WC_Order::get_user_id PHP Method

    public function get_user_id($context = 'view')
    {
        return $this->get_customer_id($context);
    }

 public static function get_role_price($product)
 {
     global $post, $woocommerce;
     if (is_admin()) {
         //admin screen
         if (!empty($_POST['selected_user_id'])) {
             $user = get_user_by('id', $_POST['selected_user_id']);
         } else {
             //!empty($_POST['order_id'])
             $order = new WC_Order($_POST['order_id']);
             $user_id = $order->get_user_id();
             $user = get_user_by('id', $user_id);
         }
     } else {
         // user screen
         $user = wp_get_current_user();
     }
     $user_roles = $user->roles;
     if ($user_roles == null) {
         return null;
     }
     $user_role = array_shift($user_roles);
     if ($user_role !== null) {
         $role_price = get_post_meta($product->variation_id, $user_role, true);
         if (!empty($role_price)) {
             return $role_price;
         }
     }
     return null;
 }