/**
  * If the payment for a renewal order has previously failed and is then paid, we need to make sure the
  * subscription payment function is called.
  *
  * @param $user_id int The id of the user who purchased the subscription
  * @param $subscription_key string A subscription key of the form created by @see WC_Subscriptions_Manager::get_subscription_key()
  * @since 1.2
  */
 public static function process_subscription_payment_on_child_order($order_id, $payment_status = 'completed')
 {
     if (self::is_renewal($order_id, 'child')) {
         $child_order = new WC_Order($order_id);
         $parent_order = self::get_parent_order($child_order);
         $subscriptions_in_order = $child_order->get_items();
         // Should only be one subscription in the renewal order, but just in case
         foreach ($subscriptions_in_order as $item) {
             if (WC_Subscriptions_Order::is_item_a_subscription($parent_order, $item['id'])) {
                 if ('failed' == $payment_status) {
                     // Don't duplicate renewal order
                     remove_action('processed_subscription_payment_failure', __CLASS__ . '::generate_failed_payment_renewal_order', 10, 2);
                     WC_Subscriptions_Manager::process_subscription_payment_failure_on_order($parent_order->id, $item['id']);
                     // But make sure orders are still generated for other payments in the same request
                     add_action('processed_subscription_payment_failure', __CLASS__ . '::generate_failed_payment_renewal_order', 10, 2);
                 } else {
                     // Don't duplicate renewal order
                     remove_action('processed_subscription_payment', __CLASS__ . '::generate_paid_renewal_order', 10, 2);
                     WC_Subscriptions_Manager::process_subscription_payments_on_order($parent_order->id, $item['id']);
                     // But make sure orders are still generated for other payments in the same request
                     add_action('processed_subscription_payment', __CLASS__ . '::generate_paid_renewal_order', 10, 2);
                     // Reactivate the subscription - activate_subscription doesn't operate on child orders
                     $subscription_key = WC_Subscriptions_Manager::get_subscription_key($parent_order->id, $item['id']);
                     WC_Subscriptions_Manager::reactivate_subscription($parent_order->customer_user, $subscription_key);
                 }
             }
         }
     }
 }