refactor(endpoints/api/tag): refactor code for v22

this decouples the database models from the api

[TESTING->locally with docker compose]

Issue: https://coreosdev.atlassian.net/browse/QUAY-632

- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format

endpoints/api/image.py

@@ -9,6 +9,33 @@ from endpoints.exception import NotFound
 from data import model
 
 
+def image_view_pre_oci(image, image_map, include_ancestors=True):
+  command = image.command
+
+  def docker_id(aid):
+    if aid not in image_map:
+      return ''
+
+    return image_map[aid].docker_image_id
+
+  image_data = {
+    'id': image.docker_image_id,
+    'created': format_date(image.created),
+    'comment': image.comment,
+    'command': json.loads(command) if command else None,
+    'size': image.storage_image_size,
+    'uploading': image.storage_uploading,
+    'sort_index': image.ancestor_length,
+  }
+
+  if include_ancestors:
+    # Calculate the ancestors string, with the DBID's replaced with the docker IDs.
+    ancestors = [docker_id(a) for a in image.ancestor_id_list]
+    image_data['ancestors'] = '/{0}/'.format('/'.join(ancestors))
+
+  return image_data
+
+
 def image_view(image, image_map, include_ancestors=True):
   command = image.command