dataLayer.push purchase dinamizada

<?php

// Envia el evento purchase cuando se carga la página /gracias-por-su-compra/

add_action( 'wp_head', 'carlosmdh_purchase_datalayer_push' );
function carlosmdh_purchase_datalayer_push() {

    $pagina    = 'gracias-por-su-compra'; // cambiar el valor de esta variable por el slug, la id, o el nombre de la página

    if ( is_page ( $pagina )  ) {


//    global $wp;
//    if ( is_checkout() && !empty( $wp->query_vars['order-received'] ) ) {

?>
<script>
window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  event: 'purchase',
  ecommerce: {
    currency: '<?php echo $order_currency; ?>',
    value: <?php echo $order_total; ?>, // Total (+ impuestos pero sin gastos de envío)
    tax: <?php echo $order_total_tax; ?>,
    shipping: <?php echo $order_shipping_total; ?>,
    affiliation: 'afiliado3ed3455', // ID del afiliado
    transaction_id: '<?php echo $order_id ; ?>',
    coupon: '<?php echo $coupon_codes; ?>',
    items: [<?php $i = 0; foreach ($order->get_items() as $item_key => $item ): $i++; ?>{
          <?php $item_data= $item->get_data(); $product_name= $item_data['name']; $product_id= $item_data['product_id']; $variation_id = $item_data['variation_id']; $quantity = $item_data['quantity']; $product = $item->get_product(); $product_type = $product->get_type();$product_price = $product->get_price();
            $categories = '';
            $terms = get_the_terms( $product_id, 'product_cat' );
            $categories_counter = 0;
            foreach ( $terms as $term ) {
                $categories_counter++;
                $limiter = '';
                if(count($terms) != 1 && $categories_counter != count($terms)): $limiter = ','; endif;
                $categories .= $term->name . $limiter;
            }
          ?>
      item_name: '<?php echo $product_name; ?>',
      item_id: '<?php echo $product_id; ?>',
      price: '<?php echo $product_price; ?>',
      item_brand: '',
      item_category: '<?php echo $categories; ?>',
      item_variant: '<?php echo $variation_id; ?>',
      quantity: '<?php echo  $quantity; ?>'
    }
    <?php

        if($product_number != 1 && $i != $product_number): ?>,<?php endif; ?><?php endforeach ?>]
  }
});
</script>

<?php }
    }
?>