protected function setFirstAndLastClick(Pap_Common_Transaction $transaction, Pap_Tracking_Common_VisitorAffiliateCollection $collection) {
if ($collection->getSize() == 0) {
throw new Gpf_Exception('VisitorAffiliates for this visitor are empty');
}
$firstVisitorAffiliate = $collection->get(0);
$transaction->setFirstClickTime($firstVisitorAffiliate->getDateVisit());
$transaction->setFirstClickReferer($firstVisitorAffiliate->getReferrerUrl());
$transaction->setFirstClickIp($firstVisitorAffiliate->getIp());
$transaction->setFirstClickData1($firstVisitorAffiliate->getData1());
$transaction->setFirstClickData2($firstVisitorAffiliate->getData2());
$lastVisitorAffiliate = $collection->get($collection->getSize()-1);
$transaction->setLastClickTime($lastVisitorAffiliate->getDateVisit());
$transaction->setLastClickReferer($lastVisitorAffiliate->getReferrerUrl());
$transaction->setLastClickIp($lastVisitorAffiliate->getIp());
$transaction->setLastClickData1($lastVisitorAffiliate->getData1());
$transaction->setLastClickData2($lastVisitorAffiliate->getData2());
}