public function formatUntil(\MUtil_Date $dateTime = null)
    {
        if (false === $this->showUntil) { return; }
        
        if (null === $dateTime) {
            return $this->_('Survey has no time limit.');
        }

        $days = $dateTime->diffDays();

        switch ($days) {
            case 0:
                return array(
                    \MUtil_Html::create('strong', $this->_('Warning!!!')),
                    ' ',
                    $this->_('This survey must be answered today!')
                    );

            case 1:
                return array(
                    \MUtil_Html::create('strong', $this->_('Warning!!')),
                    ' ',
                    $this->_('This survey can only be answered until tomorrow!')
                    );

            case 2:
                return $this->_('Warning! This survey can only be answered for another 2 days!');

            default:
                if ($days <= 14) {
                    return sprintf($this->_('Please answer this survey within %d days.'), $days);
                }

                if ($days <= 0) {
                    return $this->_('This survey can no longer be answered.');
                }

                return sprintf($this->_('Please answer this survey before %s.'), $dateTime->toString($this->dateFormat));
        }
    }