"""WebSocket 连接管理器"""

import json
from datetime import datetime, timezone
from typing import Dict, Set

from fastapi import WebSocket


class ConnectionManager:
    """管理所有 WebSocket 连接"""

    def __init__(self):
        # user_id -> set of WebSocket connections (一个用户可能有多个标签页)
        self.active_connections: Dict[str, Set[WebSocket]] = {}

    async def connect(self, websocket: WebSocket, user_id: str):
        """接受新连接"""
        await websocket.accept()
        if user_id not in self.active_connections:
            self.active_connections[user_id] = set()
        self.active_connections[user_id].add(websocket)

    def disconnect(self, websocket: WebSocket, user_id: str):
        """断开连接"""
        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]

    async def send_to_user(self, user_id: str, event_type: str, data: dict):
        """向指定用户发送事件"""
        if user_id not in self.active_connections:
            return

        message = json.dumps({
            "type": event_type,
            "data": data,
            "timestamp": datetime.utcnow().isoformat(),
        }, ensure_ascii=False, default=str)

        disconnected = set()
        for ws in self.active_connections[user_id]:
            try:
                await ws.send_text(message)
            except Exception:
                disconnected.add(ws)

        # 清理断开的连接
        for ws in disconnected:
            self.active_connections[user_id].discard(ws)

    async def broadcast_to_conversation(self, user_ids: list[str],
                                         event_type: str, data: dict,
                                         exclude_user: str | None = None):
        """向会话中所有用户广播事件"""
        for uid in user_ids:
            if uid != exclude_user:
                await self.send_to_user(uid, event_type, data)

    async def broadcast(self, event_type: str, data: dict):
        """向所有在线用户广播"""
        for user_id in list(self.active_connections.keys()):
            await self.send_to_user(user_id, event_type, data)

    def is_online(self, user_id: str) -> bool:
        """检查用户是否在线"""
        return user_id in self.active_connections and len(self.active_connections[user_id]) > 0

    def get_online_user_ids(self) -> list[str]:
        """获取所有在线用户 ID"""
        return list(self.active_connections.keys())


# 全局单例
manager = ConnectionManager()