Procedure to clear references from RefWorks a/c via api

References cleartemp

	/**
	 * Removes all references from temp Refworks account that have not been modified for 30 minutes
	 * Then removes all empty folders
	 * Used by cron to clear down RefWorks temp account
	 */
    public static function cleartemp() {

		GLOBAL $SESSION;
		$return = "";
		//kill any previous api sessions
		parent::destroy_session();
		$rwun = references_lib::get_setting('tempun');
		$rwpw = references_lib::get_setting('temppw');
		if (!parent::check_session('',$rwun,$rwpw)) {
			//failed
			$return .= "Unable to authenticate for RefWorks temp account";
			return $return;
		}
				

		// Get all references and look for those older than an hour
		$params = array('pgnum'=>1,'pgsize'=>1000,'style'=>0);
		$result = parent::call_api('retrieve','all',$params);
		// What if $result is false?
		if ($result!==false) {
			$resxml=new domDocument();
			$resxml->loadXML($result);
			//get xml element that contains the references
			$referencelist = $resxml->getElementsByTagName('reference');
			$references = array();
			// Ugly time hack required because RW returns US Eastern Time converted to "epoch time" rather than actual epoch time
			$dt = new DateTime(NULL, new DateTimeZone('America/New_York'));
			$rwclockoff = $dt->getOffset();
			for ($a=0, $max=$referencelist->length; $a<$max; $a++) {
				$modifiedtime = $referencelist->item($a)->getElementsByTagName('md')->item(0)->nodeValue;
				$id = $referencelist->item($a)->getAttribute('id');
				$mod_time = $modifiedtime/1000+$rwclockoff;
				$timer = microtime(true);
				$age = $timer-$mod_time;
				if($age > 1800) {
					$ids[] = $id;
				}
			}
			// Create XML of reference IDs for deletion
			$xml = '';
			if (count($ids) > 0) {
				$xml .= '<RWRequest class="reference" method="get">';
				foreach ($ids as $id) {
					$xml .= '<id>'.$id.'</id>';
				}
				$xml .= '</RWRequest>';
			}

			if (strlen($xml) > 0) {
				//    Need to send this xml for deletion
				$result = parent::call_api('reference','delete','',$xml);
				if ($result!==false) {
					$return .= "Deleted ".count($ids)." references."; 
				} else {
					$return .= "Could not delete references.";
				}
			} else {
				$return .= "Did not find any references to delete";
			}
			
			// Now have deleted references older than half an hour, time to clean up any empty folders
			// Get all folders
			$result = parent::call_api('folders','all',array('pgnum'=>1,'pgsize'=>1000));
	        if (!$result) {
	            return false;
	        }
	        $resxml=new domDocument();
	        $resxml->loadXML($result);
	        $folderlist 	= $resxml->getElementsByTagName('Folders');
	        $folders = array();
			// Only interested in folders that have no references in them
	        for ($a=0, $max=$folderlist->length; $a<$max; $a++) {
	            if ($folderlist->item($a)->getAttribute('type') == 'user' && $folderlist->item($a)->getAttribute('nRefs') == '0') {
	                $folders[] = $folderlist->item($a)->nodeValue;
	            }
	        }

			if ($folders == false) {
				$folders = array();
			}
			
			foreach ($folders as $folder) {
				parent::call_api('folders','delete',array('oldValue'=>$folder));
			}
			$return .= " Tried to delete ".count($folders)." empty folders";
		} else {
			$return .= "Could not retrieve any references from RefWorks temp account";
		}
	return $return;
	}