import logging

from datetime import timedelta, datetime

from app import app
from data.database import UseThenDisconnect
from data.queue import delete_expired
from workers.worker import Worker


logger = logging.getLogger(__name__)


DELETION_DATE_THRESHOLD = timedelta(days=1)
DELETION_COUNT_THRESHOLD = 50
BATCH_SIZE = 500
QUEUE_CLEANUP_FREQUENCY = app.config.get('QUEUE_CLEANUP_FREQUENCY', 60*60*24)


class QueueCleanupWorker(Worker):
  def __init__(self):
    super(QueueCleanupWorker, self).__init__()
    self.add_operation(self._cleanup_queue, QUEUE_CLEANUP_FREQUENCY)

  def _cleanup_queue(self):
    """ Performs garbage collection on the queueitem table. """
    with UseThenDisconnect(app.config):
      while True:
        # Find all queue items older than the threshold (typically a week) and delete them.
        expiration_threshold = datetime.now() - DELETION_DATE_THRESHOLD
        deleted_count = delete_expired(expiration_threshold, DELETION_COUNT_THRESHOLD, BATCH_SIZE)
        if deleted_count == 0:
          return


if __name__ == "__main__":
  worker = QueueCleanupWorker()
  worker.start()