Course.php

            $stmt = $db->prepare(
                "SELECT 1
                 FROM `user_inst`
                 JOIN `seminar_inst` USING (`institute_id`)
                 WHERE `user_inst`.`user_id` = :user_id
                   AND `seminar_inst`.`seminar_id` = :course_id"
            );
            $stmt->execute([
                'course_id' => $this->id,
                'user_id'   => $user->id,
            ]);
            $user_in_institute = $stmt->fetchColumn();
            if (!$user_in_institute) {
                throw new \Studip\EnrolmentException(
                    _('Die einzutragende Person ist kein Mitglied einer Einrichtung, zu der die Veranstaltung zugeordnet ist.'),
                    \Studip\EnrolmentException::NO_INSTITUTE_MEMBER
                );
            }
        }

        //Load the course member object:
        $course_member = CourseMember::findOneBySQL(
            '`seminar_id` = :course_id AND `user_id` = :user_id',
            ['course_id' => $this->id, 'user_id' => $user->id]
        );
        $new_member_position = $db->fetchColumn(
            'SELECT MAX(`position`) + 1
             FROM `seminar_user`
             WHERE `status` = :status
               AND `seminar_id` = :course_id',
            ['status' => $permission_level, 'course_id' => $this->id]
        ) ?? 0;
        $number_of_lecturers = CourseMember::countByCourseAndStatus($this->id, 'dozent');

        if (!$course_member) {
            $course_member = new CourseMember();
            $course_member->seminar_id = $this->id;
            $course_member->user_id    = $user->id;
            $course_member->status     = $permission_level;
        }
        $course_member->position = $new_member_position;
        if (in_array($permission_level, ['tutor', 'dozent'])) {
            //Tutors and lecturers are always visible in the course:
            $course_member->visible = 'yes';
        } else {
            //All others may decide for themselves:
            $course_member->visible = 'unknown';
        }

        $ranks = array_flip(['user', 'autor', 'tutor', 'dozent']);

        if ($course_member->isNew()) {
            //The user shall be added to the course. Before storing, we must check
            //if the contingent shall be regarded and if there is a free seat
            //for the user:

            //TODO: Move the following check back to controllers.
            //Background: Lecturers may enforce the entry of a student, but the latter must not
            //override the checks.
            if (
                $permission_level === 'autor'
                && $regard_contingent
                && $this->isAdmissionEnabled()
                && $this->getFreeSeats() < 1
            ) {
                //There is no free seat to add another member.
                throw new \Studip\EnrolmentException(
                    sprintf(
                        _('Für %s ist kein Platz mehr in der Veranstaltung frei.'),
                        $user->getFullName()
                    ),
                    \Studip\EnrolmentException::COURSE_IS_FULL
                );
            }

            $course_member->store();

            //Delete the user from admission applications:
            $application_removed = AdmissionApplication::deleteBySQL(
                '`user_id` = :user_id AND `seminar_id` = :course_id',
                ['user_id' => $user->id, 'course_id' => $this->id]
            );
            if ($application_removed && $renumber_admission) {
                //Renumber the waitlist or the other admission list:
                AdmissionApplication::renumberAdmission($this->id);
            }

            //Remove the user from the course set, if any:
            $course_set = $this->getCourseSet();
            $removed_from_course_set = 0;
            if ($course_set) {
                $removed_from_course_set = AdmissionPriority::unsetPriority($course_set->getId(), $user->id, $this->id);
            }

            if ($permission_level === 'dozent' && Config::get()->DEPUTIES_ENABLE) {
                //Delete a possible deputy entry for the lecturer:
                $deputy = Deputy::find([$this->id, $user->id]);
                if ($deputy) {
                    $deputy->delete();
                }

                //Assign all default deputies of the lecturer to the course
                //if they are not already a lecturer of the course:
                $unassigned_deputies = Deputy::findBySQL(
                    "`range_id` = :lecturer_id
                      AND `user_id` NOT IN (
                         SELECT `user_id` FROM `seminar_user`
                         WHERE `seminar_id` = :course_id
                         AND `status` = 'dozent'
                      )",
                    [
                        'lecturer_id' => $user->id,
                        'course_id'   => $this->id
                    ]
                );
                foreach ($unassigned_deputies as $deputy) {
                    Deputy::addDeputy($deputy->user_id, $this->id);
                }
            }

            //Delete course entries in the schedule:
            ScheduleCourseDate::deleteBySQL(
                'user_id = :user_id AND course_id = :course_id',
                [
                    'user_id'   => $user->id,
                    'course_id' => $this->id
                ]
            );

            //Log the event:
            StudipLog::log('SEM_USER_ADD', $this->id, $user->id, $permission_level, 'Wurde in die Veranstaltung eingetragen');

            if ($this->parent instanceof Course) {
                $this->parent->addMember($user, $permission_level, false);
            }

            if ($send_mail) {
                setTempLanguage($user->id);
                $body = '';
                $subject = '';
                if ($application_removed) {
                    //Enrolment after being on the wait list:
                    $subject = _('Zulassung zur Veranstaltung');
                    $body = sprintf(
                        _('Sie wurden für die Veranstaltung %s zugelassen. Ihr Eintrag auf der Warteliste wurde daher entfernt.'),
                        $this->getFullName()
                    );
                } elseif ($removed_from_course_set) {
                    //Enrolment after being in a course set:
                    $subject = _('Zulassung zur Veranstaltung');
                    $body = sprintf(
                        _('Sie wurden für die Veranstaltung %s endgültig zugelassen.'),
                        $this->getFullName()
                    );
                } else {
                    //Direct enrolment without waitlist or course set:
                    $subject = _('Eintragung in Veranstaltung');
                    $body = sprintf(
                        _('Sie wurden in die Veranstaltung %s eingetragen.'),
                        $this->getFullName()
                    );
                }
                $messaging = new messaging();
                $messaging->insert_message(
                    $body,
                    $user->username,
                    '____%system%____',
                    false,
                    false,
                    '1',
                    false,
                    $subject,
                    true
                );
                restoreLanguage();
            }
        } elseif ($ranks[$course_member->status] < $ranks[$permission_level]
            && $course_member->status !== 'dozent' || $number_of_lecturers > 1) {
            //The user is already a member of the course. They shall either be promoted
            //or they are not a lecturer or there is more than one lecturer in the course
            //(please read this multiple times in case you are unsure about these conditions).

            $course_member->status = $permission_level;
            $course_member->position = $new_member_position;

            $success = !$course_member->isDirty() || $course_member->store();

            if (!$success) {
                throw new \Studip\EnrolmentException(
                    _('Die Person kann nicht hochgestuft werden.'),
                    \Studip\EnrolmentException::PROMOTION_NOT_POSSIBLE
                );
            }
        } elseif ($course_member->status === 'dozent' && $number_of_lecturers <= 1) {
            throw new \Studip\EnrolmentException(
                sprintf(
                    _('Die Person kann nicht herabgestuft werden, da mindestens eine lehrende Person (%1$s) in die Veranstaltung eingetragen sein muss! Tragen Sie deshalb zuerst eine weitere Person als lehrende Person (%1$s) ein und versuchen Sie es dann erneut!'),
                    get_title_for_status('dozent', 1, $this->status)
                ),
                \Studip\EnrolmentException::DEMOTION_NOT_POSSIBLE
            );
        }
        $this->resetRelation('members');

        return $course_member;
    }

    /**
     * Removes a user from this course.
     *
     * @param User $user The user to be removed.
     * @param bool $send_mail Whether to send a mail after the membership deletion
     *     (true) or not (false). Defaults to false.
     *
     * @return void If this method does not throw, everything went fine.
     *
     * @throws \Studip\MembershipException If the user cannot be removed from the course.
     */
    public function deleteMember(User $user, bool $send_mail = false) : void
    {
        $membership = CourseMember::findOneBySQL(
            'seminar_id = :course_id AND user_id = :user_id',
            ['course_id' => $this->id, 'user_id' => $user->id]
        );
        if (!$membership) {
            //The user is not a member of the course.
            throw new \Studip\MembershipException(
                sprintf(
                    _('%1$s ist kein Mitglied der Veranstaltung %2$s.'),
                    $user->getFullName(),
                    $this->name
                ),
                \Studip\MembershipException::NOT_A_MEMBER,
                $user
            );
        }

        if ($membership->status === 'dozent') {
            //Check if there are enough lecturers left:
            $lecturer_amount = CourseMember::countByCourseAndStatus($this->id, 'dozent');
            if ($lecturer_amount < 2) {
                //Not enough lecturers left.
                throw new \Studip\MembershipException(
                    sprintf(
                        _('In die Veranstaltung muss mindestens eine lehrende Person (%s) eingetragen sein. Um diese Person aus der Veranstaltung zu entfernen, muss zunächst eine weitere lehrende Person eingetragen werden.'),
                        get_title_for_status('dozent', 1, $this->status)
                    ),
                    \Studip\MembershipException::USER_IS_SOLE_LECTURER,
                    $user
                );
            }
        }

        //At this point, the user may be removed.
        $success = $membership->delete();
        if (!$success) {
            throw new \Studip\MembershipException(
                sprintf(
                    _('Es trat ein Fehler auf beim Austragen von %1$s aus der Veranstaltung %2$s.'),
                    $user->getFullName(),
                    $this->getFullname()
                ),
                \Studip\MembershipException::REMOVAL_FAILED,
                $user
            );
        }

        $removed_from_parent   = false;
        $removed_from_children = false;

        if ($this->parent_course) {
            //This course has a parent course.
            //Delete the user from the parent course if they are not part of
            //one of the other child courses.
            $other_memberships = CourseMember::countBySql(
                'JOIN `seminare` USING (`seminar_id`)
                 WHERE `user_id` = :user_id
                   AND `parent_course` = :parent_course_id
                   AND `seminar_id` <> :this_course_id',
                [
                    'user_id'          => $user->id,
                    'parent_course_id' => $this->parent_course->id,
                    'this_course_id'   => $this->id
                ]
            );
            if ($other_memberships === 0) {
                //No other memberships. We can delete the user from the parent course.
                $this->parent_course->deleteMember($user, false);
                $removed_from_parent = true;
            }
        }

        if ($this->children) {
            //The other way around: This course has child courses and because the user
            //has been removed from this course, they shall also be removed from all
            //child courses.
            foreach ($this->children as $child) {
                $child->deleteMember($user);
            }
            $removed_from_children = true;
        }

        if ($send_mail) {
            $messaging = new messaging();
            setTempLanguage($user->id);
            $subject = sprintf(_('%s: Anmeldung aufgehoben'), $this->getFullName());
            $body = sprintf(_('Ihre Anmeldung für die Veranstaltung %s wurde aufgehoben.'), $this->getFullName());
            $messaging->insert_message(
                $body,
                $user->username,
                '____%system%____',
                false,
                false,
                '1',
                false,
                $subject,
                true
            );
            restoreLanguage();
        }

        if ($membership->status === 'dozent') {
            //Special treatment for lecturers:
            //Remove them from course dates and remove them as deputies.

            $db = DBManager::get();
            $stmt = $db->prepare(
                'DELETE FROM `termin_related_persons`
                 WHERE `user_id` = :user_id
                   AND `range_id` IN (
                     SELECT `termin_id` FROM `termine`
                     WHERE `range_id` = :course_id
                   )'
            );
            $stmt->execute(['course_id' => $this->id, 'user_id' => $user->id]);

            if (Deputy::isActivated()) {
                //For all courses where the user is a deputy, they can be removed as deputy
                //from the course, if the other lecturers are no deputies and the current user
                //is not a deputy:
                $all_user_deputy_duties = Deputy::findByRange_id($user->id);
                foreach ($all_user_deputy_duties as $deputy_duty) {
                    $other_deputy_amount = Deputy::countBySql(
                        "JOIN `seminar_user`
                           ON `seminar_user`.`user_id` = `deputies`.`range_id`
                         WHERE `seminar_user`.`user_id` <> :deleted_user_id
                           AND `seminar_user`.`status` = 'dozent'",
                        ['deleted_user_id' => $user->id]
                    );
                    if ($other_deputy_amount === 0 && $GLOBALS['user']->id != $deputy_duty->user_id) {
                        Deputy::deleteBySQL(
                            '`range_id` = :course_id AND `user_id` = :deputy_id',
                            ['course_id' => $this->id, $deputy_duty->user_id]
                        );
                    }
                }
            }
        }

        //Delete data field entries that are related to the user and the course:
        DatafieldEntryModel::deleteBySQL(
            '`range_id` = :user_id AND `sec_range_id` = :course_id',
            ['user_id' => $user->id, 'course_id' => $this->id]
        );

        //Remove the user from course groups:
        if ($this->statusgruppen) {
            foreach ($this->statusgruppen as $group) {
                $group->removeUser($user->id, true);
            }
        }

        StudipLog::log('SEM_USER_DEL', $this->id, $user->id, 'Wurde aus der Veranstaltung entfernt');

        $this->resetRelation('members');

        //At this point, removal is complete.
    }

    /**
     * Moves a regular course member back onto the waitlist.
     *
     * @param User $user The course member to be moved back to the waitlist.
     * @param bool $send_mail Whether to send a mail to inform the user of them
     *     being moved back to the waitlist (true) or not (false). Defaults to false.
     *
     * @return void
     *
     * @throws \Studip\Exception In case the former course member cannot be moved to the waitlist.
     *
     * @throws \Studip\MembershipException In case the membership cannot be terminated.
     */
    public function moveMemberToWaitlist(User $user, bool $send_mail = false): void
    {
        $this->deleteMember($user);
        $this->addMemberToWaitlist($user, PHP_INT_MAX, false);

        if ($send_mail) {
            setTempLanguage($user->id);
            $subject = studip_interpolate(
                _('%{course}: Anmeldung aufgehoben, auf Warteliste gesetzt'),
                ['course' => $this->getFullName()]
            );
            $message = studip_interpolate(
                _('Sie wurden aus der Veranstaltung %{course} abgemeldet und auf die zugehörige Warteliste gesetzt.'),
                ['course' => $this->getFullName()]
            );
            messaging::sendSystemMessage($user->id, $subject, $message);
            restoreLanguage();
        }
    }

    /**
     * Swaps the course member position with another member. This is done by specifying a course member
     * and the new position where they shall be placed in the course.
     *
     * @param CourseMember $membership The course member to move to another position.
     *
     * @return int The new position of the course member.
     *
     * @throws \Studip\MembershipException In case when moving the member position was unsuccessful.
     */
    public function swapMemberPosition(CourseMember $membership, int $new_position): int
    {
        //At this point, the user is not at the highest position.
        //Load the member with the position $position + 1 and swap the positions.

        $next_member = CourseMember::findOneBySQL(
            '`seminar_id` = :course_id AND `status` = :permission_level AND `position` = :new_position',
            [
                'course_id'        => $this->id,
                'permission_level' => $membership->status,
                'new_position'    => strval($new_position)
            ]
        );
        $success = false;
        if ($next_member) {
            $swapped_position = $next_member->position;
            $next_member->position = $membership->position;
            $membership->position = $swapped_position;

            $next_member->store();
            $success = !$membership->isDirty() || $membership->store();
        } else {
            //There is a gap in the position numbers. The user can just be placed to the new position:
            $membership->position = $new_position;
            $success = !$membership->isDirty() || $membership->store();
        }

        if (!$success) {
            //Something went wrong.
            throw new \Studip\MembershipException(
                sprintf(
                    _('%1$s konnte nicht an die Position %2$u verschoben werden.'),
                    $membership->user->getFullName(),
                    $new_position
                ),
                \Studip\MembershipException::MOVING_POSITION_FAILED,
                $membership->user
            );
        }
        return (int) $membership->position;
    }

    /**
     * Moves a course member one position up.
     *
     * @param User $user The user to move up.
     *
     * @return int The new position of the user.
     */
    public function moveMemberUp(User $user) : int
    {
        $membership = CourseMember::findOneBySQL(
            '`seminar_id` = :course_id AND `user_id` = :user_id',
            ['course_id' => $this->id, 'user_id' => $user->id]
        );
        if (!$membership) {
            //The user is not a member.
            return -1;
        }

        if ($membership->position == 0) {
            //The user is already at the highest position.
            return 0;
        }
        return $this->swapMemberPosition($membership, intval($membership->position - 1));
    }

    /**
     * Moves a course member one position down.
     *
     * @param User $user The user to move down.
     *
     * @return int The new position of the user.
     */
    public function moveMemberDown(User $user) : int
    {
        $membership = CourseMember::findOneBySQL(
            '`seminar_id` = :course_id AND `user_id` = :user_id',
            ['course_id' => $this->id, 'user_id' => $user->id]
        );
        if (!$membership) {
            //The user is not a member.
            return -1;
        }

        //Get the maximum number for the permission level in the course:
        $stmt = DBManager::get()->prepare(
            'SELECT MAX(`position`)
             FROM `seminar_user`
             WHERE `seminar_id` = :course_id
               AND `status` = :permission_level'
        );
        $stmt->execute([
            'course_id'        => $this->id,
            'permission_level' => $membership->status,
        ]);
        $max_number = $stmt->fetchColumn();
        if ($max_number === false) {
            //Nothing there to move.
            return -1;
        }

        if ($membership->position == $max_number) {
            //The user is already at the lowest position.
            return (int) $max_number;
        }

        return $this->swapMemberPosition($membership, intval($membership->position + 1));
    }

    public function getNumParticipants()
    {
        return $this->countMembersWithStatus('user autor') + $this->getNumPrelimParticipants();
    }

    public function getNumPrelimParticipants()
    {
        return AdmissionApplication::countBySql(
            "seminar_id = ? AND status = 'accepted'",
            [$this->id]
        );
    }

    public function getNumWaiting()
    {
        return AdmissionApplication::countBySql(
            "seminar_id = ? AND status = 'awaiting'",
            [$this->id]
        );
    }

    public function getParticipantStatus($user_id)
    {
        $p_status = $this->members->findBy('user_id', $user_id)->val('status');
        if (!$p_status) {
            $p_status = $this->admission_applicants->findBy('user_id', $user_id)->val('status');
        }
        return $p_status;
    }

    /**
     * Determines the enrolment status of the user and their possibilities
     * to join the course.
     *
     * @param string $user_id The ID of the user for which to get enrolment information.
     *
     * @return \Studip\EnrolmentInformation The enrolment information
     *     for the specified user.
     */
    public function getEnrolmentInformation(string $user_id) : \Studip\EnrolmentInformation
    {
        //Check the course itself:

        if ($this->getSemClass()->isGroup()) {
            return new \Studip\EnrolmentInformation(
                _('Diese Veranstaltung ist die Hauptveranstaltung einer Veranstaltungsgruppe. Sie können sich nur in die zugehörigen Unterveranstaltungen eintragen.'),
                \Studip\Information::INFO,
                'main_course',
                false
            );
        }

        //Check the course set and if the user is on an admission list:

        if ($course_set = $this->getCourseSet()) {
            $info = new \Studip\EnrolmentInformation('');
            $info->setCodeword('course_set');
            $info->setEnrolmentAllowed(true);
            $message = _('Die Anmeldung zu dieser Veranstaltung folgt bestimmten Regeln.');
            $priority = AdmissionPriority::getPrioritiesByUser($course_set->getId(), $user_id);
            if (!empty($priority[$this->id])) {
                if ($course_set->hasAdmissionRule('LimitedAdmission')) {
                    $message .= ' ' . sprintf(
                            _('Sie stehen auf der Anmeldeliste für die automatische Platzverteilung der Veranstaltung mit der Priorität %u.'),
                            $priority[$this->id]
                        );
                } else {
                    $message .= ' ' . _('Sie stehen auf der Anmeldeliste für die automatische Platzverteilung der Veranstaltung.');
                }
            }
            $info->setMessage($message);
            return $info;
        }

        if ($this->lesezugriff == '0' && Config::get()->ENABLE_FREE_ACCESS && !$GLOBALS['perm']->get_studip_perm($this->id, $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Für diese Veranstaltung ist keine Anmeldung erforderlich.'),
                \Studip\Information::INFO,
                'free_access',
                true
            );
        }

        //Check the visibility of the course for the user:
        if (
            !$this->visible
            && !$this->isStudygroup()
            && !$GLOBALS['perm']->have_perm(Config::get()->SEM_VISIBILITY_PERM, $user_id)
        ) {
            return new \Studip\EnrolmentInformation(
                _('Sie dürfen sich in diese Veranstaltung nicht eintragen.'),
                \Studip\Information::INFO,
                'invisible',
                false
            );
        }

        //Check the lock rule for participants:
        if (LockRules::Check($this->id, 'participants')) {
            return new \Studip\EnrolmentInformation(
                _('Sie dürfen sich in diese Veranstaltung nicht selbst eintragen.'),
                \Studip\Information::INFO,
                'locked',
                false
            );
        }

        //Check the permissions of the user:

        $user = User::find($user_id);

        if (!$user) {
            return new \Studip\EnrolmentInformation(
                _('Sie sind nicht in Stud.IP angemeldet und können sich daher nicht in die Veranstaltung eintragen.'),
                \Studip\Information::WARNING,
                'nobody',
                false
            );
        }
        if (!$GLOBALS['perm']->have_perm('user', $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Sie haben keine ausreichende Berechtigung, um sich in die Veranstaltung einzutragen.'),
                \Studip\Information::INFO,
                'user',
                false
            );
        }
        if ($GLOBALS['perm']->have_perm('root', $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Sie haben root-Rechte und dürfen damit alles in Stud.IP.'),
                \Studip\Information::INFO,
                'root',
                true
            );
        }
        if ($GLOBALS['perm']->have_studip_perm('admin', $this->id, $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Sie verwalten diese Veranstaltung.'),
                \Studip\Information::INFO,
                'course_admin',
                true
            );
        }
        if ($GLOBALS['perm']->have_perm('admin', $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Als administrierende Person dürfen Sie sich nicht in eine Veranstaltung eintragen.'),
                \Studip\Information::INFO,
                'admin',
                false
            );
        }

        //Check the course membership:

        if ($GLOBALS['perm']->have_studip_perm('user', $this->id, $user_id)) {
            return new \Studip\EnrolmentInformation(
                _('Sie sind bereits in der Veranstaltung eingetragen.'),
                \Studip\Information::INFO,
                'already_member',
                true
            );
        }

        //Check the admission status:

        $admission_status = $user->admission_applications->findBy('seminar_id', $this->id)->val('status');
        if ($admission_status === 'accepted') {
            return new \Studip\EnrolmentInformation(
                _('Sie wurden für diese Veranstaltung vorläufig akzeptiert.'),
                \Studip\Information::INFO,
                'preliminary_accepted',
                false
            );
        } elseif ($admission_status === 'awaiting') {
            return new \Studip\EnrolmentInformation(
                _('Sie sind auf der Warteliste für diese Veranstaltung.'),
                \Studip\Information::INFO,
                'on_waitlist',
                false
            );
        }

        //Check the user domain:
        $user_domains = UserDomain::getUserDomainsForUser($user_id);
        if (count($user_domains) > 0) {
            //The user is in at least one domain. Check if the course is in one of them.
            $course_domains = UserDomain::getUserDomainsForSeminar($this->id);
            if (
                !UserDomain::checkUserVisibility($course_domains, $user_domains)
                && !$this->isStudygroup()
            ) {
                //The user is not in the same domain as the course and the course
                //is not a studygroup.
                return new \Studip\EnrolmentInformation(
                    _('Sie sind nicht in der gleichen Domäne wie die Veranstaltung und können sich daher nicht für die Veranstaltung eintragen.'),
                    \Studip\Information::INFO,
                    'wrong_domain',
                    false
                );
            }
        }

        //In all other cases, enrolment is allowed.
        return new \Studip\EnrolmentInformation(
            _('Sie können sich zur Veranstaltung anmelden.'),
            \Studip\Information::INFO,
            'allowed',
            true
        );
    }


    /**
    * Returns the semType object that is defined for the course
    *
    * @return SemType The semTypeObject for the course
    */
    public function getSemType()
    {
        $semTypes = SemType::getTypes();
        if (isset($semTypes[$this->status])) {
            return $semTypes[$this->status];
        }

        Log::error(sprintf('SemType not found id:%s status:%s', $this->id, $this->status));
        return new SemType(['name' => 'Fehlerhafter Veranstaltungstyp']);
    }

    /**
     * Returns the SemClass object that is defined for the course
     *
     * @return SemClass The SemClassObject for the course
     */
     public function getSemClass()
     {
         return $this->getSemType()->getClass();
     }

    /**
     * Returns the full name of a course. If the important course numbers
     * (IMPORTANT_SEMNUMBER) is set in global configs it will also display
     * the coursenumber
     *
     * @param string formatting template name
     * @return string Fullname
     */
    public function getFullName($format = 'default')
    {
        $template = [
            'name'                 => '%1$s',
            'name-semester'        => '%1$s (%4$s)',
            'number-name'          => '%3$s %1$s',
            'number-name-semester' => '%3$s %1$s (%4$s)',
            'number-type-name'     => '%3$s %2$s: %1$s',
            'sem-duration-name'    => '%4$s',
            'type-name'            => '%2$s: %1$s',
            'type-number-name'     => '%2$s: %3$s %1$s',
        ];

        if ($format === 'default' || !isset($template[$format])) {
           $format = Config::get()->IMPORTANT_SEMNUMBER ? 'type-number-name' : 'type-name';
        }
        $sem_type = $this->getSemType();
        $data[0] = $this->name;
        $data[1] = $sem_type['name'];
        $data[2] = $this->veranstaltungsnummer;
        $data[3] = $this->getTextualSemester();
        return trim(vsprintf($template[$format], array_map('trim', $data)));
    }

    /**
     * Retrieves all dates (regular and irregular) that take place
     * in a specified semester or a semester range.
     *
     * @param Semester|null $start_semester The semester for which to get all dates
     *     or the start semester of a semester range.
     * @param Semester|null $end_semester The end semester for a semester range.
     *     This can also be null in case only dates for one semester
     *     shall be retrieved.
     *
     * @param bool $with_cancelled_dates Whether to include cancelled dates (true) or not (false).
     *     Defaults to false.
     *
     * @return CourseDateList A collection of irregular and regular course dates.
     *
     * @throws \Studip\Exception In case that the end semester is before the start semester.
     */
    public function getAllDatesInSemester(
        ?Semester $start_semester = null,
        ?Semester $end_semester = null,
        bool $with_cancelled_dates = false
    ) : CourseDateList {
        $all_dates_of_course = !$start_semester && !$end_semester;

        if ($all_dates_of_course) {
            $collection = new CourseDateList();
            foreach ($this->cycles as $regular_date) {
                $collection->addRegularDate($regular_date);
            }
            foreach ($this->dates as $date) {
                if (!$date->metadate_id) {
                    $collection->addSingleDate($date);
                }
            }
            if ($with_cancelled_dates) {
                foreach ($this->ex_dates as $cancelled_date) {
                    $collection->addCancelledDate($cancelled_date);
                }
            }
            return $collection;
        } else {
            if (!$start_semester) {
                return new CourseDateList();
            }
            $beginning = $start_semester->beginn;
            $end = $start_semester->ende;
            if ($end_semester) {
                if ($end_semester->ende < $start_semester->beginn) {
                    throw new \Studip\Exception(
                        _('Das Endsemester darf nicht vor dem Startsemester liegen.'),
                        \Studip\Exception::END_BEFORE_BEGINNING
                    );
                }
                $end = $end_semester->ende;
            }

            $collection = new CourseDateList();

            SeminarCycleDate::findEachBySQL(
                function ($date) use ($collection) {
                    $collection->addCycleDate($date);
                },
                "`start_time` >= :beginning AND `end_time` <= :end
                    AND `seminar_id` = :course_id",
                [
                    'course_id' => $this->id,
                    'beginning' => $beginning,
                    'end' => $end
                ]
            );

            CourseDate::findEachBySQL(
                function ($date) use ($collection) {
                    $collection->addSingleDate($date);
                },
                "`date` >= :beginning AND `end_time` <= :end
                    AND `range_id` = :course_id
                    AND (`metadate_id` IS NULL OR `metadate_id` = '')",
                [
                    'course_id' => $this->id,
                    'beginning' => $beginning,
                    'end' => $end
                ]
            );

            if ($with_cancelled_dates) {
                CourseExDate::findEachBySQL(
                    function ($date) use ($collection) {
                        $collection->addCancelledDate($date);
                    },
                    "`date` >= :beginning AND `end_time` <= :end
                        AND `range_id` = :course_id
                        AND (`metadate_id` IS NULL OR `metadate_id` = '')",
                    [
                        'course_id' => $this->id,
                        'beginning' => $beginning,
                        'end' => $end
                    ]
                );
            }

            return $collection;
        }
    }


    /**
     * Retrieves the course dates including cancelled dates ("ex-dates").
     * The dates can be filtered by an optional time range. By default,
     * all dates are retrieved.
     *
     * @param int $range_begin The begin timestamp of the time range.
     *
     * @param int $range_end The end timestamp of the time range.
     *
     * @returns SimpleCollection A collection of all retrieved dates and
     *     cancelled dates.
     */
    public function getDatesWithExdates($range_begin = 0, $range_end = 0)
    {
        $dates = [];
        if (($range_begin > 0) && ($range_end > 0) && ($range_end > $range_begin)) {
            $ex_dates = $this->ex_dates->findBy('content', '', '<>')
                          ->findBy('date', $range_begin, '>=')
                          ->findBy('end_time', $range_end, '<=');
            $dates = $this->dates->findBy('date', $range_begin, '>=')
                          ->findBy('end_time', $range_end, '<=');
            $dates->merge($ex_dates);
        } else {
            $dates = $this->ex_dates->findBy('content', '', '<>');
            $dates->merge($this->dates);
        }
        $dates->uasort(function($a, $b) {
            return $a->date - $b->date
                ?: strnatcasecmp($a->getRoomName(), $b->getRoomName());
        });
        return $dates;
    }

    /**
     * Retrieves the first date of the course that takes place.
     *
     * @return CourseDate|null Either the first date as CourseDate or null in case
     *     the course has no dates.
     */
    public function getFirstDate() : ?CourseDate
    {
        return $this->dates->first();
    }

    /**
     * Retrieves the next date for the course. If requested, the next cancelled
     * date is retrieved if no date can be found that takes place.
     *
     * The date must start in the future or within the past hour to be regarded
     * as next date.
     *
     * @param bool $include_cancelled Include cancelled dates (true) or not.
     *     Defaults to false.
     *
     * @return CourseDate|CourseExDate|null A CourseDate or CourseExDate representing
     *     the next date or null in case there is no next date. CourseExDate instances
     *     are only returned if $include_cancelled is set to true.
     */
    public function getNextDate(bool $include_cancelled = false)
    {
        $sql = '`range_id` = :course_id AND `date` > UNIX_TIMESTAMP() - 3600
                ORDER BY `date`, `end_time`';

        $date = CourseDate::findOneBySQL($sql, ['course_id' => $this->id]);
        if (!$date && $include_cancelled) {
            //Do the same with CourseExDate:
            $date = CourseExDate::findOneBySQL($sql, ['course_id' => $this->id]);
        }
        return $date;
    }

    /**
     * Sets this courses study areas to the given values.
     *
     * @param array $ids the new study areas
     * @return bool Changes successfully saved?
     */
    public function setStudyAreas($ids)
    {
        $old = $this->study_areas->pluck('sem_tree_id');
        $added = array_diff($ids, $old);
        $removed = array_diff($old, $ids);
        $success = false;
        if ($added || $removed) {

            $this->study_areas = SimpleCollection::createFromArray(StudipStudyArea::findMany($ids));

            if ($this->store()) {
                NotificationCenter::postNotification('CourseDidChangeStudyArea', $this);
                $success = true;

                foreach ($added as $one) {