/**
  * Adds additional parameters: active category, list type and category id
  *
  * @param oxArticle $oProduct         loaded product
  * @param string    $sActCat          active category id
  * @param string    $sActManufacturer active manufacturer id
  * @param string    $sActTag          active tag
  * @param string    $sActVendor       active vendor
  *
  * @return string $sActCat
  */
 protected function _addAdditionalParams($oProduct, $sActCat, $sActManufacturer, $sActTag, $sActVendor)
 {
     $sSearchPar = oxRegistry::getConfig()->getRequestParameter('searchparam');
     $sSearchCat = oxRegistry::getConfig()->getRequestParameter('searchcnid');
     $sSearchVnd = oxRegistry::getConfig()->getRequestParameter('searchvendor');
     $sSearchMan = oxRegistry::getConfig()->getRequestParameter('searchmanufacturer');
     $sListType = oxRegistry::getConfig()->getRequestParameter('listtype');
     // search ?
     if ((!$sListType || $sListType == 'search') && ($sSearchPar || $sSearchCat || $sSearchVnd || $sSearchMan)) {
         // setting list type directly
         $sListType = 'search';
     } else {
         // such Manufacturer is available ?
         if ($sActManufacturer && $sActManufacturer == $oProduct->getManufacturerId()) {
             // setting list type directly
             $sListType = 'manufacturer';
             $sActCat = $sActManufacturer;
         } elseif ($sActVendor && substr($sActVendor, 2) == $oProduct->getVendorId()) {
             // such vendor is available ?
             $sListType = 'vendor';
             $sActCat = $sActVendor;
         } elseif ($sActTag) {
             // tag ?
             $sListType = 'tag';
         } elseif ($sActCat && $oProduct->isAssignedToCategory($sActCat)) {
             // category ?
         } else {
             list($sListType, $sActCat) = $this->_getDefaultParams($oProduct);
         }
     }
     $oParentView = $this->getParent();
     //set list type and category id
     $oParentView->setListType($sListType);
     $oParentView->setCategoryId($sActCat);
     return $sActCat;
 }