Add _catalog endpoint as specified by V2 API

Fixes #391

endpoints/v2/catalog.py

@@ -0,0 +1,32 @@
+# XXX This code is not yet ready to be run in production, and should remain disabled until such
+# XXX time as this notice is removed.
+
+from flask import jsonify, url_for
+
+from endpoints.v2 import v2_bp
+from auth.auth import process_auth
+from endpoints.decorators import anon_protect
+from data import model
+from endpoints.v2.v2util import add_pagination
+from auth.auth_context import get_authenticated_user
+
+@v2_bp.route('/_catalog', methods=['GET'])
+@process_auth
+@anon_protect
+def catalog_search():
+  url = url_for('v2.catalog_search')
+
+  username = get_authenticated_user().username if get_authenticated_user() else None
+  query = model.repository.get_visible_repositories(username, include_public=(username is None),
+                                                    limit=50)
+
+  link, query = add_pagination(query, url)
+
+  response = jsonify({
+    'repositories': ['%s/%s' % (repo.namespace_user.username, repo.name) for repo in query],
+  })
+
+  if link is not None:
+    response.headers['Link'] = link
+
+  return response