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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       * Return true if we can add a new instance to this course.
 122       *
 123       * @param int $courseid
 124       * @return boolean
 125       */
 126      public function can_add_instance($courseid) {
 127          $context = context_course::instance($courseid, MUST_EXIST);
 128  
 129          if (!has_capability('moodle/course:enrolconfig', $context) or !has_capability('enrol/self:config', $context)) {
 130              return false;
 131          }
 132  
 133          return true;
 134      }
 135  
 136      /**
 137       * Self enrol user to course
 138       *
 139       * @param stdClass $instance enrolment instance
 140       * @param stdClass $data data needed for enrolment.
 141       * @return bool|array true if enroled else eddor code and messege
 142       */
 143      public function enrol_self(stdClass $instance, $data = null) {
 144          global $DB, $USER, $CFG;
 145  
 146          // Don't enrol user if password is not passed when required.
 147          if ($instance->password && !isset($data->enrolpassword)) {
 148              return;
 149          }
 150  
 151          $timestart = time();
 152          if ($instance->enrolperiod) {
 153              $timeend = $timestart + $instance->enrolperiod;
 154          } else {
 155              $timeend = 0;
 156          }
 157  
 158          $this->enrol_user($instance, $USER->id, $instance->roleid, $timestart, $timeend);
 159  
 160          if ($instance->password and $instance->customint1 and $data->enrolpassword !== $instance->password) {
 161              // It must be a group enrolment, let's assign group too.
 162              $groups = $DB->get_records('groups', array('courseid'=>$instance->courseid), 'id', 'id, enrolmentkey');
 163              foreach ($groups as $group) {
 164                  if (empty($group->enrolmentkey)) {
 165                      continue;
 166                  }
 167                  if ($group->enrolmentkey === $data->enrolpassword) {
 168                      // Add user to group.
 169                      require_once($CFG->dirroot.'/group/lib.php');
 170                      groups_add_member($group->id, $USER->id);
 171                      break;
 172                  }
 173              }
 174          }
 175          // Send welcome message.
 176          if ($instance->customint4) {
 177              $this->email_welcome_message($instance, $USER);
 178          }
 179      }
 180  
 181      /**
 182       * Creates course enrol form, checks if form submitted
 183       * and enrols user if necessary. It can also redirect.
 184       *
 185       * @param stdClass $instance
 186       * @return string html text, usually a form in a text box
 187       */
 188      public function enrol_page_hook(stdClass $instance) {
 189          global $CFG, $OUTPUT, $USER;
 190  
 191          require_once("$CFG->dirroot/enrol/self/locallib.php");
 192  
 193          $enrolstatus = $this->can_self_enrol($instance);
 194  
 195          if (true === $enrolstatus) {
 196              // This user can self enrol using this instance.
 197              $form = new enrol_self_enrol_form(null, $instance);
 198              $instanceid = optional_param('instance', 0, PARAM_INT);
 199              if ($instance->id == $instanceid) {
 200                  if ($data = $form->get_data()) {
 201                      $this->enrol_self($instance, $data);
 202                  }
 203              }
 204          } else {
 205              // This user can not self enrol using this instance. Using an empty form to keep
 206              // the UI consistent with other enrolment plugins that returns a form.
 207              $data = new stdClass();
 208              $data->header = $this->get_instance_name($instance);
 209              $data->info = $enrolstatus;
 210  
 211              // The can_self_enrol call returns a button to the login page if the user is a
 212              // guest, setting the login url to the form if that is the case.
 213              $url = isguestuser() ? get_login_url() : null;
 214              $form = new enrol_self_empty_form($url, $data);
 215          }
 216  
 217          ob_start();
 218          $form->display();
 219          $output = ob_get_clean();
 220          return $OUTPUT->box($output);
 221      }
 222  
 223      /**
 224       * Checks if user can self enrol.
 225       *
 226       * @param stdClass $instance enrolment instance
 227       * @param bool $checkuserenrolment if true will check if user enrolment is inactive.
 228       *             used by navigation to improve performance.
 229       * @return bool|string true if successful, else error message or false.
 230       */
 231      public function can_self_enrol(stdClass $instance, $checkuserenrolment = true) {
 232          global $CFG, $DB, $OUTPUT, $USER;
 233  
 234          if ($checkuserenrolment) {
 235              if (isguestuser()) {
 236                  // Can not enrol guest.
 237                  return get_string('noguestaccess', 'enrol') . $OUTPUT->continue_button(get_login_url());
 238              }
 239              // Check if user is already enroled.
 240              if ($DB->get_record('user_enrolments', array('userid' => $USER->id, 'enrolid' => $instance->id))) {
 241                  return get_string('canntenrol', 'enrol_self');
 242              }
 243          }
 244  
 245          if ($instance->status != ENROL_INSTANCE_ENABLED) {
 246              return get_string('canntenrol', 'enrol_self');
 247          }
 248  
 249          if ($instance->enrolstartdate != 0 and $instance->enrolstartdate > time()) {
 250              return get_string('canntenrolearly', 'enrol_self', userdate($instance->enrolstartdate));
 251          }
 252  
 253          if ($instance->enrolenddate != 0 and $instance->enrolenddate < time()) {
 254              return get_string('canntenrollate', 'enrol_self', userdate($instance->enrolenddate));
 255          }
 256  
 257          if (!$instance->customint6) {
 258              // New enrols not allowed.
 259              return get_string('canntenrol', 'enrol_self');
 260          }
 261  
 262          if ($DB->record_exists('user_enrolments', array('userid' => $USER->id, 'enrolid' => $instance->id))) {
 263              return get_string('canntenrol', 'enrol_self');
 264          }
 265  
 266          if ($instance->customint3 > 0) {
 267              // Max enrol limit specified.
 268              $count = $DB->count_records('user_enrolments', array('enrolid' => $instance->id));
 269              if ($count >= $instance->customint3) {
 270                  // Bad luck, no more self enrolments here.
 271                  return get_string('maxenrolledreached', 'enrol_self');
 272              }
 273          }
 274  
 275          if ($instance->customint5) {
 276              require_once("$CFG->dirroot/cohort/lib.php");
 277              if (!cohort_is_member($instance->customint5, $USER->id)) {
 278                  $cohort = $DB->get_record('cohort', array('id' => $instance->customint5));
 279                  if (!$cohort) {
 280                      return null;
 281                  }
 282                  $a = format_string($cohort->name, true, array('context' => context::instance_by_id($cohort->contextid)));
 283                  return markdown_to_html(get_string('cohortnonmemberinfo', 'enrol_self', $a));
 284              }
 285          }
 286  
 287          return true;
 288      }
 289  
 290      /**
 291       * Return information for enrolment instance containing list of parameters required
 292       * for enrolment, name of enrolment plugin etc.
 293       *
 294       * @param stdClass $instance enrolment instance
 295       * @return stdClass instance info.
 296       */
 297      public function get_enrol_info(stdClass $instance) {
 298  
 299          $instanceinfo = new stdClass();
 300          $instanceinfo->id = $instance->id;
 301          $instanceinfo->courseid = $instance->courseid;
 302          $instanceinfo->type = $this->get_name();
 303          $instanceinfo->name = $this->get_instance_name($instance);
 304          $instanceinfo->status = $this->can_self_enrol($instance);
 305  
 306          if ($instance->password) {
 307              $instanceinfo->requiredparam = new stdClass();
 308              $instanceinfo->requiredparam->enrolpassword = get_string('password', 'enrol_self');
 309          }
 310  
 311          // If enrolment is possible and password is required then return ws function name to get more information.
 312          if ((true === $instanceinfo->status) && $instance->password) {
 313              $instanceinfo->wsfunction = 'enrol_self_get_instance_info';
 314          }
 315          return $instanceinfo;
 316      }
 317  
 318      /**
 319       * Add new instance of enrol plugin with default settings.
 320       * @param stdClass $course
 321       * @return int id of new instance
 322       */
 323      public function add_default_instance($course) {
 324          $fields = $this->get_instance_defaults();
 325  
 326          if ($this->get_config('requirepassword')) {
 327              $fields['password'] = generate_password(20);
 328          }
 329  
 330          return $this->add_instance($course, $fields);
 331      }
 332  
 333      /**
 334       * Returns defaults for new instances.
 335       * @return array
 336       */
 337      public function get_instance_defaults() {
 338          $expirynotify = $this->get_config('expirynotify');
 339          if ($expirynotify == 2) {
 340              $expirynotify = 1;
 341              $notifyall = 1;
 342          } else {
 343              $notifyall = 0;
 344          }
 345  
 346          $fields = array();
 347          $fields['status']          = $this->get_config('status');
 348          $fields['roleid']          = $this->get_config('roleid');
 349          $fields['enrolperiod']     = $this->get_config('enrolperiod');
 350          $fields['expirynotify']    = $expirynotify;
 351          $fields['notifyall']       = $notifyall;
 352          $fields['expirythreshold'] = $this->get_config('expirythreshold');
 353          $fields['customint1']      = $this->get_config('groupkey');
 354          $fields['customint2']      = $this->get_config('longtimenosee');
 355          $fields['customint3']      = $this->get_config('maxenrolled');
 356          $fields['customint4']      = $this->get_config('sendcoursewelcomemessage');
 357          $fields['customint5']      = 0;
 358          $fields['customint6']      = $this->get_config('newenrols');
 359  
 360          return $fields;
 361      }
 362  
 363      /**
 364       * Send welcome email to specified user.
 365       *
 366       * @param stdClass $instance
 367       * @param stdClass $user user record
 368       * @return void
 369       */
 370      protected function email_welcome_message($instance, $user) {
 371          global $CFG, $DB;
 372  
 373          $course = $DB->get_record('course', array('id'=>$instance->courseid), '*', MUST_EXIST);
 374          $context = context_course::instance($course->id);
 375  
 376          $a = new stdClass();
 377          $a->coursename = format_string($course->fullname, true, array('context'=>$context));
 378          $a->profileurl = "$CFG->wwwroot/user/view.php?id=$user->id&course=$course->id";
 379  
 380          if (trim($instance->customtext1) !== '') {
 381              $message = $instance->customtext1;
 382              $key = array('{$a->coursename}', '{$a->profileurl}', '{$a->fullname}', '{$a->email}');
 383              $value = array($a->coursename, $a->profileurl, fullname($user), $user->email);
 384              $message = str_replace($key, $value, $message);
 385              if (strpos($message, '<') === false) {
 386                  // Plain text only.
 387                  $messagetext = $message;
 388                  $messagehtml = text_to_html($messagetext, null, false, true);
 389              } else {
 390                  // This is most probably the tag/newline soup known as FORMAT_MOODLE.
 391                  $messagehtml = format_text($message, FORMAT_MOODLE, array('context'=>$context, 'para'=>false, 'newlines'=>true, 'filter'=>true));
 392                  $messagetext = html_to_text($messagehtml);
 393              }
 394          } else {
 395              $messagetext = get_string('welcometocoursetext', 'enrol_self', $a);
 396              $messagehtml = text_to_html($messagetext, null, false, true);
 397          }
 398  
 399          $subject = get_string('welcometocourse', 'enrol_self', format_string($course->fullname, true, array('context'=>$context)));
 400  
 401          $rusers = array();
 402          if (!empty($CFG->coursecontact)) {
 403              $croles = explode(',', $CFG->coursecontact);
 404              list($sort, $sortparams) = users_order_by_sql('u');
 405              // We only use the first user.
 406              $i = 0;
 407              do {
 408                  $rusers = get_role_users($croles[$i], $context, true, '',
 409                      'r.sortorder ASC, ' . $sort, null, '', '', '', '', $sortparams);
 410                  $i++;
 411              } while (empty($rusers) && !empty($croles[$i]));
 412          }
 413          if ($rusers) {
 414              $contact = reset($rusers);
 415          } else {
 416              $contact = core_user::get_support_user();
 417          }
 418  
 419          // Directly emailing welcome message rather than using messaging.
 420          email_to_user($user, $contact, $subject, $messagetext, $messagehtml);
 421      }
 422  
 423      /**
 424       * Enrol self cron support.
 425       * @return void
 426       */
 427      public function cron() {
 428          $trace = new text_progress_trace();
 429          $this->sync($trace, null);
 430          $this->send_expiry_notifications($trace);
 431      }
 432  
 433      /**
 434       * Sync all meta course links.
 435       *
 436       * @param progress_trace $trace
 437       * @param int $courseid one course, empty mean all
 438       * @return int 0 means ok, 1 means error, 2 means plugin disabled
 439       */
 440      public function sync(progress_trace $trace, $courseid = null) {
 441          global $DB;
 442  
 443          if (!enrol_is_enabled('self')) {
 444              $trace->finished();
 445              return 2;
 446          }
 447  
 448          // Unfortunately this may take a long time, execution can be interrupted safely here.
 449          core_php_time_limit::raise();
 450          raise_memory_limit(MEMORY_HUGE);
 451  
 452          $trace->output('Verifying self-enrolments...');
 453  
 454          $params = array('now'=>time(), 'useractive'=>ENROL_USER_ACTIVE, 'courselevel'=>CONTEXT_COURSE);
 455          $coursesql = "";
 456          if ($courseid) {
 457              $coursesql = "AND e.courseid = :courseid";
 458              $params['courseid'] = $courseid;
 459          }
 460  
 461          // Note: the logic of self enrolment guarantees that user logged in at least once (=== u.lastaccess set)
 462          //       and that user accessed course at least once too (=== user_lastaccess record exists).
 463  
 464          // First deal with users that did not log in for a really long time - they do not have user_lastaccess records.
 465          $sql = "SELECT e.*, ue.userid
 466                    FROM {user_enrolments} ue
 467                    JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'self' AND e.customint2 > 0)
 468                    JOIN {user} u ON u.id = ue.userid
 469                   WHERE :now - u.lastaccess > e.customint2
 470                         $coursesql";
 471          $rs = $DB->get_recordset_sql($sql, $params);
 472          foreach ($rs as $instance) {
 473              $userid = $instance->userid;
 474              unset($instance->userid);
 475              $this->unenrol_user($instance, $userid);
 476              $days = $instance->customint2 / 60*60*24;
 477              $trace->output("unenrolling user $userid from course $instance->courseid as they have did not log in for at least $days days", 1);
 478          }
 479          $rs->close();
 480  
 481          // Now unenrol from course user did not visit for a long time.
 482          $sql = "SELECT e.*, ue.userid
 483                    FROM {user_enrolments} ue
 484                    JOIN {enrol} e ON (e.id = ue.enrolid AND e.enrol = 'self' AND e.customint2 > 0)
 485                    JOIN {user_lastaccess} ul ON (ul.userid = ue.userid AND ul.courseid = e.courseid)
 486                   WHERE :now - ul.timeaccess > e.customint2
 487                         $coursesql";
 488          $rs = $DB->get_recordset_sql($sql, $params);
 489          foreach ($rs as $instance) {
 490              $userid = $instance->userid;
 491              unset($instance->userid);
 492              $this->unenrol_user($instance, $userid);
 493                  $days = $instance->customint2 / 60*60*24;
 494              $trace->output("unenrolling user $userid from course $instance->courseid as they have did not access course for at least $days days", 1);
 495          }
 496          $rs->close();
 497  
 498          $trace->output('...user self-enrolment updates finished.');
 499          $trace->finished();
 500  
 501          $this->process_expirations($trace, $courseid);
 502  
 503          return 0;
 504      }
 505  
 506      /**
 507       * Returns the user who is responsible for self enrolments in given instance.
 508       *
 509       * Usually it is the first editing teacher - the person with "highest authority"
 510       * as defined by sort_by_roleassignment_authority() having 'enrol/self:manage'
 511       * capability.
 512       *
 513       * @param int $instanceid enrolment instance id
 514       * @return stdClass user record
 515       */
 516      protected function get_enroller($instanceid) {
 517          global $DB;
 518  
 519          if ($this->lasternollerinstanceid == $instanceid and $this->lasternoller) {
 520              return $this->lasternoller;
 521          }
 522  
 523          $instance = $DB->get_record('enrol', array('id'=>$instanceid, 'enrol'=>$this->get_name()), '*', MUST_EXIST);
 524          $context = context_course::instance($instance->courseid);
 525  
 526          if ($users = get_enrolled_users($context, 'enrol/self:manage')) {
 527              $users = sort_by_roleassignment_authority($users, $context);
 528              $this->lasternoller = reset($users);
 529              unset($users);
 530          } else {
 531              $this->lasternoller = parent::get_enroller($instanceid);
 532          }
 533  
 534          $this->lasternollerinstanceid = $instanceid;
 535  
 536          return $this->lasternoller;
 537      }
 538  
 539      /**
 540       * Gets an array of the user enrolment actions.
 541       *
 542       * @param course_enrolment_manager $manager
 543       * @param stdClass $ue A user enrolment object
 544       * @return array An array of user_enrolment_actions
 545       */
 546      public function get_user_enrolment_actions(course_enrolment_manager $manager, $ue) {
 547          $actions = array();
 548          $context = $manager->get_context();
 549          $instance = $ue->enrolmentinstance;
 550          $params = $manager->get_moodlepage()->url->params();
 551          $params['ue'] = $ue->id;
 552          if ($this->allow_unenrol($instance) && has_capability("enrol/self:unenrol", $context)) {
 553              $url = new moodle_url('/enrol/unenroluser.php', $params);
 554              $actions[] = new user_enrolment_action(new pix_icon('t/delete', ''), get_string('unenrol', 'enrol'), $url, array('class'=>'unenrollink', 'rel'=>$ue->id));
 555          }
 556          if ($this->allow_manage($instance) && has_capability("enrol/self:manage", $context)) {
 557              $url = new moodle_url('/enrol/editenrolment.php', $params);
 558              $actions[] = new user_enrolment_action(new pix_icon('t/edit', ''), get_string('edit'), $url, array('class'=>'editenrollink', 'rel'=>$ue->id));
 559          }
 560          return $actions;
 561      }
 562  
 563      /**
 564       * Restore instance and map settings.
 565       *
 566       * @param restore_enrolments_structure_step $step
 567       * @param stdClass $data
 568       * @param stdClass $course
 569       * @param int $oldid
 570       */
 571      public function restore_instance(restore_enrolments_structure_step $step, stdClass $data, $course, $oldid) {
 572          global $DB;
 573          if ($step->get_task()->get_target() == backup::TARGET_NEW_COURSE) {
 574              $merge = false;
 575          } else {
 576              $merge = array(
 577                  'courseid'   => $data->courseid,
 578                  'enrol'      => $this->get_name(),
 579                  'roleid'     => $data->roleid,
 580              );
 581          }
 582          if ($merge and $instances = $DB->get_records('enrol', $merge, 'id')) {
 583              $instance = reset($instances);
 584              $instanceid = $instance->id;
 585          } else {
 586              if (!empty($data->customint5)) {
 587                  if ($step->get_task()->is_samesite()) {
 588                      // Keep cohort restriction unchanged - we are on the same site.
 589                  } else {
 590                      // Use some id that can not exist in order to prevent self enrolment,
 591                      // because we do not know what cohort it is in this site.
 592                      $data->customint5 = -1;
 593                  }
 594              }
 595              $instanceid = $this->add_instance($course, (array)$data);
 596          }
 597          $step->set_mapping('enrol', $oldid, $instanceid);
 598      }
 599  
 600      /**
 601       * Restore user enrolment.
 602       *
 603       * @param restore_enrolments_structure_step $step
 604       * @param stdClass $data
 605       * @param stdClass $instance
 606       * @param int $oldinstancestatus
 607       * @param int $userid
 608       */
 609      public function restore_user_enrolment(restore_enrolments_structure_step $step, $data, $instance, $userid, $oldinstancestatus) {
 610          $this->enrol_user($instance, $userid, null, $data->timestart, $data->timeend, $data->status);
 611      }
 612  
 613      /**
 614       * Restore role assignment.
 615       *
 616       * @param stdClass $instance
 617       * @param int $roleid
 618       * @param int $userid
 619       * @param int $contextid
 620       */
 621      public function restore_role_assignment($instance, $roleid, $userid, $contextid) {
 622          // This is necessary only because we may migrate other types to this instance,
 623          // we do not use component in manual or self enrol.
 624          role_assign($roleid, $userid, $contextid, '', 0);
 625      }
 626  
 627      /**
 628       * Is it possible to delete enrol instance via standard UI?
 629       *
 630       * @param stdClass $instance
 631       * @return bool
 632       */
 633      public function can_delete_instance($instance) {
 634          $context = context_course::instance($instance->courseid);
 635          return has_capability('enrol/self:config', $context);
 636      }
 637  
 638      /**
 639       * Is it possible to hide/show enrol instance via standard UI?
 640       *
 641       * @param stdClass $instance
 642       * @return bool
 643       */
 644      public function can_hide_show_instance($instance) {
 645          $context = context_course::instance($instance->courseid);
 646  
 647          if (!has_capability('enrol/self:config', $context)) {
 648              return false;
 649          }
 650  
 651          // If the instance is currently disabled, before it can be enabled,
 652          // we must check whether the password meets the password policies.
 653          if ($instance->status == ENROL_INSTANCE_DISABLED) {
 654              if ($this->get_config('requirepassword')) {
 655                  if (empty($instance->password)) {
 656                      return false;
 657                  }
 658              }
 659              // Only check the password if it is set.
 660              if (!empty($instance->password) && $this->get_config('usepasswordpolicy')) {
 661                  if (!check_password_policy($instance->password, $errmsg)) {
 662                      return false;
 663                  }
 664              }
 665          }
 666  
 667          return true;
 668      }
 669  
 670      /**
 671       * Return an array of valid options for the status.
 672       *
 673       * @return array
 674       */
 675      protected function get_status_options() {
 676          $options = array(ENROL_INSTANCE_ENABLED  => get_string('yes'),
 677                           ENROL_INSTANCE_DISABLED => get_string('no'));
 678          return $options;
 679      }
 680  
 681      /**
 682       * Return an array of valid options for the newenrols property.
 683       *
 684       * @return array
 685       */
 686      protected function get_newenrols_options() {
 687          $options = array(1 => get_string('yes'), 0 => get_string('no'));
 688          return $options;
 689      }
 690  
 691      /**
 692       * Return an array of valid options for the groupkey property.
 693       *
 694       * @return array
 695       */
 696      protected function get_groupkey_options() {
 697          $options = array(1 => get_string('yes'), 0 => get_string('no'));
 698          return $options;
 699      }
 700  
 701      /**
 702       * Return an array of valid options for the expirynotify property.
 703       *
 704       * @return array
 705       */
 706      protected function get_expirynotify_options() {
 707          $options = array(0 => get_string('no'),
 708                           1 => get_string('expirynotifyenroller', 'core_enrol'),
 709                           2 => get_string('expirynotifyall', 'core_enrol'));
 710          return $options;
 711      }
 712  
 713      /**
 714       * Return an array of valid options for the longtimenosee property.
 715       *
 716       * @return array
 717       */
 718      protected function get_longtimenosee_options() {
 719          $options = array(0 => get_string('never'),
 720                           1800 * 3600 * 24 => get_string('numdays', '', 1800),
 721                           1000 * 3600 * 24 => get_string('numdays', '', 1000),
 722                           365 * 3600 * 24 => get_string('numdays', '', 365),
 723                           180 * 3600 * 24 => get_string('numdays', '', 180),
 724                           150 * 3600 * 24 => get_string('numdays', '', 150),
 725                           120 * 3600 * 24 => get_string('numdays', '', 120),
 726                           90 * 3600 * 24 => get_string('numdays', '', 90),
 727                           60 * 3600 * 24 => get_string('numdays', '', 60),
 728                           30 * 3600 * 24 => get_string('numdays', '', 30),
 729                           21 * 3600 * 24 => get_string('numdays', '', 21),
 730                           14 * 3600 * 24 => get_string('numdays', '', 14),
 731                           7 * 3600 * 24 => get_string('numdays', '', 7));
 732          return $options;
 733      }
 734  
 735      /**
 736       * Add elements to the edit instance form.
 737       *
 738       * @param stdClass $instance
 739       * @param MoodleQuickForm $mform
 740       * @param context $context
 741       * @return bool
 742       */
 743      public function edit_instance_form($instance, MoodleQuickForm $mform, $context) {
 744          global $CFG;
 745  
 746          // Merge these two settings to one value for the single selection element.
 747          if ($instance->notifyall and $instance->expirynotify) {
 748              $instance->expirynotify = 2;
 749          }
 750          unset($instance->notifyall);
 751  
 752          $nameattribs = array('size' => '20', 'maxlength' => '255');
 753          $mform->addElement('text', 'name', get_string('custominstancename', 'enrol'), $nameattribs);
 754          $mform->setType('name', PARAM_TEXT);
 755          $mform->addRule('name', get_string('maximumchars', '', 255), 'maxlength', 255, 'server');
 756  
 757          $options = $this->get_status_options();
 758          $mform->addElement('select', 'status', get_string('status', 'enrol_self'), $options);
 759          $mform->addHelpButton('status', 'status', 'enrol_self');
 760  
 761          $options = $this->get_newenrols_options();
 762          $mform->addElement('select', 'customint6', get_string('newenrols', 'enrol_self'), $options);
 763          $mform->addHelpButton('customint6', 'newenrols', 'enrol_self');
 764          $mform->disabledIf('customint6', 'status', 'eq', ENROL_INSTANCE_DISABLED);
 765  
 766          $passattribs = array('size' => '20', 'maxlength' => '50');
 767          $mform->addElement('passwordunmask', 'password', get_string('password', 'enrol_self'), $passattribs);
 768          $mform->addHelpButton('password', 'password', 'enrol_self');
 769          if (empty($instance->id) and $this->get_config('requirepassword')) {
 770              $mform->addRule('password', get_string('required'), 'required', null, 'client');
 771          }
 772          $mform->addRule('password', get_string('maximumchars', '', 50), 'maxlength', 50, 'server');
 773  
 774          $options = $this->get_groupkey_options();
 775          $mform->addElement('select', 'customint1', get_string('groupkey', 'enrol_self'), $options);
 776          $mform->addHelpButton('customint1', 'groupkey', 'enrol_self');
 777  
 778          $roles = $this->extend_assignable_roles($context, $instance->roleid);
 779          $mform->addElement('select', 'roleid', get_string('role', 'enrol_self'), $roles);
 780  
 781          $options = array('optional' => true, 'defaultunit' => 86400);
 782          $mform->addElement('duration', 'enrolperiod', get_string('enrolperiod', 'enrol_self'), $options);
 783          $mform->addHelpButton('enrolperiod', 'enrolperiod', 'enrol_self');
 784  
 785          $options = $this->get_expirynotify_options();
 786          $mform->addElement('select', 'expirynotify', get_string('expirynotify', 'core_enrol'), $options);
 787          $mform->addHelpButton('expirynotify', 'expirynotify', 'core_enrol');
 788  
 789          $options = array('optional' => false, 'defaultunit' => 86400);
 790          $mform->addElement('duration', 'expirythreshold', get_string('expirythreshold', 'core_enrol'), $options);
 791          $mform->addHelpButton('expirythreshold', 'expirythreshold', 'core_enrol');
 792          $mform->disabledIf('expirythreshold', 'expirynotify', 'eq', 0);
 793  
 794          $options = array('optional' => true);
 795          $mform->addElement('date_time_selector', 'enrolstartdate', get_string('enrolstartdate', 'enrol_self'), $options);
 796          $mform->setDefault('enrolstartdate', 0);
 797          $mform->addHelpButton('enrolstartdate', 'enrolstartdate', 'enrol_self');
 798  
 799          $options = array('optional' => true);
 800          $mform->addElement('date_time_selector', 'enrolenddate', get_string('enrolenddate', 'enrol_self'), $options);
 801          $mform->setDefault('enrolenddate', 0);
 802          $mform->addHelpButton('enrolenddate', 'enrolenddate', 'enrol_self');
 803  
 804          $options = $this->get_longtimenosee_options();
 805          $mform->addElement('select', 'customint2', get_string('longtimenosee', 'enrol_self'), $options);
 806          $mform->addHelpButton('customint2', 'longtimenosee', 'enrol_self');
 807  
 808          $mform->addElement('text', 'customint3', get_string('maxenrolled', 'enrol_self'));
 809          $mform->addHelpButton('customint3', 'maxenrolled', 'enrol_self');
 810          $mform->setType('customint3', PARAM_INT);
 811  
 812          require_once($CFG->dirroot.'/cohort/lib.php');
 813  
 814          $cohorts = array(0 => get_string('no'));
 815          $allcohorts = cohort_get_available_cohorts($context, 0, 0, 0);
 816          if ($instance->customint5 && !isset($allcohorts[$instance->customint5])) {
 817              $c = $DB->get_record('cohort',
 818                                   array('id' => $instance->customint5),
 819                                   'id, name, idnumber, contextid, visible',
 820                                   IGNORE_MISSING);
 821              if ($c) {
 822                  // Current cohort was not found because current user can not see it. Still keep it.
 823                  $allcohorts[$instance->customint5] = $c;
 824              }
 825          }
 826          foreach ($allcohorts as $c) {
 827              $cohorts[$c->id] = format_string($c->name, true, array('context' => context::instance_by_id($c->contextid)));
 828              if ($c->idnumber) {
 829                  $cohorts[$c->id] .= ' ['.s($c->idnumber).']';
 830              }
 831          }
 832          if ($instance->customint5 && !isset($allcohorts[$instance->customint5])) {
 833              // Somebody deleted a cohort, better keep the wrong value so that random ppl can not enrol.
 834              $cohorts[$instance->customint5] = get_string('unknowncohort', 'cohort', $instance->customint5);
 835          }
 836          if (count($cohorts) > 1) {
 837              $mform->addElement('select', 'customint5', get_string('cohortonly', 'enrol_self'), $cohorts);
 838              $mform->addHelpButton('customint5', 'cohortonly', 'enrol_self');
 839          } else {
 840              $mform->addElement('hidden', 'customint5');
 841              $mform->setType('customint5', PARAM_INT);
 842              $mform->setConstant('customint5', 0);
 843          }
 844  
 845          $mform->addElement('advcheckbox', 'customint4', get_string('sendcoursewelcomemessage', 'enrol_self'));
 846          $mform->addHelpButton('customint4', 'sendcoursewelcomemessage', 'enrol_self');
 847  
 848          $options = array('cols' => '60', 'rows' => '8');
 849          $mform->addElement('textarea', 'customtext1', get_string('customwelcomemessage', 'enrol_self'), $options);
 850          $mform->addHelpButton('customtext1', 'customwelcomemessage', 'enrol_self');
 851  
 852          if (enrol_accessing_via_instance($instance)) {
 853              $warntext = get_string('instanceeditselfwarningtext', 'core_enrol');
 854              $mform->addElement('static', 'selfwarn', get_string('instanceeditselfwarning', 'core_enrol'), $warntext);
 855          }
 856      }
 857  
 858      /**
 859       * We are a good plugin and don't invent our own UI/validation code path.
 860       *
 861       * @return boolean
 862       */
 863      public function use_standard_editing_ui() {
 864          return true;
 865      }
 866  
 867      /**
 868       * Perform custom validation of the data used to edit the instance.
 869       *
 870       * @param array $data array of ("fieldname"=>value) of submitted data
 871       * @param array $files array of uploaded files "element_name"=>tmp_file_path
 872       * @param object $instance The instance loaded from the DB
 873       * @param context $context The context of the instance we are editing
 874       * @return array of "element_name"=>"error_description" if there are errors,
 875       *         or an empty array if everything is OK.
 876       * @return void
 877       */
 878      public function edit_instance_validation($data, $files, $instance, $context) {
 879          $errors = array();
 880  
 881          $checkpassword = false;
 882  
 883          if ($instance->id) {
 884              // Check the password if we are enabling the plugin again.
 885              if (($instance->status == ENROL_INSTANCE_DISABLED) && ($data['status'] == ENROL_INSTANCE_ENABLED)) {
 886                  $checkpassword = true;
 887              }
 888  
 889              // Check the password if the instance is enabled and the password has changed.
 890              if (($data['status'] == ENROL_INSTANCE_ENABLED) && ($instance->password !== $data['password'])) {
 891                  $checkpassword = true;
 892              }
 893          } else {
 894              $checkpassword = true;
 895          }
 896  
 897          if ($checkpassword) {
 898              $require = $this->get_config('requirepassword');
 899              $policy  = $this->get_config('usepasswordpolicy');
 900              if ($require and trim($data['password']) === '') {
 901                  $errors['password'] = get_string('required');
 902              } else if (!empty($data['password']) && $policy) {
 903                  $errmsg = '';
 904                  if (!check_password_policy($data['password'], $errmsg)) {
 905                      $errors['password'] = $errmsg;
 906                  }
 907              }
 908          }
 909  
 910          if ($data['status'] == ENROL_INSTANCE_ENABLED) {
 911              if (!empty($data['enrolenddate']) and $data['enrolenddate'] < $data['enrolstartdate']) {
 912                  $errors['enrolenddate'] = get_string('enrolenddaterror', 'enrol_self');
 913              }
 914          }
 915  
 916          if ($data['expirynotify'] > 0 and $data['expirythreshold'] < 86400) {
 917              $errors['expirythreshold'] = get_string('errorthresholdlow', 'core_enrol');
 918          }
 919  
 920          // Now these ones are checked by quickforms, but we may be called by the upload enrolments tool, or a webservive.
 921          if (core_text::strlen($data['name']) > 255) {
 922              $errors['name'] = get_string('err_maxlength', 'form', 255);
 923          }
 924          $validstatus = array_keys($this->get_status_options());
 925          $validnewenrols = array_keys($this->get_newenrols_options());
 926          if (core_text::strlen($data['password']) > 50) {
 927              $errors['name'] = get_string('err_maxlength', 'form', 50);
 928          }
 929          $validgroupkey = array_keys($this->get_groupkey_options());
 930          $context = context_course::instance($instance->courseid);
 931          $validroles = array_keys($this->extend_assignable_roles($context, $instance->roleid));
 932          $validexpirynotify = array_keys($this->get_expirynotify_options());
 933          $validlongtimenosee = array_keys($this->get_longtimenosee_options());
 934          $tovalidate = array(
 935              'enrolstartdate' => PARAM_INT,
 936              'enrolenddate' => PARAM_INT,
 937              'name' => PARAM_TEXT,
 938              'customint1' => $validgroupkey,
 939              'customint2' => $validlongtimenosee,
 940              'customint3' => PARAM_INT,
 941              'customint4' => PARAM_BOOL,
 942              'customint5' => PARAM_INT,
 943              'customint6' => $validnewenrols,
 944              'status' => $validstatus,
 945              'enrolperiod' => PARAM_INT,
 946              'expirynotify' => $validexpirynotify,
 947              'roleid' => $validroles
 948          );
 949          if ($data['expirynotify'] != 0) {
 950              $tovalidate['expirythreshold'] = PARAM_INT;
 951          }
 952          $typeerrors = $this->validate_param_types($data, $tovalidate);
 953          $errors = array_merge($errors, $typeerrors);
 954  
 955          return $errors;
 956      }
 957  
 958      /**
 959       * Add new instance of enrol plugin.
 960       * @param object $course
 961       * @param array $fields instance fields
 962       * @return int id of new instance, null if can not be created
 963       */
 964      public function add_instance($course, array $fields = null) {
 965          // In the form we are representing 2 db columns with one field.
 966          if (!empty($fields) && !empty($fields['expirynotify'])) {
 967              if ($fields['expirynotify'] == 2) {
 968                  $fields['expirynotify'] = 1;
 969                  $fields['notifyall'] = 1;
 970              } else {
 971                  $fields['notifyall'] = 0;
 972              }
 973          }
 974  
 975          return parent::add_instance($course, $fields);
 976      }
 977  
 978      /**
 979       * Update instance of enrol plugin.
 980       * @param stdClass $instance
 981       * @param stdClass $data modified instance fields
 982       * @return boolean
 983       */
 984      public function update_instance($instance, $data) {
 985          // In the form we are representing 2 db columns with one field.
 986          if ($data->expirynotify == 2) {
 987              $data->expirynotify = 1;
 988              $data->notifyall = 1;
 989          } else {
 990              $data->notifyall = 0;
 991          }
 992          // Keep previous/default value of disabled expirythreshold option.
 993          if (!$data->expirynotify) {
 994              $data->expirythreshold = $instance->expirythreshold;
 995          }
 996          // Add previous value of newenrols if disabled.
 997          if (!isset($data->customint6)) {
 998              $data->customint6 = $instance->customint6;
 999          }
1000  
1001          return parent::update_instance($instance, $data);
1002      }
1003  
1004      /**
1005       * Gets a list of roles that this user can assign for the course as the default for self-enrolment.
1006       *
1007       * @param context $context the context.
1008       * @param integer $defaultrole the id of the role that is set as the default for self-enrolment
1009       * @return array index is the role id, value is the role name
1010       */
1011      public function extend_assignable_roles($context, $defaultrole) {
1012          global $DB;
1013  
1014          $roles = get_assignable_roles($context, ROLENAME_BOTH);
1015          if (!isset($roles[$defaultrole])) {
1016              if ($role = $DB->get_record('role', array('id' => $defaultrole))) {
1017                  $roles[$defaultrole] = role_get_name($role, $context, ROLENAME_BOTH);
1018              }
1019          }
1020          return $roles;
1021      }
1022  }