# app/realtime/coins_hub.py
from typing import Dict, Set
from fastapi import WebSocket
import asyncio


class CoinsHub:
    def __init__(self):
        # username -> set of websockets
        self._connections: Dict[str, Set[WebSocket]] = {}
        self._lock = asyncio.Lock()

    async def connect(self, username: str, ws: WebSocket):
        await ws.accept()
        async with self._lock:
            self._connections.setdefault(username, set()).add(ws)

    async def disconnect(self, username: str, ws: WebSocket):
        async with self._lock:
            conns = self._connections.get(username)
            if not conns:
                return
            conns.discard(ws)
            if not conns:
                self._connections.pop(username, None)

    async def send_update(self, username: str, coins: int):
        async with self._lock:
            conns = list(self._connections.get(username, []))

        if not conns:
            return

        payload = {
            "event": "coins:update",
            "coins": coins,
        }

        dead: list[WebSocket] = []

        for ws in conns:
            try:
                await ws.send_json(payload)
            except Exception:
                dead.append(ws)

        if dead:
            async with self._lock:
                for ws in dead:
                    self._connections.get(username, set()).discard(ws)


coins_hub = CoinsHub()