private function getPlainCalcId($period)
    {
        if ($period) {
            $dsMax = $this->hlpPeriod->getPeriodLastDate($period);
        } else {
            $dsMax = Cfg::DEF_MAX_DATESTAMP;
        }
        /* prepare query */
        $query = $this->qbCalcGetLast->build();
        $bind = [
            QBCalcGetLast::BND_CODE => Cfg::CODE_TYPE_CALC_FORECAST_PLAIN,
            QBCalcGetLast::BND_DATE => $dsMax,
            QBCalcGetLast::BND_STATE => Cfg::CALC_STATE_COMPLETE
        ];

        /* fetch & parse data */
        $conn = $query->getConnection();
        $rs = $conn->fetchRow($query, $bind);
        $result = $rs[QBCalcGetLast::A_CALC_ID];
        return $result;
    }