在WooCommerce购物车中实现基于产品ID分组的累计附加费用

// Settings (multiple settings arrays can be added/removed if desired)
$settings = array(
    array(
        'product_id'    => array( 30, 813, 815 ), // 产品ID数组
        'amount'        => 5,                    // 单个产品费用
        'name'          => __( 'Additional service fee', 'woocommerce' ), // 费用名称
        'total_amount'  => 0,                    // 累加器，初始为0
    ),
    array(
        'product_id'    => array( 817, 819, 820 ),
        'amount'        => 25,
        'name'          => __( 'Packing fee', 'woocommerce' ),
        'total_amount'  => 0,
    ),
    array(
        'product_id'    => array( 825 ),
        'amount'        => 100,
        'name'          => __( 'Another fee', 'woocommerce' ),
        'total_amount'  => 0,
    ),
);

// Loop through cart contents
foreach ( $cart->get_cart_contents() as $cart_item ) {      
    // Get product id
    $product_id = $cart_item['product_id'];

    // Get quantity
    $quantity = $cart_item['quantity']; // 考虑产品数量

    // Loop trough settings array (determine total amount)
    foreach ( $settings as $key => $setting ) {
        // Search for the product ID
        if ( in_array( $product_id, $settings[$key]['product_id'] ) ) {
            // Addition: amount * quantity
            $settings[$key]['total_amount'] += $setting['amount'] * $quantity;
        }
    }       
}

// Loop trough settings array (output)
foreach ( $settings as $setting ) {
    // Greater than 0
    if ( $setting['total_amount'] > 0 ) {
        // Add fee (name, amount, taxable)
        $cart->add_fee( $setting['name'], $setting['total_amount'], false );    
    }
}

/**
 * 在WooCommerce购物车中为特定产品ID组累加附加费用。
 *
 * @param WC_Cart $cart WooCommerce购物车对象。
 */
function action_woocommerce_cart_calculate_fees( $cart ) {
    // 仅在前端或AJAX请求时执行，避免后台管理界面冲突
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
        return;
    }

    // 费用设置：每个数组定义一个费用类别
    // 'product_id' 包含该费用类别下的所有产品ID（数组形式）
    // 'amount' 是单个产品（或每单位）的费用
    // 'name' 是在购物车中显示的费用名称
    // 'total_amount' 是一个累加器，用于计算该费用类别的总金额，初始值为0
    $settings = array(
        array(
            'product_id'    => array( 30, 813, 815 ), // 例如：产品ID 30, 813, 815 属于“附加服务费”
            'amount'        => 5,
            'name'          => __( 'Additional service fee', 'woocommerce' ),
            'total_amount'  => 0,
        ),
        array(
            'product_id'    => array( 817, 819, 820 ), // 例如：产品ID 817, 819, 820 属于“包装费”
            'amount'        => 25,
            'name'          => __( 'Packing fee', 'woocommerce' ),
            'total_amount'  => 0,
        ),
        array(
            'product_id'    => array( 825 ), // 例如：产品ID 825 属于“其他费用”
            'amount'        => 100,
            'name'          => __( 'Another fee', 'woocommerce' ),
            'total_amount'  => 0,
        ),
    );

    // 阶段1: 遍历购物车内容，累积每个费用类别的总金额
    foreach ( $cart->get_cart_contents() as $cart_item ) {      
        $product_id = $cart_item['product_id']; // 获取购物车商品的产品ID
        $quantity   = $cart_item['quantity'];   // 获取购物车商品的数量

        // 遍历所有费用设置，检查当前购物车商品是否属于某个费用类别
        foreach ( $settings as $key => $setting ) {
            // 如果当前购物车商品的产品ID在某个费用类别的 product_id 数组中
            if ( in_array( $product_id, $settings[$key]['product_id'] ) ) {
                // 将该费用类别的总金额累加，考虑产品数量
                $settings[$key]['total_amount'] += $setting['amount'] * $quantity;
            }
        }       
    }

    // 阶段2: 遍历更新后的费用设置，将累积的总费用添加到购物车
    foreach ( $settings as $setting ) {
        // 只有当该费用类别的总金额大于0时才添加
        if ( $setting['total_amount'] > 0 ) {
            // 使用 add_fee 方法将费用添加到购物车
            // 参数：费用名称，费用金额，是否应税 (false 表示不应税)
            $cart->add_fee( $setting['name'], $setting['total_amount'], false );    
        }
    }
}
add_action( 'woocommerce_cart_calculate_fees', 'action_woocommerce_cart_calculate_fees', 10, 1 );