private function syncOAuthClient($app)
 {
     $client = OAuthClient::find($app->client_id);
     if (!$client) {
         return $this->addOAuthClient($app);
     }
     $client->name = $app->name;
     $client->save();
     $endpoint = OAuthClientEndPoint::find($app->client_id);
     $endpoint->redirect_uri = $app->redirect_uri;
     $endpoint->save();
     OAuthClientScope::where('client_id', $app->client_id)->delete();
     $scopes = [];
     $scopeString = $app->scopes;
     if ($scopeString !== null) {
         $scopes = explode(',', $scopeString);
     }
     foreach ($scopes as $scope_id) {
         $clientScope = new OAuthClientScope(['client_id' => $app->client_id, 'scope_id' => $scope_id]);
         $clientScope->save();
     }
 }