/**
  * Responds to requests to GET /routines
  */
 public function getIndex(Request $request)
 {
     $options = Routine::getOptions(['goals', 'frequencies', 'difficulties']);
     $builder = Routine::query();
     $is_admin = Auth::check() ? Auth::user()->isAdmin() : false;
     $current_user_id = Auth::check() ? Auth::user()->id : null;
     $params = $this->getSelectedParameters($request);
     $this->addParamsToQuery($builder, $params);
     $routines = $builder->with('goal', 'frequency', 'difficulty')->paginate(12);
     $this->appendSelectionToPagination($request, $routines);
     return view('routines.index', ['routines' => $routines, 'options' => $options, 'is_admin' => $is_admin, 'current_user_id' => $current_user_id, 'params' => $params]);
 }