from fastapi import WebSocket, WebSocketDisconnect
from typing import Dict, Set
import json
import logging

logger = logging.getLogger(__name__)  # 当前模块的日志记录器


class WebSocketManager:
    """WebSocket 连接管理器。

    管理用户与多个 WebSocket 连接的生命周期，
    支持单用户多连接、定向推送和全局广播功能。
    """

    def __init__(self):
        """初始化 WebSocket 连接池。"""
        self.active_connections: Dict[str, Set[WebSocket]] = {}  # 活跃连接池：{user_id: {WebSocket, ...}}

    async def connect(self, websocket: WebSocket, user_id: str):
        """接受 WebSocket 连接并注册到指定用户的连接池中。"""
        await websocket.accept()
        if user_id not in self.active_connections:
            self.active_connections[user_id] = set()
        self.active_connections[user_id].add(websocket)
        logger.info(f"WebSocket 用户 {user_id} 已连接")

    def disconnect(self, websocket: WebSocket, user_id: str):
        """断开 WebSocket 连接并从用户连接池中移除。"""
        if user_id in self.active_connections:
            self.active_connections[user_id].discard(websocket)
            if not self.active_connections[user_id]:
                del self.active_connections[user_id]
        logger.info(f"WebSocket 用户 {user_id} 已断开")

    async def send_to_user(self, user_id: str, message: dict):
        """向指定用户的所有活跃连接发送消息，自动清理断开连接。"""
        if user_id not in self.active_connections:
            return False
        dead_connections = set()
        sent_count = 0
        for connection in list(self.active_connections.get(user_id, set())):
            try:
                await connection.send_text(json.dumps(message, ensure_ascii=False))
                sent_count += 1
            except Exception:
                dead_connections.add(connection)
        for conn in dead_connections:
            self.active_connections[user_id].discard(conn)
        if not self.active_connections.get(user_id):
            self.active_connections.pop(user_id, None)
        return sent_count > 0

    async def broadcast(self, message: dict):
        """向当前所有活跃用户广播消息，遍历所有用户并调用 send_to_user。"""
        for user_id in list(self.active_connections.keys()):
            await self.send_to_user(user_id, message)


ws_manager = WebSocketManager()  # 全局 WebSocket 管理器单例