"""
事件处理
========

NoneBot 内部处理并按优先级分发事件给所有事件响应器，提供了多个插槽以进行事件的预处理等。
"""

import asyncio
from datetime import datetime
from contextlib import AsyncExitStack
from typing import TYPE_CHECKING, Any, Set, Dict, Type, Optional

from nonebot import params
from nonebot.log import logger
from nonebot.rule import TrieRule
from nonebot.handler import Handler
from nonebot.utils import escape_tag
from nonebot.matcher import Matcher, matchers
from nonebot.exception import NoLogException, StopPropagation, IgnoredException
from nonebot.typing import (T_State, T_DependencyCache, T_RunPreProcessor,
                            T_RunPostProcessor, T_EventPreProcessor,
                            T_EventPostProcessor)

if TYPE_CHECKING:
    from nonebot.adapters import Bot, Event

_event_preprocessors: Set[Handler] = set()
_event_postprocessors: Set[Handler] = set()
_run_preprocessors: Set[Handler] = set()
_run_postprocessors: Set[Handler] = set()

EVENT_PCS_PARAMS = [
    params.BotParam, params.EventParam, params.StateParam, params.DefaultParam
]
RUN_PREPCS_PARAMS = [
    params.MatcherParam, params.BotParam, params.EventParam, params.StateParam,
    params.DefaultParam
]
RUN_POSTPCS_PARAMS = [
    params.MatcherParam, params.ExceptionParam, params.BotParam,
    params.EventParam, params.StateParam, params.DefaultParam
]


def event_preprocessor(func: T_EventPreProcessor) -> T_EventPreProcessor:
    """
    :说明:

      事件预处理。装饰一个函数，使它在每次接收到事件并分发给各响应器之前执行。
    """
    _event_preprocessors.add(Handler(func, allow_types=EVENT_PCS_PARAMS))
    return func


def event_postprocessor(func: T_EventPostProcessor) -> T_EventPostProcessor:
    """
    :说明:

      事件后处理。装饰一个函数，使它在每次接收到事件并分发给各响应器之后执行。
    """
    _event_postprocessors.add(Handler(func, allow_types=EVENT_PCS_PARAMS))
    return func


def run_preprocessor(func: T_RunPreProcessor) -> T_RunPreProcessor:
    """
    :说明:

      运行预处理。装饰一个函数，使它在每次事件响应器运行前执行。
    """
    _run_preprocessors.add(Handler(func, allow_types=RUN_PREPCS_PARAMS))
    return func


def run_postprocessor(func: T_RunPostProcessor) -> T_RunPostProcessor:
    """
    :说明:

      运行后处理。装饰一个函数，使它在每次事件响应器运行后执行。
    """
    _run_postprocessors.add(Handler(func, allow_types=RUN_POSTPCS_PARAMS))
    return func


async def _check_matcher(
        priority: int,
        Matcher: Type[Matcher],
        bot: "Bot",
        event: "Event",
        state: T_State,
        stack: Optional[AsyncExitStack] = None,
        dependency_cache: Optional[T_DependencyCache] = None) -> None:
    if Matcher.expire_time and datetime.now() > Matcher.expire_time:
        try:
            matchers[priority].remove(Matcher)
        except Exception:
            pass
        return

    try:
        if not await Matcher.check_perm(
                bot, event, stack,
                dependency_cache) or not await Matcher.check_rule(
                    bot, event, state, stack, dependency_cache):
            return
    except Exception as e:
        logger.opt(colors=True, exception=e).error(
            f"<r><bg #f8bbd0>Rule check failed for {Matcher}.</bg #f8bbd0></r>")
        return

    if Matcher.temp:
        try:
            matchers[priority].remove(Matcher)
        except Exception:
            pass

    await _run_matcher(Matcher, bot, event, state, stack, dependency_cache)


async def _run_matcher(
        Matcher: Type[Matcher],
        bot: "Bot",
        event: "Event",
        state: T_State,
        stack: Optional[AsyncExitStack] = None,
        dependency_cache: Optional[T_DependencyCache] = None) -> None:
    logger.info(f"Event will be handled by {Matcher}")

    matcher = Matcher()

    coros = list(
        map(
            lambda x: x(matcher=matcher,
                        bot=bot,
                        event=event,
                        state=state,
                        _stack=stack,
                        _dependency_cache=dependency_cache),
            _run_preprocessors))
    if coros:
        try:
            await asyncio.gather(*coros)
        except IgnoredException:
            logger.opt(colors=True).info(
                f"Matcher {matcher} running is <b>cancelled</b>")
            return
        except Exception as e:
            logger.opt(colors=True, exception=e).error(
                "<r><bg #f8bbd0>Error when running RunPreProcessors. "
                "Running cancelled!</bg #f8bbd0></r>")
            return

    exception = None

    try:
        logger.debug(f"Running matcher {matcher}")
        await matcher.run(bot, event, state, stack, dependency_cache)
    except Exception as e:
        logger.opt(colors=True, exception=e).error(
            f"<r><bg #f8bbd0>Running matcher {matcher} failed.</bg #f8bbd0></r>"
        )
        exception = e

    coros = list(
        map(
            lambda x: x(matcher=matcher,
                        exception=exception,
                        bot=bot,
                        event=event,
                        state=state,
                        _stack=stack,
                        _dependency_cache=dependency_cache),
            _run_postprocessors))
    if coros:
        try:
            await asyncio.gather(*coros)
        except Exception as e:
            logger.opt(colors=True, exception=e).error(
                "<r><bg #f8bbd0>Error when running RunPostProcessors</bg #f8bbd0></r>"
            )

    if matcher.block:
        raise StopPropagation
    return


async def handle_event(bot: "Bot", event: "Event") -> None:
    """
    :说明:

       处理一个事件。调用该函数以实现分发事件。

    :参数:

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

    :示例:

    .. code-block:: python

        import asyncio
        asyncio.create_task(handle_event(bot, event))
    """
    show_log = True
    log_msg = f"<m>{escape_tag(bot.type.upper())} {escape_tag(bot.self_id)}</m> | "
    try:
        log_msg += event.get_log_string()
    except NoLogException:
        show_log = False
    if show_log:
        logger.opt(colors=True).success(log_msg)

    state: Dict[Any, Any] = {}
    dependency_cache: T_DependencyCache = {}

    async with AsyncExitStack() as stack:
        coros = list(
            map(
                lambda x: x(bot=bot,
                            event=event,
                            state=state,
                            _stack=stack,
                            _dependency_cache=dependency_cache),
                _event_preprocessors))
        if coros:
            try:
                if show_log:
                    logger.debug("Running PreProcessors...")
                await asyncio.gather(*coros)
            except IgnoredException as e:
                logger.opt(colors=True).info(
                    f"Event {escape_tag(event.get_event_name())} is <b>ignored</b>"
                )
                return
            except Exception as e:
                logger.opt(colors=True, exception=e).error(
                    "<r><bg #f8bbd0>Error when running EventPreProcessors. "
                    "Event ignored!</bg #f8bbd0></r>")
                return

        # Trie Match
        _, _ = TrieRule.get_value(bot, event, state)

        break_flag = False
        for priority in sorted(matchers.keys()):
            if break_flag:
                break

            if show_log:
                logger.debug(f"Checking for matchers in priority {priority}...")

            pending_tasks = [
                _check_matcher(priority, matcher, bot, event, state.copy(),
                               stack, dependency_cache)
                for matcher in matchers[priority]
            ]

            results = await asyncio.gather(*pending_tasks,
                                           return_exceptions=True)

            for result in results:
                if not isinstance(result, Exception):
                    continue
                if isinstance(result, StopPropagation):
                    break_flag = True
                    logger.debug("Stop event propagation")
                else:
                    logger.opt(colors=True, exception=result).error(
                        "<r><bg #f8bbd0>Error when checking Matcher.</bg #f8bbd0></r>"
                    )

        coros = list(
            map(
                lambda x: x(bot=bot,
                            event=event,
                            state=state,
                            _stack=stack,
                            _dependency_cache=dependency_cache),
                _event_postprocessors))
        if coros:
            try:
                if show_log:
                    logger.debug("Running PostProcessors...")
                await asyncio.gather(*coros)
            except Exception as e:
                logger.opt(colors=True, exception=e).error(
                    "<r><bg #f8bbd0>Error when running EventPostProcessors</bg #f8bbd0></r>"
                )