Aggiungi una confezione regalo al checkout

add_action( 'woocommerce_review_order_before_order_total', 'custom_checkbox_checkout_field' );

function custom_checkbox_checkout_field() {
    $value = WC()->session->get( 'add_a_product' );
    $product_id = 6413;
    $product = wc_get_product( $product_id );
    $product_price = $product->get_price();

    ?>
    <tr class="cart-addon-row">
        <td class="product-name">
            <?php
            woocommerce_form_field(
                'cb_add_product',
                array(
                    'type'  => 'checkbox',
                    'label' => '  <i class="fa fa-gift" style="color: #BD453F; margin-right: 5px;"></i>' . __( 'Confezione regalo' ) . ' - ' . wc_price( $product_price ),
                    'class' => array( 'form-row-wide', 'gift-box', 'checkbox' ), // Aggiunta della classe checkbox
                ),
                $value == 'yes' ? true : false
            );
            ?>
        </td>
    </tr>
    <style>
        .optional {
            display: none;
        }
        .checkbox {
            color: #BD453F;
            font-weight: bold;
            text-transform: none;
            text-align: left;
        }
    </style>
    <?php
}

// Codice jQuery per la richiesta Ajax
add_action( 'wp_footer', 'checkout_custom_jquery_script' );

function checkout_custom_jquery_script() {
    // Solo nella pagina di checkout
    if ( is_checkout() && ! is_wc_endpoint_url() ):

        // Rimuovi le variabili di sessione personalizzate di WC al caricamento
        if ( WC()->session->get( 'add_a_product' ) ) {
            WC()->session->__unset( 'add_a_product' );
        }
        if ( WC()->session->get( 'product_added_key' ) ) {
            WC()->session->__unset( 'product_added_key' );
        }
        // Codice jQuery per Ajax
        ?>
        <script type="text/javascript">
            jQuery( function($) {
                if ( typeof wc_checkout_params === 'undefined' )
                    return false;

                $('form.checkout').on( 'change', '#cb_add_product', function() {
                    var value = $(this).prop('checked') === true ? 'yes' : 'no';

                    $.ajax({
                        type: 'POST',
                        url: wc_checkout_params.ajax_url,
                        data: {
                            'action': 'add_a_product',
                            'add_a_product': value,
                        },
                        success: function (result) {
                            $('body').trigger('update_checkout');
                            console.log(result);
                        }
                    });
                });
            });
        </script>
        <?php
    endif;
}

// Ricevitore PHP Ajax di WordPress
add_action( 'wp_ajax_add_a_product', 'checkout_ajax_add_a_product' );
add_action( 'wp_ajax_nopriv_add_a_product', 'checkout_ajax_add_a_product' );

function checkout_ajax_add_a_product() {
    if ( isset( $_POST['add_a_product'] ) ) {
        WC()->session->set( 'add_a_product', esc_attr( $_POST['add_a_product'] ) );
        echo $_POST['add_a_product'];
    }
    die();
}

// Aggiungi o rimuovi il prodotto specifico
add_action( 'woocommerce_before_calculate_totals', 'adding_removing_specific_product' );

function adding_removing_specific_product( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

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

    // ID del prodotto specifico
    $product_id = 6413;

    if ( WC()->session->get( 'add_a_product' ) == 'yes' && ! WC()->session->get( 'product_added_key' ) ) {
        $cart_item_key = $cart->add_to_cart( $product_id );
        WC()->session->set( 'product_added_key', $cart_item_key );
    } elseif ( WC()->session->get( 'add_a_product' ) == 'no' && WC()->session->get( 'product_added_key' ) ) {
        $cart_item_key = WC()->session->get( 'product_added_key' );
        $cart->remove_cart_item( $cart_item_key );
        WC()->session->__unset( 'product_added_key' );
    }
}