public static function roleLabel($role = null)
    {
        switch ($role) {
            case User::ROLE_ADMIN:
                $label = 'danger';
                $name = ArrayHelper::getValue(User::getRoles(), $role);
                break;
            case User::ROLE_MODERATOR:
                $label = 'info';
                $name = ArrayHelper::getValue(User::getRoles(), $role);
                break;
            default:
                $label = 'warning';
                $name = ArrayHelper::getValue(User::getRoles(), User::ROLE_MEMBER);
        }

        return Html::tag('span', $name, ['class' => 'label label-' . $label]);
    }