/**
  * Check if user is login to system
  * @param  [type]  $user_id  [description]
  * @param  [type]  $id_token [description]
  * @return boolean           [description]
  */
 function isValidUser($user_id, $id_token)
 {
     $model = new Session_Model();
     $result = $model->selectWhere('*', "user_id = " . "'{$user_id}'");
     if (!isset($result)) {
         return false;
     }
     if ($result[0]['id_token'] == $id_token) {
         if ($result[0]['date_created'] + 3600 > time()) {
             return true;
         } else {
             return false;
         }
     } else {
         return false;
     }
 }