import json
import logging

from data import model
from data.database import ImageStorage
from app import app, storage as store
from data.database import db
from gzip import GzipFile
from tempfile import SpooledTemporaryFile


logger = logging.getLogger(__name__)


def backfill_sizes_from_json():
  query = (ImageStorage
           .select()
           .where(ImageStorage.uncompressed_size == None, ImageStorage.uploading == False)
           .limit(100))

  total = 0
  missing = 0
  batch_processed = 1

  while batch_processed > 0:
    batch_processed = 0
    with app.config['DB_TRANSACTION_FACTORY'](db):
      for image_storage in query.clone():
        total += 1
        batch_processed += 1

        if (total - 1) % 100 == 0:
          logger.debug('Storing entry: %s', total)

        # Lookup the JSON for the image.
        uuid = image_storage.uuid
        with_locations = model.get_storage_by_uuid(uuid)

        try:
          json_string = store.get_content(with_locations.locations, store.image_json_path(uuid))
          json_data = json.loads(json_string)
          size = json_data.get('Size', json_data.get('size', -1))
        except IOError:
          logger.debug('Image storage with no json %s', uuid)
          size = -1

        if size == -1:
          missing += 1

          logger.debug('Missing entry %s (%s/%s)', uuid, missing, total)

        image_storage.uncompressed_size = size
        image_storage.save()


def backfill_sizes_from_data():
  storage_ids = list(ImageStorage
           .select(ImageStorage.uuid)
           .where(ImageStorage.uncompressed_size == -1, ImageStorage.uploading == False))

  counter = 0
  for uuid in [s.uuid for s in storage_ids]:
    counter += 1

    # Load the storage with locations.
    logger.debug('Loading entry: %s (%s/%s)', uuid, counter, len(storage_ids))
    with_locations = model.get_storage_by_uuid(uuid)
    layer_size = -2

    # Read the layer from backing storage and calculate the uncompressed size. 
    try:
      logger.debug('Loading data: %s (%s bytes)', uuid, with_locations.image_size)
      CHUNK_SIZE = 512 * 1024
      with SpooledTemporaryFile(CHUNK_SIZE) as tarball:
        layer_data = store.get_content(with_locations.locations, store.image_layer_path(uuid))
        tarball.write(layer_data)
        tarball.seek(0)

        with GzipFile(fileobj=tarball, mode='rb') as gzip_file:
          gzip_file.read()
          layer_size = gzip_file.size

    except Exception as ex:
      logger.debug('Could not gunzip entry: %s. Reason: %s', uuid, ex)
      continue
    
    # Write the size to the image storage. We do so under a transaction AFTER checking to
    # make sure the image storage still exists and has not changed.
    logger.debug('Writing entry: %s. Size: %s', uuid, layer_size)
    with app.config['DB_TRANSACTION_FACTORY'](db):
      try:  
        current_record = model.get_storage_by_uuid(uuid)
      except:
        # Record no longer exists.
        continue

      if not current_record.uploading and current_record.uncompressed_size == -1:
        current_record.uncompressed_size = layer_size
        current_record.save()


if __name__ == "__main__":
  logging.basicConfig(level=logging.DEBUG)
  logging.getLogger('boto').setLevel(logging.CRITICAL)

  backfill_sizes_from_json()
  backfill_sizes_from_data()