import logging
import logging.config

from datetime import timedelta

from app import app, storage
from data.database import UseThenDisconnect, BlobUpload
from data import model
from workers.worker import Worker


logger = logging.getLogger(__name__)


DELETION_DATE_THRESHOLD = timedelta(days=2)
BLOBUPLOAD_CLEANUP_FREQUENCY = app.config.get('BLOBUPLOAD_CLEANUP_FREQUENCY', 60*60)


class BlobUploadCleanupWorker(Worker):
  def __init__(self):
    super(BlobUploadCleanupWorker, self).__init__()
    self.add_operation(self._cleanup_uploads, BLOBUPLOAD_CLEANUP_FREQUENCY)

  def _cleanup_uploads(self):
    """ Performs garbage collection on the blobupload table. """
    while True:
      # Find all blob uploads older than the threshold (typically a week) and delete them.
      with UseThenDisconnect(app.config):
        stale_upload = model.blob.get_stale_blob_upload(DELETION_DATE_THRESHOLD)
        if stale_upload is None:
          logger.debug('No additional stale blob uploads found')
          return

      # Remove the stale upload from storage.
      logger.debug('Removing stale blob upload %s', stale_upload.uuid)
      try:
        storage.cancel_chunked_upload([stale_upload.location.name], stale_upload.uuid,
                                      stale_upload.storage_metadata)
      except Exception as ex:
        logger.debug('Got error when trying to cancel chunked upload %s: %s', stale_upload.uuid,
                     ex.message)

      # Delete the stale upload's row.
      with UseThenDisconnect(app.config):
        try:
          stale_upload.delete_instance()
        except BlobUpload.DoesNotExist:
          continue

      logger.debug('Removed stale blob upload %s', stale_upload.uuid)


if __name__ == "__main__":
  logging.config.fileConfig('conf/logging_debug.conf', disable_existing_loggers=False)
  worker = BlobUploadCleanupWorker()
  worker.start()