public function selection($cat = '*', $nb = 3)
    {
        $prevs = $categories = $rows = array();
        if(is_numeric($cat)){
            $cats = array(['id_category'=>$cat]);
        }else{
            $sql = "SELECT l.id_category FROM ps_category_lang l JOIN ps_category c ON l.id_category = c.id_category WHERE l.name LIKE '$cat%' ORDER BY c.position";
            $cats = Db::getInstance()->ExecuteS($sql);
        }
        foreach ($cats as $k => $v) {
            if (in_array($v['id_category'], $prevs)) continue;
            $category = $categories[$k] = new Category($v['id_category'], (int)Context::getContext()->language->id);
            $rows[$k] = $category->getProducts((int)Context::getContext()->language->id, 1, $nb, 'position');
            $prevs[ ] = $v['id_category'];
            if ($rows === false || empty($rows))    return false;
        }
        $this->smarty->assign([
            'rows' => $rows,
            'categories' => $categories,
            'size' => $nb
        ]);
        return $this->display(__FILE__, 'selection.tpl');
    }