"""
Manages persistent per-user WebSocket connections for the notification channel.
The DB is the source of truth — this layer just delivers live pushes to connected clients.
"""
import logging

from fastapi import WebSocket

logger = logging.getLogger("app")

# user_id (str) -> active WebSocket; replaced on reconnect
connections: dict[str, WebSocket] = {}


def register(user_id: str, ws: WebSocket) -> None:
  connections[user_id] = ws


def unregister(user_id: str) -> None:
  connections.pop(user_id, None)


async def send_notification(user_id: str, notification: dict) -> None:
  """Push a single notification to the user if they're connected. No-op otherwise."""
  ws = connections.get(user_id)
  if ws:
    try:
      await ws.send_json({"type": "push", "notification": notification})
    except Exception as e:
      # Stale connection — the disconnect handler will clean it up
      logger.debug(f"WebSocket send failed (stale connection): {e}")


async def send_delete(user_id: str, notification_id: str) -> None:
  """Tell the client to remove a notification from its local list."""
  ws = connections.get(user_id)
  if ws:
    try:
      await ws.send_json({"type": "delete", "notification_id": notification_id})
    except Exception as e:
      logger.debug(f"WebSocket send failed (stale connection): {e}")