import logging
from logging.handlers import RotatingFileHandler
from pathlib import Path

def configure_logging(app):
    log_dir = Path('instance')
    log_dir.mkdir(exist_ok=True)
    handler = RotatingFileHandler(log_dir / 'app.log', maxBytes=1_000_000, backupCount=5)
    handler.setFormatter(logging.Formatter('%(asctime)s %(levelname)s [%(name)s] %(message)s'))
    app.logger.setLevel(app.config['LOG_LEVEL'])
    if not app.logger.handlers:
        app.logger.addHandler(handler)