Implement legacy image portion of the data model

This also makes use of the newly created input system

data/registry_model/registry_pre_oci_model.py

@@ -1,9 +1,11 @@
 # pylint: disable=protected-access
 
+from collections import defaultdict
+
 from data import database
 from data import model
 from data.registry_model.interface import RegistryDataInterface
-from data.registry_model.datatypes import Tag, RepositoryReference, Manifest
+from data.registry_model.datatypes import Tag, RepositoryReference, Manifest, LegacyImage
 
 
 class PreOCIModel(RegistryDataInterface):
@@ -62,5 +64,44 @@ class PreOCIModel(RegistryDataInterface):
 
     model.label.create_manifest_label(tag_manifest, key, value, source_type_name, media_type_name)
 
+  def get_legacy_images(self, repository_ref):
+    """
+    Returns an iterator of all the LegacyImage's defined in the matching repository.
+    """
+    repo = model.repository.lookup_repository(repository_ref._db_id)
+    if repo is None:
+      return None
+
+    all_images = model.image.get_repository_images_without_placements(repo)
+    all_images_map = {image.id: image for image in all_images}
+
+    all_tags = model.tag.list_repository_tags(repo.namespace_user.username, repo.name)
+    tags_by_image_id = defaultdict(list)
+    for tag in all_tags:
+      tags_by_image_id[tag.image_id].append(tag)
+
+    return [LegacyImage.for_image(image, images_map=all_images_map, tags_map=tags_by_image_id)
+            for image in all_images]
+
+  def get_legacy_image(self, repository_ref, docker_image_id, include_parents=False):
+    """
+    Returns the matching LegacyImages under the matching repository, if any. If none,
+    returns None.
+    """
+    repo = model.repository.lookup_repository(repository_ref._db_id)
+    if repo is None:
+      return None
+
+    image = model.image.get_image(repository_ref._db_id, docker_image_id)
+    if image is None:
+      return None
+
+    parent_images_map = None
+    if include_parents:
+      parent_images = model.image.get_parent_images(repo.namespace_user.username, repo.name, image)
+      parent_images_map = {image.id: image for image in parent_images}
+
+    return LegacyImage.for_image(image, images_map=parent_images_map)
+
 
 pre_oci_model = PreOCIModel()