WooCommerce – 根据购物车中商品数量的有条件累进折扣

/* The calculation:

 *  — The count => Based on quantity by item and total of items in cart

 *  — The percent is 0.05 (5%) and  it grows with each additional item (as you asked)

 *  — I add the subtotal of each item line to get the total sum…

 */

function cart_progressive_discount() {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )

        return;

    $cart_count = 0;

    $cart_lines_total = 0;

    foreach(WC()->cart->get_cart() as $item_key => $cart_item){

        // Adds the quantity of each item to the count

        $cart_count = $cart_count + $cart_item["quantity"];

        // Adds The items subtotal to total

        $cart_lines_total += $cart_item["line_total"];

    }

    // percent is 5%

    $percent = -0.05;

    // We fix the discount max to 50% (-0.05 * 10)

    $cart_count_max = 10;

    // Discount calculations:

    $discount = $percent * $cart_count * $cart_lines_total;

    $discount2 = $percent * $cart_count_max * $cart_lines_total;

    $discount_text = __( 'Quantity discount', 'woocommerce' );

    // For 0 or 1 item

    if( $cart_count < 2 ) {

        return;

    }

    // Between 2 and 9 items, progressive incremental discount based on item quantity (From 10% to 45%)

    elseif( $cart_count > 1 && $cart_count < 10) {

        WC()->cart->add_fee( $discount_text, $discount, false );

    }

    // Up to 9 items (Fixed discount at 50%)

    else {

        WC()->cart->add_fee( $discount_text, $discount2, false );

    }

}

add_action( 'woocommerce_cart_calculate_fees','cart_progressive_discount' );