Woocommerce – Product Variation Preorder price

Im kinda new to woocommerce dev and haven’t developped in PHP for ages.

With the help of [@LoicTheAztec][1], I implemented Preording on my Woocommerce store using this :

    // Admin Variation custom fields
    add_action( 'woocommerce_product_after_variable_attributes', 'ab_preorder_variation_fields', 10, 3 );
    function ab_preorder_variation_fields( $loop, $variation_data, $variation ) {
    
        echo '<div class="options_group form-row form-row-full">';
        
        // Is Preordable
        woocommerce_wp_checkbox(
            array(
                'id'            => '_ab_preorder_checkbox['.$loop.']',
                'wrapper_class' => 'show_if_simple',
                'label'         => __(' Disponible à la précommande', 'woocommerce' ),
                'description'   => __( 'Disponible à la précommande', 'woocommerce' ),
                'desc_tip'    => true,
                'value' => get_post_meta( $variation->ID, '_ab_preorder_checkbox', true )
            )
        );
    
        // Custom Preorder Price
        woocommerce_wp_text_input(
            array(
                'id'                => '_ab_preorder_custom_price['.$loop.']',
                'label'             => __( 'Prix à la précommande', 'woocommerce' ),
                'placeholder'       => '',
                'desc_tip'          => true,
                'description'       => __( "Prix à la précommande", 'woocommerce' ),
                'type'              => 'number',
                'custom_attributes' => array(
                        'step'  => 'any',
                        'min'   => '0'
                    ),
                'value' => get_post_meta( $variation->ID, '_ab_preorder_custom_price', true )
            )
        );
    
        // Date de livraison estimée
        woocommerce_wp_text_input(
            array(
                'id'          => '_ab_preorder_estimated_date['.$loop.']',
                'label'       => __( 'Date de livraison estimé', 'woocommerce' ),
                'desc_tip'    => true,
                'description' => __( "Date de livraison estimé", "woocommerce" ),
                'type'        => 'date',
                'value' => get_post_meta( $variation->ID, '_ab_preorder_estimated_date', true )
            )
        );
    
        echo '</div>';
    }
    
    // Save admin Variations custom fields values
    add_action( 'woocommerce_admin_process_variation_object', 'ab_preorder_variation_fields_saving', 10, 2 );
    function ab_preorder_variation_fields_saving( $variation, $loop ) {
        if( isset($_POST['_ab_preorder_checkbox'][$loop]) ) {
            $variation->update_meta_data( '_ab_preorder_checkbox', esc_attr($_POST['_ab_preorder_checkbox'][$loop]) );
        }
    
        if( isset($_POST['_ab_preorder_custom_price'][$loop]) ) {
            $variation->update_meta_data( '_ab_preorder_custom_price', esc_attr($_POST['_ab_preorder_custom_price'][$loop]) );
        }
    
        if( isset($_POST['_ab_preorder_estimated_date'][$loop]) ) {
            $variation->update_meta_data( '_ab_preorder_estimated_date', esc_attr($_POST['_ab_preorder_estimated_date'][$loop]) );
        }
    }
    
    // Set the variation backorder price
    add_filter('woocommerce_product_variation_get_regular_price', 'custom_price', 99, 2 );
    add_filter('woocommerce_product_variation_get_price', 'custom_price', 99, 2 );
    function custom_price( $price, $product ) {
        if ( $product->get_stock_quantity() == 0 && $product->get_meta('_ab_preorder_checkbox') === 'yes' ) {
            $backorder_price = $product->get_meta('_ab_preorder_custom_price');
            
            if( $backorder_price > 0 ) {
                $price = (float) $backorder_price;
            }
        }
        return $price;
    }
    
    // Display prefixed backorder price and estimated delivery on single product pages
    add_filter( 'woocommerce_available_variation', 'ab_available_variation_custom_field', 10, 3 );
    function ab_available_variation_custom_field( $variation_data, $product, $variation ) {
        if ( $variation->get_stock_quantity() == 0 && $variation->get_meta('_ab_preorder_checkbox') === 'yes' ) {
            if ( $estimated_delivery_date = $variation->get_meta('_ab_preorder_estimated_date') ) {
                // Display estimated delivery date
                $variation_data['availability_html'] .= sprintf( '<p class="stock date-precommande">%s : %s</p>',
                __("Date de livraison estimée (précommande)", "woocommerce"), $estimated_delivery_date );
            }
            
            // Displayed prefixed formatted price
            $variation_data['price_html'] = '<span class="price-prefix">'.__("Prix à la précommande", "") .'<span> : ' . wc_price( $variation_data['display_price'] );
        }
        return $variation_data;
    }
    
    // Display on estimated delivery date on cart and checkout
    add_filter( 'woocommerce_get_item_data', 'display_acf_on_cart_and_checkout', 10, 2 );
    function display_acf_on_cart_and_checkout( $cart_data, $cart_item ) {
        if ( $cart_item['variation_id'] > 0 && $cart_item['data']->get_stock_quantity() == 0
        && $cart_item['data']->get_meta('_ab_preorder_checkbox') === 'yes' ) {
            if ( $estimated_delivery_date = $cart_item['data']->get_meta('_ab_preorder_estimated_date') ) {
                $custom_items[] = array( "name" => __("Date de livraison estimée", "woocommerce"),  "value" => $estimated_delivery_date );
            }
        }
        return $custom_items;
    }

When i want to allow preordering on a product, i just need to check the _ab_preorder_checkbox (Disponible à la précommande) checkbox and enter a _ab_preorder_custom_price and an estimated delivery date _ab_preorder_estimated_date.

Everything works good, the problem im facing is : When i have only one copy left from a product and the client tries to order more than just one (2-3), the product gets added to the cart with the original price and not with the preorder discount.

The behavior i want to have is : When i have X copies left of a product and the client decides to order X+Y copies, i want to set the original price for the X copies and the preorder price _ab_preorder_custom_price for the Y copies.

I tought about using the woocommerce_before_calculate_totals hook but im not sure about how to implement that and i don’t know if the best solution.

Can anyone help me up with that please?

Regards

The page I need help with: [log in to see the link]