public function getActiveThemes()
    {
        $themes = &gplcart_static('module.active.themes');

        if (isset($themes)) {
            return $themes;
        }

        $themes = array($this->config->get('theme_backend', 'backend'));

        if (!$this->db->isInitialized()) {
            return $themes;
        }

        $stores = $this->db->fetchAll('SELECT * FROM store', array());

        foreach ($stores as $store) {
            $data = unserialize($store['data']);
            foreach ($data as $key => $value) {
                if (strpos($key, 'theme') === 0) {
                    $themes[] = $value;
                }
            }
        }

        return $themes;
    }