import logging

from peewee import JOIN_LEFT_OUTER

from peewee import (CharField, BigIntegerField, BooleanField, ForeignKeyField, DateTimeField,
                    TextField)

from data.database import BaseModel, db, db_for_update
from app import app, storage
from data import model


logger = logging.getLogger(__name__)


class Repository(BaseModel):
  pass


# Vendor the information from tables we will be writing to at the time of this migration
class ImageStorage(BaseModel):
  uuid = CharField(index=True, unique=True)
  checksum = CharField(null=True)
  image_size = BigIntegerField(null=True)
  uncompressed_size = BigIntegerField(null=True)
  uploading = BooleanField(default=True, null=True)


class Image(BaseModel):
  # This class is intentionally denormalized. Even though images are supposed
  # to be globally unique we can't treat them as such for permissions and
  # security reasons. So rather than Repository <-> Image being many to many
  # each image now belongs to exactly one repository.
  docker_image_id = CharField(index=True)
  repository = ForeignKeyField(Repository)

  # '/' separated list of ancestory ids, e.g. /1/2/6/7/10/
  ancestors = CharField(index=True, default='/', max_length=64535, null=True)

  storage = ForeignKeyField(ImageStorage, index=True, null=True)

  created = DateTimeField(null=True)
  comment = TextField(null=True)
  command = TextField(null=True)
  aggregate_size = BigIntegerField(null=True)
  v1_json_metadata = TextField(null=True)


class ImageStorageLocation(BaseModel):
  name = CharField(unique=True, index=True)


class ImageStoragePlacement(BaseModel):
  storage = ForeignKeyField(ImageStorage)
  location = ForeignKeyField(ImageStorageLocation)


def image_json_path(storage_uuid):
  base_path = storage._image_path(storage_uuid)
  return '{0}json'.format(base_path)


def backfill_v1_metadata():
  """ Copies metadata from image storages to their images. """
  logger.debug('Image v1 metadata backfill: Began execution')

  while True:
    batch_image_ids = list(Image
                           .select(Image.id)
                           .join(ImageStorage)
                           .where(Image.v1_json_metadata >> None, ImageStorage.uploading == False)
                           .limit(100))

    if len(batch_image_ids) == 0:
      logger.debug('Image v1 metadata backfill: Backfill completed')
      return

    logger.debug('Image v1 metadata backfill: Found %s records to update', len(batch_image_ids))
    for one_id in batch_image_ids:
      with app.config['DB_TRANSACTION_FACTORY'](db):
        try:
          logger.debug('Loading image: %s', one_id.id)

          raw_query = (ImageStoragePlacement
                       .select(ImageStoragePlacement, Image, ImageStorage, ImageStorageLocation)
                       .join(ImageStorageLocation)
                       .switch(ImageStoragePlacement)
                       .join(ImageStorage, JOIN_LEFT_OUTER)
                       .join(Image)
                       .where(Image.id == one_id.id))

          placement_query = db_for_update(raw_query)

          repo_image_list = model.image.invert_placement_query_results(placement_query)
          if len(repo_image_list) > 1:
            logger.error('Found more images than we requested, something is wrong with the query')
            return

          repo_image = repo_image_list[0]
          uuid = repo_image.storage.uuid
          json_path = image_json_path(uuid)

          logger.debug('Updating image: %s from: %s', repo_image.id, json_path)
          try:
            data = storage.get_content(repo_image.storage.locations, json_path)
          except IOError:
            data = "{}"
            logger.warning('failed to find v1 metadata, defaulting to {}')
          repo_image.v1_json_metadata = data
          repo_image.save()
        except ImageStoragePlacement.DoesNotExist:
          pass

if __name__ == "__main__":
  logging.basicConfig(level=logging.DEBUG)
  # logging.getLogger('peewee').setLevel(logging.CRITICAL)
  backfill_v1_metadata()