public function roleId(array $values)
    {
        $count = count($values);
        $ids = array_filter($values, 'ctype_digit');

        if ($count != count($ids)) {
            return $this->translation->text('@field has invalid value', array(
                '@field' => $this->translation->text('Condition')));
        }

        $exists = array_filter($values, function ($role_id) {

            if ($role_id == 0) {
                return true;
            }

            $role = $this->role->get($role_id);
            return isset($role['role_id']);
        });

        if ($count != count($exists)) {
            return $this->translation->text('@name is unavailable', array(
                '@name' => $this->translation->text('Role')));
        }

        return true;
    }