/**
* Remove all not needed and add all the necessary filter to the product collection
*
* @param Mage_Catalog_Model_Resource_Product_Link_Product_Collection $collection
* @param array $productIds
* @param string $idFieldName
*
* @return FACTFinder_Recommendation_Model_Observer
*/
protected function _processCollection($collection, $productIds, $idFieldName)
{
$select = $collection->getSelect();
$linkParts = array('links', 'link_attribute_position_int');
// remove link parts from from
$from = $select->getPart(Zend_Db_Select::FROM);
foreach ($linkParts as $linkPart) {
unset($from[$linkPart]);
}
$select->setPart(Zend_Db_Select::FROM, $from);
// reset all where conditions
$select->reset(Zend_Db_Select::WHERE);
// remove link part from columns
$columns = $select->getPart(Zend_Db_Select::COLUMNS);
foreach ($columns as $index => $column) {
if (in_array($column[0], $linkParts)) {
unset($columns[$index]);
}
}
$select->setPart(Zend_Db_Select::COLUMNS, $columns);
$handler = Mage::getModel('factfinder_recommendation/handler_recommendations', $productIds);
$recommendations = $handler->getRecommendedIds();
if ($recommendations) {
$collection->addAttributeToFilter($idFieldName, array('in' => $recommendations));
$order = new Zend_Db_Expr($collection->getConnection()->quoteInto('find_in_set(`e`.`' . $idFieldName . '`, ?)', implode(',', $recommendations)));
$select->order($order);
} else {
// do not load anything
$collection->addAttributeToFilter($idFieldName, array('in' => array(-1)));
}
return $this;
}
