public function getMainUser()
    {
        $currentUser = $this->getUser();

        if ($this->_mainUser === null && $currentUser->getIsGuest() === false) {
            $session = Yii::$app->getSession();
            if ($session->has('main_user')) {
                $mainUserId = $session->get('main_user');
                $mainIdentity = call_user_func([$currentUser->identityClass, 'findIdentity'], $mainUserId);
            } else {
                $mainIdentity = $currentUser->identity;
            }

            $mainUser = clone $currentUser;
            $mainUser->setIdentity($mainIdentity);
            $this->_mainUser = $mainUser;
        }

        return $this->_mainUser;
    }