<?php
/**
* Base class for course query backends
*/
abstract class CourseBackend
{
/*
* Static part for handling interfaces
*/
/**
* @var array list of known backends
* $error boolean true if there was an error
* $errormsg string with the error message
*/
private static $backendTypes = false;
public $error;
public $errormsg;
public $serverID;
public $location;
/**
* CourseBackend constructor.
*/
public final function __construct()
{
$this->location = "";
$this->error = false;
$this->errormsg = "";
}
/**
* Load all known backend types. This is done
* by including *.inc.php from inc/coursebackend/.
*/
public static function loadDb()
{
if (self::$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();
/**
* @returns array with parameter name as key and type as value
*/
public abstract function getCredentials();
/**
* @return boolean true if the connection works, false otherwise
*/
public abstract function checkConnection();
/**
* uses json to setCredentials, the json must follow the form given in
* getCredentials
*
* @param string $data array with the credentials
* @param string $url address of the server
* @param int $serverID ID of the server
* @returns void
*/
public abstract function setCredentials($data, $url, $serverID);
/**
* @return int desired caching time of results, in seconds. 0 = no caching
*/
public abstract function getCacheTime();
/**
* @return int age after which timetables are no longer refreshed should be
* greater then CacheTime
*/
public abstract function getRefreshTime();
/**
* Internal version of fetch, to be overridden by subclasses.
*
* @param $roomIds
* @return array a multidimensional array that uses the roomID as key
* and has the schedules as string in the value
*/
protected abstract function fetchSchedulesInternal($roomId);
/**
* Method for fetching the schedule of the given rooms on a server.
*
* @param int $roomId int of room ID to fetch
* @param int $serverid id of the server
* @return string|bool some jsonstring as result, or false on error
*/
public final function fetchSchedule($roomIDs)
{
$sqlr = implode(",", $roomIDs);
$sqlr = '(' . $sqlr . ')';
$q = "SELECT locationid, calendar, serverroomid, lastcalendarupdate FROM location_info WHERE locationid IN " . $sqlr;
$dbquery1 = Database::simpleQuery($q);
$result = [];
$sRoomIDs = [];
foreach ($dbquery1->fetchAll(PDO::FETCH_ASSOC) as $row) {
$sRoomID = $row['serverroomid'];
$lastUpdate = $row['lastcalendarupdate'];
$calendar = $row['calendar'];
//Check if in cache if lastUpdate is null then it is interpreted as 1970
if (strtotime($lastUpdate) > strtotime("-" . $this->getCacheTime() . "seconds") && $this->getCacheTime() > 0) {
$result[$row['locationid']] = json_decode($calendar);
} else {
$sRoomIDs[$row['locationid']] = $sRoomID;
}
}
//Check if we should refresh other rooms recently requested by front ends
if ($this->getCacheTime() > 0 && $this->getRefreshTime() > 0) {
$dbquery4 = Database::simpleQuery("SELECT locationid ,serverroomid, lastcalendarupdate FROM location_info WHERE serverid= :id", array('id' => $this->serverID));
foreach ($dbquery4->fetchAll(PDO::FETCH_COLUMN) as $row) {
if (isset($row['lastcalendarupdate'])) {
$lastUpdate = $row['lastcalendarupdate'];
if (strtotime($lastUpdate) > strtotime("-" . $this->getRefreshTime() . "seconds") && strtotime($lastUpdate) > strtotime("-" . $this->getCacheTime() . "seconds")) {
$sRoomIDs[$row['locationid']] = $row['serverroomid'];
}
}
}
}
$results = $this->fetchSchedulesInternal($sRoomIDs);
if ($results === false) {
return false;
}
$newResult = [];
foreach ($sRoomIDs as $location => $serverRoom) {
$newResult[$location] = $results[$serverRoom];
}
if ($this->getCacheTime() > 0) {
foreach ($newResult as $key => $value) {
$value = json_encode($value);
$now = strtotime('Now');
Database::simpleQuery("UPDATE location_info SET calendar = :ttable, lastcalendarupdate = :now WHERE locationid = :id ", array('id' => $key, 'ttable' => $value, 'now' => $now));
}
}
//get all schedules that are wanted from roomIDs
foreach ($roomIDs as $id) {
$result[$id] = $newResult[$id];
}
return $result;
}
/**
* @return false if there was no error string with error message if there was one
*/
public final function getError()
{
if ($this->error) {
return $this->errormsg;
}
return false;
}
}
