from image.docker.interfaces import ContentRetriever
from data.database import Manifest
from data.model.blob import get_repository_blob_by_digest
from data.model.storage import get_storage_locations, get_layer_path

class RepositoryContentRetriever(ContentRetriever):
  """ Implementation of the ContentRetriever interface for manifests that retrieves
      config blobs and child manifests for the specified repository.
  """
  def __init__(self, repository_id, storage):
    self.repository_id = repository_id
    self.storage = storage

  @classmethod
  def for_repository(cls, repository_id, storage):
    return RepositoryContentRetriever(repository_id, storage)

  def get_manifest_bytes_with_digest(self, digest):
    """ Returns the bytes of the manifest with the given digest or None if none found. """
    query = (Manifest
             .select()
             .where(Manifest.repository == self.repository_id)
             .where(Manifest.digest == digest))

    try:
      return query.get().manifest_bytes
    except Manifest.DoesNotExist:
      return None

  def get_blob_bytes_with_digest(self, digest):
    """ Returns the bytes of the blob with the given digest or None if none found. """
    blob = get_repository_blob_by_digest(self.repository_id, digest)
    if blob is None:
      return None

    placements = list(get_storage_locations(blob.uuid))
    return self.storage.get_content(placements, get_layer_path(blob))