"""
权限
====

每个 ``Matcher`` 拥有一个 ``Permission`` ，其中是 **异步** ``PermissionChecker`` 的集合，只要有一个 ``PermissionChecker`` 检查结果为 ``True`` 时就会继续运行。

\:\:\:tip 提示
``PermissionChecker`` 既可以是 async function 也可以是 sync function
\:\:\:
"""

import asyncio
from typing import Union, Optional, Callable, NoReturn, Awaitable, TYPE_CHECKING

from nonebot.utils import run_sync
from nonebot.typing import T_PermissionChecker

if TYPE_CHECKING:
    from nonebot.adapters import Bot, Event


class Permission:
    __slots__ = ("checkers",)

    def __init__(
            self, *checkers: Callable[["Bot", "Event"],
                                      Awaitable[bool]]) -> None:
        """
        :参数:

          * ``*checkers: Callable[[Bot, Event], Awaitable[bool]]``: **异步** PermissionChecker
        """
        self.checkers = set(checkers)
        """
        :说明:

          存储 ``PermissionChecker``

        :类型:

          * ``Set[Callable[[Bot, Event], Awaitable[bool]]]``
        """

    async def __call__(self, bot: "Bot", event: "Event") -> bool:
        """
        :说明:

          检查是否满足某个权限

        :参数:

          * ``bot: Bot``: Bot 对象
          * ``event: Event``: Event 对象

        :返回:

          - ``bool``
        """
        if not self.checkers:
            return True
        results = await asyncio.gather(
            *map(lambda c: c(bot, event), self.checkers))
        return any(results)

    def __and__(self, other) -> NoReturn:
        raise RuntimeError("And operation between Permissions is not allowed.")

    def __or__(
        self, other: Optional[Union["Permission",
                                    T_PermissionChecker]]) -> "Permission":
        checkers = self.checkers.copy()
        if other is None:
            return self
        elif isinstance(other, Permission):
            checkers |= other.checkers
        elif asyncio.iscoroutinefunction(other):
            checkers.add(other)  # type: ignore
        else:
            checkers.add(run_sync(other))
        return Permission(*checkers)


async def _message(bot: "Bot", event: "Event") -> bool:
    return event.get_type() == "message"


async def _notice(bot: "Bot", event: "Event") -> bool:
    return event.get_type() == "notice"


async def _request(bot: "Bot", event: "Event") -> bool:
    return event.get_type() == "request"


async def _metaevent(bot: "Bot", event: "Event") -> bool:
    return event.get_type() == "meta_event"


MESSAGE = Permission(_message)
"""
- **说明**: 匹配任意 ``message`` 类型事件，仅在需要同时捕获不同类型事件时使用。优先使用 message type 的 Matcher。
"""
NOTICE = Permission(_notice)
"""
- **说明**: 匹配任意 ``notice`` 类型事件，仅在需要同时捕获不同类型事件时使用。优先使用 notice type 的 Matcher。
"""
REQUEST = Permission(_request)
"""
- **说明**: 匹配任意 ``request`` 类型事件，仅在需要同时捕获不同类型事件时使用。优先使用 request type 的 Matcher。
"""
METAEVENT = Permission(_metaevent)
"""
- **说明**: 匹配任意 ``meta_event`` 类型事件，仅在需要同时捕获不同类型事件时使用。优先使用 meta_event type 的 Matcher。
"""


def USER(*user: str, perm: Permission = Permission()):
    """
    :说明:

      在白名单内且满足 perm

    :参数:

      * ``*user: str``: 白名单
      * ``perm: Permission``: 需要同时满足的权限
    """

    async def _user(bot: "Bot", event: "Event") -> bool:
        return event.get_session_id() in user and await perm(bot, event)

    return Permission(_user)


async def _superuser(bot: "Bot", event: "Event") -> bool:
    return event.get_type() == "message" and event.get_user_id(
    ) in bot.config.superusers


SUPERUSER = Permission(_superuser)
"""
- **说明**: 匹配任意超级用户消息类型事件
"""