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

#  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 permissions.

This module should not import any other module from the application.

"""
import typing as t

from flask import Flask, abort

from accounting.utils.user import get_current_user


def has_permission(rule: t.Callable[[], bool]) -> t.Callable:
    """The permission decorator to check whether the current user is allowed.

    :param rule: The permission rule.
    :return: The view decorator.
    """

    def decorator(view: t.Callable) -> t.Callable:
        """The view decorator to decorate a view with permission tests.

        :param view: The view.
        :return: The decorated view.
        """

        def decorated_view(*args, **kwargs):
            """The decorated view that tests against a permission rule.

            :param args: The arguments of the view.
            :param kwargs: The keyword arguments of the view.
            :return: The response of the view.
            :raise Forbidden: When the user is denied.
            """
            if not rule():
                abort(403)
            return view(*args, **kwargs)

        return decorated_view

    return decorator


__can_view_func: t.Callable[[], bool] = lambda: True
"""The callback that returns whether the current user can view the accounting
data."""
__can_edit_func: t.Callable[[], bool] = lambda: True
"""The callback that returns whether the current user can edit the accounting
data."""


def can_view() -> bool:
    """Returns whether the current user can view the account data.

    :return: True if the current user can view the accounting data, or False
        otherwise.
    """
    return __can_view_func()


def can_edit() -> bool:
    """Returns whether the current user can edit the account data.

    The user has to log in.

    :return: True if the current user can edit the accounting data, or False
        otherwise.
    """
    if get_current_user() is None:
        return False
    return __can_edit_func()


def init_app(app: Flask, can_view_func: t.Callable[[], bool] | None = None,
             can_edit_func: t.Callable[[], bool] | None = None) -> None:
    """Initializes the application.

    :param app: The Flask 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.
    """
    global __can_view_func, __can_edit_func
    if can_view_func is not None:
        __can_view_func = can_view_func
    if can_edit_func is not None:
        __can_edit_func = can_edit_func
    app.jinja_env.globals["can_view_accounting"] = can_view
    app.jinja_env.globals["can_edit_accounting"] = can_edit