public function getArchiveDay()
    {
        $day = $this->request->param('Day');

        if (preg_match('/^[0-9]{1,2}$/', $day)) {
            if (checkdate($this->getArchiveMonth(), $day, $this->getArchiveYear())) {
                return (int) $day;
            }
        }

        return null;
    }