current code from svn, revision 62608

1 files changed, 1856 insertions, 0 deletions

diff --git a/lib/functions.php b/lib/functions.php
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+<?php
+# Lifter002: DONE - not applicable
+# Lifter003: TEST
+# Lifter007: TODO
+# Lifter010: DONE - not applicable
+/**
+ * functions.php
+ *
+ * The Stud.IP-Core functions. Look to the descriptions to get further details
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * @author      Cornelis Kater <ckater@gwdg.de>
+ * @author      Suchi & Berg GmbH <info@data-quest.de>
+ * @author      Ralf Stockmann <rstockm@gwdg.de>
+ * @author      André Noack <andre.noack@gmx.net>
+ * @license     http://www.gnu.org/licenses/gpl-2.0.html GPL version 2
+ * @category    Stud.IP
+ * @access      public
+ * @package     studip_cores
+ * @modulegroup library
+ * @module      functions.php
+ */
+
+// +---------------------------------------------------------------------------+
+// This file is part of Stud.IP
+// functions.php
+// Stud.IP Kernfunktionen
+// Copyright (C) 2002 Cornelis Kater <ckater@gwdg.de>, Suchi & Berg GmbH <info@data-quest.de>,
+// Ralf Stockmann <rstockm@gwdg.de>, André Noack André Noack <andre.noack@gmx.net>
+// +---------------------------------------------------------------------------+
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or any later version.
+// +---------------------------------------------------------------------------+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+// +---------------------------------------------------------------------------+
+
+
+require_once 'lib/object.inc.php';
+require_once 'lib/user_visible.inc.php';
+
+/**
+ * returns an array containing name and type of the passed objeact
+ * denoted by $range_id
+ *
+ * @global array $SEM_TYPE
+ * @global array $INST_TYPE
+ * @global array $SEM_TYPE_MISC_NAME
+ *
+ * @param string $range_id    the id of the object
+ * @param string $object_type the type of the object
+ *
+ * @return array  an array containing name and type of the object
+ */
+function get_object_name($range_id, $object_type)
+{
+    global $SEM_TYPE,$INST_TYPE, $SEM_TYPE_MISC_NAME;
+
+    if ($object_type == "sem") {
+        $query = "SELECT status, Name FROM seminare WHERE Seminar_id = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$range_id]);
+        $row = $statement->fetch(PDO::FETCH_ASSOC);
+
+        if ($SEM_TYPE[$row['status']]['name'] == $SEM_TYPE_MISC_NAME) {
+            $type = _('Veranstaltung');
+        } else {
+            $type = $SEM_TYPE[$row['status']]['name'];
+        }
+        if (!$type) {
+            $type = _('Veranstaltung');
+        }
+        $name = $row['Name'];
+    } else if ($object_type == 'inst' || $object_type == 'fak') {
+        $query = "SELECT type, Name FROM Institute WHERE Institut_id = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$range_id]);
+        $row = $statement->fetch(PDO::FETCH_ASSOC);
+
+        $type = $INST_TYPE[$row['type']]['name'];
+        if (!$type) {
+            $type = _('Einrichtung');
+        }
+        $name = $row['Name'];
+    }
+
+    return compact('name', 'type');
+}
+
+/**
+ * Returns a sorm object for a given range_id
+ *
+ * @param string the range_id
+ * @return SimpleORMap Course/Institute/User/Statusgruppen/
+ */
+function get_object_by_range_id($range_id) {
+    $possible_sorms = "Course Institute User";
+    foreach(words($possible_sorms) as $sorm) {
+        if ($object = $sorm::find($range_id)) {
+            return $object;
+        }
+    }
+    return false;
+}
+
+/**
+ * This function checks, if there is an open Veranstaltung or Einrichtung
+ *
+ * @throws CheckObjectException
+ *
+ * @return void
+ */
+function checkObject()
+{
+    if (!Context::get()) {
+        throw new CheckObjectException(_('Sie haben kein Objekt gewählt.'));
+    }
+}
+
+
+/**
+ * This function checks, if given module
+ * is allowed for this stud.ip-object.
+ *
+ * @throws CheckObjectException
+ * @param string $module the module to check for
+ * @param bool $is_plugin_name is the module name old style ( "wiki","scm") or new style (the name of the plugin)
+ * @return StudipModule
+ */
+function checkObjectModule($module, $is_plugin_name = false)
+{
+    if ($context = Context::get()) {
+        if (!$is_plugin_name) {
+            $module_name = "Core" . ucfirst($module);
+        } else {
+            $module_name = $module;
+        }
+
+        $studip_module = PluginManager::getInstance()->getPlugin($module_name);
+        if (!$studip_module || !$studip_module->isActivated($context->getId())) {
+            throw new CheckObjectException(sprintf(_('Das Inhaltselement "%s" ist für dieses Objekt leider nicht verfügbar.'), ucfirst($module)));
+        }
+        return $studip_module;
+    }
+}
+
+/**
+ * This function closes a opened Veranstaltung or Einrichtung
+ *
+ * @return void
+ */
+function closeObject()
+{
+    Context::close();
+}
+
+/**
+ * This function determines the type of the passed id
+ *
+ * The function recognizes the following types at the moment:
+ * Einrichtungen, Veranstaltungen, Statusgruppen and Fakultaeten
+ *
+ * @staticvar array $object_type_cache
+ *
+ * @param string $id         the id of the object
+ * @param array  $check_only an array to narrow the search, may contain
+ *                            'sem', 'inst', 'fak', 'group' or 'dokument' (optional)
+ *
+ * @return string  return "inst" (Einrichtung), "sem" (Veranstaltung),
+ *                 "fak" (Fakultaeten), "group" (Statusgruppe), "dokument" (Dateien)
+ *
+ */
+function get_object_type($id, $check_only = [])
+{
+    static $cache = null;
+
+    // Nothing to check
+    if (!$id) {
+        return false;
+    }
+
+    // Id is global
+    if ($id === 'studip') {
+        return 'global';
+    }
+
+    // Initialize cache array
+    if ($cache === null) {
+        $cache = new StudipCachedArray('/StudipObjectTypes');
+    }
+
+    // Read from cache if available
+    if (isset($cache[$id]) && is_string($cache[$id])) {
+        return $cache[$id];
+    }
+
+    // Tests for specific types
+    $tests = [
+        'sem'        => "SELECT 1 FROM seminare WHERE Seminar_id = ?",
+        'date'       => "SELECT 1 FROM termine WHERE termin_id = ?",
+        'user'       => "SELECT 1 FROM auth_user_md5 WHERE user_id = ?",
+        'group'      => "SELECT 1 FROM statusgruppen WHERE statusgruppe_id = ?",
+        'dokument'   => "SELECT 1 FROM file_refs WHERE id = ?",
+        'range_tree' => "SELECT 1 FROM range_tree WHERE item_id = ?",
+    ];
+
+    // Test for every type if no specific types are provided
+    $check_all = !count($check_only);
+
+    // Loop through tests
+    foreach ($tests as $key => $query) {
+        if ($check_all || in_array($key, $check_only)) {
+            if (!$check_all
+                && isset($cache[$id])
+                && is_array($cache[$id])
+                && in_array($key, $cache[$id])
+            ) {
+                return false;
+            }
+
+            $present = DBManager::get()->fetchColumn($query, [$id]);
+            if ($present) {
+                return $cache[$id] = $key;
+            }
+        }
+    }
+
+    // Institute or faculty?
+    if ($check_all || in_array('inst', $check_only) || in_array('fak', $check_only)) {
+        $query = "SELECT Institut_id = fakultaets_id FROM Institute WHERE Institut_id = ?";
+        $is_fak = DBManager::get()->fetchColumn($query, [$id]);
+        if ($is_fak !== false) {
+            return $cache[$id] = $is_fak ? 'fak' : 'inst';
+        }
+    }
+    if ($check_all) {
+        // None of the above
+        return $cache[$id] = false;
+    } else {
+        $cache[$id] = $check_only;
+        return false;
+    }
+}
+
+/**
+ * This function calculates one of the group colors unique for the semester of
+ * the passed timestamp
+ *
+ * It calculates a unique color number to create the initial entry for a new user in a seminar.
+ * It will create a unique number for every semester and will start over, if the max. number
+ * (7) is reached.
+ *
+ * @param integer $sem_start_time the timestamp of the start time from the Semester
+ *
+ * @return integer  the color number
+ *
+ */
+function select_group($sem_start_time)
+{
+    //Farben Algorhytmus, erzeugt eindeutige Farbe fuer jedes Semester. Funktioniert ab 2001 die naechsten 1000 Jahre.....
+    $year_of_millenium=date ("Y", $sem_start_time) % 1000;
+    $index=$year_of_millenium * 2;
+    if (date ("n", $sem_start_time) > 6)
+        $index++;
+    $group=($index % 7) + 1;
+
+    return $group;
+}
+
+/**
+ * The function shortens a string, but it uses the first 2/3 and the last 1/3
+ *
+ * The parts will be divided by a "[...]". The functions is to use like php's
+ * mb_substr function.
+ *
+ * @param string  $what  the original string
+ * @param integer $start start pos, 0 is the first pos
+ * @param integer $end   end pos
+ *
+ * @return string
+ *
+ *
+ */
+function my_substr($what, $start, $end)
+{
+    $length=$end-$start;
+    $what_length = mb_strlen($what);
+    // adding 5 because: mb_strlen("[...]") == 5
+    if ($what_length > $length + 5) {
+        $what = mb_substr($what, $start, round(($length / 3) * 2))
+              . "[...]" . mb_substr($what, $what_length - round($length / 3), $what_length);
+    }
+    return $what;
+}
+
+/**
+ * Retrieves the fullname for a given user_id
+ *
+ * @param string $user_id   if omitted, current user_id is used
+ * @param string $format    output format
+ * @param bool   $htmlready if true, htmlReady is applied to all output-strings
+ *
+ * @return string
+ */
+function get_fullname($user_id = "", $format = "full" , $htmlready = false)
+{
+    static $cache;
+    global $user, $_fullname_sql;
+
+    if (!$user_id) {
+        $user_id = $user->id;
+    }
+
+    if (User::findCurrent()->id === $user_id) {
+        $fullname = User::findCurrent()->getFullName($format);
+        return $htmlready ? htmlReady($fullname) : $fullname;
+    }
+
+    $hash = md5($user_id . $format);
+    if (!isset($cache[$hash])) {
+        $query = "SELECT {$_fullname_sql[$format]}
+                  FROM auth_user_md5
+                  LEFT JOIN user_info USING (user_id)
+                  WHERE user_id = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user_id]);
+        $cache[$hash] = $statement->fetchColumn() ?: _('unbekannt');
+    }
+
+    return $htmlready ? htmlReady($cache[$hash]) : $cache[$hash];
+}
+
+/**
+ * Retrieves the fullname for a given username
+ *
+ * @param string $uname     if omitted, current user_id is used
+ * @param string $format    output format
+ * @param bool   $htmlready if true, htmlReady is applied to all output-strings
+ *
+ * @return       string
+ */
+function get_fullname_from_uname($uname = "", $format = "full", $htmlready = false)
+{
+    static $cache;
+    global $auth, $_fullname_sql;
+
+    if (!$uname) {
+        $uname = $auth->auth['uname'];
+    }
+
+    $hash = md5($uname . $format);
+    if (!isset($cache[$hash])) {
+        $query = "SELECT {$_fullname_sql[$format]}
+                  FROM auth_user_md5
+                  LEFT JOIN user_info USING (user_id)
+                  WHERE username = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$uname]);
+        $cache[$hash] = $statement->fetchColumn() ?: _('unbekannt');
+    }
+
+    return $htmlready ? htmlReady($cache[$hash]) : $cache[$hash];
+}
+
+/**
+ * Retrieves the username for a given user_id
+ *
+ * @global object $auth
+ * @staticvar array $cache
+ *
+ * @param string $user_id if omitted, current username will be returned
+ *
+ * @return string
+ *
+ */
+function get_username($user_id = "")
+{
+    static $cache = [];
+    global $auth;
+
+    if (!$user_id || $user_id == $auth->auth['uid']) {
+        return $auth->auth['uname'];
+    }
+
+    if (!isset($cache[$user_id])) {
+        $query = "SELECT username FROM auth_user_md5 WHERE user_id = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user_id]);
+        $cache[$user_id] = $statement->fetchColumn();
+    }
+
+    return $cache[$user_id];
+}
+
+/**
+ * Retrieves the userid for a given username
+ *
+ * uses global $online array if user is online
+ *
+ * @global object $auth
+ * @staticvar array $cache
+ *
+ * @param string $username if omitted, current user_id will be returned
+ *
+ * @return string
+ */
+function get_userid($username = "")
+{
+    static $cache = [];
+    global $auth;
+
+    if (!$username || $username == $auth->auth['uname']) {
+        return $auth->auth['uid'];
+    }
+
+    // Read id from database if no cached version is available
+    if (!isset($cache[$username])) {
+        $query = "SELECT user_id FROM auth_user_md5 WHERE username = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$username]);
+        $cache[$username] = $statement->fetchColumn();
+    }
+
+    return $cache[$username];
+}
+
+
+/**
+ * Return an array containing the nodes of the sem-tree-path
+ *
+ * @param string $seminar_id the seminar to get the path for
+ * @param int    $depth      the depth
+ * @param string $delimeter  a string to separate the path parts
+ *
+ * @return array
+ */
+function get_sem_tree_path($seminar_id, $depth = false, $delimeter = ">")
+{
+    $the_tree = TreeAbstract::GetInstance("StudipSemTree");
+    $view = DbView::getView('sem_tree');
+    $ret = null;
+    $view->params[0] = $seminar_id;
+    $rs = $view->get_query("view:SEMINAR_SEM_TREE_GET_IDS");
+    while ($rs->next_record()){
+        $ret[$rs->f('sem_tree_id')] = $the_tree->getShortPath($rs->f('sem_tree_id'), NULL, $delimeter, $depth ? $depth - 1 : 0);
+    }
+    return $ret;
+}
+
+/**
+ * check_and_set_date
+ *
+ * Checks if given date is valid and sets field in array accordingly.
+ * (E.g. $admin_admission_data['admission_enddate'])
+ *
+ * @param mixed $tag    day or placeholder for day
+ * @param mixed $monat  month or placeholder for month
+ * @param mixed $jahr   year or placeholder for year
+ * @param mixed $stunde hours or placeholder for hours
+ * @param mixed $minute minutes or placeholder for minutes
+ * @param array &$arr   Reference to array to update. If NULL, only check is performed
+ * @param mixed $field  Name of field in array to be set
+ *
+ * @return bool  true if date was valid, false else
+ */
+function check_and_set_date($tag, $monat, $jahr, $stunde, $minute, &$arr, $field)
+{
+
+    $check=TRUE; // everything ok?
+    if (($jahr>0) && ($jahr<100))
+        $jahr=$jahr+2000;
+
+    if ($monat == _("mm")) $monat=0;
+    if ($tag == _("tt")) $tag=0;
+    if ($jahr == _("jjjj")) $jahr=0;
+    //if ($stunde == _("hh")) $stunde=0;
+    if ($minute == _("mm")) $minute=0;
+
+    if (($monat) && ($tag) && ($jahr)) {
+        if ($stunde==_("hh")) {
+            $check=FALSE;
+        }
+
+        if ((!checkdate((int)$monat, (int)$tag, (int)$jahr) && ((int)$monat) && ((int)$tag) && ((int)$jahr))) {
+            $check=FALSE;
+        }
+
+        if (($stunde > 24) || ($minute > 59)
+            || ($stunde == 24 && $minute > 0) ) {
+            $check=FALSE;
+        }
+
+        if ($stunde == 24) {
+            $stunde = 23;
+            $minute = 59;
+        }
+
+        if ($arr) {
+            if ($check) {
+                $arr[$field] = mktime((int)$stunde,(int)$minute, 0,$monat,$tag,$jahr);
+            } else {
+                $arr[$field] = -1;
+            }
+        }
+    }
+    return $check;
+}
+
+
+/**
+ * gets an entry from the studip configuration table
+ *
+ * @param string $key the key for the config entry
+ * @return string  the value
+ * @deprecated since Stud.IP 5.0
+ */
+function get_config($key)
+{
+    return Config::get()->$key;
+}
+
+/**
+ * reset the order-positions for the lecturers in the passed seminar,
+ * starting at the passed position
+ *
+ * @param string $s_id     the seminar to work on
+ * @param int    $position the position to start with
+ *
+ * @return void
+ */
+function re_sort_dozenten($s_id, $position)
+{
+    $query = "UPDATE seminar_user
+              SET position = position - 1
+              WHERE Seminar_id = ? AND status = 'dozent' AND position > ?";
+    $statement = DBManager::get()->prepare($query);
+    $statement->execute([$s_id, $position]);
+}
+
+/**
+ * reset the order-positions for the tutors in the passed seminar,
+ * starting at the passed position
+ *
+ * @param string $s_id     the seminar to work on
+ * @param int    $position the position to start with
+ *
+ * @return void
+ */
+function re_sort_tutoren($s_id, $position)
+{
+    $query = "UPDATE seminar_user
+              SET position = position - 1
+              WHERE Seminar_id = ? AND status = 'tutor' AND position > ?";
+    $statement = DBManager::get()->prepare($query);
+    $statement->execute([$s_id, $position]);
+}
+
+/**
+ * return the highest position-number increased by one for the
+ * passed user-group in the passed seminar
+ *
+ * @param string $status     can be on of 'tutor', 'dozent', ...
+ * @param string $seminar_id the seminar to work on
+ *
+ * @return int  the next available position
+ */
+function get_next_position($status, $seminar_id)
+{
+    $query = "SELECT MAX(position) + 1
+              FROM seminar_user
+              WHERE Seminar_id = ? AND status = ?";
+    $statement = DBManager::get()->prepare($query);
+    $statement->execute([$seminar_id, $status]);
+
+   return $statement->fetchColumn() ?: 0;
+}
+
+/**
+ * converts a string to a float, depending on the locale
+ *
+ * @param string $str the string to convert to float
+ *
+ * @return float the string casted to float
+ */
+function StringToFloat($str)
+{
+    $str = mb_substr((string)$str,0,13);
+    $locale = localeconv();
+    $from = ($locale["thousands_sep"] ? $locale["thousands_sep"] : ',');
+    $to = ($locale["decimal_point"] ? $locale["decimal_point"] : '.');
+    if(mb_strstr($str, $from)){
+        $conv_str = str_replace($from, $to, $str);
+        $my_float = (float)$conv_str;
+        if ($conv_str === (string)$my_float) return $my_float;
+    }
+    return (float)$str;
+}
+
+/**
+ * check which perms the currently logged in user had in the
+ * passed archived seminar
+ *
+ * @global array $perm
+ * @global object $auth
+ * @staticvar array $archiv_perms
+ *
+ * @param string $seminar_id the seminar in the archive
+ *
+ * @return string the perm the user had
+ */
+function archiv_check_perm($seminar_id)
+{
+    static $archiv_perms;
+    global $perm, $user;
+
+    $u_id = $user->id;
+
+    // root darf sowieso ueberall dran
+    if ($perm->have_perm('root')) {
+        return 'admin';
+    }
+
+    if (!is_array($archiv_perms)){
+        $query = "SELECT seminar_id, status FROM archiv_user WHERE user_id = ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$u_id]);
+        $archiv_perms = $statement->fetchGrouped(PDO::FETCH_COLUMN);
+
+        if ($perm->have_perm("admin")){
+            $query = "SELECT archiv.seminar_id, 'admin'
+                      FROM user_inst
+                      INNER JOIN archiv ON (heimat_inst_id = institut_id)
+                      WHERE user_inst.user_id = ? AND user_inst.inst_perms = 'admin'";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$u_id]);
+            $temp_perms = $statement->fetchGrouped(PDO::FETCH_COLUMN);
+
+            $archiv_perms = array_merge($archiv_perms, $temp_perms);
+        }
+        if ($perm->is_fak_admin()){
+            $query = "SELECT archiv.seminar_id, 'admin'
+                      FROM user_inst
+                      INNER JOIN Institute ON (user_inst.institut_id = Institute.fakultaets_id)
+                      INNER JOIN archiv ON (archiv.heimat_inst_id = Institute.institut_id)
+                      WHERE user_inst.user_id = ? AND user_inst.inst_perms = 'admin'";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$u_id]);
+            $temp_perms = $statement->fetchGrouped(PDO::FETCH_COLUMN);
+
+            $archiv_perms = array_merge($archiv_perms, $temp_perms);
+        }
+    }
+    return $archiv_perms[$seminar_id];
+}
+
+/**
+ * retrieve a list of all online users
+ *
+ * @global object $user
+ * @global array  $_fullname_sql
+ *
+ * @param int    $active_time filter: the time in minutes until last life-sign
+ * @param string $name_format format the fullname shall have
+ *
+ * @return array
+ */
+function get_users_online($active_time = 5, $name_format = 'full_rev')
+{
+    if (!isset($GLOBALS['_fullname_sql'][$name_format])) {
+        $sql_fullname = array_keys($GLOBALS['_fullname_sql']);
+        $name_format = reset($sql_fullname);
+    }
+
+    $query = "SELECT a.username AS temp, a.username, {$GLOBALS['_fullname_sql'][$name_format]} AS name,
+                     ABS(CAST(UNIX_TIMESTAMP() AS SIGNED) - CAST(last_lifesign AS SIGNED)) AS last_action,
+                     a.user_id, IF(owner_id IS NOT NULL, 1, 0) AS is_buddy, " . get_vis_query('a', 'online') . " AS is_visible,
+                     a.visible
+              FROM user_online uo
+              JOIN auth_user_md5 a ON (a.user_id = uo.user_id)
+              LEFT JOIN user_info ON (user_info.user_id = uo.user_id)
+              LEFT JOIN user_visibility ON (user_visibility.user_id = uo.user_id)
+              LEFT JOIN contact ON (owner_id = ? AND contact.user_id = a.user_id)
+              WHERE last_lifesign > ? AND uo.user_id <> ?
+              ORDER BY {$GLOBALS['_fullname_sql'][$name_format]} ASC";
+    $statement = DBManager::get()->prepare($query);
+    $statement->execute([
+        $GLOBALS['user']->id,
+        time() - $active_time * 60,
+        $GLOBALS['user']->id,
+    ]);
+    $online = $statement->fetchGrouped();
+
+    // measure users online
+    if ($active_time === 10) {
+        Metrics::gauge('core.users_online', sizeof($online));
+    }
+
+    return $online;
+}
+
+/**
+ * get the number of currently online users
+ *
+ * @param int $active_time filter: the time in minutes until last life-sign
+ *
+ * @return int
+ */
+function get_users_online_count($active_time = 10)
+{
+    $cache = StudipCacheFactory::getCache();
+    $online_count = $cache->read("online_count/{$active_time}");
+    if ($online_count === false) {
+        $query = "SELECT COUNT(*) FROM user_online
+                  WHERE last_lifesign > ?";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([time() - $active_time * 60]);
+        $online_count = $statement->fetchColumn();
+        $cache->write("online_count/{$active_time}", $online_count, 180);
+    }
+    if ($GLOBALS['user']->id && $GLOBALS['user']->id !== 'nobody') {
+        --$online_count;
+    }
+    return $online_count > 0 ? $online_count : 0;
+}
+
+/**
+ * return a studip-ticket
+ *
+ * @return string a unique id referring to a newly created ticket
+ */
+function get_ticket()
+{
+    return Seminar_Session::get_ticket();
+}
+
+/**
+ * check if the passed ticket is valid
+ *
+ * @param string $studipticket the ticket-id to check
+ *
+ * @return bool
+ */
+function check_ticket($studipticket)
+{
+    return Seminar_Session::check_ticket($studipticket);
+}
+
+/**
+ * searches
+ *
+ * @global array $perm
+ * @global object $user
+ * @global array $_fullname_sql
+ *
+ * @param string $search_str  optional search-string
+ * @param string $search_user optional user to search for
+ * @param bool   $show_sem    if true, the seminar is added to the result
+ *
+ * @return array
+ */
+function search_range($search_str = false, $search_user = false, $show_sem = true)
+{
+    global $perm, $user, $_fullname_sql;
+
+    // Helper function that obtains the correct name for an entity taking
+    // in account whether the semesters should be displayed or not
+    $formatName = function ($row) use ($show_sem) {
+        $name = $row['Name'];
+        if ($show_sem) {
+            $name = sprintf('%s (%s%s)',
+                            $name,
+                            $row['startsem'],
+                            $row['startsem'] != $row['endsem'] ? ' - ' . $row['endsem'] : '');
+        }
+        return $name;
+    };
+
+    $search_result = [];
+    $show_sem_sql1 = ", s.start_time, (SELECT semester_data.name FROM semester_data WHERE s.start_time >= semester_data.`beginn` AND s.start_time <= semester_data.`ende` LIMIT 1) AS startsem, IF(semester_courses.semester_id IS NULL, '"._("unbegrenzt")."', (SELECT semester_data.name FROM semester_data LEFT JOIN semester_courses USING (semester_id) WHERE semester_courses.course_id = s.Seminar_id ORDER BY semester_data.`beginn` DESC LIMIT 1)) AS endsem ";
+    $show_sem_sql2 = "LEFT JOIN semester_courses ON (semester_courses.course_id = s.Seminar_id) ";
+
+
+    if ($search_str && $perm->have_perm('root')) {
+        if ($search_user) {
+            $query = "SELECT user_id, CONCAT({$_fullname_sql['full']}, ' (', username, ')') AS name
+                      FROM auth_user_md5 AS a
+                      LEFT JOIN user_info USING (user_id)
+                      WHERE CONCAT(Vorname, ' ', Nachname, ' ', username) LIKE CONCAT('%', ?, '%')
+                      ORDER BY Nachname, Vorname";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$search_str]);
+            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+                $search_result[$row['user_id']] = [
+                    'type' => 'user',
+                    'name' => $row['name'],
+                ];
+            }
+        }
+
+        $_hidden = _('(versteckt)');
+        $query = "SELECT Seminar_id, IF(s.visible = 0, CONCAT(s.Name, ' {$_hidden}'), s.Name) AS Name %s
+                  FROM seminare AS s %s
+                  WHERE s.Name LIKE CONCAT('%%', ?, '%%')
+                  GROUP BY s.Seminar_id
+                  ORDER BY start_time DESC, Name";
+        $query = $show_sem
+               ? sprintf($query, $show_sem_sql1, $show_sem_sql2)
+               : sprintf($query, '', '');
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$search_str]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Seminar_id']] = [
+                'type'      => 'sem',
+                'name'      => $formatName($row),
+                'starttime' => $row['start_time'],
+                'startsem'  => $row['startsem'],
+            ];
+        }
+
+        $query = "SELECT Institut_id, Name, IF(Institut_id = fakultaets_id, 'fak', 'inst') AS type
+                  FROM Institute
+                  WHERE Name LIKE CONCAT('%', ?, '%')
+                  ORDER BY Name";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$search_str]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Institut_id']] = [
+                'type' => $row['type'],
+                'name' => $row['Name'],
+            ];
+        }
+    } elseif ($search_str && $perm->have_perm('admin')) {
+        $_hidden = _('(versteckt)');
+        $query = "SELECT s.Seminar_id, IF(s.visible = 0, CONCAT(s.Name, ' {$_hidden}'), s.Name) AS Name %s
+                  FROM user_inst AS a
+                  JOIN seminare AS s USING (Institut_id) %s
+                  WHERE a.user_id = ? AND a.inst_perms = 'admin' AND s.Name LIKE CONCAT('%%', ?, '%%')
+                  ORDER BY start_time";
+        $query = $show_sem
+               ? sprintf($query, $show_sem_sql1, $show_sem_sql2)
+               : sprintf($query, '', '');
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user->id, $search_str]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Seminar_id']] = [
+                'type'      => 'sem',
+                'name'      => $formatName($row),
+                'starttime' => $row['start_time'],
+                'startsem'  => $row['startsem'],
+            ];
+        }
+
+        $query = "SELECT b.Institut_id, b.Name
+                  FROM user_inst AS a
+                  JOIN Institute AS b USING (Institut_id)
+                  WHERE a.user_id = ? AND a.inst_perms = 'admin'
+                    AND a.institut_id != b.fakultaets_id AND b.Name LIKE CONCAT('%', ?, '%')
+                  ORDER BY Name";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user->id, $search_str]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Institut_id']] = [
+                'type' => 'inst',
+                'name' => $row['Name'],
+            ];
+        }
+        if ($perm->is_fak_admin()) {
+            $_hidden = _('(versteckt)');
+            $query = "SELECT s.Seminar_id, IF(s.visible = 0, CONCAT(s.Name, ' {$_hidden}'), s.Name) AS Name %s
+                      FROM user_inst AS a
+                      JOIN Institute AS b ON (a.Institut_id = b.Institut_id AND b.Institut_id = b.fakultaets_id)
+                      JOIN Institute AS c ON (c.fakultaets_id = b.Institut_id AND c.fakultaets_id != c.Institut_id)
+                      JOIN seminare AS s ON (s.Institut_id = c.Institut_id) %s
+                      WHERE a.user_id = ? AND a.inst_perms = 'admin'
+                        AND s.Name LIKE CONCAT('%%', ?, '%%')
+                      ORDER BY start_time DESC, Name";
+            $query = $show_sem
+                   ? sprintf($query, $show_sem_sql1, $show_sem_sql2)
+                   : sprintf($query, '', '');
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$user->id, $search_str]);
+            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+                $search_result[$row['Seminar_id']] = [
+                    'type'      => 'sem',
+                    'name'      => $formatName($row),
+                    'starttime' => $row['start_time'],
+                    'startsem'  => $row['startsem'],
+                ];
+            }
+
+            $query = "SELECT c.Institut_id, c.Name
+                      FROM user_inst AS a
+                      JOIN Institute AS b ON (a.Institut_id = b.Institut_id AND b.Institut_id = b.fakultaets_id)
+                      JOIN Institute AS c ON (c.fakultaets_id = b.institut_id AND c.fakultaets_id != c.institut_id)
+                      WHERE a.user_id = ? AND a.inst_perms = 'admin'
+                        AND c.Name LIKE CONCAT('%', ?, '%')
+                      ORDER BY Name";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$user->id, $search_str]);
+            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+                $search_result[$row['Institut_id']] = [
+                    'type' => 'inst',
+                    'name' => $row['Name'],
+                ];
+            }
+
+            $query = "SELECT b.Institut_id, b.Name
+                      FROM user_inst AS a
+                      JOIN Institute AS b ON (a.Institut_id = b.Institut_id AND b.Institut_id = b.fakultaets_id)
+                      WHERE a.user_id = ? AND a.inst_perms = 'admin'
+                        AND b.Name LIKE CONCAT('%', ?, '%')
+                      ORDER BY Name";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([$user->id, $search_str]);
+            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+                $search_result[$row['Institut_id']] = [
+                    'type' => 'inst',
+                    'name' => $row['Name'],
+                ];
+            }
+        }
+    } elseif ($perm->have_perm('tutor') || $perm->have_perm('autor')) {
+        // autors my also have evaluations and news in studygroups with proper rights
+        $_hidden = _('(versteckt)');
+        $query = "SELECT s.Seminar_id, IF(s.visible = 0, CONCAT(s.Name, ' {$_hidden}'), s.Name) AS Name %s
+                  FROM seminar_user AS a
+                  JOIN seminare AS s USING (Seminar_id) %s
+                  WHERE a.user_id = ? AND a.status IN ('tutor', 'dozent')
+                  ORDER BY start_time DESC, Name";
+        $query = $show_sem
+               ? sprintf($query, $show_sem_sql1, $show_sem_sql2)
+               : sprintf($query, '', '');
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user->id]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Seminar_id']] = [
+                'type'      => 'sem',
+                'name'      => $formatName($row),
+                'starttime' => $row['start_time'],
+                'startsem'  => $row['startsem'],
+            ];
+        }
+
+        $query = "SELECT Institut_id, b.Name,
+                         IF (Institut_id = fakultaets_id, 'fak', 'inst') AS type
+                  FROM user_inst AS a
+                  JOIN Institute AS b USING (Institut_id)
+                  WHERE a.user_id = ? AND a.inst_perms IN ('dozent','tutor')
+                  ORDER BY Name";
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user->id]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Institut_id']] = [
+                'name' => $row['Name'],
+                'type' => $row['type'],
+            ];
+        }
+    }
+
+    if (Config::get()->DEPUTIES_ENABLE) {
+        $_hidden = _('(versteckt)');
+        $_deputy = _('Vertretung');
+        $query = "SELECT s.Seminar_id,
+                         CONCAT(IF(s.visible = 0, CONCAT(s.Name, ' {$_hidden}'), s.Name), ' [{$_deputy}]') AS Name %s
+                  FROM seminare AS s
+                  JOIN deputies AS d ON (s.Seminar_id = d.range_id) %s
+                  WHERE d.user_id = ?
+                  ORDER BY s.start_time DESC, Name";
+        $query = $show_sem
+               ? sprintf($query, $show_sem_sql1, $show_sem_sql2)
+               : sprintf($query, '', '');
+        $statement = DBManager::get()->prepare($query);
+        $statement->execute([$user->id]);
+        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+            $search_result[$row['Seminar_id']] = [
+                'type'      => 'sem',
+                'name'      => $formatName($row),
+                'starttime' => $row['start_time'],
+                'startsem'  => $row['startsem'],
+            ];
+        }
+        if (Deputy::isEditActivated()) {
+            $query = "SELECT a.user_id, a.username, 'user' AS type,
+                             CONCAT({$_fullname_sql['full']}, ' (', username, ')') AS name
+                      FROM auth_user_md5 AS a
+                      JOIN user_info USING (user_id)
+                      JOIN deputies AS d ON (a.user_id = d.range_id)
+                      WHERE d.user_id = ?
+                      ORDER BY name ASC";
+            $statement = DBManager::get()->prepare($query);
+            $statement->execute([
+                $user->id
+            ]);
+            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
+                $search_result[$row['user_id']] = $row;
+            }
+        }
+    }
+
+    return $search_result ?: null;
+}
+
+/**
+ * format_help_url($keyword)
+ * returns URL for given help keyword
+ *
+ * @param string $keyword the help-keyword
+ *
+ * @return string the help-url
+ */
+function format_help_url($keyword)
+{
+    $helppage = $keyword;
+
+    // $loc is only set if special help view for installation is known
+    $loc = "";
+
+    $locationid = Config::get()->EXTERNAL_HELP_LOCATIONID;
+    if ($locationid && $locationid !== 'default') {
+        $loc = $locationid . '/';
+    }
+
+    // all help urls need short language tag (de, en)
+    $lang = 'de';
+    if ($_SESSION['_language']) {
+        [$lang] = explode('_', $_SESSION['_language']);
+    }
+
+    // determine Stud.IP version as of MAJOR.MINOR
+    // from SOFTWARE_VERSION. That variable MUST match pattern MAJOR.MINOR.*
+    preg_match('/^(\d+\.\d+)/', $GLOBALS['SOFTWARE_VERSION'], $v);
+    $version = $v[0];
+
+    $help_query = sprintf('https://hilfe.studip.de/help/%s/%s/%s%s',
+                          $version, $lang, $loc, $helppage);
+    return $help_query;
+}
+
+/**
+ * Splits a string by space characters and returns these words as an array.
+ * If an array is given, returns the array itself.
+ *
+ * @param mixed   $what what to split
+ * @return array  the words of the string as array
+ */
+function words($what) {
+    return is_array($what) ? $what : preg_split('/ /', $what, -1, PREG_SPLIT_NO_EMPTY);
+}
+
+/**
+ * Encodes a string or array from UTF-8 to Stud.IP encoding (WINDOWS-1252/ISO-8859-1 with numeric HTML-ENTITIES)
+ *
+ * @param mixed $data a string in UTF-8 or an array with all strings encoded in utf-8
+ *
+ * @return string  the string in WINDOWS-1252/HTML-ENTITIES
+ */
+function legacy_studip_utf8decode($data)
+{
+    if (is_array($data)) {
+        $new_data = [];
+        foreach ($data as $key => $value) {
+            $key = legacy_studip_utf8decode($key);
+            $new_data[$key] = legacy_studip_utf8decode($value);
+        }
+        return $new_data;
+    }
+
+    if (!preg_match('/[\200-\377]/', $data)) {
+        return $data;
+    } else {
+        $windows1252 = [
+            "\x80" => '&#8364;',
+            "\x81" => '&#65533;',
+            "\x82" => '&#8218;',
+            "\x83" => '&#402;',
+            "\x84" => '&#8222;',
+            "\x85" => '&#8230;',
+            "\x86" => '&#8224;',
+            "\x87" => '&#8225;',
+            "\x88" => '&#710;',
+            "\x89" => '&#8240;',
+            "\x8A" => '&#352;',
+            "\x8B" => '&#8249;',
+            "\x8C" => '&#338;',
+            "\x8D" => '&#65533;',
+            "\x8E" => '&#381;',
+            "\x8F" => '&#65533;',
+            "\x90" => '&#65533;',
+            "\x91" => '&#8216;',
+            "\x92" => '&#8217;',
+            "\x93" => '&#8220;',
+            "\x94" => '&#8221;',
+            "\x95" => '&#8226;',
+            "\x96" => '&#8211;',
+            "\x97" => '&#8212;',
+            "\x98" => '&#732;',
+            "\x99" => '&#8482;',
+            "\x9A" => '&#353;',
+            "\x9B" => '&#8250;',
+            "\x9C" => '&#339;',
+            "\x9D" => '&#65533;',
+            "\x9E" => '&#382;',
+            "\x9F" => '&#376;'];
+        return str_replace(
+            array_values($windows1252),
+            array_keys($windows1252),
+            utf8_decode(mb_encode_numericentity(
+                $data,
+                [0x100, 0xffff, 0, 0xffff],
+                'UTF-8'
+            ))
+        );
+    }
+}
+
+/**
+ * Special stud.ip version of json_decode() that also converts the data
+ * from utf8 and creates an associative array by default (this differs
+ * from the default behavior of json_decode() !).
+ *
+ * @param String $json
+ * @param bool   $assoc
+ * @param int    $depth
+ * @param int    $options
+ * @deprecated since Stud.IP 5.0
+ */
+function studip_json_decode($json, $assoc = true, $depth = 512, $options = 0)
+{
+    $data = json_decode($json, $assoc, $depth, $options);
+
+    return $data;
+}
+
+/**
+ * Special stud.ip version of json_decode() that also converts the data
+ * to utf8.
+ *
+ * @param mixed $data
+ * @param int   $options
+ * @param int   $depth
+ * @deprecated since Stud.IP 5.0
+ */
+function studip_json_encode($data, $options = 0)
+{
+    $json = json_encode($data, $options);
+
+    return $json;
+}
+
+/**
+ * Encode an HTTP header parameter (e.g. filename for 'Content-Disposition').
+ *
+ * @param string $name  parameter name
+ * @param string $value parameter value
+ *
+ * @return string encoded header text (using RFC 2616 or 5987 encoding)
+ */
+function encode_header_parameter($name, $value)
+{
+    if (preg_match('/[\200-\377]/', $value)) {
+        // use RFC 5987 encoding (ext-parameter)
+        return $name . "*=UTF-8''" . rawurlencode($value);
+    } else {
+        // use RFC 2616 encoding (quoted-string)
+        return $name . '="' . addslashes($value) . '"';
+    }
+}
+
+/**
+ * Get the title used for the given status ('dozent', 'tutor' etc.) for the
+ * specified SEM_TYPE. Alternative titles can be defined in the config.inc.php.
+ *
+ * @global array $SEM_TYPE
+ * @global array $DEFAULT_TITLE_FOR_STATUS
+ *
+ * @param string $type     status ('dozent', 'tutor', 'autor', 'user' or 'accepted')
+ * @param int    $count    count, this determines singular or plural form of title
+ * @param int    $sem_type sem_type of course (defaults to type of current course)
+ *
+ * @return string  translated title for status
+ */
+function get_title_for_status($type, $count, $sem_type = NULL)
+{
+    global $SEM_TYPE, $DEFAULT_TITLE_FOR_STATUS;
+
+    if (is_null($sem_type)) {
+        $sem_type = Context::getArtNum();
+    }
+
+    $atype = 'title_'.$type;
+
+    if (is_array($SEM_TYPE[$sem_type][$atype])) {
+        $title = $SEM_TYPE[$sem_type][$atype];
+    } else if (isset($DEFAULT_TITLE_FOR_STATUS[$type])) {
+        $title = $DEFAULT_TITLE_FOR_STATUS[$type];
+    } else {
+        $title = ['unbekannt', 'unbekannt'];
+    }
+
+    return ngettext($title[0], $title[1], $count);
+}
+
+/**
+ * Test whether the given URL refers to some page or resource of
+ * this Stud.IP installation.
+ *
+ * @param string $url url to check
+ *
+ * @return mixed
+ */
+function is_internal_url($url)
+{
+    if (preg_match('%^[a-z]+:%', $url)) {
+        return mb_strpos($url, $GLOBALS['ABSOLUTE_URI_STUDIP']) === 0;
+    }
+
+    if ($url[0] === '/') {
+        return mb_strpos($url, $GLOBALS['CANONICAL_RELATIVE_PATH_STUDIP']) === 0;
+    }
+
+    return true;
+}
+
+/**
+ * Return the list of SEM_TYPES that represent study groups in this
+ * Stud.IP installation.
+ *
+ * @return array  list of SEM_TYPES used for study groups
+ */
+function studygroup_sem_types()
+{
+    $result = [];
+
+    foreach ($GLOBALS['SEM_TYPE'] as $id => $sem_type) {
+        if ($GLOBALS['SEM_CLASS'][$sem_type['class']]['studygroup_mode']) {
+            $result[] = $id;
+        }
+    }
+
+    return $result;
+}
+
+/**
+ * generates form fields for the submitted multidimensional array
+ *
+ * @param string $variable the name of the array, which is filled with the data
+ * @param mixed  $data     the data-array
+ * @param mixed  $parent   leave this entry as is
+ *
+ * @return string the inputs of type hidden as html
+ */
+function addHiddenFields($variable, $data, $parent = [])
+{
+    $ret = "";
+    if (is_array($data)) {
+        foreach($data as $key => $value) {
+            if (is_array($value)) {
+                $ret .= addHiddenFields($variable, $value, array_merge($parent, [$key]));
+            } else {
+                $ret.= '<input type="hidden" name="'. htmlReady($variable .'['. implode('][', array_merge($parent, [$key])) .']').'" value="'. htmlReady($value) .'">' ."\n";
+            }
+        }
+    } else {
+        $ret.= '<input type="hidden" name="'. htmlReady($variable) .'" value="'. htmlReady($data) .'">' ."\n";
+    }
+
+    return $ret;
+}
+
+/**
+ * Returns a new array that is a one-dimensional flattening of this
+ * array (recursively). That is, for every element that is an array,
+ * extract its elements into the new array.
+ *
+ * @param array $ary the array to be flattened
+ * @return array the flattened array
+ */
+function array_flatten($ary)
+{
+    $i = 0;
+    while ($i < sizeof($ary)) {
+        if (is_array($ary[$i])) {
+            array_splice($ary, $i, 1, $ary[$i]);
+        } else {
+            $i++;
+        }
+    }
+    return $ary;
+}
+
+/**
+ * Displays "relative time" - a textual representation between now and a
+ * certain timestamp, e.g. "3 hours ago".
+ *
+ * @param int  $timestamp        Timestamp to relate to.
+ * @param bool $verbose          Display long or short texts (optional)
+ * @param int  $displayed_levels How many levels shall be displayed
+ * @param int  $tolerance        Defines a tolerance area of seconds around
+ *                               now (How many seconds must have passed until
+ *                               the function won't return "now")
+ * @return String Textual representation of the difference between the passed
+ *                timestamp and now
+ */
+function reltime($timestamp, $verbose = true, $displayed_levels = 1, $tolerance = 5)
+{
+    if ($verbose) {
+        $glue = [', ', _(' und ')];
+        $levels = [
+            [60, _('%u Sekunde'), _('%u Sekunden')],
+            [60, _('%u Minute'),  _('%u Minuten')],
+            [24, _('%u Stunde'),  _('%u Stunden')],
+            [30, _('%u Tag'),     _('%u Tagen')],
+            [12, _('%u Monat'),   _('%u Monaten')],
+            [99, _('%u Jahr'),    _('%u Jahren')],
+        ];
+    } else {
+        $glue = ['', ''];
+        $levels = [
+            [60, _('%us'),   _('%us')],
+            [60, _('%umin'), _('%umin')],
+            [24, _('%uh'),   _('%uh')],
+            [30, _('%ud'),   _('%ud')],
+            [12, _('%uM'),   _('%uM')],
+            [99, _('%uy'),   _('%uy')],
+        ];
+    }
+
+    $now   = time();
+    $diff  = abs($timestamp - $now);
+
+    if ($diff < $tolerance) {
+        return _('jetzt');
+    }
+
+    $chunks = [];
+    for ($i = 0; $i < count($levels) && $diff > 0; $i++) {
+        $remainder = $diff % $levels[$i][0];
+        if ($remainder > 0) {
+            $chunks[] = sprintf(ngettext($levels[$i][1], $levels[$i][2], $remainder), $remainder);
+        }
+        $diff = floor($diff / $levels[$i][0]);
+        if ($diff === 0) {
+            break;
+        }
+    }
+
+    $chunks = array_reverse($chunks);
+    $chunks = array_slice($chunks, 0, $displayed_levels);
+    if (count($chunks) == 1) {
+        $result = $chunks[0];
+    } else {
+        $result = $chunks[0] . $glue[1] . implode($glue[0], array_slice($chunks, 1));
+    }
+    if ($verbose) {
+        $result = sprintf($timestamp < $now ? _('vor %s') : _('in %s'), $result);
+    }
+    return $result;
+}
+
+/**
+ * Displays a filesize in a (shortened) human readable form including the
+ * according units. For instance, 1234567 would be displayed as "1 MB" or
+ * 12345 would be displayed as "12 kB".
+ * The function can display the units in a short or a long form ("1 b" vs.
+ * "1 Byte").
+ * Optionally, more than one unit part can be displayed. For instance, 1234567
+ * could also be displayed as "1 MB, 234 kB, 567 b".
+ *
+ * @param int    $size             The raw filesize as integer
+ * @param bool   $verbose          Use short or long unit names
+ * @param int    $displayed_levels How many unit parts should be displayed
+ * @param String $glue             Text used to glue the different unit parts
+ *                                 together
+ * @return String The filesize in human readable form.
+ * @todo Allow "1,3 MB"
+ */
+function relsize($size, $verbose = true, $displayed_levels = 1, $glue = ', ', $truncate = false)
+{
+    $units = [
+        'B' => 'Byte',
+        'kB' => 'Kilobyte',
+        'MB' => 'Megabyte',
+        'GB' => 'Gigabyte',
+        'TB' => 'Terabyte',
+        'PB' => 'Petabyte',
+        'EB' => 'Exabyte',
+        'ZB' => 'Zettabyte',
+        'YB' => 'Yottabyte',
+    ];
+
+    $result = [];
+    foreach ($units as $short => $long) {
+        $remainder = $size % 1024;
+
+        $template = sprintf('%%.1f %s%%s', $verbose ? $long : $short);
+        $result[$template] = $remainder;
+
+        $size = floor($size / 1024);
+        if ($size == 0) {
+            break;
+        }
+    }
+
+    if ($displayed_levels == 1 && count($result) >=2 && !$truncate) {
+        $result = array_slice($result, -2);
+
+        $fraction = array_shift($result);
+        $template = key($result);
+        $size     = array_pop($result);
+
+        $result = [
+            $template => $size + $fraction / 1024,
+        ];
+    } elseif ($displayed_levels > 0) {
+        $result = array_slice($result, -$displayed_levels);
+    }
+
+    $display = [];
+    foreach ($result as $template => $size) {
+        if ($truncate || $size - floor($size) < 0.1) {
+            $template = str_replace('%.1f', '%u', $template);
+            $size     = (int)$size;
+        }
+        $display[] = sprintf($template, $size, ($verbose && $size !== 1) ? 's' : '');
+    }
+    return implode($glue, array_reverse($display));
+}
+
+/**
+ * extracts route
+ *
+ * @param string $route           route (optional, uses REQUEST_URI otherwise)
+ *
+ * @return  string  route
+ */
+function get_route($route = '')
+{
+    $route = mb_substr(parse_url($route ?: $_SERVER['REQUEST_URI'], PHP_URL_PATH), mb_strlen($GLOBALS['CANONICAL_RELATIVE_PATH_STUDIP']));
+    if (mb_strpos($route, 'plugins.php/') !== false) {
+        $trails = explode('plugins.php/', $route);
+        $pieces = explode('/', $trails[1]);
+        $route = 'plugins.php/' . $pieces[0] . ($pieces[1] ? '/' . $pieces[1] : '') . ($pieces[2] ? '/' . $pieces[2] : '');
+    } elseif (mb_strpos($route, 'dispatch.php/') !== false) {
+        $trails = explode('dispatch.php/', $route);
+        $dispatcher = new StudipDispatcher();
+        $pieces = explode('/', $trails[1]);
+        foreach ($pieces as $index => $piece) {
+            $trail .= ($trail ? '/' : '') . $piece;
+            if ($dispatcher->file_exists($trail . '.php')) {
+                $route = 'dispatch.php/' . $trail . ($pieces[$index+1] ? '/' . $pieces[$index+1] : '');
+            }
+        }
+    }
+    while (mb_substr($route, mb_strlen($route)-6, 6) == '/index') {
+        $route = mb_substr($route, 0, mb_strlen($route)-6);
+    }
+    return $route;
+}
+
+/**
+ * compares actual route to requested route
+ *
+ * @param string $requested_route         requested route (for help content or tour)
+ * @param string $current_route           current route (optional)
+ *
+ * @return  boolean  result
+ */
+function match_route($requested_route, $current_route = '')
+{
+    if (!$current_route) {
+        $current_route = get_route();
+    }
+    $route_parts = explode('?', $requested_route);
+    // if base routes don't match, return false without further checks
+    if (!fnmatch($route_parts[0], $current_route)) {
+        return false;
+    }
+    // if no parameters given and base routes do match, return true
+    if (!$route_parts[1]) {
+        return true;
+    }
+    // extract vars and check if they are set accordingly
+    $vars = [];
+    parse_str($route_parts[1], $vars);
+    if (!count($vars)) {
+        return false;
+    }
+    foreach ($vars as $name => $value) {
+        if (@$_REQUEST[$name] != $value) {
+            return false;
+        }
+    }
+    return true;
+}
+
+function studip_default_exception_handler($exception) {
+    require_once 'lib/visual.inc.php';
+
+    // send exception to metrics backend
+    if (class_exists('Metrics')) {
+        $exception_class = mb_strtolower(
+            preg_replace(
+                '/(?<=\w)([A-Z])/',
+                '_\\1',
+                get_class($exception)));
+        Metrics::increment('core.exception.' . $exception_class);
+    }
+
+    while (ob_get_level()) {
+        ob_end_clean();
+    }
+    $layout = 'layouts/base.php';
+    if ($exception instanceof AccessDeniedException) {
+        PageLayout::setTitle(_('Zugriff verweigert'));
+
+        $status = 403;
+        $template = 'access_denied_exception';
+    } else if ($exception instanceof CheckObjectException) {
+        $status = 403;
+        $template = 'check_object_exception';
+    } elseif ($exception instanceof LoginException) {
+        $GLOBALS['auth']->login_if(true);
+    } else {
+        if ($exception instanceOf Trails_Exception) {
+            $status = $exception->getCode();
+        } else {
+            $status = 500;
+        }
+        error_log($exception->__toString());
+        $template = 'unhandled_exception';
+    }
+
+    header('HTTP/1.1 ' . $status . ' ' . $exception->getMessage());
+
+    // ajax requests return JSON instead
+    // re-use the http status code determined above
+    if (!strcasecmp($_SERVER['HTTP_X_REQUESTED_WITH'], 'xmlhttprequest')) {
+        header('Content-Type: application/json; charset=UTF-8');
+        $template = 'json_exception';
+        $layout = null;
+    }
+
+
+    try {
+        $args = compact('exception', 'status');
+        ob_start();
+        echo $GLOBALS['template_factory']->render($template, $args, $layout);
+    } catch (Exception $e) {
+        ob_end_clean();
+        echo 'Error: ' . htmlReady($e->getMessage());
+    }
+    exit;
+}
+
+/**
+ * Converts a string to camelCase.
+ *
+ * @param String $string  The string that should be converted
+ * @param bool   $ucfirst Uppercase the very first character as well
+ *                        (optional, defaults to false)
+ * @return String containing the converted input string
+ */
+function strtocamelcase($string, $ucfirst = false) {
+    $string = mb_strtolower($string);
+    $chunks = preg_split('/\W+/', $string);
+    $chunks = array_map('ucfirst', $chunks);
+
+    if (!$ucfirst && count($chunks) > 0) {
+        $chunks[0] = mb_strtolower($chunks[0]);
+    }
+
+    return implode($chunks);
+}
+
+/**
+ * Converts a string to snake_case.
+ *
+ * @param String $string  The string that should be converted
+ * @return String containing the converted input string
+ */
+function strtosnakecase($string) {
+    $string = preg_replace('/\W+/', '_', $string);
+    $string = preg_replace('/(?<!^)[A-Z]/', '_$0', $string);
+    $string = mb_strtolower($string);
+    return $string;
+}
+
+/**
+ * Converts a string to kebab-case.
+ *
+ * @param String $string  The string that should be converted
+ * @return String containing the converted input string
+ */
+function strtokebabcase($string) {
+    $string = preg_replace('/\W+/', '-', $string);
+    $string = preg_replace('/(?<!^)[A-Z]/', '-$0', $string);
+    $string = mb_strtolower($string);
+    return $string;
+}
+
+/**
+ * fetch number of rows for a table
+ * for innodb this is not exact, but much faster than count(*)
+ *
+ * @param string $table  name of database table
+ * @return int number of rows
+ */
+function count_table_rows($table) {
+    $stat = DbManager::get()->fetchOne("SHOW TABLE STATUS LIKE ?", [$table]);
+    return (int)$stat['Rows'];
+}
+
+/**
+ * get the file path relative to the STUDIP_BASE_PATH
+ *
+ * @param string path of the file
+ * @return string relative path of the file
+ */
+function studip_relative_path($filepath)
+{
+    return str_replace($GLOBALS['STUDIP_BASE_PATH'] . DIRECTORY_SEPARATOR, '', $filepath);
+}
+
+
+/**
+ * converts a given array to a csv format
+ *
+ * @param array $data the data to convert, each row should be an array
+ * @param string $filename full path to a file to write to, if omitted the csv content is returned
+ * @param array $caption assoc array with captions, is written to the first line, $data is filtered by keys
+ * @param string $delimiter sets the field delimiter (one character only)
+ * @param string $enclosure sets the field enclosure (one character only)
+ * @param string $eol sets the end of line format
+ * @return mixed if $filename is given the number of written bytes, else the csv content as string
+ */
+function array_to_csv($data, $filename = null, $caption = null, $delimiter = ';' , $enclosure = '"', $eol = "\r\n", $add_bom = true )
+{
+    $fp = fopen('php://temp', 'r+');
+    $fp2 = fopen('php://temp', 'r+');
+    if ($add_bom) {
+        fwrite($fp2, "\xEF\xBB\xBF");
+    }
+    if (is_array($caption)) {
+        fputcsv($fp, array_values($caption), $delimiter, $enclosure);
+        rewind($fp);
+        $csv = stream_get_contents($fp);
+        if ($eol != PHP_EOL) {
+            $csv = trim($csv);
+            $csv .= $eol;
+        }
+        fwrite($fp2, $csv);
+        ftruncate($fp, 0);
+        rewind($fp);
+    }
+    foreach ($data as $row) {
+        if (is_array($caption)) {
+            $fields = [];
+            foreach(array_keys($caption) as $fieldname) {
+                $fields[] = $row[$fieldname];
+            }
+        } else {
+            $fields = $row;
+        }
+        fputcsv($fp, $fields, $delimiter, $enclosure);
+        rewind($fp);
+        $csv = stream_get_contents($fp);
+        if ($eol != PHP_EOL) {
+            $csv = trim($csv);
+            $csv .= $eol;
+        }
+        fwrite($fp2, $csv);
+        ftruncate($fp, 0);
+        rewind($fp);
+    }
+    fclose($fp);
+    rewind($fp2);
+    if ($filename === null) {
+        return stream_get_contents($fp2);
+    } else {
+        return file_put_contents($filename, $fp2);
+    }
+}
+
+
+/**
+* Delete a file, or a folder and its contents
+*
+* @author      Aidan Lister <aidan@php.net>
+* @version     1.0
+* @param       string   $dirname    The directory to delete
+* @return      bool     Returns true on success, false on failure
+*/
+function rmdirr($dirname){
+    // Simple delete for a file
+    if (is_file($dirname)) {
+        return @unlink($dirname);
+    } else if (!is_dir($dirname)) {
+        return false;
+    }
+
+    // Loop through the folder
+    $dir = dir($dirname);
+    while (false !== ($entry = $dir->read())) {
+        // Skip pointers
+        if ($entry == '.' || $entry == '..') {
+            continue;
+        }
+
+        // Deep delete directories
+        if (is_dir("$dirname/$entry") && !is_link("$dirname/$entry")) {
+            rmdirr("$dirname/$entry");
+        } else {
+            @unlink("$dirname/$entry");
+        }
+    }
+    // Clean up
+    $dir->close();
+    return @rmdir($dirname);
+}
+
+
+/**
+ * Determines an appropriate MIME type for a file based on the
+ * extension of the file name.
+ *
+ * @param string $filename      file name to check
+ */
+function get_mime_type($filename)
+{
+    static $mime_types = [
+        // archive types
+        'gz'   => 'application/x-gzip',
+        'tgz'  => 'application/x-gzip',
+        'bz2'  => 'application/x-bzip2',
+        'zip'  => 'application/zip',
+        // document types
+        'txt'  => 'text/plain',
+        'css'  => 'text/css',
+        'csv'  => 'text/csv',
+        'rtf'  => 'application/rtf',
+        'pdf'  => 'application/pdf',
+        'doc'  => 'application/msword',
+        'xls'  => 'application/ms-excel',
+        'ppt'  => 'application/ms-powerpoint',
+        'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+        'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+        'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+        'odp'  => 'application/vnd.oasis.opendocument.presentation',
+        'ods'  => 'application/vnd.oasis.opendocument.spreadsheet',
+        'odt'  => 'application/vnd.oasis.opendocument.text',
+        // image types
+        'gif'  => 'image/gif',
+        'jpeg' => 'image/jpeg',
+        'jpg'  => 'image/jpeg',
+        'jpe'  => 'image/jpeg',
+        'png'  => 'image/png',
+        'bmp'  => 'image/x-ms-bmp',
+        'avif' => 'image/avif',
+        'avifs' => 'image/avif-sequence',
+        'heic' => 'image/heic',
+        'heif' => 'image/heif',
+        'webp' => 'image/webp',
+        'apng' => 'image/apng',
+        // audio types
+        'mp3'  => 'audio/mp3',
+        'oga'  => 'audio/ogg',
+        'wav'  => 'audio/wave',
+        // video types
+        'mpeg' => 'video/mpeg',
+        'mpg'  => 'video/mpeg',
+        'mpe'  => 'video/mpeg',
+        'qt'   => 'video/quicktime',
+        'mov'  => 'video/quicktime',
+        'avi'  => 'video/x-msvideo',
+        'flv'  => 'video/x-flv',
+        'ogg'  => 'application/ogg',
+        'ogv'  => 'video/ogg',
+        'mp4'  => 'video/mp4',
+        'webm' => 'video/webm',
+    ];
+
+    $extension = mb_strtolower(pathinfo($filename, PATHINFO_EXTENSION));
+
+    if (isset($mime_types[$extension])) {
+        return $mime_types[$extension];
+    } else {
+        return 'application/octet-stream';
+    }
+}
+
+
+function readfile_chunked($filename, $start = null, $end = null) {
+    if (isset($start) && $start < $end) {
+        $chunksize = 1024 * 1024; // how many bytes per chunk
+        $bytes = 0;
+        $handle = fopen($filename, 'rb');
+        if ($handle === false) {
+            return false;
+        }
+        fseek($handle, $start);
+        while (!feof($handle) && ($p = ftell($handle)) <= $end) {
+            if ($p + $chunksize > $end) {
+                $chunksize = $end - $p + 1;
+            }
+            $buffer = fread($handle, $chunksize);
+            $bytes += strlen($buffer);
+            echo $buffer;
+        }
+        fclose($handle);
+        return $bytes; // return num. bytes delivered like readfile() does.
+    } else {
+        try {
+            $context = get_default_http_stream_context($filename);
+        } catch (InvalidArgumentException $e) {
+            return readfile($filename);
+        }
+        return readfile($filename, false, $context);
+    }
+}
+
+/**
+ * @param string $url
+ * @return resource
+ */
+function get_default_http_stream_context($url = '')
+{
+    $proxy = Config::get()->HTTP_PROXY;
+    if ($url) {
+        $purl = parse_url($url);
+        if (!isset($purl['scheme']) || !in_array($purl['scheme'], ['http', 'https'])) {
+            return stream_context_get_default();
+        }
+        $host = $purl['host'];
+        $whitelist = array_filter(array_map('trim', explode(',', Config::get()->HTTP_PROXY_IGNORE)));
+        if (in_array($host, $whitelist)) {
+            $proxy = '';
+        }
+    }
+    if ($proxy) {
+        $opts = ['http' => ['proxy' => 'tcp://' . $proxy]];
+    } else {
+        $opts = [];
+    }
+    return stream_context_get_default($opts);
+}