsection] = []
+        """The subsections in the section."""
+
+    @property
+    def total(self) -> Decimal:
+        """Returns the total of the section.
+
+        :return: The total of the section.
+        """
+        return sum([x.total for x in self.subsections])
+
+
+class AccountCollector:
+    """The balance sheet account collector."""
+
+    def __init__(self, currency: Currency, period: Period):
+        """Constructs the balance sheet account collector.
+
+        :param currency: The currency.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__period: Period = period
+        """The period."""
+        self.accounts: list[ReportAccount] = self.__query_balances()
+        """The balance sheet accounts."""
+
+    def __query_balances(self) -> list[ReportAccount]:
+        """Queries and returns the balances.
+
+        :return: The balances.
+        """
+        sub_conditions: list[sa.BinaryExpression] \
+            = [Account.base_code.startswith(x) for x in {"1", "2", "3"}]
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code,
+               sa.or_(*sub_conditions)]
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount)).label("balance")
+        select_balance: sa.Select \
+            = sa.select(Account.id, Account.base_code, Account.no,
+                        balance_func)\
+            .join(JournalEntry).join(Account)\
+            .filter(*conditions)\
+            .group_by(Account.id, Account.base_code, Account.no)\
+            .having(balance_func != 0)\
+            .order_by(Account.base_code, Account.no)
+        account_balances: list[sa.Row] \
+            = db.session.execute(select_balance).all()
+        self.__all_accounts: list[Account] = Account.query\
+            .filter(sa.or_(Account.id.in_({x.id for x in account_balances}),
+                           Account.base_code == "3351",
+                           Account.base_code == "3353")).all()
+        account_by_id: dict[int, Account] \
+            = {x.id: x for x in self.__all_accounts}
+        self.accounts: list[ReportAccount] \
+            = [ReportAccount(account=account_by_id[x.id],
+                             amount=x.balance,
+                             url=ledger_url(self.__currency,
+                                            account_by_id[x.id],
+                                            self.__period))
+               for x in account_balances]
+        self.__add_accumulated()
+        self.__add_current_period()
+        self.accounts.sort(key=lambda x: (x.account.base_code, x.account.no))
+        for balance in self.accounts:
+            if not balance.account.base_code.startswith("1"):
+                balance.amount = -balance.amount
+        return self.accounts
+
+    def __add_accumulated(self) -> None:
+        """Adds the accumulated profit or loss to the balances.
+
+        :return: None.
+        """
+        self.__add_owner_s_equity(Account.ACCUMULATED_CHANGE_CODE,
+                                  self.__query_accumulated(),
+                                  self.__period)
+
+    def __query_accumulated(self) -> Decimal | None:
+        """Queries and returns the accumulated profit or loss.
+
+        :return: The accumulated profit or loss.
+        """
+        if self.__period.start is None:
+            return None
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code,
+               JournalEntry.date < self.__period.start]
+        return self.__query_balance(conditions)
+
+    def __add_current_period(self) -> None:
+        """Adds the accumulated profit or loss to the balances.
+
+        :return: None.
+        """
+        self.__add_owner_s_equity(Account.NET_CHANGE_CODE,
+                                  self.__query_current_period(),
+                                  self.__period)
+
+    def __query_current_period(self) -> Decimal | None:
+        """Queries and returns the net income or loss for current period.
+
+        :return: The net income or loss for current period.
+        """
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code]
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        return self.__query_balance(conditions)
+
+    @staticmethod
+    def __query_balance(conditions: list[sa.BinaryExpression])\
+            -> Decimal:
+        """Queries the balance.
+
+        :param conditions: The SQL conditions for the balance.
+        :return: The balance.
+        """
+        conditions.extend([sa.not_(Account.base_code.startswith(x))
+                           for x in {"1", "2", "3"}])
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount))
+        select_balance: sa.Select = sa.select(balance_func)\
+            .join(JournalEntry).join(Account).filter(*conditions)
+        return db.session.scalar(select_balance)
+
+    def __add_owner_s_equity(self, code: str, amount: Decimal | None,
+                             period: Period) -> None:
+        """Adds an owner's equity balance.
+
+        :param code: The code of the account to add.
+        :param amount: The amount.
+        :param period: The period.
+        :return: None.
+        """
+        if amount is None:
+            return
+        url: str = income_statement_url(self.__currency, period)
+        # There is an existing balance.
+        account_balance_by_code: dict[str, ReportAccount] \
+            = {x.account.code: x for x in self.accounts}
+        if code in account_balance_by_code:
+            balance: ReportAccount = account_balance_by_code[code]
+            balance.amount = balance.amount + amount
+            balance.url = url
+            return
+        # Add a new balance
+        account_by_code: dict[str, Account] \
+            = {x.code: x for x in self.__all_accounts}
+        self.accounts.append(ReportAccount(account=account_by_code[code],
+                                           amount=amount,
+                                           url=url))
+
+
+class CSVHalfRow:
+    """A half row in the CSV."""
+
+    def __init__(self, title: str | None, amount: Decimal | None):
+        """The constructs a half row in the CSV.
+
+        :param title: The title.
+        :param amount: The amount.
+        """
+        self.title: str | None = title
+        """The title."""
+        self.amount: Decimal | None = amount
+        """The amount."""
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self):
+        """Constructs a row in the CSV."""
+        self.asset_title: str | None = None
+        """The title of the asset."""
+        self.asset_amount: Decimal | None = None
+        """The amount of the asset."""
+        self.liability_title: str | None = None
+        """The title of the liability."""
+        self.liability_amount: Decimal | None = None
+        """The amount of the liability."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.asset_title, self.asset_amount,
+                self.liability_title, self.liability_amount]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, currency: Currency,
+                 period: Period,
+                 has_data: bool,
+                 assets: Section,
+                 liabilities: Section,
+                 owner_s_equity: Section):
+        """Constructs the HTML page parameters.
+
+        :param currency: The currency.
+        :param period: The period.
+        :param has_data: True if there is any data, or False otherwise.
+        :param assets: The assets.
+        :param liabilities: The liabilities.
+        :param owner_s_equity: The owner's equity.
+        """
+        self.currency: Currency = currency
+        """The currency."""
+        self.period: Period = period
+        """The period."""
+        self.__has_data: bool = has_data
+        """True if there is any data, or False otherwise."""
+        self.assets: Section = assets
+        """The assets."""
+        self.liabilities: Section = liabilities
+        """The liabilities."""
+        self.owner_s_equity: Section = owner_s_equity
+        """The owner's equity."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: balance_sheet_url(currency, x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return self.__has_data
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.BALANCE_SHEET,
+                             currency=self.currency,
+                             period=self.period)
+
+    @property
+    def currency_options(self) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :return: The currency options.
+        """
+        return self._get_currency_options(
+            lambda x: balance_sheet_url(x, self.period), self.currency)
+
+
+class BalanceSheet(BaseReport):
+    """The balance sheet."""
+
+    def __init__(self, currency: Currency, period: Period):
+        """Constructs a balance sheet.
+
+        :param currency: The currency.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__period: Period = period
+        """The period."""
+        self.__has_data: bool
+        """True if there is any data, or False otherwise."""
+        self.__assets: Section
+        """The assets."""
+        self.__liabilities: Section
+        """The liabilities."""
+        self.__owner_s_equity: Section
+        """The owner's equity."""
+        self.__set_data()
+
+    def __set_data(self) -> None:
+        """Queries and sets assets, the liabilities, and the owner's equity
+        sections in the balance sheet.
+
+        :return: None.
+        """
+        balances: list[ReportAccount] = AccountCollector(
+            self.__currency, self.__period).accounts
+
+        titles: list[BaseAccount] = BaseAccount.query\
+            .filter(BaseAccount.code.in_({"1", "2", "3"})).all()
+        subtitles: list[BaseAccount] = BaseAccount.query\
+            .filter(BaseAccount.code.in_({x.account.base_code[:2]
+                                          for x in balances})).all()
+
+        sections: dict[str, Section] = {x.code: Section(x) for x in titles}
+        subsections: dict[str, Subsection] = {x.code: Subsection(x)
+                                              for x in subtitles}
+        for subsection in subsections.values():
+            sections[subsection.title.code[0]].subsections.append(subsection)
+        for balance in balances:
+            subsections[balance.account.base_code[:2]].accounts.append(balance)
+
+        self.__has_data = len(balances) > 0
+        self.__assets = sections["1"]
+        self.__liabilities = sections["2"]
+        self.__owner_s_equity = sections["3"]
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "balance-sheet-{currency}-{period}.csv"\
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
+        return csv_download(filename, self.__get_csv_rows())
+
+    def __get_csv_rows(self) -> list[CSVRow]:
+        """Composes and returns the CSV rows.
+
+        :return: The CSV rows.
+        """
+        asset_rows: list[CSVHalfRow] = self.__section_csv_rows(self.__assets)
+        liability_rows: list[CSVHalfRow] = []
+        liability_rows.extend(self.__section_csv_rows(self.__liabilities))
+        liability_rows.append(CSVHalfRow(gettext("Total"),
+                                         self.__liabilities.total))
+        liability_rows.append(CSVHalfRow(None, None))
+        liability_rows.extend(self.__section_csv_rows(self.__owner_s_equity))
+        liability_rows.append(CSVHalfRow(gettext("Total"),
+                                         self.__owner_s_equity.total))
+        rows: list[CSVRow] = [CSVRow() for _ in
+                              range(max(len(asset_rows), len(liability_rows)))]
+        for i in range(len(rows)):
+            if i < len(asset_rows):
+                rows[i].asset_title = asset_rows[i].title
+                rows[i].asset_amount = asset_rows[i].amount
+            if i < len(liability_rows) and liability_rows[i].title is not None:
+                rows[i].liability_title = liability_rows[i].title
+                rows[i].liability_amount = liability_rows[i].amount
+        total: CSVRow = CSVRow()
+        total.asset_title = gettext("Total")
+        total.asset_amount = self.__assets.total
+        total.liability_title = gettext("Total")
+        total.liability_amount \
+            = self.__liabilities.total + self.__owner_s_equity.total
+        rows.append(total)
+        return rows
+
+    @staticmethod
+    def __section_csv_rows(section: Section) -> list[CSVHalfRow]:
+        """Gathers the CSV rows for a section.
+
+        :param section: The section.
+        :return: The CSV rows for the section.
+        """
+        rows: list[CSVHalfRow] \
+            = [CSVHalfRow(section.title.title.title(), None)]
+        for subsection in section.subsections:
+            rows.append(CSVHalfRow(f" {subsection.title.title.title()}", None))
+            for account in subsection.accounts:
+                rows.append(CSVHalfRow(f"  {str(account.account).title()}",
+                                       account.amount))
+        return rows
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        params: PageParams = PageParams(currency=self.__currency,
+                                        period=self.__period,
+                                        has_data=self.__has_data,
+                                        assets=self.__assets,
+                                        liabilities=self.__liabilities,
+                                        owner_s_equity=self.__owner_s_equity)
+        return render_template("accounting/report/balance-sheet.html",
+                               report=params)

src/accounting/report/reports/income_expenses.py

@@ -0,0 +1,460 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The income and expenses log.
+
+"""
+from datetime import date
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import url_for, render_template, Response
+from sqlalchemy.orm import selectinload
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.option_link import OptionLink
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import income_expenses_url
+from accounting.utils.cast import be
+from accounting.utils.current_account import CurrentAccount
+from accounting.utils.pagination import Pagination
+
+
+class ReportLineItem:
+    """A line item in the report."""
+
+    def __init__(self, line_item: JournalEntryLineItem | None = None):
+        """Constructs the line item in the report.
+
+        :param line_item: The journal entry line item.
+        """
+        self.is_brought_forward: bool = False
+        """Whether this is the brought-forward line item."""
+        self.is_total: bool = False
+        """Whether this is the total line item."""
+        self.date: date | None = None
+        """The date."""
+        self.account: Account | None = None
+        """The account."""
+        self.description: str | None = None
+        """The description."""
+        self.income: Decimal | None = None
+        """The income amount."""
+        self.expense: Decimal | None = None
+        """The expense amount."""
+        self.balance: Decimal | None = None
+        """The balance."""
+        self.note: str | None = None
+        """The note."""
+        self.url: str | None = None
+        """The URL to the journal entry line item."""
+        if line_item is not None:
+            self.date = line_item.journal_entry.date
+            self.account = line_item.account
+            self.description = line_item.description
+            self.income = None if line_item.is_debit else line_item.amount
+            self.expense = line_item.amount if line_item.is_debit else None
+            self.note = line_item.journal_entry.note
+            self.url = url_for("accounting.journal-entry.detail",
+                               journal_entry=line_item.journal_entry)
+
+
+class LineItemCollector:
+    """The line item collector."""
+
+    def __init__(self, currency: Currency, account: CurrentAccount,
+                 period: Period):
+        """Constructs the line item collector.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__account: CurrentAccount = account
+        """The account."""
+        self.__period: Period = period
+        """The period"""
+        self.brought_forward: ReportLineItem | None
+        """The brought-forward line item."""
+        self.line_items: list[ReportLineItem]
+        """The line items."""
+        self.total: ReportLineItem | None
+        """The total line item."""
+        self.brought_forward = self.__get_brought_forward()
+        self.line_items = self.__query_line_items()
+        self.total = self.__get_total()
+        self.__populate_balance()
+
+    def __get_brought_forward(self) -> ReportLineItem | None:
+        """Queries, composes and returns the brought-forward line item.
+
+        :return: The brought-forward line item, or None if the period starts
+            from the beginning.
+        """
+        if self.__period.start is None:
+            return None
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount))
+        select: sa.Select = sa.Select(balance_func)\
+            .join(JournalEntry).join(Account)\
+            .filter(be(JournalEntryLineItem.currency_code
+                       == self.__currency.code),
+                    self.__account_condition,
+                    JournalEntry.date < self.__period.start)
+        balance: int | None = db.session.scalar(select)
+        if balance is None:
+            return None
+        line_item: ReportLineItem = ReportLineItem()
+        line_item.is_brought_forward = True
+        line_item.date = self.__period.start
+        line_item.account = Account.accumulated_change()
+        line_item.description = gettext("Brought forward")
+        if balance > 0:
+            line_item.income = balance
+        elif balance < 0:
+            line_item.expense = -balance
+        line_item.balance = balance
+        return line_item
+
+    def __query_line_items(self) -> list[ReportLineItem]:
+        """Queries and returns the line items.
+
+        :return: The line items.
+        """
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code,
+               self.__account_condition]
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        journal_entry_with_account: sa.Select = sa.Select(JournalEntry.id).\
+            join(JournalEntryLineItem).join(Account).filter(*conditions)
+
+        return [ReportLineItem(x)
+                for x in JournalEntryLineItem.query
+                .join(JournalEntry).join(Account)
+                .filter(JournalEntryLineItem.journal_entry_id
+                        .in_(journal_entry_with_account),
+                        JournalEntryLineItem.currency_code
+                        == self.__currency.code,
+                        sa.not_(self.__account_condition))
+                .order_by(JournalEntry.date,
+                          JournalEntry.no,
+                          JournalEntryLineItem.is_debit,
+                          JournalEntryLineItem.no)
+                .options(selectinload(JournalEntryLineItem.account),
+                         selectinload(JournalEntryLineItem.journal_entry))]
+
+    @property
+    def __account_condition(self) -> sa.BinaryExpression:
+        if self.__account.code == CurrentAccount.CURRENT_AL_CODE:
+            return CurrentAccount.sql_condition()
+        return Account.id == self.__account.id
+
+    def __get_total(self) -> ReportLineItem | None:
+        """Composes the total line item.
+
+        :return: The total line item, or None if there is no data.
+        """
+        if self.brought_forward is None and len(self.line_items) == 0:
+            return None
+        line_item: ReportLineItem = ReportLineItem()
+        line_item.is_total = True
+        line_item.description = gettext("Total")
+        line_item.income = sum([x.income for x in self.line_items
+                                if x.income is not None])
+        line_item.expense = sum([x.expense for x in self.line_items
+                                 if x.expense is not None])
+        line_item.balance = line_item.income - line_item.expense
+        if self.brought_forward is not None:
+            line_item.balance \
+                = self.brought_forward.balance + line_item.balance
+        return line_item
+
+    def __populate_balance(self) -> None:
+        """Populates the balance of the line items.
+
+        :return: None.
+        """
+        balance: Decimal = 0 if self.brought_forward is None \
+            else self.brought_forward.balance
+        for line_item in self.line_items:
+            if line_item.income is not None:
+                balance = balance + line_item.income
+            if line_item.expense is not None:
+                balance = balance - line_item.expense
+            line_item.balance = balance
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self, journal_entry_date: date | str | None,
+                 account: str | None,
+                 description: str | None,
+                 income: str | Decimal | None,
+                 expense: str | Decimal | None,
+                 balance: str | Decimal | None,
+                 note: str | None):
+        """Constructs a row in the CSV.
+
+        :param journal_entry_date: The journal entry date.
+        :param account: The account.
+        :param description: The description.
+        :param income: The income.
+        :param expense: The expense.
+        :param balance: The balance.
+        :param note: The note.
+        """
+        self.date: date | str | None = journal_entry_date
+        """The date."""
+        self.account: str | None = account
+        """The account."""
+        self.description: str | None = description
+        """The description."""
+        self.income: str | Decimal | None = income
+        """The income."""
+        self.expense: str | Decimal | None = expense
+        """The expense."""
+        self.balance: str | Decimal | None = balance
+        """The balance."""
+        self.note: str | None = note
+        """The note."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.date, self.account, self.description,
+                self.income, self.expense, self.balance, self.note]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, currency: Currency,
+                 account: CurrentAccount,
+                 period: Period,
+                 has_data: bool,
+                 pagination: Pagination[ReportLineItem],
+                 brought_forward: ReportLineItem | None,
+                 line_items: list[ReportLineItem],
+                 total: ReportLineItem | None):
+        """Constructs the HTML page parameters.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        :param has_data: True if there is any data, or False otherwise.
+        :param brought_forward: The brought-forward line item.
+        :param line_items: The line items.
+        :param total: The total line item.
+        """
+        self.currency: Currency = currency
+        """The currency."""
+        self.account: CurrentAccount = account
+        """The account."""
+        self.period: Period = period
+        """The period."""
+        self.__has_data: bool = has_data
+        """True if there is any data, or False otherwise."""
+        self.pagination: Pagination[ReportLineItem] = pagination
+        """The pagination."""
+        self.brought_forward: ReportLineItem | None = brought_forward
+        """The brought-forward line item."""
+        self.line_items: list[ReportLineItem] = line_items
+        """The line items."""
+        self.total: ReportLineItem | None = total
+        """The total line item."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: income_expenses_url(currency, account, x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return self.__has_data
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        if self.account.account is None:
+            return ReportChooser(ReportType.INCOME_EXPENSES,
+                                 currency=self.currency,
+                                 account=Account.cash(),
+                                 period=self.period)
+        return ReportChooser(ReportType.INCOME_EXPENSES,
+                             currency=self.currency,
+                             account=self.account.account,
+                             period=self.period)
+
+    @property
+    def currency_options(self) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :return: The currency options.
+        """
+        return self._get_currency_options(
+            lambda x: income_expenses_url(x, self.account, self.period),
+            self.currency)
+
+    @property
+    def account_options(self) -> list[OptionLink]:
+        """Returns the account options.
+
+        :return: The account options.
+        """
+        current_al: CurrentAccount \
+            = CurrentAccount.current_assets_and_liabilities()
+        options: list[OptionLink] \
+            = [OptionLink(str(current_al),
+                          income_expenses_url(self.currency, current_al,
+                                              self.period),
+                          self.account.id == 0)]
+        in_use: sa.Select = sa.Select(JournalEntryLineItem.account_id)\
+            .join(Account)\
+            .filter(be(JournalEntryLineItem.currency_code
+                       == self.currency.code),
+                    CurrentAccount.sql_condition())\
+            .group_by(JournalEntryLineItem.account_id)
+        options.extend([OptionLink(str(x),
+                                   income_expenses_url(
+                                       self.currency,
+                                       CurrentAccount(x),
+                                       self.period),
+                                   x.id == self.account.id)
+                        for x in Account.query.filter(Account.id.in_(in_use))
+                       .order_by(Account.base_code, Account.no).all()])
+        return options
+
+
+class IncomeExpenses(BaseReport):
+    """The income and expenses log."""
+
+    def __init__(self, currency: Currency, account: CurrentAccount,
+                 period: Period):
+        """Constructs an income and expenses log.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__account: CurrentAccount = account
+        """The account."""
+        self.__period: Period = period
+        """The period."""
+        collector: LineItemCollector = LineItemCollector(
+            self.__currency, self.__account, self.__period)
+        self.__brought_forward: ReportLineItem | None \
+            = collector.brought_forward
+        """The brought-forward line item."""
+        self.__line_items: list[ReportLineItem] = collector.line_items
+        """The line items."""
+        self.__total: ReportLineItem | None = collector.total
+        """The total line item."""
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "income-expenses-{currency}-{account}-{period}.csv"\
+            .format(currency=self.__currency.code, account=self.__account.code,
+                    period=period_spec(self.__period))
+        return csv_download(filename, self.__get_csv_rows())
+
+    def __get_csv_rows(self) -> list[CSVRow]:
+        """Composes and returns the CSV rows.
+
+        :return: The CSV rows.
+        """
+        rows: list[CSVRow] = [CSVRow(gettext("Date"), gettext("Account"),
+                                     gettext("Description"), gettext("Income"),
+                                     gettext("Expense"), gettext("Balance"),
+                                     gettext("Note"))]
+        if self.__brought_forward is not None:
+            rows.append(CSVRow(self.__brought_forward.date,
+                               str(self.__brought_forward.account).title(),
+                               self.__brought_forward.description,
+                               self.__brought_forward.income,
+                               self.__brought_forward.expense,
+                               self.__brought_forward.balance,
+                               None))
+        rows.extend([CSVRow(x.date, str(x.account).title(), x.description,
+                            x.income, x.expense, x.balance, x.note)
+                     for x in self.__line_items])
+        if self.__total is not None:
+            rows.append(CSVRow(gettext("Total"), None, None,
+                               self.__total.income, self.__total.expense,
+                               self.__total.balance, None))
+        return rows
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        all_line_items: list[ReportLineItem] = []
+        if self.__brought_forward is not None:
+            all_line_items.append(self.__brought_forward)
+        all_line_items.extend(self.__line_items)
+        if self.__total is not None:
+            all_line_items.append(self.__total)
+        pagination: Pagination[ReportLineItem] \
+            = Pagination[ReportLineItem](all_line_items, is_reversed=True)
+        page_line_items: list[ReportLineItem] = pagination.list
+        has_data: bool = len(page_line_items) > 0
+        brought_forward: ReportLineItem | None = None
+        if len(page_line_items) > 0 and page_line_items[0].is_brought_forward:
+            brought_forward = page_line_items[0]
+            page_line_items = page_line_items[1:]
+        total: ReportLineItem | None = None
+        if len(page_line_items) > 0 and page_line_items[-1].is_total:
+            total = page_line_items[-1]
+            page_line_items = page_line_items[:-1]
+        params: PageParams = PageParams(currency=self.__currency,
+                                        account=self.__account,
+                                        period=self.__period,
+                                        has_data=has_data,
+                                        pagination=pagination,
+                                        brought_forward=brought_forward,
+                                        line_items=page_line_items,
+                                        total=total)
+        return render_template("accounting/report/income-expenses.html",
+                               report=params)

src/accounting/report/reports/income_statement.py

@@ -0,0 +1,326 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The income statement.
+
+"""
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import render_template, Response
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, BaseAccount, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.option_link import OptionLink
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import ledger_url, income_statement_url
+
+
+class ReportAccount:
+    """An account in the report."""
+
+    def __init__(self, account: Account, amount: Decimal, url: str):
+        """Constructs an account in the report.
+
+        :param account: The account.
+        :param amount: The amount.
+        :param url: The URL to the ledger of the account.
+        """
+        self.account: Account = account
+        """The account."""
+        self.amount: Decimal = amount
+        """The amount of the account."""
+        self.url: str = url
+        """The URL to the ledger of the account."""
+
+
+class AccumulatedTotal:
+    """An accumulated total."""
+
+    def __init__(self, title: str):
+        """Constructs an accumulated total.
+
+        :param title: The title.
+        """
+        self.title: str = title
+        """The account."""
+        self.amount: Decimal = Decimal("0")
+        """The amount of the account."""
+
+
+class Subsection:
+    """A subsection."""
+
+    def __init__(self, title: BaseAccount):
+        """Constructs a subsection.
+
+        :param title: The title account.
+        """
+        self.title: BaseAccount = title
+        """The title account."""
+        self.accounts: list[ReportAccount] = []
+        """The accounts in the subsection."""
+
+    @property
+    def total(self) -> Decimal:
+        """Returns the total of the subsection.
+
+        :return: The total of the subsection.
+        """
+        return sum([x.amount for x in self.accounts])
+
+
+class Section:
+    """A section."""
+
+    def __init__(self, title: BaseAccount, accumulated_title: str):
+        """Constructs a section.
+
+        :param title: The title account.
+        :param accumulated_title: The title for the accumulated total.
+        """
+        self.title: BaseAccount = title
+        """The title account."""
+        self.subsections: list[Subsection] = []
+        """The subsections in the section."""
+        self.accumulated: AccumulatedTotal \
+            = AccumulatedTotal(accumulated_title)
+
+    @property
+    def total(self) -> Decimal:
+        """Returns the total of the section.
+
+        :return: The total of the section.
+        """
+        return sum([x.total for x in self.subsections])
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self, text: str | None, amount: str | Decimal | None):
+        """Constructs a row in the CSV.
+
+        :param text: The text.
+        :param amount: The amount.
+        """
+        self.text: str | None = text
+        """The text."""
+        self.amount: str | Decimal | None = amount
+        """The amount."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.text, self.amount]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, currency: Currency,
+                 period: Period,
+                 has_data: bool,
+                 sections: list[Section], ):
+        """Constructs the HTML page parameters.
+
+        :param currency: The currency.
+        :param period: The period.
+        :param has_data: True if there is any data, or False otherwise.
+        """
+        self.currency: Currency = currency
+        """The currency."""
+        self.period: Period = period
+        """The period."""
+        self.__has_data: bool = has_data
+        """True if there is any data, or False otherwise."""
+        self.sections: list[Section] = sections
+        """The sections in the income statement."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: income_statement_url(currency, x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return self.__has_data
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.INCOME_STATEMENT,
+                             currency=self.currency,
+                             period=self.period)
+
+    @property
+    def currency_options(self) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :return: The currency options.
+        """
+        return self._get_currency_options(
+            lambda x: income_statement_url(x, self.period), self.currency)
+
+
+class IncomeStatement(BaseReport):
+    """The income statement."""
+
+    def __init__(self, currency: Currency, period: Period):
+        """Constructs an income statement.
+
+        :param currency: The currency.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__period: Period = period
+        """The period."""
+        self.__has_data: bool
+        """True if there is any data, or False otherwise."""
+        self.__sections: list[Section]
+        """The sections."""
+        self.__set_data()
+
+    def __set_data(self) -> None:
+        """Queries and sets data sections in the income statement.
+
+        :return: None.
+        """
+        balances: list[ReportAccount] = self.__query_balances()
+
+        titles: list[BaseAccount] = BaseAccount.query\
+            .filter(BaseAccount.code.in_({"4", "5", "6", "7", "8", "9"})).all()
+        subtitles: list[BaseAccount] = BaseAccount.query\
+            .filter(BaseAccount.code.in_({x.account.base_code[:2]
+                                          for x in balances})).all()
+
+        total_titles: dict[str, str] \
+            = {"4": gettext("total operating revenue"),
+               "5": gettext("gross income"),
+               "6": gettext("operating income"),
+               "7": gettext("before tax income"),
+               "8": gettext("after tax income"),
+               "9": gettext("net income or loss for current period")}
+
+        sections: dict[str, Section] \
+            = {x.code: Section(x, total_titles[x.code]) for x in titles}
+        subsections: dict[str, Subsection] \
+            = {x.code: Subsection(x) for x in subtitles}
+        for subsection in subsections.values():
+            sections[subsection.title.code[0]].subsections.append(subsection)
+        for balance in balances:
+            subsections[balance.account.base_code[:2]].accounts.append(balance)
+
+        self.__has_data = len(balances) > 0
+        self.__sections = sorted(sections.values(), key=lambda x: x.title.code)
+        total: Decimal = Decimal("0")
+        for section in self.__sections:
+            total = total + section.total
+            section.accumulated.amount = total
+
+    def __query_balances(self) -> list[ReportAccount]:
+        """Queries and returns the balances.
+
+        :return: The balances.
+        """
+        sub_conditions: list[sa.BinaryExpression] \
+            = [Account.base_code.startswith(str(x)) for x in range(4, 10)]
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code,
+               sa.or_(*sub_conditions)]
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, -JournalEntryLineItem.amount),
+            else_=JournalEntryLineItem.amount)).label("balance")
+        select_balances: sa.Select = sa.select(Account.id, balance_func)\
+            .join(JournalEntry).join(Account)\
+            .filter(*conditions)\
+            .group_by(Account.id)\
+            .having(balance_func != 0)\
+            .order_by(Account.base_code, Account.no)
+        balances: list[sa.Row] = db.session.execute(select_balances).all()
+        accounts: dict[int, Account] \
+            = {x.id: x for x in Account.query
+               .filter(Account.id.in_([x.id for x in balances])).all()}
+        return [ReportAccount(account=accounts[x.id],
+                              amount=x.balance,
+                              url=ledger_url(self.__currency,
+                                             accounts[x.id],
+                                             self.__period))
+                for x in balances]
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "income-statement-{currency}-{period}.csv"\
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
+        return csv_download(filename, self.__get_csv_rows())
+
+    def __get_csv_rows(self) -> list[CSVRow]:
+        """Composes and returns the CSV rows.
+
+        :return: The CSV rows.
+        """
+        total_str: str = gettext("Total")
+        rows: list[CSVRow] = [CSVRow(None, gettext("Amount"))]
+        for section in self.__sections:
+            rows.append(CSVRow(str(section.title).title(), None))
+            for subsection in section.subsections:
+                rows.append(CSVRow(f" {str(subsection.title).title()}", None))
+                for account in subsection.accounts:
+                    rows.append(CSVRow(f"  {str(account.account).title()}",
+                                       account.amount))
+                rows.append(CSVRow(f" {total_str}", subsection.total))
+            rows.append(CSVRow(section.accumulated.title.title(),
+                               section.accumulated.amount))
+            rows.append(CSVRow(None, None))
+        rows = rows[:-1]
+        return rows
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        params: PageParams = PageParams(currency=self.__currency,
+                                        period=self.__period,
+                                        has_data=self.__has_data,
+                                        sections=self.__sections)
+        return render_template("accounting/report/income-statement.html",
+                               report=params)

src/accounting/report/reports/journal.py

@@ -0,0 +1,220 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The journal.
+
+"""
+from datetime import date
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import render_template, Response
+from sqlalchemy.orm import selectinload
+
+from accounting.locale import gettext
+from accounting.models import Currency, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import journal_url
+from accounting.utils.pagination import Pagination
+
+
+class ReportLineItem:
+    """A line item in the report."""
+
+    def __init__(self, line_item: JournalEntryLineItem):
+        """Constructs the line item in the report.
+
+        :param line_item: The journal entry line item.
+        """
+        self.line_item: JournalEntryLineItem = line_item
+        """The journal entry line item."""
+        self.journal_entry: JournalEntry = line_item.journal_entry
+        """The journal entry."""
+        self.currency: Currency = line_item.currency
+        """The account."""
+        self.account: Account = line_item.account
+        """The account."""
+        self.description: str | None = line_item.description
+        """The description."""
+        self.debit: Decimal | None = line_item.debit
+        """The debit amount."""
+        self.credit: Decimal | None = line_item.credit
+        """The credit amount."""
+        self.amount: Decimal = line_item.amount
+        """The amount."""
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self, journal_entry_date: str | date,
+                 currency: str,
+                 account: str,
+                 description: str | None,
+                 debit: str | Decimal | None,
+                 credit: str | Decimal | None,
+                 note: str | None):
+        """Constructs a row in the CSV.
+
+        :param journal_entry_date: The journal entry date.
+        :param description: The description.
+        :param debit: The debit amount.
+        :param credit: The credit amount.
+        :param note: The note.
+        """
+        self.date: str | date = journal_entry_date
+        """The date."""
+        self.currency: str = currency
+        """The currency."""
+        self.account: str = account
+        """The account."""
+        self.description: str | None = description
+        """The description."""
+        self.debit: str | Decimal | None = debit
+        """The debit amount."""
+        self.credit: str | Decimal | None = credit
+        """The credit amount."""
+        self.note: str | None = note
+        """The note."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.date, self.currency, self.account, self.description,
+                self.debit, self.credit, self.note]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, period: Period,
+                 pagination: Pagination[JournalEntryLineItem],
+                 line_items: list[JournalEntryLineItem]):
+        """Constructs the HTML page parameters.
+
+        :param period: The period.
+        :param line_items: The line items.
+        """
+        self.period: Period = period
+        """The period."""
+        self.pagination: Pagination[JournalEntryLineItem] = pagination
+        """The pagination."""
+        self.line_items: list[JournalEntryLineItem] = line_items
+        """The line items."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: journal_url(x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return len(self.line_items) > 0
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.JOURNAL,
+                             period=self.period)
+
+
+def get_csv_rows(line_items: list[JournalEntryLineItem]) -> list[CSVRow]:
+    """Composes and returns the CSV rows from the line items.
+
+    :param line_items: The line items.
+    :return: The CSV rows.
+    """
+    rows: list[CSVRow] = [CSVRow(gettext("Date"), gettext("Currency"),
+                                 gettext("Account"), gettext("Description"),
+                                 gettext("Debit"), gettext("Credit"),
+                                 gettext("Note"))]
+    rows.extend([CSVRow(x.journal_entry.date, x.currency.code,
+                        str(x.account).title(), x.description,
+                        x.debit, x.credit, x.journal_entry.note)
+                 for x in line_items])
+    return rows
+
+
+class Journal(BaseReport):
+    """The journal."""
+
+    def __init__(self, period: Period):
+        """Constructs a journal.
+
+        :param period: The period.
+        """
+        self.__period: Period = period
+        """The period."""
+        self.__line_items: list[JournalEntryLineItem] \
+            = self.__query_line_items()
+        """The line items."""
+
+    def __query_line_items(self) -> list[JournalEntryLineItem]:
+        """Queries and returns the line items.
+
+        :return: The line items.
+        """
+        conditions: list[sa.BinaryExpression] = []
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        return JournalEntryLineItem.query.join(JournalEntry)\
+            .filter(*conditions)\
+            .order_by(JournalEntry.date,
+                      JournalEntry.no,
+                      JournalEntryLineItem.is_debit.desc(),
+                      JournalEntryLineItem.no)\
+            .options(selectinload(JournalEntryLineItem.account),
+                     selectinload(JournalEntryLineItem.currency),
+                     selectinload(JournalEntryLineItem.journal_entry)).all()
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = f"journal-{period_spec(self.__period)}.csv"
+        return csv_download(filename, get_csv_rows(self.__line_items))
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        pagination: Pagination[JournalEntryLineItem] \
+            = Pagination[JournalEntryLineItem](self.__line_items,
+                                               is_reversed=True)
+        params: PageParams = PageParams(period=self.__period,
+                                        pagination=pagination,
+                                        line_items=pagination.list)
+        return render_template("accounting/report/journal.html",
+                               report=params)

src/accounting/report/reports/ledger.py

@@ -0,0 +1,417 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The ledger.
+
+"""
+from datetime import date
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import url_for, render_template, Response
+from sqlalchemy.orm import selectinload
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.option_link import OptionLink
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import ledger_url
+from accounting.utils.cast import be
+from accounting.utils.pagination import Pagination
+
+
+class ReportLineItem:
+    """A line item in the report."""
+
+    def __init__(self, line_item: JournalEntryLineItem | None = None):
+        """Constructs the line item in the report.
+
+        :param line_item: The journal entry line item.
+        """
+        self.is_brought_forward: bool = False
+        """Whether this is the brought-forward line item."""
+        self.is_total: bool = False
+        """Whether this is the total line item."""
+        self.date: date | None = None
+        """The date."""
+        self.description: str | None = None
+        """The description."""
+        self.debit: Decimal | None = None
+        """The debit amount."""
+        self.credit: Decimal | None = None
+        """The credit amount."""
+        self.balance: Decimal | None = None
+        """The balance."""
+        self.note: str | None = None
+        """The note."""
+        self.url: str | None = None
+        """The URL to the journal entry line item."""
+        if line_item is not None:
+            self.date = line_item.journal_entry.date
+            self.description = line_item.description
+            self.debit = line_item.amount if line_item.is_debit else None
+            self.credit = None if line_item.is_debit else line_item.amount
+            self.note = line_item.journal_entry.note
+            self.url = url_for("accounting.journal-entry.detail",
+                               journal_entry=line_item.journal_entry)
+
+
+class LineItemCollector:
+    """The line item collector."""
+
+    def __init__(self, currency: Currency, account: Account, period: Period):
+        """Constructs the line item collector.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__account: Account = account
+        """The account."""
+        self.__period: Period = period
+        """The period"""
+        self.brought_forward: ReportLineItem | None
+        """The brought-forward line item."""
+        self.line_items: list[ReportLineItem]
+        """The line items."""
+        self.total: ReportLineItem | None
+        """The total line item."""
+        self.brought_forward = self.__get_brought_forward()
+        self.line_items = self.__query_line_items()
+        self.total = self.__get_total()
+        self.__populate_balance()
+
+    def __get_brought_forward(self) -> ReportLineItem | None:
+        """Queries, composes and returns the brought-forward line item.
+
+        :return: The brought-forward line item, or None if the report starts
+            from the beginning.
+        """
+        if self.__period.start is None:
+            return None
+        if self.__account.is_nominal:
+            return None
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount))
+        select: sa.Select = sa.Select(balance_func).join(JournalEntry)\
+            .filter(be(JournalEntryLineItem.currency_code
+                       == self.__currency.code),
+                    be(JournalEntryLineItem.account_id
+                       == self.__account.id),
+                    JournalEntry.date < self.__period.start)
+        balance: int | None = db.session.scalar(select)
+        if balance is None:
+            return None
+        line_item: ReportLineItem = ReportLineItem()
+        line_item.is_brought_forward = True
+        line_item.date = self.__period.start
+        line_item.description = gettext("Brought forward")
+        if balance > 0:
+            line_item.debit = balance
+        elif balance < 0:
+            line_item.credit = -balance
+        line_item.balance = balance
+        return line_item
+
+    def __query_line_items(self) -> list[ReportLineItem]:
+        """Queries and returns the line items.
+
+        :return: The line items.
+        """
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code,
+               JournalEntryLineItem.account_id == self.__account.id]
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        return [ReportLineItem(x) for x in JournalEntryLineItem.query
+                .join(JournalEntry)
+                .filter(*conditions)
+                .order_by(JournalEntry.date,
+                          JournalEntry.no,
+                          JournalEntryLineItem.is_debit.desc(),
+                          JournalEntryLineItem.no)
+                .options(selectinload(JournalEntryLineItem.journal_entry))
+                .all()]
+
+    def __get_total(self) -> ReportLineItem | None:
+        """Composes the total line item.
+
+        :return: The total line item, or None if there is no data.
+        """
+        if self.brought_forward is None and len(self.line_items) == 0:
+            return None
+        line_item: ReportLineItem = ReportLineItem()
+        line_item.is_total = True
+        line_item.description = gettext("Total")
+        line_item.debit = sum([x.debit for x in self.line_items
+                               if x.debit is not None])
+        line_item.credit = sum([x.credit for x in self.line_items
+                                if x.credit is not None])
+        line_item.balance = line_item.debit - line_item.credit
+        if self.brought_forward is not None:
+            line_item.balance \
+                = self.brought_forward.balance + line_item.balance
+        return line_item
+
+    def __populate_balance(self) -> None:
+        """Populates the balance of the line items.
+
+        :return: None.
+        """
+        if self.__account.is_nominal:
+            return None
+        balance: Decimal = 0 if self.brought_forward is None \
+            else self.brought_forward.balance
+        for line_item in self.line_items:
+            if line_item.debit is not None:
+                balance = balance + line_item.debit
+            if line_item.credit is not None:
+                balance = balance - line_item.credit
+            line_item.balance = balance
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self, journal_entry_date: date | str | None,
+                 description: str | None,
+                 debit: str | Decimal | None,
+                 credit: str | Decimal | None,
+                 balance: str | Decimal | None,
+                 note: str | None):
+        """Constructs a row in the CSV.
+
+        :param journal_entry_date: The journal entry date.
+        :param description: The description.
+        :param debit: The debit amount.
+        :param credit: The credit amount.
+        :param balance: The balance.
+        :param note: The note.
+        """
+        self.date: date | str | None = journal_entry_date
+        """The date."""
+        self.description: str | None = description
+        """The description."""
+        self.debit: str | Decimal | None = debit
+        """The debit amount."""
+        self.credit: str | Decimal | None = credit
+        """The credit amount."""
+        self.balance: str | Decimal | None = balance
+        """The balance."""
+        self.note: str | None = note
+        """The note."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.date, self.description,
+                self.debit, self.credit, self.balance, self.note]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, currency: Currency,
+                 account: Account,
+                 period: Period,
+                 has_data: bool,
+                 pagination: Pagination[ReportLineItem],
+                 brought_forward: ReportLineItem | None,
+                 line_items: list[ReportLineItem],
+                 total: ReportLineItem | None):
+        """Constructs the HTML page parameters.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        :param has_data: True if there is any data, or False otherwise.
+        :param brought_forward: The brought-forward line item.
+        :param line_items: The line items.
+        :param total: The total line item.
+        """
+        self.currency: Currency = currency
+        """The currency."""
+        self.account: Account = account
+        """The account."""
+        self.period: Period = period
+        """The period."""
+        self.__has_data: bool = has_data
+        """True if there is any data, or False otherwise."""
+        self.pagination: Pagination[ReportLineItem] = pagination
+        """The pagination."""
+        self.brought_forward: ReportLineItem | None = brought_forward
+        """The brought-forward line item."""
+        self.line_items: list[ReportLineItem] = line_items
+        """The line items."""
+        self.total: ReportLineItem | None = total
+        """The total line item."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: ledger_url(currency, account, x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return self.__has_data
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.LEDGER,
+                             currency=self.currency,
+                             account=self.account,
+                             period=self.period)
+
+    @property
+    def currency_options(self) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :return: The currency options.
+        """
+        return self._get_currency_options(
+            lambda x: ledger_url(x, self.account, self.period), self.currency)
+
+    @property
+    def account_options(self) -> list[OptionLink]:
+        """Returns the account options.
+
+        :return: The account options.
+        """
+        in_use: sa.Select = sa.Select(JournalEntryLineItem.account_id)\
+            .filter(be(JournalEntryLineItem.currency_code
+                       == self.currency.code))\
+            .group_by(JournalEntryLineItem.account_id)
+        return [OptionLink(str(x), ledger_url(self.currency, x, self.period),
+                           x.id == self.account.id)
+                for x in Account.query.filter(Account.id.in_(in_use))
+                .order_by(Account.base_code, Account.no).all()]
+
+
+class Ledger(BaseReport):
+    """The ledger."""
+
+    def __init__(self, currency: Currency, account: Account, period: Period):
+        """Constructs a ledger.
+
+        :param currency: The currency.
+        :param account: The account.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__account: Account = account
+        """The account."""
+        self.__period: Period = period
+        """The period."""
+        collector: LineItemCollector = LineItemCollector(
+            self.__currency, self.__account, self.__period)
+        self.__brought_forward: ReportLineItem | None \
+            = collector.brought_forward
+        """The brought-forward line item."""
+        self.__line_items: list[ReportLineItem] = collector.line_items
+        """The line items."""
+        self.__total: ReportLineItem | None = collector.total
+        """The total line item."""
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "ledger-{currency}-{account}-{period}.csv"\
+            .format(currency=self.__currency.code, account=self.__account.code,
+                    period=period_spec(self.__period))
+        return csv_download(filename, self.__get_csv_rows())
+
+    def __get_csv_rows(self) -> list[CSVRow]:
+        """Composes and returns the CSV rows.
+
+        :return: The CSV rows.
+        """
+        rows: list[CSVRow] = [CSVRow(gettext("Date"), gettext("Description"),
+                                     gettext("Debit"), gettext("Credit"),
+                                     gettext("Balance"), gettext("Note"))]
+        if self.__brought_forward is not None:
+            rows.append(CSVRow(self.__brought_forward.date,
+                               self.__brought_forward.description,
+                               self.__brought_forward.debit,
+                               self.__brought_forward.credit,
+                               self.__brought_forward.balance,
+                               None))
+        rows.extend([CSVRow(x.date, x.description,
+                            x.debit, x.credit, x.balance, x.note)
+                     for x in self.__line_items])
+        if self.__total is not None:
+            rows.append(CSVRow(gettext("Total"), None,
+                               self.__total.debit, self.__total.credit,
+                               self.__total.balance, None))
+        return rows
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        all_line_items: list[ReportLineItem] = []
+        if self.__brought_forward is not None:
+            all_line_items.append(self.__brought_forward)
+        all_line_items.extend(self.__line_items)
+        if self.__total is not None:
+            all_line_items.append(self.__total)
+        pagination: Pagination[ReportLineItem] \
+            = Pagination[ReportLineItem](all_line_items, is_reversed=True)
+        page_line_items: list[ReportLineItem] = pagination.list
+        has_data: bool = len(page_line_items) > 0
+        brought_forward: ReportLineItem | None = None
+        if len(page_line_items) > 0 and page_line_items[0].is_brought_forward:
+            brought_forward = page_line_items[0]
+            page_line_items = page_line_items[1:]
+        total: ReportLineItem | None = None
+        if len(page_line_items) > 0 and page_line_items[-1].is_total:
+            total = page_line_items[-1]
+            page_line_items = page_line_items[:-1]
+        params: PageParams = PageParams(currency=self.__currency,
+                                        account=self.__account,
+                                        period=self.__period,
+                                        has_data=has_data,
+                                        pagination=pagination,
+                                        brought_forward=brought_forward,
+                                        line_items=page_line_items,
+                                        total=total)
+        return render_template("accounting/report/ledger.html",
+                               report=params)

src/accounting/report/reports/search.py

@@ -0,0 +1,216 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/8
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The search.
+
+"""
+from datetime import datetime
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import Response, render_template, request
+from sqlalchemy.orm import selectinload
+
+from accounting.locale import gettext
+from accounting.models import Currency, CurrencyL10n, Account, AccountL10n, \
+    JournalEntry, JournalEntryLineItem
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import csv_download
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.utils.cast import be
+from accounting.utils.pagination import Pagination
+from accounting.utils.query import parse_query_keywords
+from .journal import get_csv_rows
+
+
+class LineItemCollector:
+    """The line item collector."""
+
+    def __init__(self):
+        """Constructs the line item collector."""
+        self.line_items: list[JournalEntryLineItem] = self.__query_line_items()
+        """The line items."""
+
+    def __query_line_items(self) -> list[JournalEntryLineItem]:
+        """Queries and returns the line items.
+
+        :return: The line items.
+        """
+        keywords: list[str] = parse_query_keywords(request.args.get("q"))
+        if len(keywords) == 0:
+            return []
+        conditions: list[sa.BinaryExpression] = []
+        for k in keywords:
+            sub_conditions: list[sa.BinaryExpression] \
+                = [JournalEntryLineItem.description.icontains(k),
+                   JournalEntryLineItem.account_id.in_(
+                       self.__get_account_condition(k)),
+                   JournalEntryLineItem.currency_code.in_(
+                       self.__get_currency_condition(k)),
+                   JournalEntryLineItem.journal_entry_id.in_(
+                       self.__get_journal_entry_condition(k))]
+            try:
+                sub_conditions.append(
+                    JournalEntryLineItem.amount == Decimal(k))
+            except ArithmeticError:
+                pass
+            conditions.append(sa.or_(*sub_conditions))
+        return JournalEntryLineItem.query.join(JournalEntry)\
+            .filter(*conditions)\
+            .order_by(JournalEntry.date,
+                      JournalEntry.no,
+                      JournalEntryLineItem.is_debit,
+                      JournalEntryLineItem.no)\
+            .options(selectinload(JournalEntryLineItem.account),
+                     selectinload(JournalEntryLineItem.currency),
+                     selectinload(JournalEntryLineItem.journal_entry)).all()
+
+    @staticmethod
+    def __get_account_condition(k: str) -> sa.Select:
+        """Composes and returns the condition to filter the account.
+
+        :param k: The keyword.
+        :return: The condition to filter the account.
+        """
+        code: sa.BinaryExpression = Account.base_code + "-" \
+            + sa.func.substr("000" + sa.cast(Account.no, sa.String),
+                             sa.func.char_length(sa.cast(Account.no,
+                                                         sa.String)) + 1)
+        select_l10n: sa.Select = sa.select(AccountL10n.account_id)\
+            .filter(AccountL10n.title.icontains(k))
+        conditions: list[sa.BinaryExpression] \
+            = [Account.base_code.contains(k),
+               Account.title_l10n.icontains(k),
+               code.contains(k),
+               Account.id.in_(select_l10n)]
+        if k in gettext("Needs Offset"):
+            conditions.append(Account.is_need_offset)
+        return sa.select(Account.id).filter(sa.or_(*conditions))
+
+    @staticmethod
+    def __get_currency_condition(k: str) -> sa.Select:
+        """Composes and returns the condition to filter the currency.
+
+        :param k: The keyword.
+        :return: The condition to filter the currency.
+        """
+        select_l10n: sa.Select = sa.select(CurrencyL10n.currency_code)\
+            .filter(CurrencyL10n.name.icontains(k))
+        return sa.select(Currency.code).filter(
+            sa.or_(Currency.code.icontains(k),
+                   Currency.name_l10n.icontains(k),
+                   Currency.code.in_(select_l10n)))
+
+    @staticmethod
+    def __get_journal_entry_condition(k: str) -> sa.Select:
+        """Composes and returns the condition to filter the journal entry.
+
+        :param k: The keyword.
+        :return: The condition to filter the journal entry.
+        """
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntry.note.icontains(k)]
+        journal_entry_date: datetime
+        try:
+            journal_entry_date = datetime.strptime(k, "%Y")
+            conditions.append(
+                be(sa.extract("year", JournalEntry.date)
+                   == journal_entry_date.year))
+        except ValueError:
+            pass
+        try:
+            journal_entry_date = datetime.strptime(k, "%Y/%m")
+            conditions.append(sa.and_(
+                sa.extract("year", JournalEntry.date)
+                == journal_entry_date.year,
+                sa.extract("month", JournalEntry.date)
+                == journal_entry_date.month))
+        except ValueError:
+            pass
+        try:
+            journal_entry_date = datetime.strptime(f"2000/{k}", "%Y/%m/%d")
+            conditions.append(sa.and_(
+                sa.extract("month", JournalEntry.date)
+                == journal_entry_date.month,
+                sa.extract("day", JournalEntry.date)
+                == journal_entry_date.day))
+        except ValueError:
+            pass
+        return sa.select(JournalEntry.id).filter(sa.or_(*conditions))
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, pagination: Pagination[JournalEntryLineItem],
+                 line_items: list[JournalEntryLineItem]):
+        """Constructs the HTML page parameters.
+
+        :param line_items: The search result line items.
+        """
+        self.pagination: Pagination[JournalEntryLineItem] = pagination
+        """The pagination."""
+        self.line_items: list[JournalEntryLineItem] = line_items
+        """The line items."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return len(self.line_items) > 0
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.SEARCH)
+
+
+class Search(BaseReport):
+    """The search."""
+
+    def __init__(self):
+        """Constructs a search."""
+        self.__line_items: list[JournalEntryLineItem] \
+            = LineItemCollector().line_items
+        """The line items."""
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "search-{q}.csv".format(q=request.args["q"])
+        return csv_download(filename, get_csv_rows(self.__line_items))
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        pagination: Pagination[JournalEntryLineItem] \
+            = Pagination[JournalEntryLineItem](self.__line_items,
+                                               is_reversed=True)
+        params: PageParams = PageParams(pagination=pagination,
+                                        line_items=pagination.list)
+        return render_template("accounting/report/search.html",
+                               report=params)

src/accounting/report/reports/trial_balance.py

@@ -0,0 +1,243 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The trial balance.
+
+"""
+from decimal import Decimal
+
+import sqlalchemy as sa
+from flask import Response, render_template
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, Account, JournalEntry, \
+    JournalEntryLineItem
+from accounting.report.period import Period, PeriodChooser
+from accounting.report.utils.base_page_params import BasePageParams
+from accounting.report.utils.base_report import BaseReport
+from accounting.report.utils.csv_export import BaseCSVRow, csv_download, \
+    period_spec
+from accounting.report.utils.option_link import OptionLink
+from accounting.report.utils.report_chooser import ReportChooser
+from accounting.report.utils.report_type import ReportType
+from accounting.report.utils.urls import ledger_url, trial_balance_url
+
+
+class ReportAccount:
+    """An account in the report."""
+
+    def __init__(self, account: Account, amount: Decimal, url: str):
+        """Constructs an account in the report.
+
+        :param account: The account.
+        :param amount: The amount.
+        :param url: The URL to the ledger of the account.
+        """
+        self.account: Account = account
+        """The account."""
+        self.debit: Decimal | None = amount if amount > 0 else None
+        """The debit amount."""
+        self.credit: Decimal | None = -amount if amount < 0 else None
+        """The credit amount."""
+        self.url: str = url
+        """The URL to the ledger of the account."""
+
+
+class Total:
+    """The totals."""
+
+    def __init__(self, debit: Decimal, credit: Decimal):
+        """Constructs the total in the trial balance.
+
+        :param debit: The debit amount.
+        :param credit: The credit amount.
+        """
+        self.debit: Decimal | None = debit
+        """The debit amount."""
+        self.credit: Decimal | None = credit
+        """The credit amount."""
+
+
+class CSVRow(BaseCSVRow):
+    """A row in the CSV."""
+
+    def __init__(self, text: str | None,
+                 debit: str | Decimal | None,
+                 credit: str | Decimal | None):
+        """Constructs a row in the CSV.
+
+        :param text: The text.
+        :param debit: The debit amount.
+        :param credit: The credit amount.
+        """
+        self.text: str | None = text
+        """The text."""
+        self.debit: str | Decimal | None = debit
+        """The debit amount."""
+        self.credit: str | Decimal | None = credit
+        """The credit amount."""
+
+    @property
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+        return [self.text, self.debit, self.credit]
+
+
+class PageParams(BasePageParams):
+    """The HTML page parameters."""
+
+    def __init__(self, currency: Currency,
+                 period: Period,
+                 accounts: list[ReportAccount],
+                 total: Total):
+        """Constructs the HTML page parameters.
+
+        :param currency: The currency.
+        :param period: The period.
+        :param accounts: The accounts in the trial balance.
+        :param total: The total of the trial balance.
+        """
+        self.currency: Currency = currency
+        """The currency."""
+        self.period: Period = period
+        """The period."""
+        self.accounts: list[ReportAccount] = accounts
+        """The accounts in the trial balance."""
+        self.total: Total = total
+        """The total of the trial balance."""
+        self.period_chooser: PeriodChooser = PeriodChooser(
+            lambda x: trial_balance_url(currency, x))
+        """The period chooser."""
+
+    @property
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+        return len(self.accounts) > 0
+
+    @property
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+        return ReportChooser(ReportType.TRIAL_BALANCE,
+                             currency=self.currency,
+                             period=self.period)
+
+    @property
+    def currency_options(self) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :return: The currency options.
+        """
+        return self._get_currency_options(
+            lambda x: trial_balance_url(x, self.period), self.currency)
+
+
+class TrialBalance(BaseReport):
+    """The trial balance."""
+
+    def __init__(self, currency: Currency, period: Period):
+        """Constructs a trial balance.
+
+        :param currency: The currency.
+        :param period: The period.
+        """
+        self.__currency: Currency = currency
+        """The currency."""
+        self.__period: Period = period
+        """The period."""
+        self.__accounts: list[ReportAccount]
+        """The accounts in the trial balance."""
+        self.__total: Total
+        """The total of the trial balance."""
+        self.__set_data()
+
+    def __set_data(self) -> None:
+        """Queries and sets data sections in the trial balance.
+
+        :return: None.
+        """
+        conditions: list[sa.BinaryExpression] \
+            = [JournalEntryLineItem.currency_code == self.__currency.code]
+        if self.__period.start is not None:
+            conditions.append(JournalEntry.date >= self.__period.start)
+        if self.__period.end is not None:
+            conditions.append(JournalEntry.date <= self.__period.end)
+        balance_func: sa.Function = sa.func.sum(sa.case(
+            (JournalEntryLineItem.is_debit, JournalEntryLineItem.amount),
+            else_=-JournalEntryLineItem.amount)).label("balance")
+        select_balances: sa.Select = sa.select(Account.id, balance_func)\
+            .join(JournalEntry).join(Account)\
+            .filter(*conditions)\
+            .group_by(Account.id)\
+            .having(balance_func != 0)\
+            .order_by(Account.base_code, Account.no)
+        balances: list[sa.Row] = db.session.execute(select_balances).all()
+        accounts: dict[int, Account] \
+            = {x.id: x for x in Account.query
+               .filter(Account.id.in_([x.id for x in balances])).all()}
+        self.__accounts = [ReportAccount(account=accounts[x.id],
+                                         amount=x.balance,
+                                         url=ledger_url(self.__currency,
+                                                        accounts[x.id],
+                                                        self.__period))
+                           for x in balances]
+        self.__total = Total(
+            sum([x.debit for x in self.__accounts if x.debit is not None]),
+            sum([x.credit for x in self.__accounts if x.credit is not None]))
+
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+        filename: str = "trial-balance-{currency}-{period}.csv"\
+            .format(currency=self.__currency.code,
+                    period=period_spec(self.__period))
+        return csv_download(filename, self.__get_csv_rows())
+
+    def __get_csv_rows(self) -> list[CSVRow]:
+        """Composes and returns the CSV rows.
+
+        :return: The CSV rows.
+        """
+        rows: list[CSVRow] = [CSVRow(gettext("Account"), gettext("Debit"),
+                                     gettext("Credit"))]
+        rows.extend([CSVRow(str(x.account).title(), x.debit, x.credit)
+                     for x in self.__accounts])
+        rows.append(CSVRow(gettext("Total"), self.__total.debit,
+                           self.__total.credit))
+        return rows
+
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """
+        params: PageParams = PageParams(currency=self.__currency,
+                                        period=self.__period,
+                                        accounts=self.__accounts,
+                                        total=self.__total)
+        return render_template("accounting/report/trial-balance.html",
+                               report=params)

src/accounting/report/template_filters.py

@@ -0,0 +1,37 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The template filters for the reports.
+
+"""
+from decimal import Decimal
+
+from accounting.template_filters import format_amount as core_format_amount
+
+
+def format_amount(value: Decimal | None) -> str | None:
+    """Formats an amount for the report.
+
+    :param value: The amount.
+    :return: The formatted amount text.
+    """
+    if value is None:
+        return ""
+    is_negative: bool = value < 0
+    formatted: str = core_format_amount(abs(value))
+    if is_negative:
+        formatted = f"({formatted})"
+    return formatted

src/accounting/report/utils/__init__.py

@@ -0,0 +1,19 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The utilities for the reports.
+
+"""

src/accounting/report/utils/base_page_params.py

@@ -0,0 +1,88 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The page parameters of a report.
+
+"""
+import typing as t
+from abc import ABC, abstractmethod
+from urllib.parse import urlparse, ParseResult, parse_qsl, urlencode, \
+    urlunparse
+
+import sqlalchemy as sa
+from flask import request
+
+from accounting import db
+from accounting.models import Currency, JournalEntryLineItem
+from accounting.utils.journal_entry_types import JournalEntryType
+from .option_link import OptionLink
+from .report_chooser import ReportChooser
+
+
+class BasePageParams(ABC):
+    """The base HTML page parameters class."""
+
+    @property
+    @abstractmethod
+    def has_data(self) -> bool:
+        """Returns whether there is any data on the page.
+
+        :return: True if there is any data, or False otherwise.
+        """
+
+    @property
+    @abstractmethod
+    def report_chooser(self) -> ReportChooser:
+        """Returns the report chooser.
+
+        :return: The report chooser.
+        """
+
+    @property
+    def journal_entry_types(self) -> t.Type[JournalEntryType]:
+        """Returns the journal entry types.
+
+        :return: The journal entry types.
+        """
+        return JournalEntryType
+
+    @property
+    def csv_uri(self) -> str:
+        uri: str = request.full_path if request.query_string \
+            else request.path
+        uri_p: ParseResult = urlparse(uri)
+        params: list[tuple[str, str]] = parse_qsl(uri_p.query)
+        params = [x for x in params if x[0] != "as"]
+        params.append(("as", "csv"))
+        parts: list[str] = list(uri_p)
+        parts[4] = urlencode(params)
+        return urlunparse(parts)
+
+    @staticmethod
+    def _get_currency_options(get_url: t.Callable[[Currency], str],
+                              active_currency: Currency) -> list[OptionLink]:
+        """Returns the currency options.
+
+        :param get_url: The callback to return the URL of a currency.
+        :param active_currency: The active currency.
+        :return: The currency options.
+        """
+        in_use: set[str] = set(db.session.scalars(
+            sa.select(JournalEntryLineItem.currency_code)
+            .group_by(JournalEntryLineItem.currency_code)).all())
+        return [OptionLink(str(x), get_url(x), x.code == active_currency.code)
+                for x in Currency.query.filter(Currency.code.in_(in_use))
+                .order_by(Currency.code).all()]

src/accounting/report/utils/base_report.py

@@ -0,0 +1,40 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/8
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The base report.
+
+"""
+from abc import ABC, abstractmethod
+
+from flask import Response
+
+
+class BaseReport(ABC):
+    """The base report class."""
+
+    @abstractmethod
+    def csv(self) -> Response:
+        """Returns the report as CSV for download.
+
+        :return: The response of the report for download.
+        """
+
+    @abstractmethod
+    def html(self) -> str:
+        """Composes and returns the report as HTML.
+
+        :return: The report as HTML.
+        """

src/accounting/report/utils/csv_export.py

@@ -0,0 +1,108 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/7
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The utilities to export the report as CSV for download.
+
+"""
+import csv
+from abc import ABC, abstractmethod
+from datetime import timedelta, date
+from decimal import Decimal
+from io import StringIO
+
+from flask import Response
+
+from accounting.report.period import Period
+
+
+class BaseCSVRow(ABC):
+    """The base CSV row."""
+
+    @property
+    @abstractmethod
+    def values(self) -> list[str | Decimal | None]:
+        """Returns the values of the row.
+
+        :return: The values of the row.
+        """
+
+
+def csv_download(filename: str, rows: list[BaseCSVRow]) -> Response:
+    """Exports the data rows as a CSV file for download.
+
+    :param filename: The download file name.
+    :param rows: The data rows.
+    :return: The response for download the CSV file.
+    """
+    with StringIO() as fp:
+        writer = csv.writer(fp)
+        writer.writerows([x.values for x in rows])
+        fp.seek(0)
+        response: Response = Response(fp.read(), mimetype="text/csv")
+        response.headers["Content-Disposition"] \
+            = f"attachment; filename={filename}"
+        return response
+
+
+def period_spec(period: Period) -> str:
+    """Constructs the period specification to be used in the filename.
+
+    :param period: The period.
+    :return: The period specification to be used in the filename.
+    """
+    start: str | None = __get_start_str(period.start)
+    end: str | None = __get_end_str(period.end)
+    if period.start is None and period.end is None:
+        return "all-time"
+    if start == end:
+        return start
+    if period.start is None:
+        return f"until-{end}"
+    if period.end is None:
+        return f"since-{start}"
+    return f"{start}-{end}"
+
+
+def __get_start_str(start: date | None) -> str | None:
+    """Returns the string representation of the start date.
+
+    :param start: The start date.
+    :return: The string representation of the start date, or None if the start
+        date is None.
+    """
+    if start is None:
+        return None
+    if start.month == 1 and start.day == 1:
+        return str(start.year)
+    if start.day == 1:
+        return start.strftime("%Y%m")
+    return start.strftime("%Y%m%d")
+
+
+def __get_end_str(end: date | None) -> str | None:
+    """Returns the string representation of the end date.
+
+    :param end: The end date.
+    :return: The string representation of the end date, or None if the end
+        date is None.
+    """
+    if end is None:
+        return None
+    if end.month == 12 and end.day == 31:
+        return str(end.year)
+    if (end + timedelta(days=1)).day == 1:
+        return end.strftime("%Y%m")
+    return end.strftime("%Y%m%d")

src/accounting/report/utils/option_link.py

@@ -0,0 +1,41 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/5
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The option link.
+
+"""
+
+
+class OptionLink:
+    """An option link."""
+
+    def __init__(self, title: str, url: str, is_active: bool,
+                 fa_icon: str | None = None):
+        """Constructs an option link.
+
+        :param title: The title.
+        :param url: The URL.
+        :param is_active: True if active, or False otherwise
+        :param fa_icon: The font-awesome icon, if any.
+        """
+        self.title: str = title
+        """The title."""
+        self.url: str = url
+        """The URL."""
+        self.is_active: bool = is_active
+        """True if active, or False otherwise."""
+        self.fa_icon: str | None = fa_icon
+        """The font-awesome icon, if any."""

src/accounting/report/utils/report_chooser.py

@@ -0,0 +1,159 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The report chooser.
+
+This file is largely taken from the NanoParma ERP project, first written in
+2021/9/16 by imacat (imacat@nanoparma.com).
+
+"""
+import re
+import typing as t
+
+from flask_babel import LazyString
+
+from accounting import db
+from accounting.locale import gettext
+from accounting.models import Currency, Account
+from accounting.report.period import Period, get_period
+from accounting.template_globals import default_currency_code
+from accounting.utils.current_account import CurrentAccount
+from .option_link import OptionLink
+from .report_type import ReportType
+from .urls import journal_url, ledger_url, income_expenses_url, \
+    trial_balance_url, income_statement_url, balance_sheet_url
+
+
+class ReportChooser:
+    """The report chooser."""
+
+    def __init__(self, active_report: ReportType,
+                 period: Period | None = None,
+                 currency: Currency | None = None,
+                 account: Account | None = None):
+        """Constructs the report chooser.
+
+        :param active_report: The active report.
+        :param period: The period.
+        :param currency: The currency.
+        :param account: The account.
+        """
+        self.__active_report: ReportType = active_report
+        """The currently active report."""
+        self.__period: Period = get_period() if period is None else period
+        """The period."""
+        self.__currency: Currency = db.session.get(
+            Currency, default_currency_code()) \
+            if currency is None else currency
+        """The currency."""
+        self.__account: Account = Account.cash() if account is None \
+            else account
+        """The currency."""
+        self.__reports: list[OptionLink] = []
+        """The links to the reports."""
+        self.current_report: str | LazyString = ""
+        """The title of the current report."""
+        self.is_search: bool = active_report == ReportType.SEARCH
+        """Whether the current report is the search page."""
+        self.__reports.append(self.__income_expenses)
+        self.__reports.append(self.__ledger)
+        self.__reports.append(self.__journal)
+        self.__reports.append(self.__trial_balance)
+        self.__reports.append(self.__income_statement)
+        self.__reports.append(self.__balance_sheet)
+        for report in self.__reports:
+            if report.is_active:
+                self.current_report = report.title
+        if self.is_search:
+            self.current_report = gettext("Search")
+
+    @property
+    def __income_expenses(self) -> OptionLink:
+        """Returns the income and expenses log.
+
+        :return: The income and expenses log.
+        """
+        account: Account = self.__account
+        if not re.match(r"[12][12]", account.base_code):
+            account: Account = Account.cash()
+        return OptionLink(gettext("Income and Expenses Log"),
+                          income_expenses_url(self.__currency,
+                                              CurrentAccount(account),
+                                              self.__period),
+                          self.__active_report == ReportType.INCOME_EXPENSES,
+                          fa_icon="fa-solid fa-money-bill-wave")
+
+    @property
+    def __ledger(self) -> OptionLink:
+        """Returns the ledger.
+
+        :return: The ledger.
+        """
+        return OptionLink(gettext("Ledger"),
+                          ledger_url(self.__currency, self.__account,
+                                     self.__period),
+                          self.__active_report == ReportType.LEDGER,
+                          fa_icon="fa-solid fa-clipboard")
+
+    @property
+    def __journal(self) -> OptionLink:
+        """Returns the journal.
+
+        :return: The journal.
+        """
+        return OptionLink(gettext("Journal"), journal_url(self.__period),
+                          self.__active_report == ReportType.JOURNAL,
+                          fa_icon="fa-solid fa-book")
+
+    @property
+    def __trial_balance(self) -> OptionLink:
+        """Returns the trial balance.
+
+        :return: The trial balance.
+        """
+        return OptionLink(gettext("Trial Balance"),
+                          trial_balance_url(self.__currency, self.__period),
+                          self.__active_report == ReportType.TRIAL_BALANCE,
+                          fa_icon="fa-solid fa-scale-unbalanced")
+
+    @property
+    def __income_statement(self) -> OptionLink:
+        """Returns the income statement.
+
+        :return: The income statement.
+        """
+        return OptionLink(gettext("Income Statement"),
+                          income_statement_url(self.__currency, self.__period),
+                          self.__active_report == ReportType.INCOME_STATEMENT,
+                          fa_icon="fa-solid fa-file-invoice-dollar")
+
+    @property
+    def __balance_sheet(self) -> OptionLink:
+        """Returns the balance sheet.
+
+        :return: The balance sheet.
+        """
+        return OptionLink(gettext("Balance Sheet"),
+                          balance_sheet_url(self.__currency, self.__period),
+                          self.__active_report == ReportType.BALANCE_SHEET,
+                          fa_icon="fa-solid fa-scale-balanced")
+
+    def __iter__(self) -> t.Iterator[OptionLink]:
+        """Returns the iteration of the reports.
+
+        :return: The iteration of the reports.
+        """
+        return iter(self.__reports)

src/accounting/report/utils/report_type.py

@@ -0,0 +1,38 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/4
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The report types.
+
+"""
+from enum import Enum
+
+
+class ReportType(Enum):
+    """The report types."""
+    JOURNAL: str = "journal"
+    """The journal."""
+    LEDGER: str = "ledger"
+    """The ledger."""
+    INCOME_EXPENSES: str = "income-expenses"
+    """The income and expenses log."""
+    TRIAL_BALANCE: str = "trial-balance"
+    """The trial balance."""
+    INCOME_STATEMENT: str = "income-statement"
+    """The income statement."""
+    BALANCE_SHEET: str = "balance-sheet"
+    """The balance sheet."""
+    SEARCH: str = "search"
+    """The search."""

src/accounting/report/utils/urls.py

@@ -0,0 +1,118 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/9
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The utilities to get the ledger URL.
+
+"""
+from flask import url_for
+
+from accounting.models import Currency, Account
+from accounting.report.period import Period
+from accounting.template_globals import default_currency_code
+from accounting.utils.current_account import CurrentAccount
+from accounting.utils.options import options
+
+
+def journal_url(period: Period) \
+        -> str:
+    """Returns the URL of a journal.
+
+    :param period: The period.
+    :return: The URL of the journal.
+    """
+    if period.is_default:
+        return url_for("accounting-report.journal-default")
+    return url_for("accounting-report.journal", period=period)
+
+
+def ledger_url(currency: Currency, account: Account, period: Period) \
+        -> str:
+    """Returns the URL of a ledger.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The URL of the ledger.
+    """
+    if period.is_default:
+        return url_for("accounting-report.ledger-default",
+                       currency=currency, account=account)
+    return url_for("accounting-report.ledger",
+                   currency=currency, account=account,
+                   period=period)
+
+
+def income_expenses_url(currency: Currency, account: CurrentAccount,
+                        period: Period) -> str:
+    """Returns the URL of an income and expenses log.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The URL of the income and expenses log.
+    """
+    if currency.code == default_currency_code() \
+            and account.code == options.default_ie_account_code \
+            and period.is_default:
+        return url_for("accounting-report.default")
+    if period.is_default:
+        return url_for("accounting-report.income-expenses-default",
+                       currency=currency, account=account)
+    return url_for("accounting-report.income-expenses",
+                   currency=currency, account=account,
+                   period=period)
+
+
+def trial_balance_url(currency: Currency, period: Period) -> str:
+    """Returns the URL of a trial balance.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The URL of the trial balance.
+    """
+    if period.is_default:
+        return url_for("accounting-report.trial-balance-default",
+                       currency=currency)
+    return url_for("accounting-report.trial-balance",
+                   currency=currency, period=period)
+
+
+def income_statement_url(currency: Currency, period: Period) -> str:
+    """Returns the URL of an income statement.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The URL of the income statement.
+    """
+    if period.is_default:
+        return url_for("accounting-report.income-statement-default",
+                       currency=currency)
+    return url_for("accounting-report.income-statement",
+                   currency=currency, period=period)
+
+
+def balance_sheet_url(currency: Currency, period: Period) -> str:
+    """Returns the URL of a balance sheet.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The URL of the balance sheet.
+    """
+    if period.is_default:
+        return url_for("accounting-report.balance-sheet-default",
+                       currency=currency)
+    return url_for("accounting-report.balance-sheet",
+                   currency=currency, period=period)

src/accounting/report/views.py

@@ -0,0 +1,299 @@
+# The Mia! Accounting Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/3/3
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The views for the report management.
+
+"""
+from flask import Blueprint, request, Response
+
+from accounting import db
+from accounting.models import Currency, Account
+from accounting.report.period import Period, get_period
+from accounting.template_globals import default_currency_code
+from accounting.utils.current_account import CurrentAccount
+from accounting.utils.options import options
+from accounting.utils.permission import has_permission, can_view
+from .reports import Journal, Ledger, IncomeExpenses, TrialBalance, \
+    IncomeStatement, BalanceSheet, Search
+from .template_filters import format_amount
+
+bp: Blueprint = Blueprint("accounting-report", __name__)
+"""The view blueprint for the reports."""
+bp.add_app_template_filter(format_amount, "accounting_report_format_amount")
+
+
+@bp.get("", endpoint="default")
+@has_permission(can_view)
+def get_default_report() -> str | Response:
+    """Returns the income and expenses log in the default period.
+
+    :return: The income and expenses log in the default period.
+    """
+    return __get_income_expenses(
+        db.session.get(Currency, default_currency_code()),
+        options.default_ie_account,
+        get_period())
+
+
+@bp.get("journal", endpoint="journal-default")
+@has_permission(can_view)
+def get_default_journal() -> str | Response:
+    """Returns the journal in the default period.
+
+    :return: The journal in the default period.
+    """
+    return __get_journal(get_period())
+
+
+@bp.get("journal/<period:period>", endpoint="journal")
+@has_permission(can_view)
+def get_journal(period: Period) -> str | Response:
+    """Returns the journal.
+
+    :param period: The period.
+    :return: The journal in the period.
+    """
+    return __get_journal(period)
+
+
+def __get_journal(period: Period) -> str | Response:
+    """Returns the journal.
+
+    :param period: The period.
+    :return: The journal in the period.
+    """
+    report: Journal = Journal(period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("ledger/<currency:currency>/<account:account>",
+        endpoint="ledger-default")
+@has_permission(can_view)
+def get_default_ledger(currency: Currency, account: Account) -> str | Response:
+    """Returns the ledger in the default period.
+
+    :param currency: The currency.
+    :param account: The account.
+    :return: The ledger in the default period.
+    """
+    return __get_ledger(currency, account, get_period())
+
+
+@bp.get("ledger/<currency:currency>/<account:account>/<period:period>",
+        endpoint="ledger")
+@has_permission(can_view)
+def get_ledger(currency: Currency, account: Account, period: Period) \
+        -> str | Response:
+    """Returns the ledger.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The ledger in the period.
+    """
+    return __get_ledger(currency, account, period)
+
+
+def __get_ledger(currency: Currency, account: Account, period: Period) \
+        -> str | Response:
+    """Returns the ledger.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The ledger in the period.
+    """
+    report: Ledger = Ledger(currency, account, period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("income-expenses/<currency:currency>/<ieAccount:account>",
+        endpoint="income-expenses-default")
+@has_permission(can_view)
+def get_default_income_expenses(currency: Currency, account: CurrentAccount) \
+        -> str | Response:
+    """Returns the income and expenses log in the default period.
+
+    :param currency: The currency.
+    :param account: The account.
+    :return: The income and expenses log in the default period.
+    """
+    return __get_income_expenses(currency, account, get_period())
+
+
+@bp.get(
+    "income-expenses/<currency:currency>/<ieAccount:account>/<period:period>",
+    endpoint="income-expenses")
+@has_permission(can_view)
+def get_income_expenses(currency: Currency, account: CurrentAccount,
+                        period: Period) -> str | Response:
+    """Returns the income and expenses log.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The income and expenses log in the period.
+    """
+    return __get_income_expenses(currency, account, period)
+
+
+def __get_income_expenses(currency: Currency, account: CurrentAccount,
+                          period: Period) -> str | Response:
+    """Returns the income and expenses log.
+
+    :param currency: The currency.
+    :param account: The account.
+    :param period: The period.
+    :return: The income and expenses log in the period.
+    """
+    report: IncomeExpenses = IncomeExpenses(currency, account, period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("trial-balance/<currency:currency>",
+        endpoint="trial-balance-default")
+@has_permission(can_view)
+def get_default_trial_balance(currency: Currency) -> str | Response:
+    """Returns the trial balance in the default period.
+
+    :param currency: The currency.
+    :return: The trial balance in the default period.
+    """
+    return __get_trial_balance(currency, get_period())
+
+
+@bp.get("trial-balance/<currency:currency>/<period:period>",
+        endpoint="trial-balance")
+@has_permission(can_view)
+def get_trial_balance(currency: Currency, period: Period) -> str | Response:
+    """Returns the trial balance.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The trial balance in the period.
+    """
+    return __get_trial_balance(currency, period)
+
+
+def __get_trial_balance(currency: Currency, period: Period) -> str | Response:
+    """Returns the trial balance.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The trial balance in the period.
+    """
+    report: TrialBalance = TrialBalance(currency, period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("income-statement/<currency:currency>",
+        endpoint="income-statement-default")
+@has_permission(can_view)
+def get_default_income_statement(currency: Currency) -> str | Response:
+    """Returns the income statement in the default period.
+
+    :param currency: The currency.
+    :return: The income statement in the default period.
+    """
+    return __get_income_statement(currency, get_period())
+
+
+@bp.get("income-statement/<currency:currency>/<period:period>",
+        endpoint="income-statement")
+@has_permission(can_view)
+def get_income_statement(currency: Currency, period: Period) -> str | Response:
+    """Returns the income statement.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The income statement in the period.
+    """
+    return __get_income_statement(currency, period)
+
+
+def __get_income_statement(currency: Currency, period: Period) \
+        -> str | Response:
+    """Returns the income statement.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The income statement in the period.
+    """
+    report: IncomeStatement = IncomeStatement(currency, period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("balance-sheet/<currency:currency>",
+        endpoint="balance-sheet-default")
+@has_permission(can_view)
+def get_default_balance_sheet(currency: Currency) -> str | Response:
+    """Returns the balance sheet in the default period.
+
+    :param currency: The currency.
+    :return: The balance sheet in the default period.
+    """
+    return __get_balance_sheet(currency, get_period())
+
+
+@bp.get("balance-sheet/<currency:currency>/<period:period>",
+        endpoint="balance-sheet")
+@has_permission(can_view)
+def get_balance_sheet(currency: Currency, period: Period) \
+        -> str | Response:
+    """Returns the balance sheet.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The balance sheet in the period.
+    """
+    return __get_balance_sheet(currency, period)
+
+
+def __get_balance_sheet(currency: Currency, period: Period) \
+        -> str | Response:
+    """Returns the balance sheet.
+
+    :param currency: The currency.
+    :param period: The period.
+    :return: The balance sheet in the period.
+    """
+    report: BalanceSheet = BalanceSheet(currency, period)
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()
+
+
+@bp.get("search", endpoint="search")
+@has_permission(can_view)
+def search() -> str | Response:
+    """Returns the search result.
+
+    :return: The search result.
+    """
+    report: Search = Search()
+    if "as" in request.args and request.args["as"] == "csv":
+        return report.csv()
+    return report.html()

src/accounting/static/css/style.css

@@ -1,4 +1,4 @@
-/* The Mia! Accounting Flask Project
+/* The Mia! Accounting Project
  * style.css: The style sheet for the accounting application.
  */
 
@@ -24,16 +24,6 @@
 .accounting-clickable {
     cursor: pointer;
 }
-.btn-group .btn .accounting-search-input {
-    min-height: calc(1em + .5rem + 2px);
-    padding: 0 0.5rem;
-}
-.btn-group .btn .accounting-search-label button {
-    border: none;
-    background-color: transparent;
-    color: inherit;
-    padding-right: 0;
-}
 .form-floating > textarea.form-control {
     height: 6rem;
 }
@@ -41,6 +31,64 @@
     color: #141619;
     background-color: #D3D3D4;
 }
+.form-control.accounting-disabled {
+    background-color: #e9ecef;
+}
+
+/** The toolbar */
+.accounting-toolbar {
+    display: flex;
+}
+.accounting-toolbar .input-group > .input-group-text {
+    padding: 0;
+    background-color: transparent;
+    color: inherit;
+    border: 0;
+}
+.accounting-toolbar .input-group > .input-group-text > button {
+    background-color: transparent;
+    color: inherit;
+    border: 0;
+}
+.accounting-toolbar form.btn > .form-control {
+    min-height: calc(1.5em + 2px);
+    padding-top: 0.1rem;
+    padding-bottom: 0.1rem;
+}
+@media(min-width: 768px) {
+    .accounting-toolbar > .btn, .accounting-toolbar > .btn-group > .btn {
+        border-radius: 0;
+    }
+    .accounting-toolbar > .btn:first-child, .accounting-toolbar > .btn-group:first-child > .btn {
+        border-top-left-radius: 0.375rem;
+        border-bottom-left-radius: 0.375rem;
+    }
+    .accounting-toolbar > .btn:last-child, .accounting-toolbar > .btn-group:last-child > .btn {
+        border-top-right-radius: 0.375rem;
+        border-bottom-right-radius: 0.375rem;
+    }
+    .accounting-toolbar .btn.input-group {
+        width: 16rem;
+    }
+}
+@media(max-width:767px) {
+    .accounting-toolbar > .btn:not(form), .accounting-toolbar > .btn-group > .btn {
+        height: 3.2rem;
+        width: 3.2rem;
+        border-radius: 50%;
+        margin-right: 0.5rem;
+    }
+    .accounting-toolbar > a.btn, .accounting-toolbar > .btn-group > a.btn {
+        padding-top: 0.7rem;
+    }
+    .accounting-toolbar > form.btn {
+        width: 12rem;
+        height: 2.6rem;
+        border-radius: 0.375rem;
+        margin-top: 0.3rem;
+        margin-left: 1rem;
+    }
+}
 
 /** The card layout */
 .accounting-card {
@@ -58,6 +106,42 @@
     font-size: 1.4rem;
     color: #373b3e;
 }
+.accounting-sheet {
+    padding: 2em 1.5em;
+    margin: 1em;
+    background-color: #F8F9FA;
+    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
+}
+.accounting-sheet h2 {
+    border-bottom: thick double slategray;
+}
+
+/* Links between objects */
+.accounting-original-line-item {
+    border-top: thin solid darkslategray;
+    padding: 0.2rem 0.5rem;
+}
+.accounting-original-line-item a {
+    color: inherit;
+    text-decoration: none;
+}
+.accounting-original-line-item a:hover {
+    color: inherit;
+}
+.accounting-offset-line-items {
+    border-top: thin solid darkslategray;
+    padding: 0.2rem 0.5rem;
+}
+.accounting-offset-line-items ul li {
+    list-style: none;
+}
+.accounting-offset-line-items ul li a {
+    color: inherit;
+    text-decoration: none;
+}
+.accounting-offset-line-items ul li a:hover {
+    color: inherit;
+}
 
 /** The option selector */
 .accounting-selector-list {
@@ -65,49 +149,199 @@
     overflow-y: scroll;
 }
 
-/** The transaction management */
+/** The journal entry management */
 .accounting-currency-control {
     background-color: transparent;
 }
 .accounting-currency-content {
     width: calc(100% - 3rem);
 }
-.accounting-entry-content {
+.accounting-line-item-content {
     width: calc(100% - 3rem);
     background-color: transparent;
 }
-.accounting-entry-control {
-    border-color: transparent;
-}
-.accounting-transaction-card {
-    padding: 2em 1.5em;
-    margin: 1em;
-    background-color: #F8F9FA;
-    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
-}
-.accounting-transaction-card h2 {
-    border-bottom: thick double slategray;
-}
 .accounting-list-group-stripped .list-group-item:nth-child(2n+1) {
     background-color: #f2f2f2;
 }
-.accounting-list-group-stripped .list-group-item-success:nth-child(2n+1) {
-    background-color: #c7dbd2;
-}
 .accounting-list-group-hover .list-group-item:hover {
     background-color: #ececec;
 }
-.accounting-transaction-entry {
+.accounting-journal-entry-line-item {
     border: none;
 }
-.accounting-transaction-entry-header {
+.accounting-journal-entry-line-item-header {
     font-weight: bolder;
     border-bottom: thick double slategray;
 }
-.list-group-item.accounting-transaction-entry-total {
+.list-group-item.accounting-journal-entry-line-item-total {
     font-weight: bolder;
     border-top: thick double slategray;
 }
+.accounting-line-item-editor-original-line-item-content {
+    width: calc(100% - 3rem);
+}
+
+/* The report table */
+.accounting-report-table-header, .accounting-report-table-footer {
+    font-size: 1.2rem;
+    font-weight: bolder;
+}
+.accounting-report-table-header {
+    border-bottom: thin solid slategray;
+}
+.accounting-report-table-footer {
+    font-style: italic;
+    border-top: thin solid slategray;
+}
+.accounting-report-table-row {
+    display: grid;
+}
+a.accounting-report-table-row {
+    color: inherit;
+    text-decoration: none;
+}
+.accounting-report-table-row > div {
+    padding: .5rem;
+}
+.accounting-report-table .accounting-amount {
+    text-align: right;
+}
+.accounting-report-table-body .accounting-amount {
+    font-style: italic;
+}
+.accounting-report-table-body .accounting-report-table-row:nth-child(2n+1) {
+    background-color: #f2f2f2;
+}
+.accounting-report-table-body .accounting-report-table-row:hover {
+    background-color: rgba(0, 0, 0, 0.075);
+}
+.accounting-journal-table .accounting-report-table-row {
+    grid-template-columns: 1fr 1fr 2fr 4fr 1fr 1fr;
+}
+.accounting-ledger-real-table .accounting-report-table-row {
+    grid-template-columns: 1fr 4fr 1fr 1fr 1fr;
+}
+.accounting-ledger-real-table .accounting-report-table-footer .accounting-report-table-row {
+    grid-template-columns: 5fr 1fr 1fr 1fr;
+}
+.accounting-ledger-nominal-table .accounting-report-table-row {
+    grid-template-columns: 1fr 4fr 1fr 1fr;
+}
+.accounting-ledger-nominal-table .accounting-report-table-footer .accounting-report-table-row {
+    grid-template-columns: 5fr 1fr 1fr;
+}
+.accounting-income-expenses-table .accounting-report-table-row {
+    grid-template-columns: 1fr 2fr 4fr 1fr 1fr 1fr;
+}
+.accounting-income-expenses-table .accounting-report-table-footer .accounting-report-table-row {
+    grid-template-columns: 7fr 1fr 1fr 1fr;
+}
+.accounting-trial-balance-table .accounting-report-table-header {
+    border-bottom: thick double slategray;
+}
+.accounting-trial-balance-table .accounting-report-table-footer {
+    border-top: thick double slategray;
+}
+.accounting-trial-balance-table .accounting-report-table-row {
+    grid-template-columns: 3fr 1fr 1fr;
+}
+.accounting-income-statement-table .accounting-report-table-body {
+    border-top: thick double slategray;
+    border-bottom: thick double slategray;
+}
+.accounting-income-statement-table .accounting-report-table-row {
+    display: flex;
+    justify-content: space-between;
+}
+.accounting-income-statement-table .accounting-report-table-header .accounting-report-table-row {
+    display: block;
+}
+.accounting-income-statement-section, .accounting-income-statement-total {
+    font-size: 1.2rem;
+    font-weight: bolder;
+}
+.accounting-income-statement-subsection, .accounting-income-statement-subtotal {
+    font-size: 1.1rem;
+}
+.accounting-income-statement-subtotal {
+    border-top: thin solid darkslategray;
+}
+/* Indents */
+.accounting-income-statement-subsection {
+    margin-left: 0.5rem;
+    margin-right: 0.5rem;
+}
+.accounting-income-statement-account, .accounting-income-statement-subtotal {
+    margin-left: 1rem;
+    margin-right: 1rem;
+}
+/* A visual blank line between categories */
+.accounting-income-statement-section {
+    margin-top: 2rem;
+}
+.accounting-income-statement-section:first-child {
+    margin-top: 0;
+}
+.accounting-income-statement-total {
+    margin-bottom: 2rem;
+}
+.accounting-income-statement-total:last-child {
+    margin-bottom: 0;
+}
+.accounting-balance-sheet-section, .accounting-balance-sheet-total {
+    font-size: 1.2rem;
+    font-weight: bolder;
+}
+.accounting-balance-sheet-section {
+    border-bottom: thick double darkslategray;
+}
+.accounting-balance-sheet-total {
+    border-top: thick double darkslategray;
+}
+.accounting-balance-sheet-subtotal {
+    font-size: 1.1rem;
+    font-weight: bolder;
+    border-top: thick double darkslategray;
+}
+.accounting-balance-sheet-account {
+    margin-left: 0.5rem;
+}
+.accounting-balance-sheet-total .accounting-amount, .accounting-balance-sheet-subtotal, .accounting-amount {
+    font-style: italic;
+}
+
+/* The accounting report */
+.accounting-mobile-journal-credit {
+    padding-left: 1rem;
+}
+
+/* The description editor */
+.accounting-description-editor-buttons {
+    max-height: 7rem;
+    overflow-y: scroll;
+}
+.accounting-description-editor-buttons .btn {
+    margin-bottom: 0.3rem;
+}
+
+/* The order of the journal entries in a same day */
+.accounting-journal-entry-order-item, .accounting-journal-entry-order-item:hover {
+    color: inherit;
+    text-decoration: none;
+}
+.accounting-journal-entry-order-item-currency {
+    margin-left: 0.5rem;
+    border-top: thin solid lightgray;
+    margin-top: 0.2rem;
+}
+
+/* The illustration of the description template for the recurring transactions */
+.accounting-recurring-description-template-illustration p {
+    margin: 0.2rem 0;
+}
+.accounting-recurring-description-template-illustration ul {
+    margin: 0;
+}
 
 /* The Material Design text field (floating form control in Bootstrap) */
 .accounting-material-text-field {
@@ -133,7 +367,7 @@
 .accounting-material-fab {
     position: fixed;
     right: 2rem;
-    bottom: 1rem;
+    bottom: 2rem;
     z-index: 10;
     flex-direction: column-reverse;
 }

src/accounting/static/js/account-form.js

@@ -1,4 +1,4 @@
-/* The Mia! Accounting Flask Project
+/* The Mia! Accounting Project
  * account-form.js: The JavaScript for the account form
  */
 
@@ -20,164 +20,408 @@
 /* Author: imacat@mail.imacat.idv.tw (imacat)
  * First written: 2023/2/1
  */
+"use strict";
 
 // Initializes the page JavaScript.
-document.addEventListener("DOMContentLoaded", function () {
-    initializeBaseAccountSelector();
-    document.getElementById("accounting-base-code")
-        .onchange = validateBase;
-    document.getElementById("accounting-title")
-        .onchange = validateTitle;
-    document.getElementById("accounting-form")
-        .onsubmit = validateForm;
+document.addEventListener("DOMContentLoaded", () => {
+    AccountForm.initialize();
 });
 
 /**
- * Initializes the base account selector.
+ * The account form.
  *
  * @private
  */
-function initializeBaseAccountSelector() {
-    const selector = document.getElementById("accounting-base-selector-modal");
-    const base = document.getElementById("accounting-base");
-    const baseCode = document.getElementById("accounting-base-code");
-    const baseContent = document.getElementById("accounting-base-content");
-    const options = Array.from(document.getElementsByClassName("accounting-base-option"));
-    const btnClear = document.getElementById("accounting-btn-clear-base");
-    selector.addEventListener("show.bs.modal", function () {
-        base.classList.add("accounting-not-empty");
-        options.forEach(function (item) {
-            item.classList.remove("active");
-        });
-        const selected = document.getElementById("accounting-base-option-" + baseCode.value);
-        if (selected !== null) {
-            selected.classList.add("active");
-        }
-    });
-    selector.addEventListener("hidden.bs.modal", function () {
-        if (baseCode.value === "") {
-            base.classList.remove("accounting-not-empty");
-        }
-    });
-    options.forEach(function (option) {
-        option.onclick = function () {
-            baseCode.value = option.dataset.code;
-            baseContent.innerText = option.dataset.content;
-            btnClear.classList.add("btn-danger");
-            btnClear.classList.remove("btn-secondary")
-            btnClear.disabled = false;
-            validateBase();
-            bootstrap.Modal.getInstance(selector).hide();
+class AccountForm {
+
+    /**
+     * The base account selector
+     * @type {BaseAccountSelector}
+     */
+    #baseAccountSelector;
+
+    /**
+     * The form element
+     * @type {HTMLFormElement}
+     */
+    #formElement;
+
+    /**
+     * The control of the base account
+     * @type {HTMLDivElement}
+     */
+    #baseControl;
+
+    /**
+     * The input of the base account
+     * @type {HTMLInputElement}
+     */
+    #baseCode;
+
+    /**
+     * The base account
+     * @type {HTMLDivElement}
+     */
+    #base;
+
+    /**
+     * The error message for the base account
+     * @type {HTMLDivElement}
+     */
+    #baseError;
+
+    /**
+     * The title
+     * @type {HTMLInputElement}
+     */
+    #title;
+
+    /**
+     * The error message of the title
+     * @type {HTMLDivElement}
+     */
+    #titleError;
+
+    /**
+     * The control of the is-need-offset option
+     * @type {HTMLDivElement}
+     */
+    #isNeedOffsetControl;
+
+    /**
+     * The is-need-offset option
+     * @type {HTMLInputElement}
+     */
+    #isNeedOffset;
+
+    /**
+     * Constructs the account form.
+     *
+     */
+    constructor() {
+        this.#baseAccountSelector = new BaseAccountSelector(this);
+        this.#formElement = document.getElementById("accounting-form");
+        this.#baseControl = document.getElementById("accounting-base-control");
+        this.#baseCode = document.getElementById("accounting-base-code");
+        this.#base = document.getElementById("accounting-base");
+        this.#baseError = document.getElementById("accounting-base-error");
+        this.#title = document.getElementById("accounting-title");
+        this.#titleError = document.getElementById("accounting-title-error");
+        this.#isNeedOffsetControl = document.getElementById("accounting-is-need-offset-control");
+        this.#isNeedOffset = document.getElementById("accounting-is-need-offset");
+        this.#formElement.onsubmit = () => {
+            return this.#validate();
+        };
+        this.#baseControl.onclick = () => {
+            this.#baseControl.classList.add("accounting-not-empty");
+            this.#baseAccountSelector.onOpen();
         };
-    });
-    btnClear.onclick = function () {
-        baseCode.value = "";
-        baseContent.innerText = "";
-        btnClear.classList.add("btn-secondary")
-        btnClear.classList.remove("btn-danger");
-        btnClear.disabled = true;
-        validateBase();
-        bootstrap.Modal.getInstance(selector).hide();
     }
-    initializeBaseAccountQuery();
-}
 
-/**
- * Initializes the query on the base account options.
+    /**
+     * Returns the base code.
      *
- * @private
+     * @return {string|null}
      */
-function initializeBaseAccountQuery() {
-    const query = document.getElementById("accounting-base-selector-query");
-    const optionList = document.getElementById("accounting-base-option-list");
-    const options = Array.from(document.getElementsByClassName("accounting-base-option"));
-    const queryNoResult = document.getElementById("accounting-base-option-no-result");
-    query.addEventListener("input", function () {
-        if (query.value === "") {
-            options.forEach(function (option) {
-                option.classList.remove("d-none");
-            });
-            optionList.classList.remove("d-none");
-            queryNoResult.classList.add("d-none");
-            return
+    get baseCode() {
+        return this.#baseCode.value === ""? null: this.#baseCode.value;
     }
-        let hasAnyMatched = false;
-        options.forEach(function (option) {
-            const queryValues = JSON.parse(option.dataset.queryValues);
-            let isMatched = false;
-            for (const queryValue of queryValues) {
-                if (queryValue.includes(query.value)) {
-                    isMatched = true;
-                    break;
-                }
-            }
-            if (isMatched) {
-                option.classList.remove("d-none");
-                hasAnyMatched = true;
-            } else {
-                option.classList.add("d-none");
-            }
-        });
-        if (!hasAnyMatched) {
-            optionList.classList.add("d-none");
-            queryNoResult.classList.remove("d-none");
-        } else {
-            optionList.classList.remove("d-none");
-            queryNoResult.classList.add("d-none");
-        }
-    });
-}
 
-/**
+    /**
+     * The callback when the base account selector is closed.
+     *
+     */
+    onBaseAccountSelectorClosed() {
+        if (this.#baseCode.value === "") {
+            this.#baseControl.classList.remove("accounting-not-empty");
+        }
+    }
+
+    /**
+     * Saves the selected base account.
+     *
+     * @param account {BaseAccountOption} the selected base account
+     */
+    saveBaseAccount(account) {
+        this.#baseCode.value = account.code;
+        this.#base.innerText = account.text;
+        if (["1", "2", "3"].includes(account.code.substring(0, 1))) {
+            this.#isNeedOffsetControl.classList.remove("d-none");
+            this.#isNeedOffset.disabled = false;
+        } else {
+            this.#isNeedOffsetControl.classList.add("d-none");
+            this.#isNeedOffset.disabled = true;
+            this.#isNeedOffset.checked = false;
+        }
+        this.#validateBase();
+    }
+
+    /**
+     * Clears the base account.
+     *
+     */
+    clearBaseAccount() {
+        this.#baseCode.value = "";
+        this.#base.innerText = "";
+        this.#validateBase();
+    }
+
+    /**
      * Validates the form.
      *
      * @returns {boolean} true if valid, or false otherwise
- * @private
      */
-function validateForm() {
+    #validate() {
         let isValid = true;
-    isValid = validateBase() && isValid;
-    isValid = validateTitle() && isValid;
+        isValid = this.#validateBase() && isValid;
+        isValid = this.#validateTitle() && isValid;
         return isValid;
-}
+    }
 
-/**
+    /**
      * Validates the base account.
      *
      * @returns {boolean} true if valid, or false otherwise
- * @private
      */
-function validateBase() {
-    const field = document.getElementById("accounting-base-code");
-    const error = document.getElementById("accounting-base-code-error");
-    const displayField = document.getElementById("accounting-base");
-    field.value = field.value.trim();
-    if (field.value === "") {
-        displayField.classList.add("is-invalid");
-        error.innerText = A_("Please select the base account.");
+    #validateBase() {
+        if (this.#baseCode.value === "") {
+            this.#baseControl.classList.add("is-invalid");
+            this.#baseError.innerText = A_("Please select the base account.");
             return false;
         }
-    displayField.classList.remove("is-invalid");
-    error.innerText = "";
+        this.#baseControl.classList.remove("is-invalid");
+        this.#baseError.innerText = "";
         return true;
-}
+    }
 
-/**
+    /**
      * Validates the title.
      *
      * @returns {boolean} true if valid, or false otherwise
- * @private
      */
-function validateTitle() {
-    const field = document.getElementById("accounting-title");
-    const error = document.getElementById("accounting-title-error");
-    field.value = field.value.trim();
-    if (field.value === "") {
-        field.classList.add("is-invalid");
-        error.innerText = A_("Please fill in the title.");
+    #validateTitle() {
+        this.#title.value = this.#title.value.trim();
+        if (this.#title.value === "") {
+            this.#title.classList.add("is-invalid");
+            this.#titleError.innerText = A_("Please fill in the title.");
             return false;
         }
-    field.classList.remove("is-invalid");
-    error.innerText = "";
+        this.#title.classList.remove("is-invalid");
+        this.#titleError.innerText = "";
         return true;
+    }
+
+    /**
+     * The account form
+     * @type {AccountForm} the form
+     */
+    static #form;
+
+    static initialize() {
+        this.#form = new AccountForm();
+    }
+}
+
+/**
+ * The base account selector.
+ *
+ * @private
+ */
+class BaseAccountSelector {
+
+    /**
+     * The account form
+     * @type {AccountForm}
+     */
+    form;
+
+    /**
+     * The selector modal
+     * @type {HTMLDivElement}
+     */
+    #modal;
+
+    /**
+     * The query input
+     * @type {HTMLInputElement}
+     */
+    #query;
+
+    /**
+     * The error message when the query has no result
+     * @type {HTMLParagraphElement}
+     */
+    #queryNoResult;
+
+    /**
+     * The option list
+     * @type {HTMLUListElement}
+     */
+    #optionList;
+
+    /**
+     * The options
+     * @type {BaseAccountOption[]}
+     */
+    #options;
+
+    /**
+     * The button to clear the base account value
+     * @type {HTMLButtonElement}
+     */
+    #clearButton;
+
+    /**
+     * Constructs the base account selector.
+     *
+     * @param form {AccountForm} the form
+     */
+    constructor(form) {
+        this.form = form;
+        const prefix = "accounting-base-selector";
+        this.#modal = document.getElementById(`${prefix}-modal`);
+        this.#query = document.getElementById(`${prefix}-query`);
+        this.#queryNoResult = document.getElementById(`${prefix}-option-no-result`);
+        this.#optionList = document.getElementById(`${prefix}-option-list`);
+        this.#options = Array.from(document.getElementsByClassName(`${prefix}-option`)).map((element) => new BaseAccountOption(this, element));
+        this.#clearButton = document.getElementById(`${prefix}-clear`);
+
+        this.#modal.addEventListener("hidden.bs.modal", () => this.form.onBaseAccountSelectorClosed());
+        this.#query.oninput = () => this.#filterOptions();
+        this.#clearButton.onclick = () => this.form.clearBaseAccount();
+    }
+
+    /**
+     * Filters the options.
+     *
+     */
+    #filterOptions() {
+        let isAnyMatched = false;
+        for (const option of this.#options) {
+            if (option.isMatched(this.#query.value)) {
+                option.setShown(true);
+                isAnyMatched = true;
+            } else {
+                option.setShown(false);
+            }
+        }
+        if (!isAnyMatched) {
+            this.#optionList.classList.add("d-none");
+            this.#queryNoResult.classList.remove("d-none");
+        } else {
+            this.#optionList.classList.remove("d-none");
+            this.#queryNoResult.classList.add("d-none");
+        }
+    }
+
+    /**
+     * The callback when the base account selector is shown.
+     *
+     */
+    onOpen() {
+        this.#query.value = "";
+        this.#filterOptions();
+        for (const option of this.#options) {
+            option.setActive(option.code === this.form.baseCode);
+        }
+        if (this.form.baseCode === null) {
+            this.#clearButton.classList.add("btn-secondary")
+            this.#clearButton.classList.remove("btn-danger");
+            this.#clearButton.disabled = true;
+        } else {
+            this.#clearButton.classList.add("btn-danger");
+            this.#clearButton.classList.remove("btn-secondary")
+            this.#clearButton.disabled = false;
+        }
+    }
+}
+
+/**
+ * A base account option.
+ *
+ */
+class BaseAccountOption {
+
+    /**
+     * The element
+     * @type {HTMLLIElement}
+     */
+    #element;
+
+    /**
+     * The account code
+     * @type {string}
+     */
+    code;
+
+    /**
+     * The account text
+     * @type {string}
+     */
+    text;
+
+    /**
+     * The values to query against
+     * @type {string[]}
+     */
+    #queryValues;
+
+    /**
+     * Constructs the account in the base account selector.
+     *
+     * @param selector {BaseAccountSelector} the base account selector
+     * @param element {HTMLLIElement} the element
+     */
+    constructor(selector, element) {
+        this.#element = element;
+        this.code = element.dataset.code;
+        this.text = element.dataset.text;
+        this.#queryValues = JSON.parse(element.dataset.queryValues);
+
+        this.#element.onclick = () => selector.form.saveBaseAccount(this);
+    }
+
+    /**
+     * Returns whether the account matches the query.
+     *
+     * @param query {string} the query term
+     * @return {boolean} true if the option matches, or false otherwise
+     */
+    isMatched(query) {
+        if (query === "") {
+            return true;
+        }
+        for (const queryValue of this.#queryValues) {
+            if (queryValue.toLowerCase().includes(query.toLowerCase())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Sets whether the option is shown.
+     *
+     * @param isShown {boolean} true to show, or false otherwise
+     */
+    setShown(isShown) {
+        if (isShown) {
+            this.#element.classList.remove("d-none");
+        } else {
+            this.#element.classList.add("d-none");
+        }
+    }
+
+    /**
+     * Sets whether the option is active.
+     *
+     * @param isActive {boolean} true if active, or false otherwise
+     */
+    setActive(isActive) {
+        if (isActive) {
+            this.#element.classList.add("active");
+        } else {
+            this.#element.classList.remove("active");
+        }
+    }
 }

src/accounting/static/js/account-order.js

@@ -1,4 +1,4 @@
-/* The Mia! Accounting Flask Project
+/* The Mia! Accounting Project
  * account-order.js: The JavaScript for the account order
  */
 
@@ -20,18 +20,20 @@
 /* Author: imacat@mail.imacat.idv.tw (imacat)
  * First written: 2023/2/2
  */
+"use strict";
 
 // Initializes the page JavaScript.
-document.addEventListener("DOMContentLoaded", function () {
+document.addEventListener("DOMContentLoaded", () => {
     const list = document.getElementById("accounting-order-list");
     if (list !== null) {
-        const onReorder = function () {
+        const onReorder = () => {
             const accounts = Array.from(list.children);
             for (let i = 0; i < accounts.length; i++) {
-                const no = document.getElementById("accounting-order-" + accounts[i].dataset.id + "-no");
-                const code = document.getElementById("accounting-order-" + accounts[i].dataset.id + "-code");
+                const no = document.getElementById(`accounting-order-${accounts[i].dataset.id}-no`);
+                const code = document.getElementById(`accounting-order-${accounts[i].dataset.id}-code`);
                 no.value = String(i + 1);
-                code.innerText = list.dataset.baseCode + "-" + ("000" + (i + 1)).slice(-3);
+                const zeroPaddedNo = `000${no.value}`.slice(-3)
+                code.innerText = `${list.dataset.baseCode}-${zeroPaddedNo}`;
             }
         };
         initializeDragAndDropReordering(list, onReorder);

src/accounting/static/js/currency-form.js

@@ -1,4 +1,4 @@
-/* The Mia! Accounting Flask Project
+/* The Mia! Accounting Project
  * currency-form.js: The JavaScript for the currency form
  */
 
@@ -20,155 +20,155 @@
 /* Author: imacat@mail.imacat.idv.tw (imacat)
  * First written: 2023/2/6
  */
+"use strict";
 
 // Initializes the page JavaScript.
-document.addEventListener("DOMContentLoaded", function () {
-    document.getElementById("accounting-code")
-        .onchange = validateCode;
-    document.getElementById("accounting-name")
-        .onchange = validateName;
-    document.getElementById("accounting-form")
-        .onsubmit = validateForm;
+document.addEventListener("DOMContentLoaded", () => {
+    CurrencyForm.initialize();
 });
 
 /**
- * The asynchronous validation result
- * @type {object}
+ * The currency form.
+ *
  * @private
  */
-let isAsyncValid = {};
+class CurrencyForm {
 
-/**
+    /**
+     * The form.
+     * @type {HTMLFormElement}
+     */
+    #formElement;
+
+    /**
+     * The code
+     * @type {HTMLInputElement}
+     */
+    #code;
+
+    /**
+     * The error message of the code
+     * @type {HTMLDivElement}
+     */
+    #codeError;
+
+    /**
+     * The name
+     * @type {HTMLInputElement}
+     */
+    #name;
+
+    /**
+     * The error message of the name
+     * @type {HTMLDivElement}
+     */
+    #nameError;
+
+    /**
+     * Constructs the currency form.
+     *
+     */
+    constructor() {
+        this.#formElement = document.getElementById("accounting-form");
+        this.#code = document.getElementById("accounting-code");
+        this.#codeError = document.getElementById("accounting-code-error");
+        this.#name = document.getElementById("accounting-name");
+        this.#nameError = document.getElementById("accounting-name-error");
+        this.#code.onchange = () => {
+            this.#validateCode().then();
+        };
+        this.#name.onchange = () => {
+            this.#validateName();
+        };
+        this.#formElement.onsubmit = () => {
+            this.#validate().then((isValid) => {
+                if (isValid) {
+                    this.#formElement.submit();
+                }
+            });
+            return false;
+        };
+    }
+
+    /**
      * Validates the form.
      *
- * @returns {boolean} true if valid, or false otherwise
- * @private
+     * @returns {Promise<boolean>} true if valid, or false otherwise
      */
-function validateForm() {
-    isAsyncValid = {
-        "code": false,
-        "_sync": false,
-    };
+    async #validate() {
         let isValid = true;
-    isValid = validateCode() && isValid;
-    isValid = validateName() && isValid;
-    isAsyncValid["_sync"] = isValid;
-    submitFormIfAllAsyncValid();
-    return false;
-}
-
-/**
- * Submits the form if the whole form passed the asynchronous
- * validations.
- *
- * @private
- */
-function submitFormIfAllAsyncValid() {
-    let isValid = true;
-    Object.keys(isAsyncValid).forEach(function (key) {
-        isValid = isAsyncValid[key] && isValid;
-    });
-    if (isValid) {
-        document.getElementById("accounting-form").submit()
+        isValid = await this.#validateCode() && isValid;
+        isValid = this.#validateName() && isValid;
+        return isValid;
     }
-}
 
-/**
+    /**
      * Validates the code.
      *
      * @param changeEvent {Event} the change event, if invoked from onchange
- * @returns {boolean} true if valid, or false otherwise
- * @private
+     * @returns {Promise<boolean>} true if valid, or false otherwise
      */
-function validateCode(changeEvent = null) {
-    const key = "code";
-    const isSubmission = changeEvent === null;
-    let hasAsyncValidation = false;
-    const field = document.getElementById("accounting-code");
-    const error = document.getElementById("accounting-code-error");
-    field.value = field.value.trim();
-    if (field.value === "") {
-        field.classList.add("is-invalid");
-        error.innerText = A_("Please fill in the code.");
+    async #validateCode(changeEvent = null) {
+        this.#code.value = this.#code.value.trim();
+        if (this.#code.value === "") {
+            this.#code.classList.add("is-invalid");
+            this.#codeError.innerText = A_("Please fill in the code.");
             return false;
         }
-    const blocklist = JSON.parse(field.dataset.blocklist);
-    if (blocklist.includes(field.value)) {
-        field.classList.add("is-invalid");
-        error.innerText = A_("This code is not available.");
+        const blocklist = JSON.parse(this.#code.dataset.blocklist);
+        if (blocklist.includes(this.#code.value)) {
+            this.#code.classList.add("is-invalid");
+            this.#codeError.innerText = A_("This code is not available.");
             return false;
         }
-    if (!field.value.match(/^[A-Z]{3}$/)) {
-        field.classList.add("is-invalid");
-        error.innerText = A_("Code can only be composed of 3 upper-cased letters.");
+        if (!this.#code.value.match(/^[A-Z]{3}$/)) {
+            this.#code.classList.add("is-invalid");
+            this.#codeError.innerText = A_("Code can only be composed of 3 upper-cased letters.");
             return false;
         }
-    const original = field.dataset.original;
-    if (original === "" || field.value !== original) {
-        hasAsyncValidation = true;
-        validateAsyncCodeIsDuplicated(isSubmission, key);
+        const original = this.#code.dataset.original;
+        if (original === "" || this.#code.value !== original) {
+            const response = await fetch(`${this.#code.dataset.existsUrl}?q=${encodeURIComponent(this.#code.value)}`);
+            const data = await response.json();
+            if (data["exists"]) {
+                this.#code.classList.add("is-invalid");
+                this.#codeError.innerText = A_("Code conflicts with another currency.");
+                return false;
             }
-    if (!hasAsyncValidation) {
-        isAsyncValid[key] = true;
-        field.classList.remove("is-invalid");
-        error.innerText = "";
         }
+        this.#code.classList.remove("is-invalid");
+        this.#codeError.innerText = "";
         return true;
-}
+    }
 
-/**
- * Validates asynchronously whether the code is duplicated.
- * The boolean validation result is stored in isAsyncValid[key].
- *
- * @param isSubmission {boolean} whether this is invoked from a form submission
- * @param key {string} the key to store the result in isAsyncValid
- * @private
- */
-function validateAsyncCodeIsDuplicated(isSubmission, key) {
-    const field = document.getElementById("accounting-code");
-    const error = document.getElementById("accounting-code-error");
-    const url = field.dataset.existsUrl;
-    const onLoad = function () {
-        if (this.status === 200) {
-            const result = JSON.parse(this.responseText);
-            if (result["exists"]) {
-                field.classList.add("is-invalid");
-                error.innerText = A_("Code conflicts with another currency.");
-                if (isSubmission) {
-                    isAsyncValid[key] = false;
-                }
-                return;
-            }
-            field.classList.remove("is-invalid");
-            error.innerText = "";
-            if (isSubmission) {
-                isAsyncValid[key] = true;
-                submitFormIfAllAsyncValid();
-            }
-        }
-    };
-    const request = new XMLHttpRequest();
-    request.onload = onLoad;
-    request.open("GET", url + "?q=" + encodeURIComponent(field.value));
-    request.send();
-}
-
-/**
+    /**
      * Validates the name.
      *
      * @returns {boolean} true if valid, or false otherwise
- * @private
      */
-function validateName() {
-    const field = document.getElementById("accounting-name");
-    const error = document.getElementById("accounting-name-error");
-    field.value = field.value.trim();
-    if (field.value === "") {
-        field.classList.add("is-invalid");
-        error.innerText = A_("Please fill in the name.");
+    #validateName() {
+        this.#name.value = this.#name.value.trim();
+        if (this.#name.value === "") {
+            this.#name.classList.add("is-invalid");
+            this.#nameError.innerText = A_("Please fill in the name.");
             return false;
         }
-    field.classList.remove("is-invalid");
-    error.innerText = "";
+        this.#name.classList.remove("is-invalid");
+        this.#nameError.innerText = "";
         return true;
+    }
+
+    /**
+     * The form
+     * @type {CurrencyForm}
+     */
+    static #form;
+
+    /**
+     * Initializes the currency form.
+     *
+     */
+    static initialize() {
+        this.#form = new CurrencyForm();
+    }
 }

src/accounting/static/js/drag-and-drop-reorder.js

@@ -1,4 +1,4 @@
-/* The Mia! Accounting Flask Project
+/* The Mia! Accounting Project
  * drag-and-drop-reorder.js: The JavaScript for the reorder a list with drag-and-drop
  */
 
@@ -20,6 +20,7 @@
 /* Author: imacat@mail.imacat.idv.tw (imacat)
  * First written: 2023/2/3
  */
+"use strict";
 
 /**
  * Initializes the drag-and-drop reordering on a list.
@@ -42,21 +43,21 @@ function initializeDragAndDropReordering(list, onReorder) {
 function initializeMouseDragAndDropReordering(list, onReorder) {
     const items = Array.from(list.children);
     let dragged = null;
-    items.forEach(function (item) {
+    for (const item of items) {
         item.draggable = true;
-        item.addEventListener("dragstart", function () {
+        item.addEventListener("dragstart", () => {
             dragged = item;
             dragged.classList.add("accounting-dragged");
         });
-        item.addEventListener("dragover", function () {
+        item.addEventListener("dragover", () => {
             onDragOver(dragged, item);
             onReorder();
         });
-        item.addEventListener("dragend", function () {
+        item.addEventListener("dragend", () => {
             dragged.classList.remove("accounting-dragged");
             dragged = null;
         });
-    });
+    }
 }
 
 /**
@@ -68,20 +69,20 @@ function initializeMouseDragAndDropReordering(list, onReorder) {
  */
 function initializeTouchDragAndDropReordering(list, onReorder) {
     const items = Array.from(list.children);
-    items.forEach(function (item) {
-        item.addEventListener("touchstart", function () {
+    for (const item of items) {
+        item.addEventListener("touchstart", () => {
             item.classList.add("accounting-dragged");
         });
-        item.addEventListener("touchmove", function (event) {
+        item.addEventListener("touchmove", (event) => {
             const touch = event.targetTouches[0];
             const target = document.elementFromPoint(touch.pageX, touch.pageY);
             onDragOver(item, target);
             onReorder();
         });
-        item.addEventListener("touchend", function () {
+        item.addEventListener("touchend", () => {
             item.classList.remove("accounting-dragged");
         });
-    });
+    }
 }
 
 /**

src/accounting/static/js/journal-entry-account-selector.js

@@ -0,0 +1,312 @@
+/* The Mia! Accounting Project
+ * journal-entry-account-selector.js: The JavaScript for the account selector of the journal entry form
+ */
+
+/*  Copyright (c) 2023 imacat.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/* Author: imacat@mail.imacat.idv.tw (imacat)
+ * First written: 2023/2/28
+ */
+"use strict";
+
+/**
+ * The account selector.
+ *
+ */
+class JournalEntryAccountSelector {
+
+    /**
+     * The line item editor
+     * @type {JournalEntryLineItemEditor}
+     */
+    lineItemEditor;
+
+    /**
+     * Either "debit" or "credit"
+     * @type {string}
+     */
+    #debitCredit;
+
+    /**
+     * The button to clear the account
+     * @type {HTMLButtonElement}
+     */
+    #clearButton
+
+    /**
+     * The query input
+     * @type {HTMLInputElement}
+     */
+    #query;
+
+    /**
+     * The error message when the query has no result
+     * @type {HTMLParagraphElement}
+     */
+    #queryNoResult;
+
+    /**
+     * The option list
+     * @type {HTMLUListElement}
+     */
+    #optionList;
+
+    /**
+     * The options
+     * @type {JournalEntryAccountOption[]}
+     */
+    #options;
+
+    /**
+     * The more item to show all accounts
+     * @type {HTMLLIElement}
+     */
+    #more;
+
+    /**
+     * Whether to show all accounts
+     * @type {boolean}
+     */
+    #isShowMore = false;
+
+    /**
+     * Constructs an account selector.
+     *
+     * @param lineItemEditor {JournalEntryLineItemEditor} the line item editor
+     * @param debitCredit {string} either "debit" or "credit"
+     */
+    constructor(lineItemEditor, debitCredit) {
+        this.lineItemEditor = lineItemEditor
+        this.#debitCredit = debitCredit;
+        const prefix = `accounting-account-selector-${debitCredit}`;
+        this.#query = document.getElementById(`${prefix}-query`);
+        this.#queryNoResult = document.getElementById(`${prefix}-option-no-result`);
+        this.#optionList = document.getElementById(`${prefix}-option-list`);
+        this.#options = Array.from(document.getElementsByClassName(`${prefix}-option`)).map((element) => new JournalEntryAccountOption(this, element));
+        this.#more = document.getElementById(`${prefix}-more`);
+        this.#clearButton = document.getElementById(`${prefix}-btn-clear`);
+
+        this.#more.onclick = () => {
+            this.#isShowMore = true;
+            this.#more.classList.add("d-none");
+            this.#filterOptions();
+        };
+        this.#query.oninput = () => this.#filterOptions();
+        this.#clearButton.onclick = () => this.lineItemEditor.clearAccount();
+    }
+
+    /**
+     * Filters the options.
+     *
+     */
+    #filterOptions() {
+        const codesInUse = this.#getCodesUsedInForm();
+        let isAnyMatched = false;
+        for (const option of this.#options) {
+            if (option.isMatched(this.#isShowMore, codesInUse, this.#query.value)) {
+                option.setShown(true);
+                isAnyMatched = true;
+            } else {
+                option.setShown(false);
+            }
+        }
+        if (!isAnyMatched) {
+            this.#optionList.classList.add("d-none");
+            this.#queryNoResult.classList.remove("d-none");
+        } else {
+            this.#optionList.classList.remove("d-none");
+            this.#queryNoResult.classList.add("d-none");
+        }
+    }
+
+    /**
+     * Returns the account codes that are used in the form.
+     *
+     * @return {string[]} the account codes that are used in the form
+     */
+    #getCodesUsedInForm() {
+        const inUse = this.lineItemEditor.form.getAccountCodesUsed(this.#debitCredit);
+        if (this.lineItemEditor.account !== null) {
+            inUse.push(this.lineItemEditor.account.code);
+        }
+        return inUse
+    }
+
+    /**
+     * The callback when the account selector is shown.
+     *
+     */
+    onOpen() {
+        this.#query.value = "";
+        this.#isShowMore = false;
+        this.#more.classList.remove("d-none");
+        this.#filterOptions();
+        for (const option of this.#options) {
+            option.setActive(this.lineItemEditor.account !== null && option.code === this.lineItemEditor.account.code);
+        }
+        if (this.lineItemEditor.account === null) {
+            this.#clearButton.classList.add("btn-secondary");
+            this.#clearButton.classList.remove("btn-danger");
+            this.#clearButton.disabled = true;
+        } else {
+            this.#clearButton.classList.add("btn-danger");
+            this.#clearButton.classList.remove("btn-secondary");
+            this.#clearButton.disabled = false;
+        }
+    }
+
+    /**
+     * Returns the account selector instances.
+     *
+     * @param lineItemEditor {JournalEntryLineItemEditor} the line item editor
+     * @return {{debit: JournalEntryAccountSelector, credit: JournalEntryAccountSelector}}
+     */
+    static getInstances(lineItemEditor) {
+        const selectors = {}
+        const modals = Array.from(document.getElementsByClassName("accounting-account-selector"));
+        for (const modal of modals) {
+            selectors[modal.dataset.debitCredit] = new JournalEntryAccountSelector(lineItemEditor, modal.dataset.debitCredit);
+        }
+        return selectors;
+    }
+}
+
+/**
+ * An account option
+ *
+ */
+class JournalEntryAccountOption {
+
+    /**
+     * The element
+     * @type {HTMLLIElement}
+     */
+    #element;
+
+    /**
+     * The account code
+     * @type {string}
+     */
+    code;
+
+    /**
+     * The account text
+     * @type {string}
+     */
+    text;
+
+    /**
+     * Whether the account is in use
+     * @type {boolean}
+     */
+    #isInUse;
+
+    /**
+     * Whether line items in the account need offset
+     * @type {boolean}
+     */
+    isNeedOffset;
+
+    /**
+     * The values to query against
+     * @type {string[]}
+     */
+    #queryValues;
+
+    /**
+     * Constructs the account in the account selector.
+     *
+     * @param selector {JournalEntryAccountSelector} the account selector
+     * @param element {HTMLLIElement} the element
+     */
+    constructor(selector, element) {
+        this.#element = element;
+        this.code = element.dataset.code;
+        this.text = element.dataset.text;
+        this.#isInUse = element.classList.contains("accounting-account-is-in-use");
+        this.isNeedOffset = element.classList.contains("accounting-account-is-need-offset");
+        this.#queryValues = JSON.parse(element.dataset.queryValues);
+
+        this.#element.onclick = () => selector.lineItemEditor.saveAccount(this);
+    }
+
+    /**
+     * Returns whether the account matches the query.
+     *
+     * @param isShowMore {boolean} true to show all accounts, or false to show only those in use
+     * @param codesInUse {string[]} the account codes that are used in the form
+     * @param query {string} the query term
+     * @return {boolean} true if the option matches, or false otherwise
+     */
+    isMatched(isShowMore, codesInUse, query) {
+        return this.#isInUseMatched(isShowMore, codesInUse) && this.#isQueryMatched(query);
+    }
+
+    /**
+     * Returns whether the account matches the "in-use" condition.
+     *
+     * @param isShowMore {boolean} true to show all accounts, or false to show only those in use
+     * @param codesInUse {string[]} the account codes that are used in the form
+     * @return {boolean} true if the option matches, or false otherwise
+     */
+    #isInUseMatched(isShowMore, codesInUse) {
+        return isShowMore || this.#isInUse || codesInUse.includes(this.code);
+    }
+
+    /**
+     * Returns whether the account matches the query term.
+     *
+     * @param query {string} the query term
+     * @return {boolean} true if the option matches, or false otherwise
+     */
+    #isQueryMatched(query) {
+        if (query === "") {
+            return true;
+        }
+        for (const queryValue of this.#queryValues) {
+            if (queryValue.toLowerCase().includes(query.toLowerCase())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Sets whether the option is shown.
+     *
+     * @param isShown {boolean} true to show, or false otherwise
+     */
+    setShown(isShown) {
+        if (isShown) {
+            this.#element.classList.remove("d-none");
+        } else {
+            this.#element.classList.add("d-none");
+        }
+    }
+
+    /**
+     * Sets whether the option is active.
+     *
+     * @param isActive {boolean} true if active, or false otherwise
+     */
+    setActive(isActive) {
+        if (isActive) {
+            this.#element.classList.add("active");
+        } else {
+            this.#element.classList.remove("active");
+        }
+    }
+}