"""
WebSocketStream — legacy bridge between the EventBus and WebSocket clients.

NOTE: The real broadcasting is now done in backend/main.py via
`_ws_broadcast` which properly awaits the async send. This class is kept
for backward compatibility with the api.py facade, but its `attach_bus`
method is a no-op (the actual wiring happens in main.py).

F-15 remediation: the shared ``clients`` list is now guarded by a lock
so concurrent register/unregister calls from multiple WS handlers
can't race.
"""

from __future__ import annotations

import threading
from typing import Any, List

from backend.events.bus import EventBus


class WebSocketStream:
    def __init__(self) -> None:
        self._lock = threading.Lock()
        self.clients: List[Any] = []  # shared with main.py's hub.clients

    def attach_bus(self, bus: EventBus) -> None:
        """No-op — broadcasting is wired in backend/main.py via _ws_broadcast.

        Kept for backward compat with api.py's attach_ws_stream().
        """
        pass

    def register_client(self, client: Any) -> None:
        with self._lock:
            self.clients.append(client)

    def unregister_client(self, client: Any) -> None:
        with self._lock:
            try:
                self.clients.remove(client)
            except ValueError:
                pass

    def snapshot_clients(self) -> List[Any]:
        """Return a snapshot copy of the client list (safe for iteration)."""
        with self._lock:
            return list(self.clients)