Code-Snippets-Functions/Execute a function on a child site/WooCommerce/when-resubscribing-add-a-simple-product-in-subscriptions.txt

add_action( 'woocommerce_checkout_init', 'add_product_with_resubscription' );
function add_product_with_resubscription() {
    $cart = WC()->cart;

    $simple_product_id = 18; // Define the simple product ID to be added
    $subscr_product_id = 138; // Define the targeted product subscription ID
    $simple_is_in_cart = $is_resubscription = false; // Initializing

    // Loop through cart items
    foreach ( $cart->get_cart() as $item ) { 
        // Check for a specific resubscription
        if( isset($item['subscription_resubscribe']) 
        && in_array($subscr_product_id, [$item['product_id'], $item['variation_id']]) ) {
            $is_resubscription = true;
        }
        // Check that the simple product is not yet in cart
        if( $simple_product_id == $item['product_id'] ) {
            $simple_is_in_cart = true;
        }
    }

    // Add to cart the simple product and recalculate totals
    if ( $is_resubscription && !$simple_is_in_cart ) {
        $cart->add_to_cart($simple_product_id);
        $cart->calculate_totals();
    }
}