我需要开发一个插件，适用于购物车折扣，如果x数量的产品已经购买。有人能告诉我需要使用的代码/API的方向吗。

无法从中找到任何内容https://docs.woothemes.com/documentation/plugins/woocommerce/woocommerce-codex/ 而且，不要仅仅为了获得这样一些简单的功能而花100多美元购买官方批量折扣插件。

我发现了WooCommerce\'s get_total_discount() function 应用woocommerce_cart_total_discount 过滤器，但我似乎无法成功地进入该过滤器。。。

function mwe_calculate_discount( $total_discount, $cart ) {

    //global $woocommerce;
    $num_products_required_for_discount = 4;

    echo "<!-- Discount? -->";

    $number_products = $cart->cart_contents_count;
    if ($number_products >= $num_products_required_for_discount) {

        echo "<!-- QUALIFIES FOR DISCOUNT! -->";

        for ($i = 0; $i < $number_products; $i++) {

            // Get the reduced price of the product - TODO

            // Calculate $product_discount
            $product_discount = 11.11; // TODO

            // Add $product_discount to the $total_discount
            $total_discount += $product_discount;
        }

        echo "<!-- Total discount: $total_discount -->";

    }
    else {

        echo "<!-- NO DISCOUNT -->";

    }

    return $total_discount;

}
add_filter(\'woocommerce_cart_total_discount\', \'mwe_calculate_discount\', 10, 2);