"""
链式和广播事件的独立调度算法。
"""

from __future__ import annotations

import inspect
import time
from collections.abc import Callable
from contextlib import AbstractContextManager, nullcontext
from typing import Any

from app.runtime.correlation import correlation_scope
from app.runtime.event.binding import EventBindingResolver
from app.runtime.event.registry import EventRegistry
from app.runtime.execution import run_in_threadpool
from app.runtime.log import bind_plugin_instance, logger
from app.runtime.observability import observe_duration
from app.schemas.types import EventType


def _instance_binding_scope(class_name: str) -> AbstractContextManager[None]:
    """
    处理器归属某个类时绑定其插件实例日志上下文，自由函数处理器不绑定。

    ``class_name`` 就是声明该处理器的类的 ``__name__``；宿主类处理器同样会
    命中这里，但缓存里没有它们的等级覆盖记录，过滤时自然回落全局等级。
    """
    return bind_plugin_instance(class_name) if class_name else nullcontext()


class EventDispatcher:
    """
    基于订阅快照执行链式或广播事件，不拥有注册和生命周期状态。
    """

    def __init__(
        self,
        *,
        registry: EventRegistry,
        binding_resolver: EventBindingResolver,
        event_factory: Callable[..., Any],
        error_handler: Callable[..., None],
        async_handle_sink: Callable[[Any], bool],
        sync_handle_sink: Callable[
            [Callable[..., Any], tuple[Any, ...]],
            bool,
        ],
    ) -> None:
        """
        注入注册表、绑定器、生命周期提交器和错误策略回调。
        """
        self._registry = registry
        self._binding_resolver = binding_resolver
        self._event_factory = event_factory
        self._error_handler = error_handler
        self._async_handle_sink = async_handle_sink
        self._sync_handle_sink = sync_handle_sink

    def _begin_chain_dispatch(
        self, event: Any
    ) -> tuple[tuple[str, int, Callable[..., Any]], ...]:
        """
        冻结启用处理器快照，并统一空快照与开始生命周期记录。
        """
        handlers = self._registry.chain_snapshot(event.event_type)
        enabled = tuple(
            (handler_id, priority, handler)
            for handler_id, (priority, handler) in handlers
            if self._registry.is_handler_enabled(handler)
        )
        if not enabled:
            logger.debug("No enabled handlers found for chain event: %s", event)
            return ()
        self._log_lifecycle(event, "Started")
        return enabled

    @staticmethod
    def _log_chain_handler_completed(
        handler: Callable[..., Any],
        priority: int,
        started_at: float,
        event: Any,
    ) -> None:
        """
        统一记录同步与异步处理器完成耗时和优先级。
        """
        logger.debug(
            "%s (Priority: %s), completed in %.3fs for event: %s",
            EventRegistry.handler_identifier(handler),
            priority,
            time.time() - started_at,
            event,
        )

    def _complete_chain_dispatch(self, event: Any) -> bool:
        """
        统一提交链式事件完成生命周期并返回已处理标识。
        """
        self._log_lifecycle(event, "Completed")
        return True

    def dispatch_chain(self, event: Any) -> bool:
        """
        同步按优先级顺序执行链式事件快照。
        """
        enabled = self._begin_chain_dispatch(event)
        if not enabled:
            return False
        for _handler_id, priority, handler in enabled:
            started_at = time.time()
            self.invoke_sync(handler, event)
            EventDispatcher._log_chain_handler_completed(
                handler, priority, started_at, event
            )
        return self._complete_chain_dispatch(event)

    async def async_dispatch_chain(self, event: Any) -> bool:
        """
        异步按优先级顺序执行链式事件快照。
        """
        enabled = self._begin_chain_dispatch(event)
        if not enabled:
            return False
        for _handler_id, priority, handler in enabled:
            started_at = time.time()
            await self.invoke_async(handler, event)
            EventDispatcher._log_chain_handler_completed(
                handler, priority, started_at, event
            )
        return self._complete_chain_dispatch(event)

    def dispatch_broadcast(self, event: Any) -> None:
        """
        按订阅快照把广播事件投递到线程池或主事件循环。
        """
        handlers = self._registry.broadcast_snapshot(event.event_type)
        if not handlers:
            logger.debug("No handlers found for broadcast event: %s", event)
            return
        target_plugin_id = None
        if event.event_type == EventType.MessageAction and isinstance(
            event.event_data,
            dict,
        ):
            target_plugin_id = event.event_data.get("__mp_target_plugin_id")
        for handler_id, handler in handlers:
            if target_plugin_id and not self.should_dispatch_to_target_plugin(
                handler,
                handler_id,
                str(target_plugin_id),
            ):
                continue
            if isinstance(event.event_data, dict):
                event_data = event.event_data.copy()
                event_data.pop("__mp_target_plugin_id", None)
            else:
                event_data = event.event_data
            isolated = self._event_factory(
                event_type=event.event_type,
                event_data=event_data,
                priority=event.priority,
                correlation_id=event.correlation_id,
            )
            if inspect.iscoroutinefunction(handler):
                coroutine = self.safe_invoke_async(handler, isolated)
                self._async_handle_sink(coroutine)
            else:
                self._sync_handle_sink(
                    self.safe_invoke_sync,
                    (handler, isolated),
                )

    def dispatch_broadcast_strict(
        self,
        event: Any,
        async_runner: Callable[[Any], Any],
    ) -> None:
        """
        串行执行广播处理器并等待完成，任一处理失败时向调用方抛出。
        """
        handlers = self._registry.broadcast_snapshot(event.event_type)
        target_plugin_id = None
        if event.event_type == EventType.MessageAction and isinstance(
            event.event_data,
            dict,
        ):
            target_plugin_id = event.event_data.get("__mp_target_plugin_id")
        for handler_id, handler in handlers:
            if not self._registry.is_handler_enabled(handler):
                continue
            if target_plugin_id and not self.should_dispatch_to_target_plugin(
                handler,
                handler_id,
                str(target_plugin_id),
            ):
                continue
            if isinstance(event.event_data, dict):
                event_data = event.event_data.copy()
                event_data.pop("__mp_target_plugin_id", None)
            else:
                event_data = event.event_data
            isolated = self._event_factory(
                event_type=event.event_type,
                event_data=event_data,
                priority=event.priority,
                correlation_id=event.correlation_id,
            )
            if inspect.iscoroutinefunction(handler):
                async_runner(self.invoke_async_strict(handler, isolated))
            else:
                self.invoke_sync_strict(handler, isolated)

    async def dispatch_broadcast_async_strict(self, event: Any) -> None:
        """
        异步串行等待广播处理器完成，供实时配置重载入口使用。
        """
        handlers = self._registry.broadcast_snapshot(event.event_type)
        target_plugin_id = None
        if event.event_type == EventType.MessageAction and isinstance(
            event.event_data,
            dict,
        ):
            target_plugin_id = event.event_data.get("__mp_target_plugin_id")
        for handler_id, handler in handlers:
            if not self._registry.is_handler_enabled(handler):
                continue
            if target_plugin_id and not self.should_dispatch_to_target_plugin(
                handler,
                handler_id,
                str(target_plugin_id),
            ):
                continue
            if isinstance(event.event_data, dict):
                event_data = event.event_data.copy()
                event_data.pop("__mp_target_plugin_id", None)
            else:
                event_data = event.event_data
            isolated = self._event_factory(
                event_type=event.event_type,
                event_data=event_data,
                priority=event.priority,
                correlation_id=event.correlation_id,
            )
            if inspect.iscoroutinefunction(handler):
                await self.invoke_async_strict(
                    handler,
                    isolated,
                    skip_unresolved=True,
                    run_sync_in_threadpool=True,
                )
            else:
                # 复用统一严格调用路径，保持 owner 的线程池声明和错误策略一致。
                await self.invoke_async_strict(
                    handler,
                    isolated,
                    skip_unresolved=True,
                    run_sync_in_threadpool=True,
                )

    def safe_invoke_sync(self, handler: Callable[..., object], event: Any) -> None:
        """
        仅在处理器启用时执行同步调用。
        """
        if self._registry.is_handler_enabled(handler):
            self.invoke_sync(handler, event)

    async def safe_invoke_async(self, handler: Callable[..., object], event: Any) -> None:
        """
        仅在处理器启用时执行异步调用。
        """
        if self._registry.is_handler_enabled(handler):
            await self.invoke_async(handler, event)

    def invoke_sync(self, handler: Callable[..., object], event: Any) -> None:
        """
        解析实例绑定并同步调用处理器。
        """
        resolved = self._binding_resolver.resolve(handler)
        if not resolved:
            return
        method, binding, class_name, method_name = resolved
        with correlation_scope(event.correlation_id):
            try:
                with observe_duration(
                    "event.handler.duration",
                    event_type=event.event_type.value,
                    handler_type="bound" if class_name else "function",
                ), _instance_binding_scope(class_name):
                    method(event)
            except Exception as err:
                self._error_handler(
                    event=event,
                    module_name=binding.owner_name,
                    class_name=class_name,
                    method_name=method_name,
                    e=err,
                )

    def invoke_sync_strict(
        self,
        handler: Callable[..., object],
        event: Any,
        *,
        skip_unresolved: bool = False,
    ) -> None:
        """
        解析并执行同步处理器，按需跳过未激活 owner，实际错误向调用方传播。
        """
        resolved = self._binding_resolver.resolve(handler)
        if not resolved:
            if skip_unresolved:
                return
            raise RuntimeError("事件处理器实例不可用")
        method, binding, class_name, method_name = resolved
        with correlation_scope(event.correlation_id):
            try:
                with observe_duration(
                    "event.handler.duration",
                    event_type=event.event_type.value,
                    handler_type="bound" if class_name else "function",
                ), _instance_binding_scope(class_name):
                    method(event)
            except Exception as err:
                self._error_handler(
                    event=event,
                    module_name=binding.owner_name,
                    class_name=class_name,
                    method_name=method_name,
                    e=err,
                )
                raise

    async def invoke_async(self, handler: Callable[..., object], event: Any) -> None:
        """
        解析实例绑定，并按处理器类型选择协程、线程池或同步调用。
        """
        resolved = self._binding_resolver.resolve(handler)
        if not resolved:
            return
        method, binding, class_name, method_name = resolved
        with correlation_scope(event.correlation_id):
            try:
                with observe_duration(
                    "event.handler.duration",
                    event_type=event.event_type.value,
                    handler_type="bound" if class_name else "function",
                ), _instance_binding_scope(class_name):
                    if inspect.iscoroutinefunction(method):
                        await method(event)
                    elif binding.run_sync_in_threadpool or not class_name:
                        await run_in_threadpool(method, event)
                    else:
                        method(event)
            except Exception as err:
                self._error_handler(
                    event=event,
                    module_name=binding.owner_name,
                    class_name=class_name,
                    method_name=method_name,
                    e=err,
                )

    async def invoke_async_strict(
        self,
        handler: Callable[..., object],
        event: Any,
        *,
        skip_unresolved: bool = False,
        run_sync_in_threadpool: bool = False,
    ) -> None:
        """
        解析并等待处理器完成，按需跳过未激活 owner 或移交同步处理器线程池。
        """
        resolved = self._binding_resolver.resolve(handler)
        if not resolved:
            if skip_unresolved:
                return
            raise RuntimeError("事件处理器实例不可用")
        method, binding, class_name, method_name = resolved
        with correlation_scope(event.correlation_id):
            try:
                with observe_duration(
                    "event.handler.duration",
                    event_type=event.event_type.value,
                    handler_type="bound" if class_name else "function",
                ), _instance_binding_scope(class_name):
                    if inspect.iscoroutinefunction(method):
                        await method(event)
                    elif run_sync_in_threadpool or binding.run_sync_in_threadpool or not class_name:
                        await run_in_threadpool(method, event)
                    else:
                        method(event)
            except Exception as err:
                self._error_handler(
                    event=event,
                    module_name=binding.owner_name,
                    class_name=class_name,
                    method_name=method_name,
                    e=err,
                )
                raise

    @staticmethod
    def should_dispatch_to_target_plugin(
        handler: Callable[..., object],
        handler_identifier: str,
        target_plugin_id: str,
    ) -> bool:
        """
        只把定向输入事件投递给标识和声明均匹配的目标插件。

        目标匹配按运行实例身份判断，不能只看处理器的限定名：分身共享源码，其
        ``__qualname__`` 保持源类名不变，只比类名会让定向到分身的事件全部落空，
        而定向到本体的事件被本体连同它的全部分身一起收到。实例身份编码在处理器
        标识的模块段里（``app.plugins.<实例ID>``）；不是插件处理器时回落到类名比较，
        保持宿主侧处理器的既有行为。
        """
        class_name, method_name = EventBindingResolver.parse_handler_names(handler)
        parts = (handler_identifier or "").split(".")
        if len(parts) < 2 or parts[-2:] != [class_name, method_name]:
            return False
        module_path = ".".join(parts[:-2])
        prefix = "app.plugins."
        if module_path.startswith(prefix):
            owner_id = module_path[len(prefix):].split(".")[0]
            return owner_id.casefold() == target_plugin_id.casefold()
        return class_name == target_plugin_id

    @staticmethod
    def _log_lifecycle(event: Any, stage: str) -> None:
        """
        记录事件调度的开始和完成阶段。
        """
        logger.debug("%s - %s", stage, event)