/**
* get the time spent on the site as a DateInterval
* returns null if unable to calculate the interval.
* @param Mage_Log_Model_Visitor
* @return DateInterval
*/
protected function _getTimeSpentOnSite(Mage_Log_Model_Visitor $visitorLog = null)
{
if ($visitorLog) {
$start = date_create_from_format(self::MAGE_DATETIME_FORMAT, $visitorLog->getFirstVisitAt()) ?: null;
$end = date_create_from_format(self::MAGE_DATETIME_FORMAT, $visitorLog->getLastVisitAt()) ?: null;
if ($start && $end && $start < $end) {
$timeSpentOnSite = $end->diff($start);
}
}
return isset($timeSpentOnSite) ? $timeSpentOnSite : null;
}
