/**
 *  Add coupon code to order details and emails
 */

// Shows the coupon code used on the order details page and in email sent to customer and admin. 
// https://forums.classicpress.net/t/how-to-include-extra-fields-in-classic-commerce-emails/2607/4

add_filter('woocommerce_get_order_item_totals', 'cc_add_coupon_codes_to_order_item_totals', 10, 3);

function cc_add_coupon_codes_to_order_item_totals($rows, $order, $tax_display) {
  // Have any coupons been used in $order?
  if(! $order->get_used_coupons()) {
    return $rows;
  }

  $new_rows  = [];

  foreach($rows as $key => $total) {
    $new_rows[$key] = $total;

    if($key === 'discount') {
      $coupons = $order->get_used_coupons();
      // Adds row to show coupon codes used in $order. Displays after discount row.
      $new_rows['coupon_codes'] = [
          'label'	=> __('Coupons used:', 'classic-commerce'),
          'value'	=> implode(', ', $coupons),
      ];
    }
  }

  return $new_rows;
}