import redis.asyncio as redis
from app.config import settings
import json
from typing import Any, Dict

redis_pool = redis.from_url(settings.REDIS_URL, encoding="utf-8", decode_responses=True)

async def get_redis():
    return redis_pool 

# ---------------------------------------------------------------------------
# Helper functions for Pub/Sub messaging
# ---------------------------------------------------------------------------

async def broadcast_event(channel: str, event: Dict[str, Any]) -> None:
    """Serialize the given event as JSON and publish it on the specified Redis channel.

    This is primarily used by API endpoints to notify WebSocket consumers of
    real-time changes (e.g. an item being claimed). Consumers subscribe to the
    corresponding channel (see ``subscribe_to_channel``) and relay the JSON
    payload to connected clients.
    """

    redis_conn = await get_redis()
    # NOTE: ``json.dumps`` ensures we only send textual data over the wire
    # which plays nicely with WebSocket ``send_text`` in the frontend.
    await redis_conn.publish(channel, json.dumps(event))

async def subscribe_to_channel(channel: str):
    """Return a PubSub instance already subscribed to *channel*.

    The caller is responsible for reading messages from the returned ``pubsub``
    object and for eventually invoking :func:`unsubscribe_from_channel` to
    clean up resources.
    """

    redis_conn = await get_redis()
    pubsub = redis_conn.pubsub()
    await pubsub.subscribe(channel)
    return pubsub

async def unsubscribe_from_channel(channel: str, pubsub) -> None:
    """Unsubscribe from *channel* and properly close the PubSub connection."""

    try:
        await pubsub.unsubscribe(channel)
    finally:
        # Close the pubsub object to release the underlying connection back to
        # the pool. We ignore any exceptions here because we are often in a
        # ``finally`` block during WebSocket shutdown.
        await pubsub.close()