WooCommerce - woocommerce_thankyou hook demo

<?php
  // Demo of woocommerce_thankyou hook
  // code goes in functions.php for child theme
  add_action ('woocommerce_thankyou', 'myfunction');
  function myfunction($order_id) {
    $order = new WC_Order($order_id);
    $items = $order->get_items();
    foreach ($items as $item) {
      $item_metas = $item['item_meta'];
      $product_ids = $item_metas['_product_id'];
      foreach ($product_ids as $product_id) {
        switch ($product_id) {
          case 1:
            break;
          case 2:
            break;
          default:
        }
        echo '<p>'.$item['name'].' '.$product_id.'</p>';
      }
    }
  }