"""应用生命周期管理 —— 回调注册模式"""

import asyncio
import logging
from typing import Callable, Awaitable, List

logger = logging.getLogger(__name__)

StartupCallback = Callable[[], Awaitable[None]]
ShutdownCallback = Callable[[], Awaitable[None]]


class AppContext:
    """管理应用启动/关闭生命周期

    使用方式：
        ctx = AppContext()
        ctx.on_startup(db.init_pools)
        ctx.on_startup(log_service.start)
        ctx.on_shutdown(db.close_pools)
        ctx.on_shutdown(log_service.stop)

        # 在 Quart/FastAPI 生命周期中调用
        await ctx.start_up()
        await ctx.shutdown()
    """

    def __init__(self):
        self._startup_callbacks: List[StartupCallback] = []
        self._shutdown_callbacks: List[ShutdownCallback] = []

    def on_startup(self, callback: StartupCallback) -> "AppContext":
        """注册启动回调（支持链式调用）"""
        self._startup_callbacks.append(callback)
        return self

    def on_shutdown(self, callback: ShutdownCallback) -> "AppContext":
        """注册关闭回调（支持链式调用）"""
        self._shutdown_callbacks.append(callback)
        return self

    async def start_up(self) -> None:
        """按注册顺序执行所有启动回调"""
        logger.info("应用启动中...")
        results = await asyncio.gather(
            *(cb() for cb in self._startup_callbacks),
            return_exceptions=True,
        )
        for i, result in enumerate(results):
            if isinstance(result, Exception):
                logger.error(f"启动回调 [{i}] 失败: {result}")
        logger.info("应用启动完成")

    async def shutdown(self) -> None:
        """按注册逆序执行所有关闭回调"""
        logger.info("应用关闭中...")
        for callback in reversed(self._shutdown_callbacks):
            try:
                await callback()
            except Exception as e:
                logger.error(f"关闭回调失败: {e}")
        logger.info("应用已关闭")