Add support for linking to external users in entity search

data/users/federated.py

@@ -7,7 +7,7 @@ from util.validation import generate_valid_usernames
 
 logger = logging.getLogger(__name__)
 
-VerifiedCredentials = namedtuple('VerifiedCredentials', ['username', 'email'])
+UserInformation = namedtuple('UserInformation', ['username', 'email', 'id'])
 
 class FederatedUsers(object):
   """ Base class for all federated users systems. """
@@ -15,11 +15,26 @@ class FederatedUsers(object):
   def __init__(self, federated_service):
     self._federated_service = federated_service
 
+  @property
+  def federated_service(self):
+    return self._federated_service
+
+  def get_user(self, username_or_email):
+    """ Retrieves the user with the given username or email, returning a tuple containing
+        a UserInformation (if success) and the error message (on failure).
+    """
+    raise NotImplementedError
+
   def verify_credentials(self, username_or_email, password):
     """ Verifies the given credentials against the backing federated service, returning
-        a tuple containing a VerifiedCredentials (if success) and the error message (if failed). """
+        a tuple containing a UserInformation (on success) and the error message (on failure).
+    """
     raise NotImplementedError
 
+  def query_users(self, query, limit=20):
+    """ If implemented, get_user must be implemented as well. """
+    return (None, 'Not supported')
+
   def _get_federated_user(self, username, email):
     db_user = model.user.verify_federated_login(self._federated_service, username)
     if not db_user:
@@ -34,7 +49,8 @@ class FederatedUsers(object):
         return (None, 'Unable to pick a username. Please report this to your administrator.')
 
       db_user = model.user.create_federated_user(valid_username, email, self._federated_service,
-                                                 username, set_password_notification=False)
+                                                 username,
+                                                 set_password_notification=False)
     else:
       # Update the db attributes from the federated service.
       db_user.email = email
@@ -42,6 +58,13 @@ class FederatedUsers(object):
 
     return (db_user, None)
 
+  def link_user(self, username_or_email):
+    (credentials, err_msg) = self.get_user(username_or_email)
+    if credentials is None:
+      return (None, err_msg)
+
+    return self._get_federated_user(credentials.username, credentials.email)
+
   def verify_and_link_user(self, username_or_email, password):
     """ Verifies the given credentials and, if valid, creates/links a database user to the
         associated federated service.