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<?php
/**
* Base class for course query backends
*/
abstract class CourseBackend
{
/*
* Static part for handling interfaces
*/
/**
* @var array list of known backends
*/
private static $backendTypes = false;
/**
* Load all known backend types. This is done
* by including *.inc.php from inc/coursebackend/.
*/
public static function loadDb()
{
if (self::$backendTypes !== false)
return;
self::$backendTypes = array();
foreach (glob(dirname(__FILE__) . '/coursebackend/coursebackend_*.inc.php', GLOB_NOSORT) as $file) {
require_once $file;
preg_match('#coursebackend_([^/\.]+)\.inc\.php$#i', $file, $out);
if (!class_exists('coursebackend_' . $out[1])) {
trigger_error("Backend type source unit $file doesn't seem to define class CourseBackend_{$out[1]}", E_USER_ERROR);
}
self::$backendTypes[$out[1]] = true;
}
}
/**
* Get all known config module types.
*
* @return array list of modules
*/
public static function getList()
{
self::loadDb();
return array_keys(self::$backendTypes);
}
/**
* Get fresh instance of ConfigModule subclass for given module type.
*
* @param string $moduleType name of module type
* @return \ConfigModule module instance
*/
public static function getInstance($moduleType)
{
self::loadDb();
if (!isset(self::$backendTypes[$moduleType])) {
error_log('Unknown module type: ' . $moduleType);
return false;
}
if (!is_object(self::$backendTypes[$moduleType])) {
$class = "coursebackend_$moduleType";
self::$backendTypes[$moduleType] = new $class;
}
return self::$backendTypes[$moduleType];
}
/*
* TODO: Insert required methods here
*/
/**
* @return string return display name of backend
*/
public abstract function getDisplayName();
/**
* initializes the class with url it needs to connect to.
*/
public abstract function __construct($url);
/**
* @returns array with parameter name as key and type as value
*/
public abstract function getCredentials();
/**
* uses json to setCredentials, the json must follow the form given in
* getCredentials
* @returns void
*/
public abstract function setCredentials($json);
/**
* @return int desired caching time of results, in seconds. 0 = no caching
*/
public abstract function getCacheTime();
/**
* @return int age after which ttables are no longer refreshed should be
* greater then CacheTime
*/
public abstract function getRefreshTime();
/**
* Internal version of fetch, to be overridden by subclasses.
* @param $roomIds
* @return array a multidemensional array that uses the roomID as key
* and has the sheduls as string in the value
*/
protected abstract function fetchSchedulesInternal($roomId);
/**
* Method for fetching the schedule of the given room.
* @param int $roomId int of room ID to fetch
* @return string|bool some jsonstring as result, or false on error
*/
public final function fetchSchedule($roomID)
{
$dbquery1 = Database::simpleQuery("SELECT servertype, serverid, serverroomid, lastcalenderupdate FROM location_info WHERE locationid = :id", array('id' => $roomID));
$dbd1=$dbquery1->fetch(PDO::FETCH_ASSOC);
$serverID = $dbd1['serverid'];
$sroomID = $dbd1['serverroomid'];
$lastUpdate = $dbd1['lastcalenderupdate'];
//Check if in cache
if(strtotime($lastUpdate) > strtotime("-".$this->getCacheTime()."seconds") && $this->getCacheTime()>0) {
$dbquery3 = Database::simpleQuery("SELECT calendar FROM location_info WHERE locationid = :id", array('id' => $sroomID));
$dbd3=$dbquery3->fetch(PDO::FETCH_ASSOC);
return $dbd3['callendar'];
}
//Check if we should refresh other rooms recently requested by front ends
elseif ($this->getCacheTime()>0) {
$dbquery4 = Database::simpleQuery("SELECT serverroomid, lastcalenderupdate FROM location_info WHERE serverid= :id", array('id' => $serverID));
$roomIDs[] = $sroomID;
foreach($dbquery4->fetchAll(PDO::FETCH_COLUMN) as $row){
if($row['lastcalenderupdate']<$this->getRefreshTime()){
$roomIDs[] = $row['serverroomid'];
}
}
$roomIDs = array_unique($roomIDs);
}
else {
$roomIDs[] = $sroomID;
}
$dbquery2 = Database::simpleQuery("SELECT serverurl FROM `setting_location_info` WHERE serverid = :id", array('id' => $serverID));
$dbd2=$dbquery2->fetch(PDO::FETCH_ASSOC);
$result = $this->fetchSchedulesInternal($roomIDs);
if($this->getCacheTime()>0){
foreach ($result as $key => $value) {
$now = strtotime('Now');
$dbquery1 = Database::simpleQuery("UPDATE location_info SET calendar = :ttable, lastcalenderupdate = :now WHERE locationid = :id ", array('id' => $key,'ttable' => $result[$key],'now'=> $now));
}
}
return $result[$roomID];
}
}
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