"""WebSocket服务 - 对应Go的internal/websocket/server.go"""
import asyncio
import json
from datetime import datetime
from typing import Dict, Set, Optional
from dataclasses import dataclass, field

from fastapi import WebSocket, WebSocketDisconnect

from app.core.logger import info, error


@dataclass
class WSClient:
    """WebSocket客户端"""
    id: str
    websocket: WebSocket
    subscriptions: Set[str] = field(default_factory=set)
    
    async def send(self, message: dict):
        """发送消息"""
        try:
            await self.websocket.send_json(message)
        except Exception as e:
            error(f"Failed to send message to client {self.id}: {e}")


class WebSocketManager:
    """WebSocket连接管理器"""
    
    def __init__(self):
        self.clients: Dict[str, WSClient] = {}
        self.subscriptions: Dict[str, Set[str]] = {}  # symbol -> set of client_ids
        self.max_symbols_per_client = 100
        self.lock = asyncio.Lock()
    
    async def connect(self, websocket: WebSocket, client_id: str) -> WSClient:
        """建立连接"""
        await websocket.accept()
        
        client = WSClient(id=client_id, websocket=websocket)
        
        async with self.lock:
            self.clients[client_id] = client
        
        info(f"WebSocket client connected: {client_id}, total: {len(self.clients)}")
        return client
    
    async def disconnect(self, client_id: str):
        """断开连接"""
        async with self.lock:
            if client_id in self.clients:
                client = self.clients.pop(client_id)
                
                # 清理订阅
                for symbol in client.subscriptions:
                    if symbol in self.subscriptions:
                        self.subscriptions[symbol].discard(client_id)
                        if not self.subscriptions[symbol]:
                            del self.subscriptions[symbol]
        
        info(f"WebSocket client disconnected: {client_id}, total: {len(self.clients)}")
    
    async def subscribe(self, client_id: str, symbols: list) -> bool:
        """订阅标的"""
        async with self.lock:
            if client_id not in self.clients:
                return False
            
            client = self.clients[client_id]
            
            # 检查订阅数量限制
            if len(client.subscriptions) + len(symbols) > self.max_symbols_per_client:
                return False
            
            for symbol in symbols:
                client.subscriptions.add(symbol)
                
                if symbol not in self.subscriptions:
                    self.subscriptions[symbol] = set()
                self.subscriptions[symbol].add(client_id)
        
        return True
    
    async def unsubscribe(self, client_id: str, symbols: list):
        """取消订阅"""
        async with self.lock:
            if client_id not in self.clients:
                return
            
            client = self.clients[client_id]
            
            for symbol in symbols:
                client.subscriptions.discard(symbol)
                
                if symbol in self.subscriptions:
                    self.subscriptions[symbol].discard(client_id)
                    if not self.subscriptions[symbol]:
                        del self.subscriptions[symbol]
    
    async def broadcast_to_symbol(self, symbol: str, message: dict):
        """向订阅了某标的的所有客户端广播"""
        client_ids = set()
        
        async with self.lock:
            if symbol in self.subscriptions:
                client_ids = self.subscriptions[symbol].copy()
        
        # 在锁外发送消息
        for client_id in client_ids:
            if client_id in self.clients:
                try:
                    await self.clients[client_id].send(message)
                except Exception as e:
                    error(f"Failed to broadcast to {client_id}: {e}")
    
    def get_stats(self) -> dict:
        """获取统计信息"""
        return {
            "total_clients": len(self.clients),
            "total_subscriptions": len(self.subscriptions)
        }


# 全局WebSocket管理器实例
ws_manager = WebSocketManager()


class WebSocketServer:
    """WebSocket服务器"""
    
    def __init__(self):
        self.manager = ws_manager
    
    async def handle(self, websocket: WebSocket, client_id: str):
        """处理WebSocket连接"""
        client = await self.manager.connect(websocket, client_id)
        
        try:
            while True:
                # 接收消息
                data = await websocket.receive_text()
                
                try:
                    msg = json.loads(data)
                    action = msg.get("action")
                    symbols = msg.get("symbols", [])
                    
                    if action == "subscribe":
                        success = await self.manager.subscribe(client_id, symbols)
                        if success:
                            await client.send({
                                "type": "ack",
                                "action": "subscribe",
                                "symbols": symbols,
                                "ts": datetime.now().isoformat()
                            })
                        else:
                            await client.send({
                                "type": "error",
                                "code": 1003,
                                "message": "Too many subscriptions or subscription failed",
                                "ts": datetime.now().isoformat()
                            })
                    
                    elif action == "unsubscribe":
                        await self.manager.unsubscribe(client_id, symbols)
                        await client.send({
                            "type": "ack",
                            "action": "unsubscribe",
                            "symbols": symbols,
                            "ts": datetime.now().isoformat()
                        })
                    
                    else:
                        await client.send({
                            "type": "error",
                            "code": 1001,
                            "message": "Unknown action",
                            "ts": datetime.now().isoformat()
                        })
                
                except json.JSONDecodeError:
                    await client.send({
                        "type": "error",
                        "code": 1000,
                        "message": "Invalid message format",
                        "ts": datetime.now().isoformat()
                    })
        
        except WebSocketDisconnect:
            await self.manager.disconnect(client_id)
        except Exception as e:
            error(f"WebSocket error for client {client_id}: {e}")
            await self.manager.disconnect(client_id)
    
    async def send_heartbeat(self):
        """发送心跳（可由定时任务调用）"""
        message = {
            "type": "heartbeat",
            "ts": datetime.now().isoformat()
        }
        
        # 向所有客户端发送心跳
        clients_copy = list(self.manager.clients.values())
        for client in clients_copy:
            try:
                await client.send(message)
            except Exception:
                pass