/**
* Calculate cache product compare collection
*
* @param bool $logout
* @return Mage_Catalog_Helper_Product_Compare
*/
public function calculate($logout = false)
{
// first visit
if (!$this->_catalogSession->hasCatalogCompareItemsCount() && !$this->_customerId) {
$count = 0;
} else {
/** @var $collection Mage_Catalog_Model_Resource_Eav_Mysql4_Product_Compare_Item_Collection */
$collection = Mage::getResourceModel('catalog/product_compare_item_collection')->useProductItem(true);
if (!$logout && $this->_customerSession->isLoggedIn()) {
$collection->setCustomerId($this->_customerSession->getCustomerId());
} elseif ($this->_customerId) {
$collection->setCustomerId($this->_customerId);
} else {
$collection->setVisitorId($this->_logVisitor->getId());
}
/* Price data is added to consider item stock status using price index */
$collection->addPriceData();
$this->_productVisibility->addVisibleInSiteFilterToCollection($collection);
$count = $collection->getSize();
}
$this->_catalogSession->setCatalogCompareItemsCount($count);
return $this;
}
