public function register(Container $app)
 {
     $app['maintenance.enabled'] = false;
     if ($this->isMaintenanceMode) {
         $app['maintenance.enabled'] = true;
         if ($this->htmlFile) {
             $app['maintenance.html'] = file_get_contents($this->htmlFile);
             $app->match('/{path}', function () use($app) {
                 return new Response($app['maintenance.html'], 503);
             })->assert('path', '.*');
         } elseif (isset($app['twig']) && $this->twigTemplate) {
             $app['maintenance.twig_template'] = $this->twigTemplate;
             $app->match('/{path}', function () use($app) {
                 $response = new Response();
                 $response->setStatusCode(503);
                 $response->setContent($app['twig']->render($app['maintenance.twig_template']));
                 return $response;
             })->assert('path', '.*');
         } else {
             $app->match('/{path}', function () use($app) {
                 return $app->abort(503);
             })->assert('path', '.*');
         }
     }
 }