问在Woocommerce中自动使用一种运输方式的优惠券

EN

// Add / remove coupon based on cosen shipping
add_action( 'woocommerce_before_calculate_totals', 'adding_removing_coupon_shipping_based' );
function adding_removing_coupon_shipping_based( $cart ) {
    if (is_admin() && !defined('DOING_AJAX'))
        return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    // HERE the specific coupon code
    $coupon_code = 'discount4';

    $coupon_code     = wc_format_coupon_code( $coupon_code );
    $chosen_shipping = WC()->session->get('chosen_shipping_methods')[0];
    $applied_coupons = $cart->get_applied_coupons();

    $is_free = strpos( $chosen_shipping, 'free_shipping' ) !== false;
    $is_applied = in_array( $coupon_code, $applied_coupons );


    if ( $is_applied && $is_free )
        $cart->remove_coupon( $coupon_code );
    elseif ( ! $is_applied && ! $is_free )
        $cart->apply_coupon( $coupon_code );
}