"""本模块定义了事件处理主要流程。

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。

FrontMatter:
    sidebar_position: 2
    description: nonebot.message 模块
"""

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

from nonebot.log import logger
from nonebot.rule import TrieRule
from nonebot.dependencies import Dependent
from nonebot.matcher import Matcher, matchers
from nonebot.utils import escape_tag, run_coro_with_catch
from nonebot.exception import (
    NoLogException,
    StopPropagation,
    IgnoredException,
    SkippedException,
)
from nonebot.typing import (
    T_State,
    T_DependencyCache,
    T_RunPreProcessor,
    T_RunPostProcessor,
    T_EventPreProcessor,
    T_EventPostProcessor,
)
from nonebot.internal.params import (
    ArgParam,
    BotParam,
    EventParam,
    StateParam,
    DependParam,
    DefaultParam,
    MatcherParam,
    ExceptionParam,
)

if TYPE_CHECKING:
    from nonebot.adapters import Bot, Event

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

EVENT_PCS_PARAMS = (
    DependParam,
    BotParam,
    EventParam,
    StateParam,
    DefaultParam,
)
RUN_PREPCS_PARAMS = (
    DependParam,
    BotParam,
    EventParam,
    StateParam,
    ArgParam,
    MatcherParam,
    DefaultParam,
)
RUN_POSTPCS_PARAMS = (
    DependParam,
    ExceptionParam,
    BotParam,
    EventParam,
    StateParam,
    ArgParam,
    MatcherParam,
    DefaultParam,
)


def event_preprocessor(func: T_EventPreProcessor) -> T_EventPreProcessor:
    """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(
        Dependent[Any].parse(call=func, allow_types=EVENT_PCS_PARAMS)
    )
    return func


def event_postprocessor(func: T_EventPostProcessor) -> T_EventPostProcessor:
    """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(
        Dependent[Any].parse(call=func, allow_types=EVENT_PCS_PARAMS)
    )
    return func


def run_preprocessor(func: T_RunPreProcessor) -> T_RunPreProcessor:
    """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(
        Dependent[Any].parse(call=func, allow_types=RUN_PREPCS_PARAMS)
    )
    return func


def run_postprocessor(func: T_RunPostProcessor) -> T_RunPostProcessor:
    """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(
        Dependent[Any].parse(call=func, allow_types=RUN_POSTPCS_PARAMS)
    )
    return func


async def _apply_event_preprocessors(
    bot: "Bot",
    event: "Event",
    state: T_State,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
    show_log: bool = True,
) -> bool:
    """运行事件预处理。

    参数:
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        stack: 异步上下文栈
        dependency_cache: 依赖缓存
        show_log: 是否显示日志

    返回:
        是否继续处理事件
    """
    if not _event_preprocessors:
        return True

    if show_log:
        logger.debug("Running PreProcessors...")

    try:
        await asyncio.gather(
            *(
                run_coro_with_catch(
                    proc(
                        bot=bot,
                        event=event,
                        state=state,
                        stack=stack,
                        dependency_cache=dependency_cache,
                    ),
                    (SkippedException,),
                )
                for proc in _event_preprocessors
            )
        )
    except IgnoredException:
        logger.opt(colors=True).info(
            f"Event {escape_tag(event.get_event_name())} is <b>ignored</b>"
        )
        return False
    except Exception as e:
        logger.opt(colors=True, exception=e).error(
            "<r><bg #f8bbd0>Error when running EventPreProcessors. "
            "Event ignored!</bg #f8bbd0></r>"
        )
        return False

    return True


async def _apply_event_postprocessors(
    bot: "Bot",
    event: "Event",
    state: T_State,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
    show_log: bool = True,
) -> None:
    """运行事件后处理。

    参数:
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        stack: 异步上下文栈
        dependency_cache: 依赖缓存
        show_log: 是否显示日志
    """
    if not _event_postprocessors:
        return

    if show_log:
        logger.debug("Running PostProcessors...")

    try:
        await asyncio.gather(
            *(
                run_coro_with_catch(
                    proc(
                        bot=bot,
                        event=event,
                        state=state,
                        stack=stack,
                        dependency_cache=dependency_cache,
                    ),
                    (SkippedException,),
                )
                for proc in _event_postprocessors
            )
        )
    except Exception as e:
        logger.opt(colors=True, exception=e).error(
            "<r><bg #f8bbd0>Error when running EventPostProcessors</bg #f8bbd0></r>"
        )


async def _apply_run_preprocessors(
    bot: "Bot",
    event: "Event",
    state: T_State,
    matcher: Matcher,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
) -> bool:
    """运行事件响应器运行前处理。

    参数:
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        matcher: 事件响应器
        stack: 异步上下文栈
        dependency_cache: 依赖缓存

    返回:
        是否继续处理事件
    """
    if not _run_preprocessors:
        return True

    # ensure matcher function can be correctly called
    with matcher.ensure_context(bot, event):
        try:
            await asyncio.gather(
                *(
                    run_coro_with_catch(
                        proc(
                            matcher=matcher,
                            bot=bot,
                            event=event,
                            state=state,
                            stack=stack,
                            dependency_cache=dependency_cache,
                        ),
                        (SkippedException,),
                    )
                    for proc in _run_preprocessors
                )
            )
        except IgnoredException:
            logger.opt(colors=True).info(f"{matcher} running is <b>cancelled</b>")
            return False
        except Exception as e:
            logger.opt(colors=True, exception=e).error(
                "<r><bg #f8bbd0>Error when running RunPreProcessors. "
                "Running cancelled!</bg #f8bbd0></r>"
            )
            return False

    return True


async def _apply_run_postprocessors(
    bot: "Bot",
    event: "Event",
    matcher: Matcher,
    exception: Optional[Exception] = None,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
) -> None:
    """运行事件响应器运行后处理。

    参数:
        bot: Bot 对象
        event: Event 对象
        matcher: 事件响应器
        exception: 事件响应器运行异常
        stack: 异步上下文栈
        dependency_cache: 依赖缓存
    """
    if not _run_postprocessors:
        return

    with matcher.ensure_context(bot, event):
        try:
            await asyncio.gather(
                *(
                    run_coro_with_catch(
                        proc(
                            matcher=matcher,
                            exception=exception,
                            bot=bot,
                            event=event,
                            state=matcher.state,
                            stack=stack,
                            dependency_cache=dependency_cache,
                        ),
                        (SkippedException,),
                    )
                    for proc in _run_postprocessors
                )
            )
        except Exception as e:
            logger.opt(colors=True, exception=e).error(
                "<r><bg #f8bbd0>Error when running RunPostProcessors</bg #f8bbd0></r>"
            )


async def _check_matcher(
    Matcher: Type[Matcher],
    bot: "Bot",
    event: "Event",
    state: T_State,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
) -> bool:
    """检查事件响应器是否符合运行条件。

    请注意，过时的事件响应器将被**销毁**。对于未过时的事件响应器，将会一次检查其响应类型、权限和规则。

    参数:
        Matcher: 要检查的事件响应器
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        stack: 异步上下文栈
        dependency_cache: 依赖缓存

    返回:
        bool: 是否符合运行条件
    """
    if Matcher.expire_time and datetime.now() > Matcher.expire_time:
        with contextlib.suppress(Exception):
            Matcher.destroy()
        return False

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

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

    return True


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:
    """运行事件响应器。

    临时事件响应器将在运行前被**销毁**。

    参数:
        Matcher: 事件响应器
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        stack: 异步上下文栈
        dependency_cache: 依赖缓存

    异常:
        StopPropagation: 阻止事件继续传播
    """
    logger.info(f"Event will be handled by {Matcher}")

    if Matcher.temp:
        with contextlib.suppress(Exception):
            Matcher.destroy()

    matcher = Matcher()

    if not await _apply_run_preprocessors(
        bot=bot,
        event=event,
        state=state,
        matcher=matcher,
        stack=stack,
        dependency_cache=dependency_cache,
    ):
        return

    exception = None

    try:
        logger.debug(f"Running {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} failed.</bg #f8bbd0></r>"
        )
        exception = e

    await _apply_run_postprocessors(
        bot=bot,
        event=event,
        matcher=matcher,
        exception=exception,
        stack=stack,
        dependency_cache=dependency_cache,
    )

    if matcher.block:
        raise StopPropagation


async def check_and_run_matcher(
    Matcher: Type[Matcher],
    bot: "Bot",
    event: "Event",
    state: T_State,
    stack: Optional[AsyncExitStack] = None,
    dependency_cache: Optional[T_DependencyCache] = None,
) -> None:
    """检查并运行事件响应器。

    参数:
        Matcher: 事件响应器
        bot: Bot 对象
        event: Event 对象
        state: 会话状态
        stack: 异步上下文栈
        dependency_cache: 依赖缓存
    """
    if not await _check_matcher(
        Matcher=Matcher,
        bot=bot,
        event=event,
        state=state,
        stack=stack,
        dependency_cache=dependency_cache,
    ):
        return

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


async def handle_event(bot: "Bot", event: "Event") -> None:
    """处理一个事件。调用该函数以实现分发事件。

    参数:
        bot: Bot 对象
        event: Event 对象

    用法:
        ```python
        import asyncio
        asyncio.create_task(handle_event(bot, event))
        ```
    """
    show_log = True
    log_msg = f"<m>{escape_tag(bot.type)} {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 = {}

    # create event scope context
    async with AsyncExitStack() as stack:
        if not await _apply_event_preprocessors(
            bot=bot,
            event=event,
            state=state,
            stack=stack,
            dependency_cache=dependency_cache,
        ):
            return

        # Trie Match
        try:
            TrieRule.get_value(bot, event, state)
        except Exception as e:
            logger.opt(colors=True, exception=e).warning(
                "Error while parsing command for event"
            )

        break_flag = False
        # iterate through all priority until stop propagation
        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_and_run_matcher(
                    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>"
                    )

        if show_log:
            logger.debug("Checking for matchers completed")

        await _apply_event_postprocessors(bot, event, state, stack, dependency_cache)