public function search($criteria)
    {
        $this->loadModel('Content.Contents');

        try {
            $contents = $this->Contents->search($criteria);
            if ($contents->clause('limit')) {
                $this->paginate['limit'] = $contents->clause('limit');
            }

            // TO-DO: ask search-engine for operator presence
            if (strpos($criteria, 'language:') === false) {
                $contents = $contents->where([
                    'Contents.status >' => 0,
                    'Contents.language IN' => ['', null, I18n::locale()] // any or concrete
                ]);
            }

            $contents = $this->paginate($contents);
        } catch (\Exception $e) {
            $contents = new Collection([]);
        }

        $this->set(compact('contents', 'criteria'));
        $this->viewMode('search-result');
    }