/**
* given an acknowledgment feed file, load into a DOMDocument object
* attach it into a DOMXPath object and then query it using a constant
* that hold XPath for extracting the related exported file
* and then return an array of key acknowledgment map to the given acknowledgment file
* and a 'related' key mapped to the extracted exported file in the acknowledgment file
* @param string $ackFile the full path to the acknowledgment to extract the exported file related to it
* @param string $exportedDir the directory to where exported sent file exists
* @return array
*/
protected function _extractAckExportedFile($ackFile, $exportedDir)
{
$doc = $this->_coreHelper->getNewDomDocument();
$doc->load($ackFile);
$xpath = $this->_coreHelper->getNewDOMXPath($doc);
return [self::ACK_KEY => $ackFile, self::RELATED_KEY => $exportedDir . DS . $this->_coreHelper->extractNodeVal($xpath->query(self::XPATH_ACK_EXPORTED_FILE, $this->_coreHelper->getDomElement($doc)))];
}
