protected function getAssignmentOptions($userId)
    {
        $options = array();

        /* @var $am CAuthManager|AuthBehavior */
        $am = Yii::app()->authManager;

        $assignments = $am->getAuthAssignments($userId);
        $assignedItems = array_keys($assignments);

        /* @var $authItems CAuthItem[] */
        $authItems = $am->getAuthItems();
        foreach ($authItems as $itemName => $item) {
            if (!in_array($itemName, $assignedItems)) {
                $options[$this->capitalize($this->getItemTypeText($item->type, true))][$itemName] = $item->description;
            }
        }

        return $options;
    }