# 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