"""Redis-based distributed locking for task coordination."""
import logging
import os
from contextlib import contextmanager
from typing import Generator

import redis

logger = logging.getLogger("uvicorn.error")


def get_redis_client() -> redis.Redis:
    """Get Redis client from Celery broker URL."""
    broker_url = os.getenv("CELERY_BROKER_URL", "redis://localhost:6379/0")
    return redis.from_url(broker_url, decode_responses=True)


@contextmanager
def redis_lock(
    lock_name: str, timeout: int = 3600 * 4
) -> Generator[bool, None, None]:
    """Distributed lock using Redis.

    Args:
        lock_name: Unique name for the lock
        timeout: Lock expiration time in seconds (default: 4 hours)

    Yields:
        bool: True if lock was acquired, False otherwise

    Example:
        with redis_lock("scrape_listings") as acquired:
            if not acquired:
                logger.warning("Another scrape is already running")
                return
            # ... do work ...
    """
    client = get_redis_client()
    lock_key = f"lock:{lock_name}"

    # Try to acquire the lock
    acquired = client.set(lock_key, "1", nx=True, ex=timeout)

    try:
        yield bool(acquired)
    finally:
        # Release the lock only if we acquired it
        if acquired:
            client.delete(lock_key)
            logger.info(f"Released lock: {lock_name}")