public function loginAction()
    {
        $form = new Application_Form_Login();
        $request = $this->getRequest();

        if ($request->isPost() && $form->isValid($request->getPost())) {

            $adapter = new Application_Model_AuthAdapter(
                    $this->_getParam('username'), $this->_getParam('password')
            );
            $result = $adapter->authenticate();

            if ($result->isValid()) {
                $_SESSION['loggedIn'] = true;
                $this->_redirect('/admin');
            } else {
                $form->setDescription('Nieprawidłowy użytkownik/hasło');
            }
        }

        $this->view->form = $form;
    }