import json
import logging
from fastapi import WebSocket

logger = logging.getLogger(__name__)


class ConnectionManager:
    def __init__(self) -> None:
        self._connections: set[WebSocket] = set()

    async def connect(self, ws: WebSocket) -> None:
        await ws.accept()
        self._connections.add(ws)
        logger.info(f"WS client connected. Total: {len(self._connections)}")

    def disconnect(self, ws: WebSocket) -> None:
        self._connections.discard(ws)
        logger.info(f"WS client disconnected. Total: {len(self._connections)}")

    async def broadcast(self, data: dict) -> None:
        if not self._connections:
            return
        message = json.dumps(data, default=str)
        dead: set[WebSocket] = set()
        for ws in self._connections:
            try:
                await ws.send_text(message)
            except Exception:
                dead.add(ws)
        self._connections -= dead


# Singleton — imported by both the MQTT subscriber and the WS route
manager = ConnectionManager()