from abc import ABCMeta, abstractproperty, abstractmethod
from six import add_metaclass

@add_metaclass(ABCMeta)
class ManifestInterface(object):
  """ Defines the interface for the various manifests types supported. """
  @abstractproperty
  def schema_version(self):
    """ The version of the schema, or None for lists. """

  @abstractproperty
  def digest(self):
    """ The digest of the manifest, including type prefix. """
    pass

  @abstractproperty
  def media_type(self):
    """ The media type of the schema. """
    pass

  @abstractproperty
  def manifest_dict(self):
    """ Returns the manifest as a dictionary ready to be serialized to JSON. """
    pass

  @abstractproperty
  def bytes(self):
    """ Returns the bytes of the manifest. """
    pass

  @abstractproperty
  def layers(self):
    """ Returns the layers of this manifest, from base to leaf or None if none. """
    pass

  @abstractproperty
  def leaf_layer_v1_image_id(self):
    """ Returns the Docker V1 image ID for the leaf (top) layer, if any, or None if none. """
    pass

  @abstractproperty
  def legacy_image_ids(self):
    """ Returns the Docker V1 image IDs for the layers of this manifest or None if not applicable.
    """
    pass

  @abstractproperty
  def blob_digests(self):
    """ Returns an iterator over all the blob digests referenced by this manifest,
        from base to leaf. The blob digests are strings with prefixes. For manifests that reference
        config as a blob, the blob will be included here.
    """

  @abstractmethod
  def child_manifests(self, lookup_manifest_fn):
    """ Returns an iterator of all manifests that live under this manifest, if any or None if none.
        The lookup_manifest_fn is a function that, when given a blob content SHA, returns the
        contents of that blob in storage if any or None if none.
    """

  @abstractmethod
  def get_manifest_labels(self, lookup_config_fn):
    """ Returns a dictionary of all the labels defined inside this manifest or None if none. """
    pass

  @abstractmethod
  def unsigned(self):
    """ Returns an unsigned version of this manifest. """

  @abstractmethod
  def generate_legacy_layers(self, images_map, lookup_config_fn):
    """
    Rewrites Docker v1 image IDs and returns a generator of DockerV1Metadata.

    If Docker gives us a layer with a v1 image ID that already points to existing
    content, but the checksums don't match, then we need to rewrite the image ID
    to something new in order to ensure consistency.

    Returns None if there are no legacy images associated with the manifest.
    """

  @abstractmethod
  def get_v1_compatible_manifest(self, namespace_name, repo_name, tag_name, lookup_fn):
    """ Returns the manifest that is compatible with V1, by virtue of being `amd64` and `linux`.
        If none, returns None.
    """