lib.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Manual enrolment plugin main library file.
 *
 * @package    enrol_manual
 * @copyright  2010 Petr Skoda {@link http://skodak.org}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

class enrol_manual_plugin extends enrol_plugin {

    protected $lasternoller = null;
    protected $lasternollercourseid = 0;

    public function roles_protected() {
        // Users may tweak the roles later.
        return false;
    }

    public function allow_enrol(stdClass $instance) {
        // Users with enrol cap may unenrol other users manually manually.
        return true;
    }

    public function allow_unenrol(stdClass $instance) {
        // Users with unenrol cap may unenrol other users manually manually.
        return true;
    }

    public function allow_manage(stdClass $instance) {
        // Users with manage cap may tweak period and status.
        return true;
    }

    /**
     * Returns link to manual enrol UI if exists.
     * Does the access control tests automatically.
     *
     * @param stdClass $instance
     * @return moodle_url
     */
    public function get_manual_enrol_link($instance) {
        $name = $this->get_name();
        if ($instance->enrol !== $name) {
            throw new coding_exception('invalid enrol instance!');
        }

        if (!enrol_is_enabled($name)) {
            return NULL;
        }

        $context = context_course::instance($instance->courseid, MUST_EXIST);

        if (!has_capability('enrol/manual:manage', $context) or !has_capability('enrol/manual:enrol', $context) or !has_capability('enrol/manual:unenrol', $context)) {
            return NULL;
        }

        return new moodle_url('/enrol/manual/manage.php', array('enrolid'=>$instance->id, 'id'=>$instance->courseid));
    }

    /**
     * Returns enrolment instance manage link.
     *
     * By defaults looks for manage.php file and tests for manage capability.
     *
     * @param navigation_node $instancesnode
     * @param stdClass $instance
     * @return moodle_url;
     */
    public function add_course_navigation($instancesnode, stdClass $instance) {
        if ($instance->enrol !== 'manual') {
             throw new coding_exception('Invalid enrol instance type!');
        }

        $context = context_course::instance($instance->courseid);
        if (has_capability('enrol/manual:config', $context)) {
            $managelink = new moodle_url('/enrol/manual/edit.php', array('courseid'=>$instance->courseid));
            $instancesnode->add($this->get_instance_name($instance), $managelink, navigation_node::TYPE_SETTING);
        }
    }

    /**
     * Returns edit icons for the page with list of instances.
     * @param stdClass $instance
     * @return array
     */
    public function get_action_icons(stdClass $instance) {
        global $OUTPUT;

        if ($instance->enrol !== 'manual') {
            throw new coding_exception('invalid enrol instance!');
        }
        $context = context_course::instance($instance->courseid);

        $icons = array();

        if (has_capability('enrol/manual:manage', $context)) {
            $managelink = new moodle_url("/enrol/manual/manage.php", array('enrolid'=>$instance->id));
            $icons[] = $OUTPUT->action_icon($managelink, new pix_icon('i/users', get_string('enrolusers', 'enrol_manual'), 'core', array('class'=>'iconsmall')));
        }
        if (has_capability('enrol/manual:config', $context)) {
            $editlink = new moodle_url("/enrol/manual/edit.php", array('courseid'=>$instance->courseid));
            $icons[] = $OUTPUT->action_icon($editlink, new pix_icon('i/edit', get_string('edit'), 'core', array('class'=>'icon')));
        }

        return $icons;
    }

    /**
     * Returns link to page which may be used to add new instance of enrolment plugin in course.
     * @param int $courseid
     * @return moodle_url page url
     */
    public function get_newinstance_link($courseid) {
        global $DB;

        $context = context_course::instance($courseid, MUST_EXIST);

        if (!has_capability('moodle/course:enrolconfig', $context) or !has_capability('enrol/manual:config', $context)) {
            return NULL;
        }

        if ($DB->record_exists('enrol', array('courseid'=>$courseid, 'enrol'=>'manual'))) {
            return NULL;
        }

        return new moodle_url('/enrol/manual/edit.php', array('courseid'=>$courseid));
    }

    /**
     * Add new instance of enrol plugin with default settings.
     * @param stdClass $course
     * @return int id of new instance, null if can not be created
     */
    public function add_default_instance($course) {
        $expirynotify = $this->get_config('expirynotify', 0);
        if ($expirynotify == 2) {
            $expirynotify = 1;
            $notifyall = 1;
        } else {
            $notifyall = 0;
        }
        $fields = array(
            'status'          => $this->get_config('status'),
            'roleid'          => $this->get_config('roleid', 0),
            'enrolperiod'     => $this->get_config('enrolperiod', 0),
            'expirynotify'    => $expirynotify,
            'notifyall'       => $notifyall,
            'expirythreshold' => $this->get_config('expirythreshold', 86400),
        );
        return $this->add_instance($course, $fields);
    }

    /**
     * Add new instance of enrol plugin.
     * @param stdClass $course
     * @param array instance fields
     * @return int id of new instance, null if can not be created
     */
    public function add_instance($course, array $fields = NULL) {
        global $DB;

        if ($DB->record_exists('enrol', array('courseid'=>$course->id, 'enrol'=>'manual'))) {
            // only one instance allowed, sorry
            return NULL;
        }

        return parent::add_instance($course, $fields);
    }

    /**
     * Returns a button to manually enrol users through the manual enrolment plugin.
     *
     * By default the first manual enrolment plugin instance available in the course is used.
     * If no manual enrolment instances exist within the course then false is returned.
     *
     * This function also adds a quickenrolment JS ui to the page so that users can be enrolled
     * via AJAX.
     *
     * @param course_enrolment_manager $manager
     * @return enrol_user_button
     */
    public function get_manual_enrol_button(course_enrolment_manager $manager) {
        global $CFG;

        $instance = null;
        $instances = array();
        foreach ($manager->get_enrolment_instances() as $tempinstance) {
            if ($tempinstance->enrol == 'manual') {
                if ($instance === null) {
                    $instance = $tempinstance;
                }
                $instances[] = array('id' => $tempinstance->id, 'name' => $this->get_instance_name($tempinstance));
            }
        }
        if (empty($instance)) {
            return false;
        }

        if (!$manuallink = $this->get_manual_enrol_link($instance)) {
            return false;
        }

        $button = new enrol_user_button($manuallink, get_string('enrolusers', 'enrol_manual'), 'get');
        $button->class .= ' enrol_manual_plugin';

        $startdate = $manager->get_course()->startdate;
        $startdateoptions = array();
        $timeformat = get_string('strftimedatefullshort');
        if ($startdate > 0) {
            $startdateoptions[2] = get_string('coursestart') . ' (' . userdate($startdate, $timeformat) . ')';
        }
        $today = time();
        $today = make_timestamp(date('Y', $today), date('m', $today), date('d', $today), 0, 0, 0);
        $startdateoptions[3] = get_string('today') . ' (' . userdate($today, $timeformat) . ')' ;
        $defaultduration = $instance->enrolperiod > 0 ? $instance->enrolperiod / 86400 : '';

        $modules = array('moodle-enrol_manual-quickenrolment', 'moodle-enrol_manual-quickenrolment-skin');
        $arguments = array(
            'instances'           => $instances,
            'courseid'            => $instance->courseid,
            'ajaxurl'             => '/enrol/manual/ajax.php',
            'url'                 => $manager->get_moodlepage()->url->out(false),
            'optionsStartDate'    => $startdateoptions,
            'defaultRole'         => $instance->roleid,
            'defaultDuration'     => $defaultduration,
            'disableGradeHistory' => $CFG->disablegradehistory,
            'recoverGradesDefault'=> ''
        );

        if ($CFG->recovergradesdefault) {
            $arguments['recoverGradesDefault'] = ' checked="checked"';
        }

        $function = 'M.enrol_manual.quickenrolment.init';
        $button->require_yui_module($modules, $function, array($arguments));
        $button->strings_for_js(array(
            'ajaxoneuserfound',
            'ajaxxusersfound',
            'ajaxnext25',
            'enrol',
            'enrolmentoptions',
            'enrolusers',
            'errajaxfailedenrol',
            'errajaxsearch',
            'none',
            'usersearch',
            'unlimitedduration',
            'startdatetoday',
            'durationdays',
            'enrolperiod',
            'finishenrollingusers',
            'recovergrades'), 'enrol');
        $button->strings_for_js('assignroles', 'role');
        $button->strings_for_js('startingfrom', 'moodle');

        return $button;
    }

    /**
     * Enrol cron support.
     * @return void
     */
    public function cron() {
        $this->sync(null, true);
        $this->send_notifications(true);
    }

    /**
     * Sync all meta course links.
     *
     * @param int $courseid one course, empty mean all
     * @param bool $verbose verbose CLI output
     * @return int 0 means ok, 1 means error, 2 means plugin disabled
     */
    public function sync($courseid = null, $verbose = false) {
        global $DB;

        if (!enrol_is_enabled('manual')) {
            return 2;
        }

        // Unfortunately this may take a long time, execution can be interrupted safely here.
        @set_time_limit(0);
        raise_memory_limit(MEMORY_HUGE);

        if ($verbose) {
            mtrace('Verifying manual enrolment expiration...');
        }

        $params = array('now'=>time(), 'useractive'=>ENROL_USER_ACTIVE, 'courselevel'=>CONTEXT_COURSE);
        $coursesql = "";
        if ($courseid) {
            $coursesql = "AND e.courseid = :courseid";
            $params['courseid'] = $courseid;
        }

        // Deal with expired accounts.
        $action = $this->get_config('expiredaction', ENROL_EXT_REMOVED_KEEP);

        if ($action == ENROL_EXT_REMOVED_UNENROL) {
            $instances = array();
            $sql = "SELECT ue.*, e.courseid, c.id AS contextid
                      FROM {user_enrolments} ue
                      JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'manual')
                      JOIN {context} c ON (c.instanceid = e.courseid AND c.contextlevel = :courselevel)
                     WHERE ue.timeend > 0 AND ue.timeend < :now
                           $coursesql";
            $rs = $DB->get_recordset_sql($sql, $params);
            foreach ($rs as $ue) {
                if (empty($instances[$ue->enrolid])) {
                    $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
                }
                $instance = $instances[$ue->enrolid];
                // Always remove all manually assigned roles here, this may break enrol_self roles but we do not want hardcoded hacks here.
                role_unassign_all(array('userid'=>$ue->userid, 'contextid'=>$ue->contextid, 'component'=>'', 'itemid'=>0), true);
                $this->unenrol_user($instance, $ue->userid);
                if ($verbose) {
                    mtrace("  unenrolling expired user $ue->userid from course $instance->courseid");
                }
            }
            $rs->close();
            unset($instances);

        } else if ($action == ENROL_EXT_REMOVED_SUSPENDNOROLES) {
            $instances = array();
            $sql = "SELECT ue.*, e.courseid, c.id AS contextid
                      FROM {user_enrolments} ue
                      JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'manual')
                      JOIN {context} c ON (c.instanceid = e.courseid AND c.contextlevel = :courselevel)
                     WHERE ue.timeend > 0 AND ue.timeend < :now
                           AND ue.status = :useractive
                           $coursesql";
            $rs = $DB->get_recordset_sql($sql, $params);
            foreach ($rs as $ue) {
                if (empty($instances[$ue->enrolid])) {
                    $instances[$ue->enrolid] = $DB->get_record('enrol', array('id'=>$ue->enrolid));
                }
                $instance = $instances[$ue->enrolid];
                // Always remove all manually assigned roles here, this may break enrol_self roles but we do not want hardcoded hacks here.
                role_unassign_all(array('userid'=>$ue->userid, 'contextid'=>$ue->contextid, 'component'=>'', 'itemid'=>0), true);
                $this->update_user_enrol($instance, $ue->userid, ENROL_USER_SUSPENDED);
                if ($verbose) {
                    mtrace("  suspending expired user $ue->userid in course $instance->courseid");
                }
            }
            $rs->close();
            unset($instances);

        } else {
            // ENROL_EXT_REMOVED_KEEP means no changes.
        }

        if ($verbose) {
            mtrace('...manual enrolment updates finished.');
        }

        return 0;
    }

    /**
     * Send notifications.
     *
     * @param bool $verbose verbose CLI output
     */
    public function send_notifications($verbose = false) {
        global $DB, $CFG;

        // Unfortunately this may take a long time, it should not be interrupted,
        // otherwise users get duplicate notification.

        @set_time_limit(0);
        raise_memory_limit(MEMORY_HUGE);

        $notifylast = $this->get_config('notifylast', 0);
        $notifyhour = $this->get_config('notifyhour', 6);
        $timenow    = time();

        $notifytime = usergetmidnight($timenow, $CFG->timezone) + ($notifyhour * 3600);

        if ($notifylast > $notifytime) {
            if ($verbose) {
                mtrace('Manual enrolment notifications were already sent today at '.userdate($notifylast, '', $CFG->timezone).'.');
            }
            return;
        } else if ($timenow < $notifytime) {
            if ($verbose) {
                mtrace('Manual enrolment notifications will be sent at '.userdate($notifytime, '', $CFG->timezone).'.');
            }
            return;
        }

        if ($verbose) {
            mtrace('Processing manual enrolment notifications...');
        }

        // Notify users responsible for enrolment once every day.
        $sql = "SELECT ue.*, e.expirynotify, e.notifyall, e.expirythreshold, e.courseid, c.fullname
                  FROM {user_enrolments} ue
                  JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'manual' AND e.expirynotify > 0 AND e.status = :enabled)
                  JOIN {course} c ON (c.id = e.courseid)
                  JOIN {user} u ON (u.id = ue.userid AND u.deleted = 0 AND u.suspended = 0)
                 WHERE ue.status = :active AND ue.timeend > 0 AND ue.timeend > :now1 AND ue.timeend < (e.expirythreshold + :now2)
              ORDER BY ue.enrolid ASC, u.lastname ASC, u.firstname ASC, u.id ASC";
        $params = array('enabled'=>ENROL_INSTANCE_ENABLED, 'active'=>ENROL_USER_ACTIVE, 'now1'=>$timenow, 'now2'=>$timenow);

        $rs = $DB->get_recordset_sql($sql, $params);

        $lastenrollid = 0;
        $users = array();

        foreach($rs as $ue) {
            if ($lastenrollid and $lastenrollid != $ue->enrolid) {
                $this->notify_expiry_enroller($lastenrollid, $users, $verbose);
                $users = array();
            }
            $lastenrollid = $ue->enrolid;

            $enroller = $this->get_enroller($ue->courseid);
            $context = context_course::instance($ue->courseid);

            $user = $DB->get_record('user', array('id'=>$ue->userid));

            $users[] = array('fullname'=>fullname($user, has_capability('moodle/site:viewfullnames', $context, $enroller)), 'timeend'=>$ue->timeend);

            if (!$ue->notifyall) {
                continue;
            }

            if ($ue->timeend - $ue->expirythreshold + 86400 < $timenow) {
                // Notify enrolled users only once at the start of the threshold.
                continue;
            }

            $this->notify_expiry_enrolled($user, $ue, $verbose);
        }
        $rs->close();

        if ($lastenrollid and $users) {
            $this->notify_expiry_enroller($lastenrollid, $users, $verbose);
        }

        if ($verbose) {
            mtrace('...notification processing finished.');
        }
        $this->set_config('notifylast', $timenow);
    }

    /**
     * Returns the user who is responsible for manual enrolments in given course.
     *
     * Usually it is the first editing teacher - the person with "highest authority"
     * as defined by sort_by_roleassignment_authority() having 'enrol/manual:manage'
     * capability.
     *
     * @param int $courseid
     * @return stdClass user record
     */
    protected function get_enroller($courseid) {
        if ($this->lasternollercourseid == $courseid and $this->lasternoller) {
            return $this->lasternoller;
        }

        $context = context_course::instance($courseid);
        if ($users = get_enrolled_users($context, 'enrol/manual:manage')) {
            $users = sort_by_roleassignment_authority($users, $context);
            $this->lasternoller = reset($users);
            unset($users);
        } else {
            $this->lasternoller = get_admin();
        }

        $this->lasternollercourseid = $courseid;

        return $this->lasternoller;
    }

    /**
     * Notify user about incoming expiration of their enrolment,
     * it is called only if notification of enrolled users (aka students) is enabled in course.
     *
     * This is executed only once for each expiring enrolment right
     * at the start of the expiration threshold.
     *
     * @param stdClass $user
     * @param stdClass $ue
     * @param bool $verbose
     */
    protected function notify_expiry_enrolled($user, $ue, $verbose) {
        global $CFG, $SESSION;

        // Some nasty hackery to get strings and dates localised for target user.
        $sessionlang = isset($SESSION->lang) ? $SESSION->lang : null;
        if (get_string_manager()->translation_exists($user->lang, false)) {
            $SESSION->lang = $user->lang;
            moodle_setlocale();
        }

        $enroller = $this->get_enroller($ue->courseid);
        $context = context_course::instance($ue->courseid);

        $subject = get_string('expirymessageenrolledsubject', 'enrol_manual', null);
        $a = new stdClass();
        $a->course   = format_string($ue->fullname, true, array('context'=>$context));
        $a->user     = fullname($user, true);
        $a->timeend  = userdate($ue->timeend, '', $user->timezone);
        $a->enroller = fullname($enroller, has_capability('moodle/site:viewfullnames', $context, $user));
        $body = get_string('expirymessageenrolledbody', 'enrol_manual', $a);

        $message = new stdClass();
        $message->notification      = 1;
        $message->component         = 'enrol_manual';
        $message->name              = 'expiry_notification';
        $message->userfrom          = $enroller;
        $message->userto            = $user;
        $message->subject           = $subject;
        $message->fullmessage       = $body;
        $message->fullmessageformat = FORMAT_MARKDOWN;
        $message->fullmessagehtml   = markdown_to_html($body);
        $message->smallmessage      = $subject;
        $message->contexturlname    = $a->course;
        $message->contexturl        = (string)new moodle_url('/course/view.php', array('id'=>$ue->courseid));

        if (message_send($message)) {
            if ($verbose) {
                mtrace("  notifying user $ue->userid that enrolment in course $ue->courseid expires on ".userdate($ue->timeend, '', $CFG->timezone));
            }
        } else {
            if ($verbose) {
                mtrace("  error notifying user $ue->userid that enrolment in course $ue->courseid expires on ".userdate($ue->timeend, '', $CFG->timezone));
            }
        }

        if ($SESSION->lang !== $sessionlang) {
            $SESSION->lang = $sessionlang;
            moodle_setlocale();
        }
    }

    /**
     * Notify person responsible for enrolments that some user enrolments will be expired soon,
     * it is called only if notification of enrollers (aka teachers) is enabled in course.
     *
     * This is called repeatedly every day for each course if there are any pending expiration
     * in the expiration threshold.
     *
     * @param int $eid
     * @param array $users
     * @param bool $verbose
     */
    protected function notify_expiry_enroller($eid, $users, $verbose) {
        global $DB, $SESSION;

        $instance = $DB->get_record('enrol', array('id'=>$eid, 'enrol'=>'manual'));
        $context = context_course::instance($instance->courseid);
        $course = $DB->get_record('course', array('id'=>$instance->courseid));

        $enroller = $this->get_enroller($instance->courseid);
        $admin = get_admin();

        // Some nasty hackery to get strings and dates localised for target user.
        $sessionlang = isset($SESSION->lang) ? $SESSION->lang : null;
        if (get_string_manager()->translation_exists($enroller->lang, false)) {
            $SESSION->lang = $enroller->lang;
            moodle_setlocale();
        }

        foreach($users as $key=>$info) {
            $users[$key] = '* '.$info['fullname'].' - '.userdate($info['timeend'], '', $enroller->timezone);
        }

        $subject = get_string('expirymessageenrollersubject', 'enrol_manual', null);
        $a = new stdClass();
        $a->course    = format_string($course->fullname, true, array('context'=>$context));
        $a->threshold = get_string('numdays', '', $instance->expirythreshold / (60*60*24));
        $a->users     = implode("\n", $users);
        $a->extendurl = (string)new moodle_url('/enrol/users.php', array('id'=>$instance->courseid));
        $body = get_string('expirymessageenrollerbody', 'enrol_manual', $a);

        $message = new stdClass();
        $message->notification      = 1;
        $message->component         = 'enrol_manual';
        $message->name              = 'expiry_notification';
        $message->userfrom          = $admin;
        $message->userto            = $enroller;
        $message->subject           = $subject;
        $message->fullmessage       = $body;
        $message->fullmessageformat = FORMAT_MARKDOWN;
        $message->fullmessagehtml   = markdown_to_html($body);
        $message->smallmessage      = $subject;
        $message->contexturlname    = $a->course;
        $message->contexturl        = $a->extendurl;

        if (message_send($message)) {
            if ($verbose) {
                mtrace("  notifying user $enroller->id about all expiring manual enrolments in course $instance->courseid");
            }
        } else {
            if ($verbose) {
                mtrace("  error notifying user $enroller->id about all expiring manual enrolments in course $instance->courseid");
            }
        }

        if ($SESSION->lang !== $sessionlang) {
            $SESSION->lang = $sessionlang;
            moodle_setlocale();
        }
    }

    /**
     * Gets an array of the user enrolment actions.
     *
     * @param course_enrolment_manager $manager
     * @param stdClass $ue A user enrolment object
     * @return array An array of user_enrolment_actions
     */
    public function get_user_enrolment_actions(course_enrolment_manager $manager, $ue) {
        $actions = array();
        $context = $manager->get_context();
        $instance = $ue->enrolmentinstance;
        $params = $manager->get_moodlepage()->url->params();
        $params['ue'] = $ue->id;
        if ($this->allow_unenrol_user($instance, $ue) && has_capability("enrol/manual:unenrol", $context)) {
            $url = new moodle_url('/enrol/unenroluser.php', $params);
            $actions[] = new user_enrolment_action(new pix_icon('t/delete', ''), get_string('unenrol', 'enrol'), $url, array('class'=>'unenrollink', 'rel'=>$ue->id));
        }
        if ($this->allow_manage($instance) && has_capability("enrol/manual:manage", $context)) {
            $url = new moodle_url('/enrol/manual/editenrolment.php', $params);
            $actions[] = new user_enrolment_action(new pix_icon('t/edit', ''), get_string('edit'), $url, array('class'=>'editenrollink', 'rel'=>$ue->id));
        }
        return $actions;
    }

    /**
     * The manual plugin has several bulk operations that can be performed.
     * @param course_enrolment_manager $manager
     * @return array
     */
    public function get_bulk_operations(course_enrolment_manager $manager) {
        global $CFG;
        require_once($CFG->dirroot.'/enrol/manual/locallib.php');
        $bulkoperations = array(
            'editselectedusers' => new enrol_manual_editselectedusers_operation($manager, $this),
            'deleteselectedusers' => new enrol_manual_deleteselectedusers_operation($manager, $this)
        );
        return $bulkoperations;
    }

    /**
     * Restore instance and map settings.
     *
     * @param restore_enrolments_structure_step $step
     * @param stdClass $data
     * @param stdClass $course
     * @param int $oldid
     */
    public function restore_instance(restore_enrolments_structure_step $step, stdClass $data, $course, $oldid) {
        global $DB;
        // There is only I manual enrol instance allowed per course.
        if ($instances = $DB->get_records('enrol', array('courseid'=>$data->courseid, 'enrol'=>'manual'), 'id')) {
            $instance = reset($instances);
            $instanceid = $instance->id;
        } else {
            $instanceid = $this->add_instance($course, (array)$data);
        }
        $step->set_mapping('enrol', $oldid, $instanceid);
    }

    /**
     * Restore user enrolment.
     *
     * @param restore_enrolments_structure_step $step
     * @param stdClass $data
     * @param stdClass $instance
     * @param int $oldinstancestatus
     * @param int $userid
     */
    public function restore_user_enrolment(restore_enrolments_structure_step $step, $data, $instance, $userid, $oldinstancestatus) {
        global $DB;

        // Note: this is a bit tricky because other types may be converted to manual enrolments,
        //       and manual is restricted to one enrolment per user.

        $ue = $DB->get_record('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$userid));
        $enrol = false;
        if ($ue and $ue->status == ENROL_USER_ACTIVE) {
            // We do not want to restrict current active enrolments, let's kind of merge the times only.
            // This prevents some teacher lockouts too.
            if ($data->status == ENROL_USER_ACTIVE) {
                if ($data->timestart > $ue->timestart) {
                    $data->timestart = $ue->timestart;
                    $enrol = true;
                }

                if ($data->timeend == 0) {
                    if ($ue->timeend != 0) {
                        $enrol = true;
                    }
                } else if ($ue->timeend == 0) {
                    $data->timeend = 0;
                } else if ($data->timeend < $ue->timeend) {
                    $data->timeend = $ue->timeend;
                    $enrol = true;
                }
            }
        } else {
            if ($instance->status == ENROL_INSTANCE_ENABLED and $oldinstancestatus != ENROL_INSTANCE_ENABLED) {
                // Make sure that user enrolments are not activated accidentally,
                // we do it only here because it is not expected that enrolments are migrated to other plugins.
                $data->status = ENROL_USER_SUSPENDED;
            }
            $enrol = true;
        }

        if ($enrol) {
            $this->enrol_user($instance, $userid, null, $data->timestart, $data->timeend, $data->status);
        }
    }

    /**
     * Restore role assignment.
     *
     * @param stdClass $instance
     * @param int $roleid
     * @param int $userid
     * @param int $contextid
     */
    public function restore_role_assignment($instance, $roleid, $userid, $contextid) {
        // This is necessary only because we may migrate other types to this instance,
        // we do not use component in manual or self enrol.
        role_assign($roleid, $userid, $contextid, '', 0);
    }

    /**
     * Restore user group membership.
     * @param stdClass $instance
     * @param int $groupid
     * @param int $userid
     */
    public function restore_group_member($instance, $groupid, $userid) {
        global $CFG;
        require_once("$CFG->dirroot/group/lib.php");

        // This might be called when forcing restore as manual enrolments.

        groups_add_member($groupid, $userid);
    }
}