# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2024 rl <rl@rlmbp>
#
# Distributed under terms of the MIT license.

"""
Airflow DAG for manually clearing (deleting) a specific Redis key used by YTDLP queues.
"""

from airflow import DAG
from airflow.exceptions import AirflowException
from airflow.models.param import Param
from airflow.operators.python import PythonOperator
from airflow.providers.redis.hooks.redis import RedisHook
from airflow.utils.dates import days_ago
from datetime import timedelta
import logging
import redis # Import redis exceptions if needed

# Configure logging
logger = logging.getLogger(__name__)

# Default settings
DEFAULT_REDIS_CONN_ID = 'redis_default'
# Provide a placeholder default, user MUST specify the queue to clear
DEFAULT_QUEUE_TO_CLEAR = 'PLEASE_SPECIFY_QUEUE_TO_CLEAR'

# --- Helper Function ---

def _get_redis_client(redis_conn_id):
    """Gets a Redis client connection using RedisHook."""
    try:
        hook = RedisHook(redis_conn_id=redis_conn_id)
        client = hook.get_conn()
        client.ping()
        logger.info(f"Successfully connected to Redis using connection '{redis_conn_id}'.")
        return client
    except redis.exceptions.AuthenticationError:
        logger.error(f"Redis authentication failed for connection '{redis_conn_id}'. Check password.")
        raise AirflowException(f"Redis authentication failed for '{redis_conn_id}'.")
    except Exception as e:
        logger.error(f"Failed to get Redis client for connection '{redis_conn_id}': {e}")
        raise AirflowException(f"Redis connection failed for '{redis_conn_id}': {e}")

# --- Python Callable for Clear Task ---

def clear_queue_callable(**context):
    """Clears (deletes) the specified Redis key (queue/hash)."""
    params = context['params']
    redis_conn_id = params['redis_conn_id']
    queue_to_clear = params['queue_to_clear'] # Specific queue/hash name

    if not queue_to_clear or queue_to_clear == DEFAULT_QUEUE_TO_CLEAR:
        raise ValueError("Parameter 'queue_to_clear' must be specified and cannot be the default placeholder.")

    logger.info(f"Attempting to clear Redis key '{queue_to_clear}' using connection '{redis_conn_id}'.")
    try:
        redis_client = _get_redis_client(redis_conn_id)
        deleted_count = redis_client.delete(queue_to_clear)
        if deleted_count > 0:
            logger.info(f"Successfully cleared Redis key '{queue_to_clear}'.")
        else:
            logger.info(f"Redis key '{queue_to_clear}' did not exist or was already empty.")
    except Exception as e:
        logger.error(f"Failed to clear Redis key '{queue_to_clear}': {e}", exc_info=True)
        raise AirflowException(f"Failed to clear Redis key: {e}")

# --- DAG Definition ---
default_args = {
    'owner': 'airflow',
    'depends_on_past': False,
    'email_on_failure': False,
    'email_on_retry': False,
    'retries': 0, # No retries for manual clear operation
    'start_date': days_ago(1)
}

with DAG(
    dag_id='ytdlp_mgmt_queue_clear',
    default_args=default_args,
    schedule_interval=None, # Manually triggered
    catchup=False,
    description='Manually clear/delete a specific YTDLP Redis queue/key (inbox, progress, result, fail). Use with caution!',
    tags=['ytdlp', 'queue', 'management', 'redis', 'manual', 'clear'],
    params={
        'redis_conn_id': Param(DEFAULT_REDIS_CONN_ID, type="string", description="Airflow Redis connection ID."),
        'queue_to_clear': Param(
            DEFAULT_QUEUE_TO_CLEAR,
            type="string",
            description="Exact name of the Redis key to clear (e.g., 'video_queue_inbox_account_xyz', 'video_queue_progress', 'video_queue_result', 'video_queue_fail')."
        ),
    }
) as dag:

    clear_queue_task = PythonOperator(
        task_id='clear_specified_queue',
        python_callable=clear_queue_callable,
        # Params are implicitly passed via context['params']
    )
    clear_queue_task.doc_md = """
    ### Clear Specified Queue/Key Task
    Deletes the Redis key specified by the `queue_to_clear` parameter.
    This can target any key, including:
    - `_inbox` (Redis List): Contains URLs waiting to be processed.
    - `_progress` (Redis Hash): Contains URLs currently being processed.
    - `_result` (Redis Hash): Contains details of successfully processed URLs.
    - `_fail` (Redis Hash): Contains details of failed URLs.

    **Warning:** This operation is destructive and cannot be undone. Ensure you specify the correct key name.
    *Trigger this task manually via the UI.*
    """