import asyncio
from typing import List
from fastapi import WebSocket
import logging

class ConnectionManager:
    def __init__(self):
        self.active_connections: List[WebSocket] = []
        self.loop: asyncio.AbstractEventLoop | None = None

    def set_loop(self, loop: asyncio.AbstractEventLoop):
        """Sets the asyncio event loop."""
        self.loop = loop

    async def connect(self, websocket: WebSocket):
        await websocket.accept()
        self.active_connections.append(websocket)

    def disconnect(self, websocket: WebSocket):
        self.active_connections.remove(websocket)

    def broadcast(self, message: str):
        """
        Thread-safely broadcasts a message to all active WebSocket connections.
        This method is designed to be called from a different thread (e.g., a ROS2 callback).
        """
        if not self.loop:
            logging.error("Event loop not set in ConnectionManager. Cannot broadcast.")
            return

        # Schedule the coroutine to be executed in the event loop
        self.loop.call_soon_threadsafe(self._broadcast_in_loop, message)

    def _broadcast_in_loop(self, message: str):
        """
        Helper to run the broadcast coroutine in the correct event loop.
        """
        asyncio.ensure_future(self._broadcast_async(message), loop=self.loop)

    async def _broadcast_async(self, message: str):
        """
        The actual async method that sends messages.
        """
        tasks = [connection.send_text(message) for connection in self.active_connections]
        await asyncio.gather(*tasks, return_exceptions=True)

# Create a single instance of the manager to be used across the application
websocket_manager = ConnectionManager()