/**
  * Process the payment.
  *
  * @param  int $order_id
  * @return array
  */
 public function process_payment($order_id)
 {
     $cart_token = isset($_POST['simplify_token']) ? wc_clean($_POST['simplify_token']) : '';
     $order = wc_get_order($order_id);
     // Processing subscription
     if ('standard' == $this->mode && ($this->order_contains_subscription($order->id) || function_exists('wcs_is_subscription') && wcs_is_subscription($order_id))) {
         return $this->process_subscription($order, $cart_token);
         // Processing pre-order
     } elseif ('standard' == $this->mode && $this->order_contains_pre_order($order->id)) {
         return $this->process_pre_order($order, $cart_token);
         // Processing regular product
     } else {
         return parent::process_payment($order_id);
     }
 }
 /**
  * Process the payment
  *
  * @param  int $order_id
  * @return array
  */
 public function process_payment($order_id)
 {
     // Processing subscription
     if (class_exists('WC_Subscriptions_Order') && WC_Subscriptions_Order::order_contains_subscription($order_id)) {
         return $this->process_subscription($order_id);
         // Processing pre-order
     } elseif (class_exists('WC_Pre_Orders_Order') && WC_Pre_Orders_Order::order_contains_pre_order($order_id)) {
         return $this->process_pre_order($order_id);
         // Processing regular product
     } else {
         return parent::process_payment($order_id);
     }
 }