import schedule
import time
import logging
from datetime import datetime
# Import locally to avoid circular import
import importlib
from .config import config

logger = logging.getLogger(__name__)

def scheduled_etl_job():
    """Execute the ETL pipeline on schedule"""
    start_time = datetime.now()
    logger.info(f"Starting scheduled ETL job at {start_time}")
    
    try:
        # Import dynamically to avoid circular import
        from .pipeline import run_etl_pipeline
        success = run_etl_pipeline()
        end_time = datetime.now()
        duration = end_time - start_time
        
        if success:
            logger.info(f"ETL job completed successfully in {duration}")
        else:
            logger.error(f"ETL job failed after {duration}")
            
    except Exception as e:
        end_time = datetime.now()
        duration = end_time - start_time
        logger.error(f"ETL job crashed after {duration}: {e}")

def start_etl_scheduler():
    """Start the ETL scheduler"""
    logger.info(f"Starting ETL scheduler with cron pattern: {config.ETL_SCHEDULE}")
    
    # Parse cron pattern (simplified for weekly schedule)
    # Format: "0 2 * * 0" = minute hour day-of-month month day-of-week
    # "0 2 * * 0" = Every Sunday at 2:00 AM
    
    if config.ETL_SCHEDULE == "0 2 * * 0":
        schedule.every().sunday.at("02:00").do(scheduled_etl_job)
        logger.info("Scheduled ETL to run every Sunday at 2:00 AM")
    else:
        # Default fallback - run once daily at 2 AM
        schedule.every().day.at("02:00").do(scheduled_etl_job)
        logger.warning(f"Unknown cron pattern {config.ETL_SCHEDULE}, defaulting to daily at 2:00 AM")
    
    # Run scheduler loop
    logger.info("ETL scheduler started")
    
    while True:
        try:
            schedule.run_pending()
            time.sleep(60)  # Check every minute
        except KeyboardInterrupt:
            logger.info("ETL scheduler stopped by user")
            break
        except Exception as e:
            logger.error(f"ETL scheduler error: {e}")
            time.sleep(300)  # Wait 5 minutes on error

if __name__ == "__main__":
    # Configure logging
    logging.basicConfig(
        level=getattr(logging, config.LOG_LEVEL.upper()),
        format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
    )
    
    # Start scheduler
    start_etl_scheduler()