Merge branch 'main' into issue-3911issue-3911

1 files changed, 1264 insertions, 0 deletions

diff --git a/lib/classes/SemBrowse.php b/lib/classes/SemBrowse.php
new file mode 100644
index 0000000..536b7e3
--- /dev/null
+++ b/lib/classes/SemBrowse.php
@@ -0,0 +1,1264 @@
+<?php
+# Lifter002: TODO
+# Lifter005: TODO
+# Lifter007: TODO
+# Lifter003: TODO
+# Lifter010: TODO
+
+require_once 'lib/dates.inc.php';
+
+class SemBrowse {
+
+    public $sem_browse_data;
+    public $persistent_fields = [
+        'level', 'cmd', 'start_item_id', 'show_class', 'group_by',
+        'search_result', 'default_sem', 'sem_status', 'show_entries', 'sset'
+    ];
+    public $search_obj;
+    public $sem_tree;
+    public $range_tree;
+    public $show_result;
+    public $sem_number;
+    public $group_by_fields = [];
+    public $target_url;
+    public $target_id;
+    public $classes_show_module;
+    public $classes_show_class;
+
+    public function __construct($sem_browse_data_init = [])
+    {
+
+        $this->group_by_fields =
+                [
+                    [
+                        'name'        => _('Semester'),
+                        'group_field' => 'sem_number'
+                    ],
+                    [
+                        'name'        => _('Bereich'),
+                        'group_field' => 'bereich'
+                    ],
+                    [
+                        'name'         => _('Lehrende'),
+                        'group_field'  => 'fullname',
+                        'unique_field' => 'username'
+                    ],
+                    [
+                        'name'        => _('Typ'),
+                        'group_field' => 'status'
+                    ],
+                    [
+                        'name'         => _('Einrichtung'),
+                        'group_field'  => 'Institut',
+                        'unique_field' => 'Institut_id'
+                    ]
+                ];
+
+        if (empty($_SESSION['sem_browse_data'])) {
+            $_SESSION['sem_browse_data'] = $sem_browse_data_init;
+        }
+        $this->sem_browse_data =& $_SESSION['sem_browse_data'];
+
+        $level_change = Request::option('start_item_id') || Request::submitted('search_sem_sem_change');
+
+        for ($i = 0; $i < count($this->persistent_fields); ++$i){
+            $persistend_field = $this->persistent_fields[$i];
+            if (Request::get($persistend_field) != null) {
+                $this->sem_browse_data[$persistend_field] = Request::option($persistend_field);
+            }
+        }
+        $this->search_obj = new StudipSemSearch(
+            'search_sem',
+            false,
+            !(is_object($GLOBALS['perm']) && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)),
+            $this->sem_browse_data['show_class'] ?? null
+        );
+
+
+        if (Request::get($this->search_obj->form_name . '_scope_choose')) {
+            $this->sem_browse_data['start_item_id'] =
+                    Request::option($this->search_obj->form_name . '_scope_choose');
+        }
+        if (Request::get($this->search_obj->form_name . '_range_choose')) {
+            $this->sem_browse_data['start_item_id'] =
+                    Request::option($this->search_obj->form_name . '_range_choose');
+        }
+        if (Request::get($this->search_obj->form_name . '_sem')) {
+            $this->sem_browse_data['default_sem'] =
+                    Request::option($this->search_obj->form_name . '_sem');
+        }
+
+        if (
+            Request::get('keep_result_set')
+            || !empty($this->sem_browse_data['sset'])
+            || (!empty($this->sem_browse_data['search_result']) && !empty($this->sem_browse_data['show_entries']))
+        ) {
+            $this->show_result = true;
+        }
+
+        if (isset($this->sem_browse_data['cmd']) && $this->sem_browse_data['cmd'] === 'xts') {
+            if ($this->search_obj->new_search_button_clicked) {
+                $this->show_result = false;
+                $this->sem_browse_data['sset'] = false;
+                $this->sem_browse_data['search_result'] = [];
+            }
+        }
+
+        if (!isset($this->sem_browse_data['default_sem'])) {
+            $this->sem_number[0] = 0;
+        } elseif ($this->sem_browse_data['default_sem'] != 'all') {
+            $this->sem_number[0] = intval($this->sem_browse_data['default_sem']);
+        } else {
+            $this->sem_number = false;
+        }
+
+        $sem_status = (!empty($this->sem_browse_data['sem_status']) && is_array($this->sem_browse_data['sem_status'])) ? $this->sem_browse_data['sem_status'] : false;
+
+        if ($this->sem_browse_data['level'] == 'vv') {
+            if (empty($this->sem_browse_data['start_item_id'])) {
+                $this->sem_browse_data['start_item_id'] = 'root';
+            }
+            $this->sem_tree = new StudipSemTreeViewSimple(
+                    $this->sem_browse_data['start_item_id'],
+                    $this->sem_number, $sem_status,
+                    !(is_object($GLOBALS['perm'])
+                            && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)));
+            if (Request::option('cmd') != 'show_sem_range'
+                    && $level_change
+                    && !$this->search_obj->search_button_clicked ) {
+                $this->get_sem_range($this->sem_browse_data['start_item_id'], false);
+                $this->show_result = true;
+                $this->sem_browse_data['show_entries'] = 'level';
+                $this->sem_browse_data['sset'] = false;
+            }
+            if ($this->search_obj->sem_change_button_clicked) {
+                $this->get_sem_range($this->sem_browse_data['start_item_id'],
+                        ($this->sem_browse_data['show_entries'] == 'sublevels'));
+                $this->show_result = true;
+            }
+        }
+
+        if ($this->sem_browse_data['level'] == 'ev'){
+            if (!$this->sem_browse_data['start_item_id']) {
+                $this->sem_browse_data['start_item_id'] = 'root';
+            }
+            $this->range_tree = new StudipSemRangeTreeViewSimple(
+                    $this->sem_browse_data['start_item_id'],
+                    $this->sem_number,
+                    $sem_status,
+                    !(is_object($GLOBALS['perm'])
+                            && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)));
+            if (Request::option('cmd') != 'show_sem_range_tree'
+                    && $level_change
+                    && !$this->search_obj->search_button_clicked ) {
+                $this->get_sem_range_tree($this->sem_browse_data['start_item_id'], false);
+                $this->show_result = true;
+                $this->sem_browse_data['show_entries'] = 'level';
+                $this->sem_browse_data['sset'] = false;
+            }
+            if ($this->search_obj->sem_change_button_clicked) {
+                $this->get_sem_range_tree($this->sem_browse_data['start_item_id'],
+                        ($this->sem_browse_data['show_entries'] == 'sublevels'));
+                $this->show_result = true;
+            }
+        }
+
+        if ($this->search_obj->search_button_clicked
+                && !$this->search_obj->new_search_button_clicked) {
+            $this->search_obj->override_sem = $this->sem_number;
+            $this->search_obj->doSearch();
+            if ($this->search_obj->found_rows) {
+                $this->sem_browse_data['search_result'] = array_flip($this->search_obj->search_result->getRows('seminar_id'));
+            } else {
+                $this->sem_browse_data['search_result'] = [];
+            }
+            $this->show_result = true;
+            $this->sem_browse_data['show_entries'] = false;
+            $this->sem_browse_data['sset'] = Request::get($this->search_obj->form_name . "_quick_search_parameter");
+        }
+
+
+        if (Request::option('cmd') == 'show_sem_range') {
+            $tmp = explode('_', Request::option('item_id'));
+            $this->get_sem_range($tmp[0], isset($tmp[1]));
+            $this->show_result = true;
+            $this->sem_browse_data['show_entries'] = (isset($tmp[1])) ? 'sublevels' : 'level';
+            $this->sem_browse_data['sset'] = false;
+        }
+
+        if (Request::option('cmd') == 'show_sem_range_tree') {
+            $tmp = explode('_', Request::option('item_id'));
+            $this->get_sem_range_tree($tmp[0],isset($tmp[1]));
+            $this->show_result = true;
+            $this->sem_browse_data['show_entries'] = (isset($tmp[1])) ? 'sublevels' : 'level';
+            $this->sem_browse_data['sset'] = false;
+        }
+
+        if (Request::option('do_show_class')
+                && count($this->sem_browse_data['sem_status'])) {
+            $this->get_sem_class();
+        }
+
+    }
+
+    /**
+     * Returns whether the search for modules has to be displayed.
+     *
+     * @return boolean True if search for modules has to be displayed.
+     */
+    private function showModules()
+    {
+        if ($this->sem_browse_data['show_class'] == 'all') {
+            return true;
+        }
+        if (!is_array($this->classes_show_module)) {
+            $this->classes_show_class = [];
+            foreach ($GLOBALS['SEM_CLASS'] as $sem_class_key => $sem_class){
+                if ($sem_class['module']) {
+                    $this->classes_show_module[] = $sem_class_key;
+                }
+            }
+        }
+        return in_array($this->sem_browse_data['show_class'], $this->classes_show_class);
+    }
+
+    public function show_class()
+    {
+        if ($this->sem_browse_data['show_class'] == 'all') {
+            return true;
+        }
+        if (!is_array($this->classes_show_class)) {
+            $this->classes_show_class = [];
+            foreach ($GLOBALS['SEM_CLASS'] as $sem_class_key => $sem_class) {
+                if ($sem_class['bereiche']) {
+                    $this->classes_show_class[] = $sem_class_key;
+                }
+            }
+        }
+        return in_array($this->sem_browse_data['show_class'], $this->classes_show_class);
+    }
+
+    public function get_sem_class()
+    {
+        $query = "SELECT `Seminar_id`
+                  FROM `seminare`
+                  WHERE `status` IN (?)";
+
+        $show_all = is_object($GLOBALS['perm'])
+                 && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM);
+        if (!$show_all) {
+            $query .= ' AND visible = 1';
+        }
+
+        $sem_ids = DBManager::get()->fetchFirst($query);
+        if (is_array($sem_ids)) {
+            $this->sem_browse_data['search_result'] = array_flip($sem_ids);
+        }
+        $this->sem_browse_data['sset'] = true;
+        $this->show_result = true;
+    }
+
+    public function get_sem_range($item_id, $with_kids)
+    {
+        if (!is_object($this->sem_tree)) {
+            $sem_status = (is_array($this->sem_browse_data['sem_status'])) ? $this->sem_browse_data['sem_status'] : false;
+            $this->sem_tree = new StudipSemTreeViewSimple(
+                    $this->sem_browse_data['start_item_id'],
+                    $this->sem_number,
+                    $sem_status,
+                    !(is_object($GLOBALS['perm'])
+                            && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)));
+        }
+        $sem_ids = $this->sem_tree->tree->getSemIds($item_id,$with_kids);
+        if (is_array($sem_ids)) {
+            $this->sem_browse_data['search_result'] = array_flip($sem_ids);
+        } else {
+            $this->sem_browse_data['search_result'] = [];
+        }
+    }
+
+    public function get_sem_range_tree($item_id, $with_kids)
+    {
+        $range_object = RangeTreeObject::GetInstance($item_id);
+        if ($with_kids) {
+            $inst_ids = $range_object->getAllObjectKids();
+        }
+        $inst_ids[] = $range_object->item_data['studip_object_id'];
+        $db_view = DbView::getView('sem_tree');
+        $db_view->params[0] = $inst_ids;
+        $db_view->params[1] = (is_object($GLOBALS['perm']) && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)) ? '' : ' AND c.visible=1';
+        $db_view->params[1] .= !empty($this->sem_browse_data['sem_status']) && is_array($this->sem_browse_data['sem_status'])
+                ? " AND c.status IN('" . join("','", $this->sem_browse_data['sem_status']) ."')"
+                : '';
+        $db_view->params[2] = is_array($this->sem_number)
+                ? ' HAVING sem_number IN ('
+                    . join(',', $this->sem_number)
+                    . ') OR (sem_number <= '
+                    . $this->sem_number[count($this->sem_number) - 1]
+                    . '  AND (sem_number_end >= '
+                    . $this->sem_number[count($this->sem_number) - 1]
+                    . ' OR sem_number_end = -1)) '
+                : '';
+        $db_snap = new DbSnapshot($db_view->get_query('view:SEM_INST_GET_SEM'));
+        if ($db_snap->numRows) {
+            $sem_ids = $db_snap->getRows('Seminar_id');
+            $this->sem_browse_data['search_result'] = array_flip($sem_ids);
+        } else {
+            $this->sem_browse_data['search_result'] = [];
+        }
+    }
+
+    /**
+     * Prints the quicksearch form.
+     */
+    private function printQuickSearch()
+    {
+        if ($this->sem_browse_data['level'] === 'vv') {
+            $this->search_obj->sem_tree =& $this->sem_tree->tree;
+            if ($this->sem_tree->start_item_id !== 'root') {
+                $this->search_obj->search_scopes[] = $this->sem_tree->start_item_id;
+            }
+        } elseif ($this->sem_browse_data['level'] === 'ev') {
+            $this->search_obj->range_tree =& $this->range_tree->tree;
+            if ($this->range_tree->start_item_id !== 'root'){
+                $this->search_obj->search_ranges[] = $this->range_tree->start_item_id;
+            }
+        }
+
+        $template = $GLOBALS['template_factory']->open('sembrowse/quick-search.php');
+        $template->search_obj      = $this->search_obj;
+        $template->sem_browse_data = $this->sem_browse_data;
+        $template->sem_tree        = $this->sem_tree;
+        $template->range_tree      = $this->range_tree;
+        $template->quicksearch     = $this->getQuicksearch();
+
+        echo $template->render();
+    }
+
+    private function getQuicksearch()
+    {
+        $quicksearch = QuickSearch::get(
+            $this->search_obj->form_name . '_quick_search',
+            new SeminarSearch()
+        );
+
+        $quicksearch->setAttributes([
+            'aria-label' => _('Suchbegriff'),
+            'autofocus'  => '',
+        ]);
+        $quicksearch->fireJSFunctionOnSelect('selectSem');
+        $quicksearch->noSelectbox();
+        $quicksearch->defaultValue(
+            $this->sem_browse_data['sset'] ?: '',
+            $this->sem_browse_data['sset'] ?: ''
+        );
+
+        return $quicksearch;
+    }
+
+    private function printExtendedSearch()
+    {
+        $template = $GLOBALS['template_factory']->open('sembrowse/extended-search.php');
+        $template->search_obj      = $this->search_obj;
+        $template->sem_browse_data = $this->sem_browse_data;
+        $template->show_class      = $this->show_class();
+        echo $template->render();
+    }
+
+    public function do_output()
+    {
+        if ($this->sem_browse_data['cmd'] == 'xts') {
+            $this->printExtendedSearch();
+        }
+        $path_id = Request::option('path_id');
+        URLHelper::addLinkParam('path_id', $path_id);
+        $this->print_level($path_id);
+    }
+
+    public function print_level($start_id = null)
+    {
+        ob_start();
+
+        echo "\n" . '<table id="sem_search_level" class="course-search" style="width: 100%">' . "\n";
+        if ($this->sem_browse_data['level'] == 'vv') {
+            echo "\n" . '<caption class="legend">'._('Studienbereiche').'<caption>';
+            echo "\n" . '<tr><td style="text-align: center">';
+            $this->sem_tree->show_entries = $this->sem_browse_data['show_entries'] ?? false;
+            $this->sem_tree->showSemTree($start_id);
+        }
+        if ($this->sem_browse_data['level'] == 'ev') {
+            echo "\n" . '<caption class="legend">'._('Einrichtungen').'<caption>';
+            echo "\n" . '<tr><td style="text-align: center">';
+            $this->range_tree->show_entries = $this->sem_browse_data['show_entries'] ?? false;
+            $this->range_tree->showSemRangeTree($start_id);
+        }
+
+        if ($this->show_result) {
+            $this->print_result();
+        }
+
+        echo '</td></tr></table>';
+        ob_end_flush();
+    }
+
+    public function print_result()
+    {
+        ob_start();
+        global $SEM_TYPE, $SEM_CLASS;
+
+        if (is_array($this->sem_browse_data['search_result'])
+                && count($this->sem_browse_data['search_result'])) {
+            if (!is_object($this->sem_tree)) {
+                $this->sem_tree = new StudipSemTreeViewSimple(
+                        $this->sem_browse_data['start_item_id'] ?? null,
+                        $this->sem_number,
+                        !empty($this->sem_browse_data['sem_status']) && is_array($this->sem_browse_data['sem_status'])
+                            ? $this->sem_browse_data['sem_status'] : false,
+                        !(is_object($GLOBALS['perm']) && $GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM))
+                );
+            }
+            $the_tree = $this->sem_tree->tree;
+
+            list($group_by_data, $sem_data) = $this->get_result();
+
+            $visibles = $sem_data;
+            if (!$GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)) {
+                $visibles = array_filter($visibles, function ($c) {
+                    return key($c['visible']) == 1;
+                });
+            }
+
+            echo '<table class="default" id="sem_search_result" style="width: calc(100% - 21px);" >';
+            foreach ($group_by_data as $group_field => $sem_ids) {
+                if (Config::get()->COURSE_SEARCH_SHOW_ADMISSION_STATE) {
+                    echo '<tr><th colspan="6">';
+                } else {
+                    echo '<tr><th colspan="5">';
+                }
+                switch ($this->sem_browse_data['group_by'] ?? null) {
+                    case 0:
+                        echo htmlReady($this->search_obj->sem_dates[$group_field]['name'] ?? '');
+                        break;
+                    case 1:
+                        if ($the_tree->tree_data[$group_field]) {
+                            echo htmlReady($the_tree->getShortPath($group_field));
+                            if (is_object($this->sem_tree)){
+                                echo $this->sem_tree->getInfoIcon($group_field);
+                            }
+                        } else {
+                            echo _('keine Studienbereiche eingetragen');
+                        }
+                        break;
+                    case 3:
+                        echo htmlReady($SEM_TYPE[$group_field]['name']
+                                . ' ('
+                                . $SEM_CLASS[$SEM_TYPE[$group_field]['class']]['name']
+                                . ')');
+                        break;
+                    default:
+                        echo htmlReady($group_field);
+                }
+                echo '</th></tr>';
+                ob_end_flush();
+                ob_start();
+                if (is_array($sem_ids['Seminar_id'])) {
+                    foreach(array_keys($sem_ids['Seminar_id']) as $seminar_id){
+                        echo $this->printCourseRow($seminar_id, $sem_data);
+                    }
+                }
+            }
+            echo '</table>';
+        } elseif ($this->search_obj->search_button_clicked
+                && !$this->search_obj->new_search_button_clicked) {
+            $details = [];
+            if ($this->search_obj->found_rows === false) {
+                $details = [_('Der Suchbegriff fehlt oder ist zu kurz')];
+            }
+            if ($details) {
+                PageLayout::postError(_('Ihre Suche ergab keine Treffer'), $details);
+            } else {
+                PageLayout::postInfo(_('Ihre Suche ergab keine Treffer'));
+            }
+            $this->sem_browse_data['sset'] = 0;
+        }
+        ob_end_flush();
+    }
+
+    public function get_result()
+    {
+        global $_fullname_sql, $user;
+        if ($this->sem_browse_data['group_by'] == 1) {
+            if (!is_object($this->sem_tree)) {
+                $the_tree = TreeAbstract::GetInstance('StudipSemTree', false);
+            } else {
+                $the_tree = $this->sem_tree->tree;
+            }
+            $sem_tree_query = '';
+            if ($this->sem_browse_data['start_item_id'] != 'root'
+                    && ($this->sem_browse_data['level'] == 'vv'
+                    || $this->sem_browse_data['level'] == 'sbb')) {
+                $allowed_ranges = $the_tree->getKidsKids($this->sem_browse_data['start_item_id']);
+                $allowed_ranges[] = $this->sem_browse_data['start_item_id'];
+                $sem_tree_query = " AND sem_tree_id IN('" . join("','", $allowed_ranges) . "') ";
+            }
+            $add_fields = 'seminar_sem_tree.sem_tree_id AS bereich,';
+            $add_query = "LEFT JOIN seminar_sem_tree ON (seminare.Seminar_id = seminar_sem_tree.seminar_id $sem_tree_query)";
+        } else if ($this->sem_browse_data['group_by'] == 4){
+            $add_fields = 'Institute.Name AS Institut,Institute.Institut_id,';
+            $add_query = 'LEFT JOIN seminar_inst
+                            ON (seminare.Seminar_id = seminar_inst.Seminar_id)
+                          LEFT JOIN Institute
+                            ON (Institute.Institut_id = seminar_inst.institut_id)';
+        } else {
+            $add_fields = '';
+            $add_query = '';
+        }
+
+        $dbv = DbView::getView('sem_tree');
+
+        $query = "
+            SELECT seminare.Seminar_id, VeranstaltungsNummer, seminare.status,
+                IF(seminare.visible = 0, CONCAT(seminare.Name, ' " . _('(versteckt)')
+                    . "'), seminare.Name) AS Name,"
+                . $add_fields
+                . $_fullname_sql['full'] . " AS fullname,
+                    auth_user_md5.username,"
+                . $dbv->sem_number_sql . ' AS sem_number, '
+                . $dbv->sem_number_end_sql . ' AS sem_number_end,
+                seminar_user.position AS position, seminare.parent_course, seminare.visible
+            FROM seminare
+                LEFT JOIN seminar_user
+                    ON (seminare.Seminar_id=seminar_user.Seminar_id AND seminar_user.status = ' . "'dozent'" . ')
+                LEFT JOIN auth_user_md5
+                    USING (user_id)
+                LEFT JOIN user_info
+                    USING (user_id) '
+                . $add_query . "
+            WHERE (seminare.Seminar_id IN('" . join("','", array_keys($this->sem_browse_data['search_result'])) . "')
+                OR seminare.parent_course IN ('" . join("','", array_keys($this->sem_browse_data['search_result'])) . "'))";
+
+        // don't show Studiengruppen if user not logged in
+        if (!$GLOBALS['user'] || $GLOBALS['user']->id == 'nobody') {
+            $studygroup_types = DBManager::get()->quote(studygroup_sem_types());
+            $query .= " AND seminare.status NOT IN ({$studygroup_types})";
+        }
+
+        $db = new DB_Seminar($query);
+        $snap = new DbSnapshot($db);
+        $group_field = $this->group_by_fields[$this->sem_browse_data['group_by']]['group_field'];
+        $data_fields[0] = 'Seminar_id';
+        if (!empty($this->group_by_fields[$this->sem_browse_data['group_by']]['unique_field'])) {
+            $data_fields[1] = $this->group_by_fields[$this->sem_browse_data['group_by']]['unique_field'];
+        }
+        if($user->id == 'nobody' && $snap->numRows == 0){
+            $group_by_data = $sem_data = [];
+        }else{
+            $group_by_data = $snap->getGroupedResult($group_field, $data_fields);
+            $sem_data = $snap->getGroupedResult('Seminar_id');
+        }
+
+        if ($this->sem_browse_data['group_by'] == 0) {
+            if($user->id == 'nobody' && $snap->numRows == 0){
+                $group_by_duration = [];
+            }else{
+                $group_by_duration = $snap->getGroupedResult('sem_number_end', ['sem_number', 'Seminar_id']);
+            }
+            foreach ($group_by_duration as $sem_number_end => $detail) {
+                if ($sem_number_end != -1
+                        && ($detail['sem_number'][$sem_number_end]
+                                && count($detail['sem_number']) == 1)) {
+                    continue;
+                }
+
+                $current_semester_index = Semester::getIndexById(Semester::findCurrent()->semester_id, true, true);
+                foreach (array_keys($detail['Seminar_id']) as $seminar_id) {
+                    $start_sem = key($sem_data[$seminar_id]['sem_number']);
+                    if ($sem_number_end == -1) {
+                        if ($this->sem_number === false) {
+                            $sem_number_end = $current_semester_index && isset($this->search_obj->sem_dates[$current_semester_index + 1]) ? $current_semester_index + 1 : count($this->search_obj->sem_dates) -1;
+                        } else {
+                            $sem_number_end = $this->sem_number[0];
+                        }
+                    }
+                    for ($i = $start_sem; $i <= $sem_number_end; ++$i) {
+                        if ($this->sem_number === false
+                                || is_array($this->sem_number)
+                                && in_array($i, $this->sem_number)) {
+                            if (!empty($group_by_data[$i]) && empty($tmp_group_by_data[$i])) {
+                                foreach (array_keys($group_by_data[$i]['Seminar_id']) as $id) {
+                                    $tmp_group_by_data[$i]['Seminar_id'][$id] = true;
+                                }
+                            }
+                            $tmp_group_by_data[$i]['Seminar_id'][$seminar_id] = true;
+                        }
+                    }
+                }
+            }
+            if (!empty($tmp_group_by_data) && is_array($tmp_group_by_data)) {
+                if ($this->sem_number !== false) {
+                    unset($group_by_data);
+                }
+                foreach ($tmp_group_by_data as $start_sem => $detail) {
+                    $group_by_data[$start_sem] = $detail;
+                }
+            }
+        }
+
+        //release memory
+        unset($snap);
+        unset($tmp_group_by_data);
+
+        foreach ($group_by_data as $group_field => $sem_ids) {
+            foreach ($sem_ids['Seminar_id'] as $seminar_id => $foo) {
+                $name = mb_strtolower(key($sem_data[$seminar_id]['Name']));
+                $name = str_replace(['ä', 'ö', 'ü'], ['ae', 'oe', 'ue'], $name);
+                if (Config::get()->IMPORTANT_SEMNUMBER && key($sem_data[$seminar_id]['VeranstaltungsNummer'])) {
+                    $name = key($sem_data[$seminar_id]['VeranstaltungsNummer']) . ' ' . $name;
+                }
+                $group_by_data[$group_field]['Seminar_id'][$seminar_id] = $name;
+            }
+            uasort($group_by_data[$group_field]['Seminar_id'], 'strnatcmp');
+        }
+
+        switch ($this->sem_browse_data['group_by']) {
+            case 0:
+                krsort($group_by_data, SORT_NUMERIC);
+                break;
+            case 1:
+                uksort($group_by_data, function($a,$b) {
+                    $the_tree = TreeAbstract::GetInstance('StudipSemTree', false);
+                    $the_tree->buildIndex();
+                    return $the_tree->tree_data[$a]['index'] - $the_tree->tree_data[$b]['index'];
+                });
+                break;
+            case 3:
+                uksort($group_by_data, function ($a,$b) {
+                    global $SEM_CLASS,$SEM_TYPE;
+                    return strnatcasecmp($SEM_TYPE[$a]['name'], $SEM_TYPE[$b]['name'])
+                        ?: strnatcasecmp(
+                               $SEM_CLASS[$SEM_TYPE[$a]['class']]['name'],
+                               $SEM_CLASS[$SEM_TYPE[$b]["class"]]['name']
+                           );
+                });
+                break;
+            default:
+                uksort($group_by_data, 'strnatcasecmp');
+        }
+
+        return [$group_by_data, $sem_data];
+    }
+
+    /**
+     * Creates HTML code for a single course row. This has been extracted
+     * into a separate function as that makes handling and outputting
+     * course children easier.
+     *
+     * @param string $seminar_id a single course id to output
+     * @param mixed $sem_data collected data for all found courses
+     * @param bool $child call in "child mode" -> force output because here children are listed
+     * @return string A HTML table row.
+     */
+    private function printCourseRow($seminar_id, &$sem_data, $child = false)
+    {
+        global $SEM_TYPE;
+
+        $row = '';
+
+        /*
+         * As we include child courses now, we need an extra check for visibility.
+         * Child courses are not shown extra, but summarized under their parent if
+         * the parent is part of the search result.
+         */
+        if (($GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)
+                || key($sem_data[$seminar_id]['visible']) == 1)
+                && (empty($sem_data[key($sem_data[$seminar_id]['parent_course'])])
+                        || $child)) {
+            // create instance of seminar-object
+            $seminar_obj = new Seminar($seminar_id);
+            // is this sem a studygroup?
+            $studygroup_mode = SeminarCategories::GetByTypeId($seminar_obj->getStatus())->studygroup_mode;
+
+            $sem_name = $seminar_obj->getFullName('type-name');
+            $seminar_number = key($sem_data[$seminar_id]['VeranstaltungsNummer']);
+
+            $visibleChildren = [];
+
+            $row .= '<tr';
+            // Set necessary classes if we are displaying subcourses.
+            if ($child) {
+                $row .= ' class="hidden-js subcourses subcourses-' . key($sem_data[$seminar_id]['parent_course']) . '"' ;
+            }
+            $row .= '>';
+
+            if ($studygroup_mode) {
+                $sem_name .= ' (' . _('Studiengruppe');
+                if ($seminar_obj->admission_prelim) $sem_name .= ', ' . _('Zutritt auf Anfrage');
+                $sem_name .= ')';
+                $row .= '<td width="1%" class="hidden-tiny-down">';
+                $row .= StudygroupAvatar::getAvatar($seminar_id)->getImageTag(Avatar::SMALL, ['title' => $seminar_obj->getName()]);
+                $row .= '</td>';
+            } else {
+                $sem_number_start = key($sem_data[$seminar_id]['sem_number']);
+                $sem_number_end = key($sem_data[$seminar_id]['sem_number_end']);
+                if ($sem_number_start != $sem_number_end) {
+                    $sem_name .= ' (' . $this->search_obj->sem_dates[$sem_number_start]['name'] . ' - ';
+                    $sem_name .= (($sem_number_end == -1)
+                            ? _('unbegrenzt')
+                            : $this->search_obj->sem_dates[$sem_number_end]['name']) . ')';
+                } elseif ($this->sem_browse_data['group_by']) {
+                    $sem_name .= " (" . $this->search_obj->sem_dates[$sem_number_start]['name'] . ')';
+                }
+                $row .= '<td width="1%" class="hidden-tiny-down">';
+                $row .= CourseAvatar::getAvatar($seminar_id)->getImageTag(Avatar::SMALL, ['title' => $seminar_obj->getName()]);
+                $row .= '</td>';
+
+            }
+            $send_from_search = URLHelper::getUrl(basename($_SERVER['PHP_SELF']), ['keep_result_set' => 1, 'cid' => null]);
+            $send_from_search_link = URLHelper::getLink($this->target_url,
+                    [
+                        $this->target_id => $seminar_id,
+                        'cid' => null,
+                        'send_from_search' => 1,
+                        'send_from_search_page' => $send_from_search
+                    ]);
+            $row .= '<td style="width: 66%" colspan="2">';
+
+            // Show the "more" icon only if there are visible children.
+            if (count($seminar_obj->children) > 0) {
+
+                // If you are not root, perhaps not all available subcourses are visible.
+                $visibleChildren = $seminar_obj->children;
+                if (!$GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM)) {
+                    $visibleChildren = $visibleChildren->filter(function($c) {
+                        return $c->visible;
+                    });
+                }
+                if (count($visibleChildren) > 0) {
+                    $row .= Icon::create('add', Icon::ROLE_CLICKABLE ,[
+                            'id' => 'show-subcourses-' . $seminar_id,
+                            'title' => sprintf(_('%u Unterveranstaltungen anzeigen'), count($visibleChildren)),
+                            'onclick' => "jQuery('tr.subcourses-" . $seminar_id . "').removeClass('hidden-js');jQuery(this).closest('tr').addClass('has-subcourses');jQuery(this).hide();jQuery('#hide-subcourses-" . $seminar_id . "').show();"
+                        ])->asImg(12) . ' ';
+                    $row .= Icon::create('remove', Icon::ROLE_CLICKABLE ,[
+                            'id' => 'hide-subcourses-' . $seminar_id,
+                            'style' => 'display:none',
+                            'title' => sprintf(_('%u Unterveranstaltungen ausblenden'), count($visibleChildren)),
+                            'onclick' => "jQuery('tr.subcourses-" . $seminar_id . "').addClass('hidden-js'); jQuery(this).closest('tr').removeClass('has-subcourses');jQuery(this).hide();jQuery('#show-subcourses-" . $seminar_id . "').show();"
+                        ])->asImg(12) . ' ';
+                }
+            }
+
+            $row .= '<a href="' . $send_from_search_link . '">';
+            if (Config::get()->IMPORTANT_SEMNUMBER && $seminar_number) {
+                $row .= htmlReady($seminar_number) . " ";
+            }
+            $row .= htmlReady($sem_name) . '</a><br>';
+            //create Turnus field
+            if ($studygroup_mode) {
+                $row .= '<div style="font-size:smaller">'
+                        . htmlReady(mb_substr($seminar_obj->description, 0, 100))
+                        . '</div>';
+            } else {
+                $temp_turnus_string = $seminar_obj->getDatesExport(
+                    [
+                        'short' => true,
+                        'shrink' => true,
+                        'semester_id' => ''
+                    ]
+                );
+                //Shorten, if string too long (add link for details.php)
+                if (mb_strlen($temp_turnus_string) > 70) {
+                    $temp_turnus_string = htmlReady(mb_substr($temp_turnus_string, 0, mb_strpos(mb_substr($temp_turnus_string, 70, mb_strlen($temp_turnus_string)), ',') + 71));
+                    $temp_turnus_string .= ' ... <a href="' . $send_from_search_link . '">(' . _('mehr') . ')</a>';
+                } else {
+                    $temp_turnus_string = htmlReady($temp_turnus_string);
+                }
+                if (!Config::get()->IMPORTANT_SEMNUMBER) {
+                    $row .= '<div style="margin-left:5px;font-size:smaller">' . htmlReady($seminar_number) . '</div>';
+                }
+                $row .= '<div style="margin-left:5px;font-size:smaller">' . $temp_turnus_string . '</div>';
+                if (count($seminar_obj->children) > 0 && count($visibleChildren) > 0) {
+                    $row .= '<div style="margin-left:5px;font-size:smaller">';
+                    $row .= sprintf(_('%u Unterveranstaltungen'), count($visibleChildren));
+                    $row .= '</div>';
+                }
+            }
+            $row .= '</td>';
+            $row .= '<td style="text-align: right">(';
+            $doz_name = [];
+            $c = 0;
+            reset($sem_data[$seminar_id]['fullname']);
+            foreach ($sem_data[$seminar_id]['username'] as $anzahl1) {
+                if ($c == 0) {
+                    $d_name = key($sem_data[$seminar_id]['fullname']);
+                    $anzahl2 = current($sem_data[$seminar_id]['fullname']);
+                    next($sem_data[$seminar_id]['fullname']);
+                    $c = $anzahl2 / $anzahl1;
+                    $doz_name = array_merge($doz_name, array_fill(0, $c, $d_name));
+                }
+                --$c;
+            }
+            $doz_uname = array_keys($sem_data[$seminar_id]['username']);
+            $doz_position = array_keys($sem_data[$seminar_id]['position']);
+            if (count($doz_name)) {
+                if (count($doz_position) != count($doz_uname)) {
+                    $doz_position = range(1, count($doz_uname));
+                }
+                array_multisort($doz_position, $doz_name, $doz_uname);
+                $i = 0;
+                foreach ($doz_name as $index => $value) {
+                    if ($value) {  // hide dozenten with empty username
+                        if ($i == 4) {
+                            $row .= '... <a href="' . $send_from_search_link . '">(' . _('mehr') . ')</a>';
+                            break;
+                        }
+                        $row .= '<a href="' . URLHelper::getLink('dispatch.php/profile', ['username' => $doz_uname[$index]]) . '">' . htmlReady($value) . '</a>';
+                        if ($i != count($doz_name) - 1) {
+                            $row .= ', ';
+                        }
+                    }
+                    ++$i;
+                }
+                $row .= ')</td>';
+                if (Config::get()->COURSE_SEARCH_SHOW_ADMISSION_STATE) {
+                    $row .= '<td>';
+                    switch (self::getStatusCourseAdmission($seminar_id,
+                            $seminar_obj->admission_prelim)) {
+                        case 1:
+                            $row .= Icon::create(
+                                'info-circle',
+                                Icon::ROLE_STATUS_YELLOW,
+                                tooltip2(_('Eingeschränkter Zugang'))
+                            );
+                            break;
+                        case 2:
+                            $row .= Icon::create(
+                                'decline-circle',
+                                Icon::ROLE_STATUS_RED,
+                                tooltip2(_('Kein Zugang'))
+                            );
+                            break;
+                        default:
+                            $row .= Icon::create(
+                                'check-circle',
+                                Icon::ROLE_STATUS_GREEN,
+                                tooltip2(_('Uneingeschränkter Zugang'))
+                            );
+                    }
+                    $row .= '</td>';
+                }
+                $row .= '</tr>';
+            }
+
+            // Process children.
+            foreach ($seminar_obj->children as $child) {
+                $row .= $this->printCourseRow($child->id, $sem_data, true);
+            }
+
+        }
+
+        return $row;
+    }
+
+
+    /**
+     * Returns a new navigation object corresponding to the given target and
+     * name of the option. The target has two possibel values "sidebar" and
+     * "course" and indicates the place where the navigation is shown.
+     * The option name is the key of an entry in the array with the navigation
+     * options.
+     *
+     * The navigation options are configured in the global configuration as an
+     * array. For further details see documentation of entry
+     * COURSE_SEARCH_NAVIGATION_OPTIONS in global configuration.
+     *
+     * This is an example with all possible options:
+     *
+     * {
+     *     // "courses", "semtree" and "rangetree" are the "old" search options.
+     *     // The link text is fixed.
+     *     "courses":{
+     *         "visible":true,
+     *         // The target indicates where the link to this search option is
+     *         // placed. Possible values are "sidebar" for a link in the sidebar
+     *         // or "courses" to show a link (maybe with picture) below the
+     *         // "course search".
+     *         "target":"sidebar"
+     *     },
+     *     "semtree":{
+     *         "visible":true,
+     *         "target":"sidebar"
+     *     },
+     *     "rangetree":{
+     *         "visible":false,
+     *         "target":"sidebar"
+     *     },
+     *     // New option to acivate the search for modules and the systematic
+     *     // search in studycourses, field of study and degrees.
+     *     "module":{
+     *         "visible":true,
+     *         "target":"sidebar"
+     *     },
+     *     // This option shows a direct link in the sidebar to an entry (level)
+     *     // in the range tree. The link text is the name of the level.
+     *     "fb3_hist":{
+     *         "visible":true,
+     *         "target":"sidebar",
+     *         "range_tree_id":"d1a07cf0c8057c664279214cc070b580"
+     *     },
+     *     // The same for an entry in the sem tree.
+     *     "grundstudium":{
+     *         "visible":true,
+     *         "target":"sidebar",
+     *         "sem_tree_id":"e1a07cf0c8057c664279214cc070b580"
+     *     },
+     *     // This shows a link in the sidebar to the course search. The text is
+     *     // availlable in two languages.
+     *     "vvz":{
+     *         "visible":true,
+     *         "target":"sidebar",
+     *         "url":"dispatch.php/search/courses?level=f&option=vav",
+     *         "title":{
+     *             "de_DE":"Veranstaltungsverzeichnis",
+     *             "en_GB":"Course Catalogue"
+     *         }
+     *     },
+     *     // This option uses an url with search option and shows a link in the
+     *     // sidebar to an entry in the range tree with all courses.
+     *     "test":{
+     *         "visible":true,
+     *         "target":"sidebar",
+     *         "url":"dispatch.php/search/courses?start_item_id=d1a07cf0c8057c664279214cc070b580&cmd=show_sem_range_tree&item_id=d1a07cf0c8057c664279214cc070b580_withkids&level=ev",
+     *         "title":{
+     *             "de_DE":"Historisches Institut",
+     *             "en_GB":"Historical Institute"
+     *         }
+     *     },
+     *     // This option shows a link to the sem tree with picture below the
+     *     // course search (target: courses).
+     *     // This is the behaviour of Stud.IP < 4.2.
+     *     "csemtree":{
+     *         "visible":true,
+     *         "target":"courses",
+     *         "url":"dispatch.php/search/courses?level=vv",
+     *         "img":{
+     *             "filename":"directory-search.png",
+     *             "attributes":{
+     *                 "size":"260@100"
+     *             }
+     *         },
+     *         "title":{
+     *             "de_DE":"Suche im Vorlesungsverzeichnis",
+     *             "en_GB":"Search course directory"
+     *         }
+     *     },
+     *     // This option shows a link to the range tree with picture below the
+     *     // course search (target: courses).
+     *     // This is the behaviour of Stud.IP < 4.2.
+     *     "crangetree":{
+     *         "visible":true,
+     *         "target":"courses",
+     *         "url":"dispatch.php/search/courses?level=ev",
+     *         "img":{
+     *             "filename":"institute-search.png",
+     *             "attributes":{
+     *                 "size":"260@100"
+     *             }
+     *         },
+     *         "title":{
+     *             "de_DE":"Suche in Einrichtungen",
+     *             "en_GB":"Search institutes"
+     *         }
+     *     }
+     * }
+     *
+     *
+     * @param string $target
+     * @param string $option_name
+     * @return Navigation|null
+     */
+    public static function getSearchOptionNavigation($target, $option_name = null): ?Navigation
+    {
+        // return first visible search option
+        if (is_null($option_name)) {
+            $options = Config::get()->COURSE_SEARCH_NAVIGATION_OPTIONS;
+            foreach ($options as $name => $option) {
+                if ($option['visible'] && $option['target'] === $target) {
+                    return self::getSearchOptionNavigation($target, $name);
+                }
+            }
+            return null;
+        }
+
+        $installed_languages = array_keys(Config::get()->INSTALLED_LANGUAGES);
+        $language = $_SESSION['_language'] ?? reset($installed_languages);
+        $option = Config::get()->COURSE_SEARCH_NAVIGATION_OPTIONS[$option_name];
+        if (!$option['visible'] || $option['target'] !== $target) {
+            return null;
+        }
+        if (empty($option['url'])) {
+            switch ($option_name) {
+                case 'courses':
+                case 'semtree':
+                    return new Navigation(_('Vorlesungsverzeichnis'),
+                            URLHelper::getURL('dispatch.php/search/courses',
+                                    [
+                                        'type' => 'semtree'
+                                    ], true));
+                case 'rangetree':
+                    return new Navigation(_('Einrichtungsverzeichnis'),
+                            URLHelper::getURL('dispatch.php/search/courses',
+                                    [
+                                        'type' => 'rangetree'
+                                    ], true));
+                case 'module':
+                    return new MVVSearchNavigation(_('Modulverzeichnis'),
+                            URLHelper::getURL('dispatch.php/search/module'),null, true);
+            }
+        } else {
+            return new Navigation($option['title'][$language],
+                    URLHelper::getURL($option['url'], ['option' => $option_name], true));
+        }
+        if (!empty($option['sem_tree_id'])) {
+            $study_area = StudipStudyArea::find($option['sem_tree_id']);
+            return new Navigation($study_area->name,
+                    URLHelper::getURL('dispatch.php/search/courses',
+                        [
+                            'start_item_id' => $option['sem_tree_id'],
+                            'path_id'       => $option['sem_tree_id'],
+                            'cmd'           => 'show_sem_range',
+                            'item_id'       => $option['sem_tree_id'] . '_withkids',
+                            'level'         => 'vv',
+                            'option'        => $option_name
+                        ], true));
+        }
+        if (!empty($option['range_tree_id'])) {
+            $item_name = DBManager::get()->fetchColumn('
+                    SELECT `name`
+                    FROM `range_tree`
+                    WHERE item_id = ?',
+                    [$option['range_tree_id']]);
+            return new Navigation($item_name,
+                    URLHelper::getURL('dispatch.php/search/courses',
+                        [
+                            'start_item_id' => $option['range_tree_id'],
+                            'path_id'       => $option['range_tree_id'],
+                            'cmd'           => 'show_sem_range_tree',
+                            'item_id'       => $option['range_tree_id'] . '_withkids',
+                            'level'         => 'ev',
+                            'option'        => $option_name
+                        ], true));
+        }
+
+        return null;
+    }
+
+    /**
+     * The class SemBrowse uses a vast number of variables stored in the
+     * session. This function sets the default values or transfers some
+     * of them to url parameters if a filter in the sidebar has been changed.
+     *
+     * @see SemBrowse::setClassesSelector()
+     * @see SemBrowse::setSemesterSelector()
+     */
+    public static function transferSessionData()
+    {
+        if (empty($_SESSION['sem_browse_data']) || Request::option('reset_all')) {
+            $_SESSION['sem_browse_data'] = [];
+        }
+
+        $_SESSION['sem_browse_data']['qs_choose'] = Request::get('search_sem_qs_choose',
+                $_SESSION['sem_browse_data']['qs_choose'] ?? null);
+
+        // simulate button clicked if semester was changed
+        $old_default_sem = $_SESSION['sem_browse_data']['default_sem'] ?? null;
+        if (Request::option('search_sem_sem', $old_default_sem) != $old_default_sem) {
+            $_SESSION['sem_browse_data']['default_sem'] = Request::option('search_sem_sem');
+            if ($_SESSION['sem_browse_data']['sset']) {
+                Request::set('search_sem_quick_search_parameter', $_SESSION['sem_browse_data']['sset']);
+                Request::set('search_sem_quick_search', $_SESSION['sem_browse_data']['sset']);
+                Request::set('search_sem_qs_choose', $_SESSION['sem_browse_data']['qs_choose']);
+                Request::set('search_sem_category', $_SESSION['sem_browse_data']['show_class']);
+                Request::set('search_sem_do_search', '1');
+                Request::set('search_sem_' . md5('is_sended'), '1');
+            } else {
+                Request::set('search_sem_category', $_SESSION['sem_browse_data']['show_class']);
+                Request::set('search_sem_sem_change', '1');
+                Request::set('search_sem_sem_select', '1');
+            }
+        }
+
+        // simulate button clicked if class was changed
+        $old_show_class = $_SESSION['sem_browse_data']['show_class'] ?? null;
+        if (Request::option('show_class', $old_show_class) != $old_show_class) {
+            $_SESSION['sem_browse_data']['show_class'] = Request::option('show_class');
+
+            if ($_SESSION['sem_browse_data']['show_class']
+                    && $_SESSION['sem_browse_data']['show_class'] != 'all') {
+                $class = $GLOBALS['SEM_CLASS'][$_SESSION['sem_browse_data']['show_class']];
+                $_SESSION['sem_browse_data']['sem_status'] = array_keys($class->getSemTypes());
+            } else {
+                $_SESSION['sem_browse_data']['sem_status'] = false;
+            }
+
+            if ($_SESSION['sem_browse_data']['sset']) {
+                Request::set('search_sem_quick_search_parameter', $_SESSION['sem_browse_data']['sset']);
+                Request::set('search_sem_quick_search', $_SESSION['sem_browse_data']['sset']);
+                Request::set('search_sem_qs_choose', $_SESSION['sem_browse_data']['qs_choose']);
+                Request::set('search_sem_category', $_SESSION['sem_browse_data']['show_class']);
+                Request::set('search_sem_do_search', '1');
+                Request::set('search_sem_' . md5('is_sended'), '1');
+            } else {
+                Request::set('search_sem_category', $_SESSION['sem_browse_data']['show_class']);
+                Request::set('search_sem_sem_change', '1');
+                Request::set('search_sem_sem_select', '1');
+            }
+        }
+
+        // set default values
+        if (empty($_SESSION['sem_browse_data']['default_sem'])) {
+            $_SESSION['sem_browse_data']['default_sem'] =
+                Semester::getIndexById(self::getDefaultSemester(), true, true)
+                        ?: 'all';
+        }
+        $_SESSION['sem_browse_data']['show_class'] =
+                $_SESSION['sem_browse_data']['show_class'] ?? 'all';
+        $_SESSION['sem_browse_data']['group_by'] =
+                $_SESSION['sem_browse_data']['group_by'] ?? '0';
+    }
+
+    /**
+     * Retrieves the default semester from session or calculate it considering
+     * the value from SEMESTER_TIME_SWITCH.
+     *
+     * @return Semester The semester object of the default semester.
+     */
+    public static function getDefaultSemester()
+    {
+        $default_sem = $_SESSION['_default_sem'];
+        if (!$default_sem) {
+            $current_sem = Semester::findDefault();
+            $default_sem = $current_sem->id;
+        }
+
+        return $default_sem;
+    }
+
+    /**
+     * Adds a widget to the sidebar to select a course class. The result set is
+     * filtered by this class.
+     *
+     * @param string $submit_url The submit url.
+     */
+    public static function setClassesSelector($submit_url)
+    {
+        $classes_filter = new SelectWidget(_('Veranstaltungsklassen'),
+                $submit_url, 'show_class');
+        $classes_filter->addElement(new SelectElement('all', _('Alle'),
+                ($_SESSION['sem_browse_data']['show_class'] ?: 'all') === 'all'));
+        foreach ($GLOBALS['SEM_CLASS'] as $key => $val) {
+            $classes_filter->addElement(new SelectElement($key, $val['name'],
+                    ($_SESSION['sem_browse_data']['show_class'] == $key)));
+        }
+        Sidebar::Get()->addWidget($classes_filter);
+    }
+
+    /**
+     * Adds a widget to the sidebar to select a semester. The result set is
+     * filtered by this semester.
+     *
+     * @param string $submit_url The submit url.
+     */
+    public static function setSemesterSelector($submit_url)
+    {
+        $semesters = Semester::findAllVisible();
+        $sidebar = Sidebar::Get();
+        $list = new SelectWidget(_('Semester'),
+                $submit_url, 'search_sem_sem');
+        $list->addElement(new SelectElement('all', _('Alle'),
+                ($_SESSION['sem_browse_data']['default_sem']) === 'all'));
+        foreach(array_reverse($semesters, true) as $i => $semester_data) {
+            $list->addElement(new SelectElement(
+                $i,
+                $semester_data['name'],
+                ($_SESSION['sem_browse_data']['default_sem'] !== 'all'
+                    && intval($_SESSION['sem_browse_data']['default_sem']) === $i)
+            ));
+        }
+        $sidebar->addWidget($list, 'filter_semester');
+    }
+
+    /**
+     * Returns the admission status for a course.
+     *
+     * @param string $seminar_id Id of the course
+     * @param bool   $prelim     State of preliminary setting
+     * @return int
+     */
+    public static function getStatusCourseAdmission($seminar_id, $prelim)
+    {
+        $sql = "SELECT COUNT(`type`) AS `types`,
+                       SUM(IF(`type` = 'LockedAdmission', 1, 0)) AS `type_locked`
+                FROM `seminar_courseset`
+	            INNER JOIN `courseset_rule` USING (`set_id`)
+	            WHERE `seminar_id` = ?
+                GROUP BY `set_id`";
+
+	    $stmt = DBManager::get()->prepare($sql);
+	    $stmt->execute([$seminar_id]);
+	    $result = $stmt->fetch();
+
+        if (!empty($result['types'])) {
+            if ($result['type_locked']) {
+                return 2;
+            }
+            return 1;
+        }
+
+        if ($prelim) {
+            return 1;
+        }
+        return 0;
+    }
+
+    /**
+     * Returns a Quick Search form to put inside a WidgetElement.
+     *
+     * @param string   $level     The Level of search , expected ('f', 'vv', 'ev')
+     * @return string $search_form_content Contains a form element with a quick search input, predefined (hidden) inputs and search button
+     */
+    public function getQuickSearchForm()
+    {
+        if ($this->sem_browse_data['level'] === 'vv') {
+            $this->search_obj->sem_tree =& $this->sem_tree->tree;
+            if ($this->sem_tree->start_item_id !== 'root') {
+                $this->search_obj->search_scopes[] = $this->sem_tree->start_item_id;
+            }
+        } elseif ($this->sem_browse_data['level'] === 'ev') {
+            $this->search_obj->range_tree =& $this->range_tree->tree;
+            if ($this->range_tree->start_item_id !== 'root'){
+                $this->search_obj->search_ranges[] = $this->range_tree->start_item_id;
+            }
+        }
+
+        $search_form_content = $this->search_obj->getFormStart(URLHelper::getLink(), ['class' => '']);
+        $quicksearch = $this->getQuicksearch();
+        $quicksearch->setInputStyle('height:22px;width: 100%;');
+        $quicksearch->withButton(['search_button_name'=> 'course_search_button']);
+        $quicksearch->disableAutocomplete();
+        $search_form_content .= $quicksearch->render();
+        $search_form_content .= $this->search_obj->getHiddenField('qs_choose','title_lecturer_number');
+
+        if($this->sem_browse_data['level'] == 'vv')
+            $search_form_content .= $this->search_obj->getHiddenField('scope_choose', $this->sem_tree->start_item_id);
+
+        if($this->sem_browse_data['level'] == 'ev')
+            $search_form_content .= $this->search_obj->getHiddenField('range_choose', $this->range_tree->start_item_id);
+
+        $search_form_content .= $this->search_obj->getHiddenField('level', $this->sem_browse_data['level']);
+        $search_form_content .= $this->search_obj->getHiddenField('sem', htmlReady($_SESSION['sem_browse_data']['default_sem']));
+
+        $search_form_content .= $this->search_obj->getFormEnd();
+        return $search_form_content;
+    }
+}