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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Self enrolment plugin.
  19   *
  20   * @package    enrol_self
  21   * @copyright  2010 Petr Skoda  {@link http://skodak.org}
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  /**
  26   * Self enrolment plugin implementation.
  27   * @author Petr Skoda
  28   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  29   */
  30  class enrol_self_plugin extends enrol_plugin {
  31  
  32      protected $lasternoller = null;
  33      protected $lasternollerinstanceid = 0;
  34  
  35      /**
  36       * Returns optional enrolment information icons.
  37       *
  38       * This is used in course list for quick overview of enrolment options.
  39       *
  40       * We are not using single instance parameter because sometimes
  41       * we might want to prevent icon repetition when multiple instances
  42       * of one type exist. One instance may also produce several icons.
  43       *
  44       * @param array $instances all enrol instances of this type in one course
  45       * @return array of pix_icon
  46       */
  47      public function get_info_icons(array $instances) {
  48          $key = false;
  49          $nokey = false;
  50          foreach ($instances as $instance) {
  51              if ($this->can_self_enrol($instance, false) !== true) {
  52                  // User can not enrol himself.
  53                  // Note that we do not check here if user is already enrolled for performance reasons -
  54                  // such check would execute extra queries for each course in the list of courses and
  55                  // would hide self-enrolment icons from guests.
  56                  continue;
  57              }
  58              if ($instance->password or $instance->customint1) {
  59                  $key = true;
  60              } else {
  61                  $nokey = true;
  62              }
  63          }
  64          $icons = array();
  65          if ($nokey) {
  66              $icons[] = new pix_icon('withoutkey', get_string('pluginname', 'enrol_self'), 'enrol_self');
  67          }
  68          if ($key) {
  69              $icons[] = new pix_icon('withkey', get_string('pluginname', 'enrol_self'), 'enrol_self');
  70          }
  71          return $icons;
  72      }
  73  
  74      /**
  75       * Returns localised name of enrol instance
  76       *
  77       * @param stdClass $instance (null is accepted too)
  78       * @return string
  79       */
  80      public function get_instance_name($instance) {
  81          global $DB;
  82  
  83          if (empty($instance->name)) {
  84              if (!empty($instance->roleid) and $role = $DB->get_record('role', array('id'=>$instance->roleid))) {
  85                  $role = ' (' . role_get_name($role, context_course::instance($instance->courseid, IGNORE_MISSING)) . ')';
  86              } else {
  87                  $role = '';
  88              }
  89              $enrol = $this->get_name();
  90              return get_string('pluginname', 'enrol_'.$enrol) . $role;
  91          } else {
  92              return format_string($instance->name);
  93          }
  94      }
  95  
  96      public function roles_protected() {
  97          // Users may tweak the roles later.
  98          return false;
  99      }
 100  
 101      public function allow_unenrol(stdClass $instance) {
 102          // Users with unenrol cap may unenrol other users manually manually.
 103          return true;
 104      }
 105  
 106      public function allow_manage(stdClass $instance) {
 107          // Users with manage cap may tweak period and status.
 108          return true;
 109      }
 110  
 111      public function show_enrolme_link(stdClass $instance) {
 112  
 113          if (true !== $this->can_self_enrol($instance, false)) {
 114              return false;
 115          }
 116  
 117          return true;
 118      }
 119  
 120      /**
 121       * Sets up navigation entries.
 122       *
 123       * @param stdClass $instancesnode
 124       * @param stdClass $instance
 125       * @return void
 126       */
 127      public function add_course_navigation($instancesnode, stdClass $instance) {
 128          if ($instance->enrol !== 'self') {
 129               throw new coding_exception('Invalid enrol instance type!');
 130          }
 131  
 132          $context = context_course::instance($instance->courseid);
 133          if (has_capability('enrol/self:config', $context)) {
 134              $managelink = new moodle_url('/enrol/self/edit.php', array('courseid'=>$instance->courseid, 'id'=>$instance->id));
 135              $instancesnode->add($this->get_instance_name($instance), $managelink, navigation_node::TYPE_SETTING);
 136          }
 137      }
 138  
 139      /**
 140       * Returns edit icons for the page with list of instances
 141       * @param stdClass $instance
 142       * @return array
 143       */
 144      public function get_action_icons(stdClass $instance) {
 145          global $OUTPUT;
 146  
 147          if ($instance->enrol !== 'self') {
 148              throw new coding_exception('invalid enrol instance!');
 149          }
 150          $context = context_course::instance($instance->courseid);
 151  
 152          $icons = array();
 153  
 154          if (has_capability('enrol/self:config', $context)) {
 155              $editlink = new moodle_url("/enrol/self/edit.php", array('courseid'=>$instance->courseid, 'id'=>$instance->id));
 156              $icons[] = $OUTPUT->action_icon($editlink, new pix_icon('t/edit', get_string('edit'), 'core',
 157                  array('class' => 'iconsmall')));
 158          }
 159  
 160          return $icons;
 161      }
 162  
 163      /**
 164       * Returns link to page which may be used to add new instance of enrolment plugin in course.
 165       * @param int $courseid
 166       * @return moodle_url page url
 167       */
 168      public function get_newinstance_link($courseid) {
 169          $context = context_course::instance($courseid, MUST_EXIST);
 170  
 171          if (!has_capability('moodle/course:enrolconfig', $context) or !has_capability('enrol/self:config', $context)) {
 172              return NULL;
 173          }
 174          // Multiple instances supported - different roles with different password.
 175          return new moodle_url('/enrol/self/edit.php', array('courseid'=>$courseid));
 176      }
 177  
 178      /**
 179       * Self enrol user to course
 180       *
 181       * @param stdClass $instance enrolment instance
 182       * @param stdClass $data data needed for enrolment.
 183       * @return bool|array true if enroled else eddor code and messege
 184       */
 185      public function enrol_self(stdClass $instance, $data = null) {
 186          global $DB, $USER, $CFG;
 187  
 188          // Don't enrol user if password is not passed when required.
 189          if ($instance->password && !isset($data->enrolpassword)) {
 190              return;
 191          }
 192  
 193          $timestart = time();
 194          if ($instance->enrolperiod) {
 195              $timeend = $timestart + $instance->enrolperiod;
 196          } else {
 197              $timeend = 0;
 198          }
 199  
 200          $this->enrol_user($instance, $USER->id, $instance->roleid, $timestart, $timeend);
 201  
 202          if ($instance->password and $instance->customint1 and $data->enrolpassword !== $instance->password) {
 203              // It must be a group enrolment, let's assign group too.
 204              $groups = $DB->get_records('groups', array('courseid'=>$instance->courseid), 'id', 'id, enrolmentkey');
 205              foreach ($groups as $group) {
 206                  if (empty($group->enrolmentkey)) {
 207                      continue;
 208                  }
 209                  if ($group->enrolmentkey === $data->enrolpassword) {
 210                      // Add user to group.
 211                      require_once($CFG->dirroot.'/group/lib.php');
 212                      groups_add_member($group->id, $USER->id);
 213                      break;
 214                  }
 215              }
 216          }
 217          // Send welcome message.
 218          if ($instance->customint4) {
 219              $this->email_welcome_message($instance, $USER);
 220          }
 221      }
 222  
 223      /**
 224       * Creates course enrol form, checks if form submitted
 225       * and enrols user if necessary. It can also redirect.
 226       *
 227       * @param stdClass $instance
 228       * @return string html text, usually a form in a text box
 229       */
 230      public function enrol_page_hook(stdClass $instance) {
 231          global $CFG, $OUTPUT, $USER;
 232  
 233          require_once("$CFG->dirroot/enrol/self/locallib.php");
 234  
 235          $enrolstatus = $this->can_self_enrol($instance);
 236  
 237          // Don't show enrolment instance form, if user can't enrol using it.
 238          if (true === $enrolstatus) {
 239              $form = new enrol_self_enrol_form(NULL, $instance);
 240              $instanceid = optional_param('instance', 0, PARAM_INT);
 241              if ($instance->id == $instanceid) {
 242                  if ($data = $form->get_data()) {
 243                      $this->enrol_self($instance, $data);
 244                  }
 245              }
 246  
 247              ob_start();
 248              $form->display();
 249              $output = ob_get_clean();
 250              return $OUTPUT->box($output);
 251          }
 252      }
 253  
 254      /**
 255       * Checks if user can self enrol.
 256       *
 257       * @param stdClass $instance enrolment instance
 258       * @param bool $checkuserenrolment if true will check if user enrolment is inactive.
 259       *             used by navigation to improve performance.
 260       * @return bool|string true if successful, else error message or false.
 261       */
 262      public function can_self_enrol(stdClass $instance, $checkuserenrolment = true) {
 263          global $DB, $USER, $CFG;
 264  
 265          if ($checkuserenrolment) {
 266              if (isguestuser()) {
 267                  // Can not enrol guest.
 268                  return get_string('canntenrol', 'enrol_self');
 269              }
 270              // Check if user is already enroled.
 271              if ($DB->get_record('user_enrolments', array('userid' => $USER->id, 'enrolid' => $instance->id))) {
 272                  return get_string('canntenrol', 'enrol_self');
 273              }
 274          }
 275  
 276          if ($instance->status != ENROL_INSTANCE_ENABLED) {
 277              return get_string('canntenrol', 'enrol_self');
 278          }
 279  
 280          if ($instance->enrolstartdate != 0 and $instance->enrolstartdate > time()) {
 281              return get_string('canntenrol', 'enrol_self');
 282          }
 283  
 284          if ($instance->enrolenddate != 0 and $instance->enrolenddate < time()) {
 285              return get_string('canntenrol', 'enrol_self');
 286          }
 287  
 288          if (!$instance->customint6) {
 289              // New enrols not allowed.
 290              return get_string('canntenrol', 'enrol_self');
 291          }
 292  
 293          if ($DB->record_exists('user_enrolments', array('userid' => $USER->id, 'enrolid' => $instance->id))) {
 294              return get_string('canntenrol', 'enrol_self');
 295          }
 296  
 297          if ($instance->customint3 > 0) {
 298              // Max enrol limit specified.
 299              $count = $DB->count_records('user_enrolments', array('enrolid' => $instance->id));
 300              if ($count >= $instance->customint3) {
 301                  // Bad luck, no more self enrolments here.
 302                  return get_string('maxenrolledreached', 'enrol_self');
 303              }
 304          }
 305  
 306          if ($instance->customint5) {
 307              require_once("$CFG->dirroot/cohort/lib.php");
 308              if (!cohort_is_member($instance->customint5, $USER->id)) {
 309                  $cohort = $DB->get_record('cohort', array('id' => $instance->customint5));
 310                  if (!$cohort) {
 311                      return null;
 312                  }
 313                  $a = format_string($cohort->name, true, array('context' => context::instance_by_id($cohort->contextid)));
 314                  return markdown_to_html(get_string('cohortnonmemberinfo', 'enrol_self', $a));
 315              }
 316          }
 317  
 318          return true;
 319      }
 320  
 321      /**
 322       * Return information for enrolment instance containing list of parameters required
 323       * for enrolment, name of enrolment plugin etc.
 324       *
 325       * @param stdClass $instance enrolment instance
 326       * @return stdClass instance info.
 327       */
 328      public function get_enrol_info(stdClass $instance) {
 329  
 330          $instanceinfo = new stdClass();
 331          $instanceinfo->id = $instance->id;
 332          $instanceinfo->courseid = $instance->courseid;
 333          $instanceinfo->type = $this->get_name();
 334          $instanceinfo->name = $this->get_instance_name($instance);
 335          $instanceinfo->status = $this->can_self_enrol($instance);
 336  
 337          if ($instance->password) {
 338              $instanceinfo->requiredparam = new stdClass();
 339              $instanceinfo->requiredparam->enrolpassword = get_string('password', 'enrol_self');
 340          }
 341  
 342          // If enrolment is possible and password is required then return ws function name to get more information.
 343          if ((true === $instanceinfo->status) && $instance->password) {
 344              $instanceinfo->wsfunction = 'enrol_self_get_instance_info';
 345          }
 346          return $instanceinfo;
 347      }
 348  
 349      /**
 350       * Add new instance of enrol plugin with default settings.
 351       * @param stdClass $course
 352       * @return int id of new instance
 353       */
 354      public function add_default_instance($course) {
 355          $fields = $this->get_instance_defaults();
 356  
 357          if ($this->get_config('requirepassword')) {
 358              $fields['password'] = generate_password(20);
 359          }
 360  
 361          return $this->add_instance($course, $fields);
 362      }
 363  
 364      /**
 365       * Returns defaults for new instances.
 366       * @return array
 367       */
 368      public function get_instance_defaults() {
 369          $expirynotify = $this->get_config('expirynotify');
 370          if ($expirynotify == 2) {
 371              $expirynotify = 1;
 372              $notifyall = 1;
 373          } else {
 374              $notifyall = 0;
 375          }
 376  
 377          $fields = array();
 378          $fields['status']          = $this->get_config('status');
 379          $fields['roleid']          = $this->get_config('roleid');
 380          $fields['enrolperiod']     = $this->get_config('enrolperiod');
 381          $fields['expirynotify']    = $expirynotify;
 382          $fields['notifyall']       = $notifyall;
 383          $fields['expirythreshold'] = $this->get_config('expirythreshold');
 384          $fields['customint1']      = $this->get_config('groupkey');
 385          $fields['customint2']      = $this->get_config('longtimenosee');
 386          $fields['customint3']      = $this->get_config('maxenrolled');
 387          $fields['customint4']      = $this->get_config('sendcoursewelcomemessage');
 388          $fields['customint5']      = 0;
 389          $fields['customint6']      = $this->get_config('newenrols');
 390  
 391          return $fields;
 392      }
 393  
 394      /**
 395       * Send welcome email to specified user.
 396       *
 397       * @param stdClass $instance
 398       * @param stdClass $user user record
 399       * @return void
 400       */
 401      protected function email_welcome_message($instance, $user) {
 402          global $CFG, $DB;
 403  
 404          $course = $DB->get_record('course', array('id'=>$instance->courseid), '*', MUST_EXIST);
 405          $context = context_course::instance($course->id);
 406  
 407          $a = new stdClass();
 408          $a->coursename = format_string($course->fullname, true, array('context'=>$context));
 409          $a->profileurl = "$CFG->wwwroot/user/view.php?id=$user->id&course=$course->id";
 410  
 411          if (trim($instance->customtext1) !== '') {
 412              $message = $instance->customtext1;
 413              $message = str_replace('{$a->coursename}', $a->coursename, $message);
 414              $message = str_replace('{$a->profileurl}', $a->profileurl, $message);
 415              if (strpos($message, '<') === false) {
 416                  // Plain text only.
 417                  $messagetext = $message;
 418                  $messagehtml = text_to_html($messagetext, null, false, true);
 419              } else {
 420                  // This is most probably the tag/newline soup known as FORMAT_MOODLE.
 421                  $messagehtml = format_text($message, FORMAT_MOODLE, array('context'=>$context, 'para'=>false, 'newlines'=>true, 'filter'=>true));
 422                  $messagetext = html_to_text($messagehtml);
 423              }
 424          } else {
 425              $messagetext = get_string('welcometocoursetext', 'enrol_self', $a);
 426              $messagehtml = text_to_html($messagetext, null, false, true);
 427          }
 428  
 429          $subject = get_string('welcometocourse', 'enrol_self', format_string($course->fullname, true, array('context'=>$context)));
 430  
 431          $rusers = array();
 432          if (!empty($CFG->coursecontact)) {
 433              $croles = explode(',', $CFG->coursecontact);
 434              list($sort, $sortparams) = users_order_by_sql('u');
 435              $rusers = get_role_users($croles, $context, true, '', 'r.sortorder ASC, ' . $sort, null, '', '', '', '', $sortparams);
 436          }
 437          if ($rusers) {
 438              $contact = reset($rusers);
 439          } else {
 440              $contact = core_user::get_support_user();
 441          }
 442  
 443          // Directly emailing welcome message rather than using messaging.
 444          email_to_user($user, $contact, $subject, $messagetext, $messagehtml);
 445      }
 446  
 447      /**
 448       * Enrol self cron support.
 449       * @return void
 450       */
 451      public function cron() {
 452          $trace = new text_progress_trace();
 453          $this->sync($trace, null);
 454          $this->send_expiry_notifications($trace);
 455      }
 456  
 457      /**
 458       * Sync all meta course links.
 459       *
 460       * @param progress_trace $trace
 461       * @param int $courseid one course, empty mean all
 462       * @return int 0 means ok, 1 means error, 2 means plugin disabled
 463       */
 464      public function sync(progress_trace $trace, $courseid = null) {
 465          global $DB;
 466  
 467          if (!enrol_is_enabled('self')) {
 468              $trace->finished();
 469              return 2;
 470          }
 471  
 472          // Unfortunately this may take a long time, execution can be interrupted safely here.
 473          core_php_time_limit::raise();
 474          raise_memory_limit(MEMORY_HUGE);
 475  
 476          $trace->output('Verifying self-enrolments...');
 477  
 478          $params = array('now'=>time(), 'useractive'=>ENROL_USER_ACTIVE, 'courselevel'=>CONTEXT_COURSE);
 479          $coursesql = "";
 480          if ($courseid) {
 481              $coursesql = "AND e.courseid = :courseid";
 482              $params['courseid'] = $courseid;
 483          }
 484  
 485          // Note: the logic of self enrolment guarantees that user logged in at least once (=== u.lastaccess set)
 486          //       and that user accessed course at least once too (=== user_lastaccess record exists).
 487  
 488          // First deal with users that did not log in for a really long time - they do not have user_lastaccess records.
 489          $sql = "SELECT e.*, ue.userid
 490                    FROM {user_enrolments} ue
 491                    JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'self' AND e.customint2 > 0)
 492                    JOIN {user} u ON u.id = ue.userid
 493                   WHERE :now - u.lastaccess > e.customint2
 494                         $coursesql";
 495          $rs = $DB->get_recordset_sql($sql, $params);
 496          foreach ($rs as $instance) {
 497              $userid = $instance->userid;
 498              unset($instance->userid);
 499              $this->unenrol_user($instance, $userid);
 500              $days = $instance->customint2 / 60*60*24;
 501              $trace->output("unenrolling user $userid from course $instance->courseid as they have did not log in for at least $days days", 1);
 502          }
 503          $rs->close();
 504  
 505          // Now unenrol from course user did not visit for a long time.
 506          $sql = "SELECT e.*, ue.userid
 507                    FROM {user_enrolments} ue
 508                    JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'self' AND e.customint2 > 0)
 509                    JOIN {user_lastaccess} ul ON (ul.userid = ue.userid AND ul.courseid = e.courseid)
 510                   WHERE :now - ul.timeaccess > e.customint2
 511                         $coursesql";
 512          $rs = $DB->get_recordset_sql($sql, $params);
 513          foreach ($rs as $instance) {
 514              $userid = $instance->userid;
 515              unset($instance->userid);
 516              $this->unenrol_user($instance, $userid);
 517                  $days = $instance->customint2 / 60*60*24;
 518              $trace->output("unenrolling user $userid from course $instance->courseid as they have did not access course for at least $days days", 1);
 519          }
 520          $rs->close();
 521  
 522          $trace->output('...user self-enrolment updates finished.');
 523          $trace->finished();
 524  
 525          $this->process_expirations($trace, $courseid);
 526  
 527          return 0;
 528      }
 529  
 530      /**
 531       * Returns the user who is responsible for self enrolments in given instance.
 532       *
 533       * Usually it is the first editing teacher - the person with "highest authority"
 534       * as defined by sort_by_roleassignment_authority() having 'enrol/self:manage'
 535       * capability.
 536       *
 537       * @param int $instanceid enrolment instance id
 538       * @return stdClass user record
 539       */
 540      protected function get_enroller($instanceid) {
 541          global $DB;
 542  
 543          if ($this->lasternollerinstanceid == $instanceid and $this->lasternoller) {
 544              return $this->lasternoller;
 545          }
 546  
 547          $instance = $DB->get_record('enrol', array('id'=>$instanceid, 'enrol'=>$this->get_name()), '*', MUST_EXIST);
 548          $context = context_course::instance($instance->courseid);
 549  
 550          if ($users = get_enrolled_users($context, 'enrol/self:manage')) {
 551              $users = sort_by_roleassignment_authority($users, $context);
 552              $this->lasternoller = reset($users);
 553              unset($users);
 554          } else {
 555              $this->lasternoller = parent::get_enroller($instanceid);
 556          }
 557  
 558          $this->lasternollerinstanceid = $instanceid;
 559  
 560          return $this->lasternoller;
 561      }
 562  
 563      /**
 564       * Gets an array of the user enrolment actions.
 565       *
 566       * @param course_enrolment_manager $manager
 567       * @param stdClass $ue A user enrolment object
 568       * @return array An array of user_enrolment_actions
 569       */
 570      public function get_user_enrolment_actions(course_enrolment_manager $manager, $ue) {
 571          $actions = array();
 572          $context = $manager->get_context();
 573          $instance = $ue->enrolmentinstance;
 574          $params = $manager->get_moodlepage()->url->params();
 575          $params['ue'] = $ue->id;
 576          if ($this->allow_unenrol($instance) && has_capability("enrol/self:unenrol", $context)) {
 577              $url = new moodle_url('/enrol/unenroluser.php', $params);
 578              $actions[] = new user_enrolment_action(new pix_icon('t/delete', ''), get_string('unenrol', 'enrol'), $url, array('class'=>'unenrollink', 'rel'=>$ue->id));
 579          }
 580          if ($this->allow_manage($instance) && has_capability("enrol/self:manage", $context)) {
 581              $url = new moodle_url('/enrol/editenrolment.php', $params);
 582              $actions[] = new user_enrolment_action(new pix_icon('t/edit', ''), get_string('edit'), $url, array('class'=>'editenrollink', 'rel'=>$ue->id));
 583          }
 584          return $actions;
 585      }
 586  
 587      /**
 588       * Restore instance and map settings.
 589       *
 590       * @param restore_enrolments_structure_step $step
 591       * @param stdClass $data
 592       * @param stdClass $course
 593       * @param int $oldid
 594       */
 595      public function restore_instance(restore_enrolments_structure_step $step, stdClass $data, $course, $oldid) {
 596          global $DB;
 597          if ($step->get_task()->get_target() == backup::TARGET_NEW_COURSE) {
 598              $merge = false;
 599          } else {
 600              $merge = array(
 601                  'courseid'   => $data->courseid,
 602                  'enrol'      => $this->get_name(),
 603                  'roleid'     => $data->roleid,
 604              );
 605          }
 606          if ($merge and $instances = $DB->get_records('enrol', $merge, 'id')) {
 607              $instance = reset($instances);
 608              $instanceid = $instance->id;
 609          } else {
 610              if (!empty($data->customint5)) {
 611                  if ($step->get_task()->is_samesite()) {
 612                      // Keep cohort restriction unchanged - we are on the same site.
 613                  } else {
 614                      // Use some id that can not exist in order to prevent self enrolment,
 615                      // because we do not know what cohort it is in this site.
 616                      $data->customint5 = -1;
 617                  }
 618              }
 619              $instanceid = $this->add_instance($course, (array)$data);
 620          }
 621          $step->set_mapping('enrol', $oldid, $instanceid);
 622      }
 623  
 624      /**
 625       * Restore user enrolment.
 626       *
 627       * @param restore_enrolments_structure_step $step
 628       * @param stdClass $data
 629       * @param stdClass $instance
 630       * @param int $oldinstancestatus
 631       * @param int $userid
 632       */
 633      public function restore_user_enrolment(restore_enrolments_structure_step $step, $data, $instance, $userid, $oldinstancestatus) {
 634          $this->enrol_user($instance, $userid, null, $data->timestart, $data->timeend, $data->status);
 635      }
 636  
 637      /**
 638       * Restore role assignment.
 639       *
 640       * @param stdClass $instance
 641       * @param int $roleid
 642       * @param int $userid
 643       * @param int $contextid
 644       */
 645      public function restore_role_assignment($instance, $roleid, $userid, $contextid) {
 646          // This is necessary only because we may migrate other types to this instance,
 647          // we do not use component in manual or self enrol.
 648          role_assign($roleid, $userid, $contextid, '', 0);
 649      }
 650  
 651      /**
 652       * Is it possible to delete enrol instance via standard UI?
 653       *
 654       * @param stdClass $instance
 655       * @return bool
 656       */
 657      public function can_delete_instance($instance) {
 658          $context = context_course::instance($instance->courseid);
 659          return has_capability('enrol/self:config', $context);
 660      }
 661  
 662      /**
 663       * Is it possible to hide/show enrol instance via standard UI?
 664       *
 665       * @param stdClass $instance
 666       * @return bool
 667       */
 668      public function can_hide_show_instance($instance) {
 669          $context = context_course::instance($instance->courseid);
 670          return has_capability('enrol/self:config', $context);
 671      }
 672  }