lib/enrollib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * This library includes the basic parts of enrol api.
  20  * It is available on each page.
  21  *
  22  * @package    core
  23  * @subpackage enrol
  24  * @copyright  2010 Petr Skoda {@link http://skodak.org}
  25  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  26  */
  27
  28 defined('MOODLE_INTERNAL') || die();
  29
  30 /** Course enrol instance enabled. (used in enrol->status) */
  31 define('ENROL_INSTANCE_ENABLED', 0);
  32
  33 /** Course enrol instance disabled, user may enter course if other enrol instance enabled. (used in enrol->status)*/
  34 define('ENROL_INSTANCE_DISABLED', 1);
  35
  36 /** User is active participant (used in user_enrolments->status)*/
  37 define('ENROL_USER_ACTIVE', 0);
  38
  39 /** User participation in course is suspended (used in user_enrolments->status) */
  40 define('ENROL_USER_SUSPENDED', 1);
  41
  42 /** Enrol info is cached for this number of seconds in require_login() */
  43 define('ENROL_REQUIRE_LOGIN_CACHE_PERIOD', 1800);
  44
  45 /** When user disappears from external source, the enrolment is completely removed */
  46 define('ENROL_EXT_REMOVED_UNENROL', 0);
  47
  48 /** When user disappears from external source, the enrolment is kept as is - one way sync */
  49 define('ENROL_EXT_REMOVED_KEEP', 1);
  50
  51 /** enrol plugin feature describing requested restore type */
  52 define('ENROL_RESTORE_TYPE', 'enrolrestore');
  53 /** User custom backup/restore class  stored in backup/moodle2/ subdirectory */
  54 define('ENROL_RESTORE_CLASS', 'class');
  55 /** Restore all custom fields from enrol table without any changes and all user_enrolments records */
  56 define('ENROL_RESTORE_EXACT', 'exact');
  57 /** Restore enrol record like ENROL_RESTORE_EXACT, but no user enrolments */
  58 define('ENROL_RESTORE_NOUSERS', 'nousers');
  59
  60 /**
  61  * When user disappears from external source, user enrolment is suspended, roles are kept as is.
  62  * In some cases user needs a role with some capability to be visible in UI - suc has in gradebook,
  63  * assignments, etc.
  64  */
  65 define('ENROL_EXT_REMOVED_SUSPEND', 2);
  66
  67 /**
  68  * When user disappears from external source, the enrolment is suspended and roles assigned
  69  * by enrol instance are removed. Please note that user may "disappear" from gradebook and other areas.
  70  * */
  71 define('ENROL_EXT_REMOVED_SUSPENDNOROLES', 3);
  72
  73 /**
  74  * Returns instances of enrol plugins
  75  * @param bool $enable return enabled only
  76  * @return array of enrol plugins name=>instance
  77  */
  78 function enrol_get_plugins($enabled) {
  79     global $CFG;
  80
  81     $result = array();
  82
  83     if ($enabled) {
  84         // sorted by enabled plugin order
  85         $enabled = explode(',', $CFG->enrol_plugins_enabled);
  86         $plugins = array();
  87         foreach ($enabled as $plugin) {
  88             $plugins[$plugin] = "$CFG->dirroot/enrol/$plugin";
  89         }
  90     } else {
  91         // sorted alphabetically
  92         $plugins = get_plugin_list('enrol');
  93         ksort($plugins);
  94     }
  95
  96     foreach ($plugins as $plugin=>$location) {
  97         if (!file_exists("$location/lib.php")) {
  98             continue;
  99         }
 100         include_once("$location/lib.php");
 101         $class = "enrol_{$plugin}_plugin";
 102         if (!class_exists($class)) {
 103             continue;
 104         }
 105
 106         $result[$plugin] = new $class();
 107     }
 108
 109     return $result;
 110 }
 111
 112 /**
 113  * Returns instance of enrol plugin
 114  * @param  string $name name of enrol plugin ('manual', 'guest', ...)
 115  * @return enrol_plugin
 116  */
 117 function enrol_get_plugin($name) {
 118     global $CFG;
 119
 120     if ($name !== clean_param($name, PARAM_SAFEDIR)) {
 121         // ignore malformed plugin names completely
 122         return null;
 123     }
 124
 125     $location = "$CFG->dirroot/enrol/$name";
 126
 127     if (!file_exists("$location/lib.php")) {
 128         return null;
 129     }
 130     include_once("$location/lib.php");
 131     $class = "enrol_{$name}_plugin";
 132     if (!class_exists($class)) {
 133         return null;
 134     }
 135
 136     return new $class();
 137 }
 138
 139 /**
 140  * Returns enrolment instances in given course.
 141  * @param int $courseid
 142  * @param bool $enabled
 143  * @return array of enrol instances
 144  */
 145 function enrol_get_instances($courseid, $enabled) {
 146     global $DB, $CFG;
 147
 148     if (!$enabled) {
 149         return $DB->get_records('enrol', array('courseid'=>$courseid), 'sortorder,id');
 150     }
 151
 152     $result = $DB->get_records('enrol', array('courseid'=>$courseid, 'status'=>ENROL_INSTANCE_ENABLED), 'sortorder,id');
 153
 154     $enabled = explode(',', $CFG->enrol_plugins_enabled);
 155     foreach ($result as $key=>$instance) {
 156         if (!in_array($instance->enrol, $enabled)) {
 157             unset($result[$key]);
 158             continue;
 159         }
 160         if (!file_exists("$CFG->dirroot/enrol/$instance->enrol/lib.php")) {
 161             // broken plugin
 162             unset($result[$key]);
 163             continue;
 164         }
 165     }
 166
 167     return $result;
 168 }
 169
 170 /**
 171  * Checks if a given plugin is in the list of enabled enrolment plugins.
 172  *
 173  * @param string $enrol Enrolment plugin name
 174  * @return boolean Whether the plugin is enabled
 175  */
 176 function enrol_is_enabled($enrol) {
 177     global $CFG;
 178
 179     if (empty($CFG->enrol_plugins_enabled)) {
 180         return false;
 181     }
 182     return in_array($enrol, explode(',', $CFG->enrol_plugins_enabled));
 183 }
 184
 185 /**
 186  * Check all the login enrolment information for the given user object
 187  * by querying the enrolment plugins
 188  *
 189  * @param object $user
 190  * @return void
 191  */
 192 function enrol_check_plugins($user) {
 193     global $CFG;
 194
 195     if (empty($user->id) or isguestuser($user)) {
 196         // shortcut - there is no enrolment work for guests and not-logged-in users
 197         return;
 198     }
 199
 200     if (is_siteadmin()) {
 201         // no sync for admin user, please use admin accounts only for admin tasks like the unix root user!
 202         // if plugin fails on sync admins need to be able to log in
 203         return;
 204     }
 205
 206     static $inprogress = array();  // To prevent this function being called more than once in an invocation
 207
 208     if (!empty($inprogress[$user->id])) {
 209         return;
 210     }
 211
 212     $inprogress[$user->id] = true;  // Set the flag
 213
 214     $enabled = enrol_get_plugins(true);
 215
 216     foreach($enabled as $enrol) {
 217         $enrol->sync_user_enrolments($user);
 218     }
 219
 220     unset($inprogress[$user->id]);  // Unset the flag
 221 }
 222
 223 /**
 224  * This function adds necessary enrol plugins UI into the course edit form.
 225  *
 226  * @param MoodleQuickForm $mform
 227  * @param object $data course edit form data
 228  * @param object $context context of existing course or parent category if course does not exist
 229  * @return void
 230  */
 231 function enrol_course_edit_form(MoodleQuickForm $mform, $data, $context) {
 232     $plugins = enrol_get_plugins(true);
 233     if (!empty($data->id)) {
 234         $instances = enrol_get_instances($data->id, false);
 235         foreach ($instances as $instance) {
 236             if (!isset($plugins[$instance->enrol])) {
 237                 continue;
 238             }
 239             $plugin = $plugins[$instance->enrol];
 240             $plugin->course_edit_form($instance, $mform, $data, $context);
 241         }
 242     } else {
 243         foreach ($plugins as $plugin) {
 244             $plugin->course_edit_form(NULL, $mform, $data, $context);
 245         }
 246     }
 247 }
 248
 249 /**
 250  * Validate course edit form data
 251  *
 252  * @param array $data raw form data
 253  * @param object $context context of existing course or parent category if course does not exist
 254  * @return array errors array
 255  */
 256 function enrol_course_edit_validation(array $data, $context) {
 257     $errors = array();
 258     $plugins = enrol_get_plugins(true);
 259
 260     if (!empty($data['id'])) {
 261         $instances = enrol_get_instances($data['id'], false);
 262         foreach ($instances as $instance) {
 263             if (!isset($plugins[$instance->enrol])) {
 264                 continue;
 265             }
 266             $plugin = $plugins[$instance->enrol];
 267             $errors = array_merge($errors, $plugin->course_edit_validation($instance, $data, $context));
 268         }
 269     } else {
 270         foreach ($plugins as $plugin) {
 271             $errors = array_merge($errors, $plugin->course_edit_validation(NULL, $data, $context));
 272         }
 273     }
 274
 275     return $errors;
 276 }
 277
 278 /**
 279  * Update enrol instances after course edit form submission
 280  * @param bool $inserted true means new course added, false course already existed
 281  * @param object $course
 282  * @param object $data form data
 283  * @return void
 284  */
 285 function enrol_course_updated($inserted, $course, $data) {
 286     global $DB, $CFG;
 287
 288     $plugins = enrol_get_plugins(true);
 289
 290     foreach ($plugins as $plugin) {
 291         $plugin->course_updated($inserted, $course, $data);
 292     }
 293 }
 294
 295 /**
 296  * Add navigation nodes
 297  * @param navigation_node $coursenode
 298  * @param object $course
 299  * @return void
 300  */
 301 function enrol_add_course_navigation(navigation_node $coursenode, $course) {
 302     global $CFG;
 303
 304     $coursecontext = get_context_instance(CONTEXT_COURSE, $course->id);
 305
 306     $instances = enrol_get_instances($course->id, true);
 307     $plugins   = enrol_get_plugins(true);
 308
 309     // we do not want to break all course pages if there is some borked enrol plugin, right?
 310     foreach ($instances as $k=>$instance) {
 311         if (!isset($plugins[$instance->enrol])) {
 312             unset($instances[$k]);
 313         }
 314     }
 315
 316     $usersnode = $coursenode->add(get_string('users'), null, navigation_node::TYPE_CONTAINER, null, 'users');
 317
 318     if ($course->id != SITEID) {
 319         // list all participants - allows assigning roles, groups, etc.
 320         if (has_capability('moodle/course:enrolreview', $coursecontext)) {
 321             $url = new moodle_url('/enrol/users.php', array('id'=>$course->id));
 322             $usersnode->add(get_string('enrolledusers', 'enrol'), $url, navigation_node::TYPE_SETTING, null, 'review', new pix_icon('i/users', ''));
 323         }
 324
 325         // manage enrol plugin instances
 326         if (has_capability('moodle/course:enrolconfig', $coursecontext) or has_capability('moodle/course:enrolreview', $coursecontext)) {
 327             $url = new moodle_url('/enrol/instances.php', array('id'=>$course->id));
 328         } else {
 329             $url = NULL;
 330         }
 331         $instancesnode = $usersnode->add(get_string('enrolmentinstances', 'enrol'), $url, navigation_node::TYPE_SETTING, null, 'manageinstances');
 332
 333         // each instance decides how to configure itself or how many other nav items are exposed
 334         foreach ($instances as $instance) {
 335             if (!isset($plugins[$instance->enrol])) {
 336                 continue;
 337             }
 338             $plugins[$instance->enrol]->add_course_navigation($instancesnode, $instance);
 339         }
 340
 341         if (!$url) {
 342             $instancesnode->trim_if_empty();
 343         }
 344     }
 345
 346     // Manage groups in this course or even frontpage
 347     if (($course->groupmode || !$course->groupmodeforce) && has_capability('moodle/course:managegroups', $coursecontext)) {
 348         $url = new moodle_url('/group/index.php', array('id'=>$course->id));
 349         $usersnode->add(get_string('groups'), $url, navigation_node::TYPE_SETTING, null, 'groups', new pix_icon('i/group', ''));
 350     }
 351
 352      if (has_any_capability(array( 'moodle/role:assign', 'moodle/role:safeoverride','moodle/role:override', 'moodle/role:review'), $coursecontext)) {
 353         // Override roles
 354         if (has_capability('moodle/role:review', $coursecontext)) {
 355             $url = new moodle_url('/admin/roles/permissions.php', array('contextid'=>$coursecontext->id));
 356         } else {
 357             $url = NULL;
 358         }
 359         $permissionsnode = $usersnode->add(get_string('permissions', 'role'), $url, navigation_node::TYPE_SETTING, null, 'override');
 360
 361         // Add assign or override roles if allowed
 362         if ($course->id == SITEID or (!empty($CFG->adminsassignrolesincourse) and is_siteadmin())) {
 363             if (has_capability('moodle/role:assign', $coursecontext)) {
 364                 $url = new moodle_url('/admin/roles/assign.php', array('contextid'=>$coursecontext->id));
 365                 $permissionsnode->add(get_string('assignedroles', 'role'), $url, navigation_node::TYPE_SETTING, null, 'roles', new pix_icon('i/roles', ''));
 366             }
 367         }
 368         // Check role permissions
 369         if (has_any_capability(array('moodle/role:assign', 'moodle/role:safeoverride','moodle/role:override', 'moodle/role:assign'), $coursecontext)) {
 370             $url = new moodle_url('/admin/roles/check.php', array('contextid'=>$coursecontext->id));
 371             $permissionsnode->add(get_string('checkpermissions', 'role'), $url, navigation_node::TYPE_SETTING, null, 'permissions', new pix_icon('i/checkpermissions', ''));
 372         }
 373      }
 374
 375      // Deal somehow with users that are not enrolled but still got a role somehow
 376     if ($course->id != SITEID) {
 377         //TODO, create some new UI for role assignments at course level
 378         if (has_capability('moodle/role:assign', $coursecontext)) {
 379             $url = new moodle_url('/enrol/otherusers.php', array('id'=>$course->id));
 380             $usersnode->add(get_string('notenrolledusers', 'enrol'), $url, navigation_node::TYPE_SETTING, null, 'otherusers', new pix_icon('i/roles', ''));
 381         }
 382     }
 383
 384     // just in case nothing was actually added
 385     $usersnode->trim_if_empty();
 386
 387     if ($course->id != SITEID) {
 388         // Unenrol link
 389         if (is_enrolled($coursecontext)) {
 390             foreach ($instances as $instance) {
 391                 if (!isset($plugins[$instance->enrol])) {
 392                     continue;
 393                 }
 394                 $plugin = $plugins[$instance->enrol];
 395                 if ($unenrollink = $plugin->get_unenrolself_link($instance)) {
 396                     $coursenode->add(get_string('unenrolme', 'core_enrol', format_string($course->shortname)), $unenrollink, navigation_node::TYPE_SETTING, null, 'unenrolself', new pix_icon('i/user', ''));
 397                     break;
 398                     //TODO. deal with multiple unenrol links - not likely case, but still...
 399                 }
 400             }
 401         } else {
 402             if (is_viewing($coursecontext)) {
 403                 // better not show any enrol link, this is intended for managers and inspectors
 404             } else {
 405                 foreach ($instances as $instance) {
 406                     if (!isset($plugins[$instance->enrol])) {
 407                         continue;
 408                     }
 409                     $plugin = $plugins[$instance->enrol];
 410                     if ($plugin->show_enrolme_link($instance)) {
 411                         $url = new moodle_url('/enrol/index.php', array('id'=>$course->id));
 412                         $coursenode->add(get_string('enrolme', 'core_enrol', format_string($course->shortname)), $url, navigation_node::TYPE_SETTING, null, 'enrolself', new pix_icon('i/user', ''));
 413                         break;
 414                     }
 415                 }
 416             }
 417         }
 418     }
 419 }
 420
 421 /**
 422  * Returns list of courses current $USER is enrolled in and can access
 423  *
 424  * - $fields is an array of field names to ADD
 425  *   so name the fields you really need, which will
 426  *   be added and uniq'd
 427  *
 428  * @param string|array $fields
 429  * @param string $sort
 430  * @param int $limit max number of courses
 431  * @return array
 432  */
 433 function enrol_get_my_courses($fields = NULL, $sort = 'visible DESC,sortorder ASC', $limit = 0) {
 434     global $DB, $USER;
 435
 436     // Guest account does not have any courses
 437     if (isguestuser() or !isloggedin()) {
 438         return(array());
 439     }
 440
 441     $basefields = array('id', 'category', 'sortorder',
 442                         'shortname', 'fullname', 'idnumber',
 443                         'startdate', 'visible',
 444                         'groupmode', 'groupmodeforce');
 445
 446     if (empty($fields)) {
 447         $fields = $basefields;
 448     } else if (is_string($fields)) {
 449         // turn the fields from a string to an array
 450         $fields = explode(',', $fields);
 451         $fields = array_map('trim', $fields);
 452         $fields = array_unique(array_merge($basefields, $fields));
 453     } else if (is_array($fields)) {
 454         $fields = array_unique(array_merge($basefields, $fields));
 455     } else {
 456         throw new coding_exception('Invalid $fileds parameter in enrol_get_my_courses()');
 457     }
 458     if (in_array('*', $fields)) {
 459         $fields = array('*');
 460     }
 461
 462     $orderby = "";
 463     $sort    = trim($sort);
 464     if (!empty($sort)) {
 465         $rawsorts = explode(',', $sort);
 466         $sorts = array();
 467         foreach ($rawsorts as $rawsort) {
 468             $rawsort = trim($rawsort);
 469             if (strpos($rawsort, 'c.') === 0) {
 470                 $rawsort = substr($rawsort, 2);
 471             }
 472             $sorts[] = trim($rawsort);
 473         }
 474         $sort = 'c.'.implode(',c.', $sorts);
 475         $orderby = "ORDER BY $sort";
 476     }
 477
 478     $wheres = array("c.id <> :siteid");
 479     $params = array('siteid'=>SITEID);
 480
 481     if (isset($USER->loginascontext) and $USER->loginascontext->contextlevel == CONTEXT_COURSE) {
 482         // list _only_ this course - anything else is asking for trouble...
 483         $wheres[] = "courseid = :loginas";
 484         $params['loginas'] = $USER->loginascontext->instanceid;
 485     }
 486
 487     $coursefields = 'c.' .join(',c.', $fields);
 488     list($ccselect, $ccjoin) = context_instance_preload_sql('c.id', CONTEXT_COURSE, 'ctx');
 489     $wheres = implode(" AND ", $wheres);
 490
 491     //note: we can not use DISTINCT + text fields due to Oracle and MS limitations, that is why we have the subselect there
 492     $sql = "SELECT $coursefields $ccselect
 493               FROM {course} c
 494               JOIN (SELECT DISTINCT e.courseid
 495                       FROM {enrol} e
 496                       JOIN {user_enrolments} ue ON (ue.enrolid = e.id AND ue.userid = :userid)
 497                      WHERE ue.status = :active AND e.status = :enabled AND ue.timestart < :now1 AND (ue.timeend = 0 OR ue.timeend > :now2)
 498                    ) en ON (en.courseid = c.id)
 499            $ccjoin
 500              WHERE $wheres
 501           $orderby";
 502     $params['userid']  = $USER->id;
 503     $params['active']  = ENROL_USER_ACTIVE;
 504     $params['enabled'] = ENROL_INSTANCE_ENABLED;
 505     $params['now1']    = round(time(), -2); // improves db caching
 506     $params['now2']    = $params['now1'];
 507
 508     $courses = $DB->get_records_sql($sql, $params, 0, $limit);
 509
 510     // preload contexts and check visibility
 511     foreach ($courses as $id=>$course) {
 512         context_instance_preload($course);
 513         if (!$course->visible) {
 514             if (!$context = get_context_instance(CONTEXT_COURSE, $id)) {
 515                 unset($courses[$id]);
 516                 continue;
 517             }
 518             if (!has_capability('moodle/course:viewhiddencourses', $context)) {
 519                 unset($courses[$id]);
 520                 continue;
 521             }
 522         }
 523         $courses[$id] = $course;
 524     }
 525
 526     //wow! Is that really all? :-D
 527
 528     return $courses;
 529 }
 530
 531 /**
 532  * Returns course enrolment information icons.
 533  *
 534  * @param object $course
 535  * @param array $instances enrol instances of this course, improves performance
 536  * @return array of pix_icon
 537  */
 538 function enrol_get_course_info_icons($course, array $instances = NULL) {
 539     $icons = array();
 540     if (is_null($instances)) {
 541         $instances = enrol_get_instances($course->id, true);
 542     }
 543     $plugins = enrol_get_plugins(true);
 544     foreach ($plugins as $name => $plugin) {
 545         $pis = array();
 546         foreach ($instances as $instance) {
 547             if ($instance->status != ENROL_INSTANCE_ENABLED or $instance->courseid != $course->id) {
 548                 debugging('Invalid instances parameter submitted in enrol_get_info_icons()');
 549                 continue;
 550             }
 551             if ($instance->enrol == $name) {
 552                 $pis[$instance->id] = $instance;
 553             }
 554         }
 555         if ($pis) {
 556             $icons = array_merge($icons, $plugin->get_info_icons($pis));
 557         }
 558     }
 559     return $icons;
 560 }
 561
 562 /**
 563  * Returns course enrolment detailed information.
 564  *
 565  * @param object $course
 566  * @return array of html fragments - can be used to construct lists
 567  */
 568 function enrol_get_course_description_texts($course) {
 569     $lines = array();
 570     $instances = enrol_get_instances($course->id, true);
 571     $plugins = enrol_get_plugins(true);
 572     foreach ($instances as $instance) {
 573         if (!isset($plugins[$instance->enrol])) {
 574             //weird
 575             continue;
 576         }
 577         $plugin = $plugins[$instance->enrol];
 578         $text = $plugin->get_description_text($instance);
 579         if ($text !== NULL) {
 580             $lines[] = $text;
 581         }
 582     }
 583     return $lines;
 584 }
 585
 586 /**
 587  * Returns list of courses user is enrolled into.
 588  *
 589  * - $fields is an array of fieldnames to ADD
 590  *   so name the fields you really need, which will
 591  *   be added and uniq'd
 592  *
 593  * @param int $userid
 594  * @param bool $onlyactive return only active enrolments in courses user may see
 595  * @param string|array $fields
 596  * @param string $sort
 597  * @return array
 598  */
 599 function enrol_get_users_courses($userid, $onlyactive = false, $fields = NULL, $sort = 'visible DESC,sortorder ASC') {
 600     global $DB;
 601
 602     // Guest account does not have any courses
 603     if (isguestuser($userid) or empty($userid)) {
 604         return(array());
 605     }
 606
 607     $basefields = array('id', 'category', 'sortorder',
 608                         'shortname', 'fullname', 'idnumber',
 609                         'startdate', 'visible',
 610                         'groupmode', 'groupmodeforce');
 611
 612     if (empty($fields)) {
 613         $fields = $basefields;
 614     } else if (is_string($fields)) {
 615         // turn the fields from a string to an array
 616         $fields = explode(',', $fields);
 617         $fields = array_map('trim', $fields);
 618         $fields = array_unique(array_merge($basefields, $fields));
 619     } else if (is_array($fields)) {
 620         $fields = array_unique(array_merge($basefields, $fields));
 621     } else {
 622         throw new coding_exception('Invalid $fileds parameter in enrol_get_my_courses()');
 623     }
 624     if (in_array('*', $fields)) {
 625         $fields = array('*');
 626     }
 627
 628     $orderby = "";
 629     $sort    = trim($sort);
 630     if (!empty($sort)) {
 631         $rawsorts = explode(',', $sort);
 632         $sorts = array();
 633         foreach ($rawsorts as $rawsort) {
 634             $rawsort = trim($rawsort);
 635             if (strpos($rawsort, 'c.') === 0) {
 636                 $rawsort = substr($rawsort, 2);
 637             }
 638             $sorts[] = trim($rawsort);
 639         }
 640         $sort = 'c.'.implode(',c.', $sorts);
 641         $orderby = "ORDER BY $sort";
 642     }
 643
 644     $params = array('siteid'=>SITEID);
 645
 646     if ($onlyactive) {
 647         $subwhere = "WHERE ue.status = :active AND e.status = :enabled AND ue.timestart < :now1 AND (ue.timeend = 0 OR ue.timeend > :now2)";
 648         $params['now1']    = round(time(), -2); // improves db caching
 649         $params['now2']    = $params['now1'];
 650         $params['active']  = ENROL_USER_ACTIVE;
 651         $params['enabled'] = ENROL_INSTANCE_ENABLED;
 652     } else {
 653         $subwhere = "";
 654     }
 655
 656     $coursefields = 'c.' .join(',c.', $fields);
 657     list($ccselect, $ccjoin) = context_instance_preload_sql('c.id', CONTEXT_COURSE, 'ctx');
 658
 659     //note: we can not use DISTINCT + text fields due to Oracle and MS limitations, that is why we have the subselect there
 660     $sql = "SELECT $coursefields $ccselect
 661               FROM {course} c
 662               JOIN (SELECT DISTINCT e.courseid
 663                       FROM {enrol} e
 664                       JOIN {user_enrolments} ue ON (ue.enrolid = e.id AND ue.userid = :userid)
 665                  $subwhere
 666                    ) en ON (en.courseid = c.id)
 667            $ccjoin
 668              WHERE c.id <> :siteid
 669           $orderby";
 670     $params['userid']  = $userid;
 671
 672     $courses = $DB->get_records_sql($sql, $params);
 673
 674     // preload contexts and check visibility
 675     foreach ($courses as $id=>$course) {
 676         context_instance_preload($course);
 677         if ($onlyactive) {
 678             if (!$course->visible) {
 679                 if (!$context = get_context_instance(CONTEXT_COURSE, $id)) {
 680                     unset($courses[$id]);
 681                     continue;
 682                 }
 683                 if (!has_capability('moodle/course:viewhiddencourses', $context, $userid)) {
 684                     unset($courses[$id]);
 685                     continue;
 686                 }
 687             }
 688         }
 689         $courses[$id] = $course;
 690     }
 691
 692     //wow! Is that really all? :-D
 693
 694     return $courses;
 695
 696 }
 697
 698 /**
 699  * Called when user is about to be deleted.
 700  * @param object $user
 701  * @return void
 702  */
 703 function enrol_user_delete($user) {
 704     global $DB;
 705
 706     $plugins = enrol_get_plugins(true);
 707     foreach ($plugins as $plugin) {
 708         $plugin->user_delete($user);
 709     }
 710
 711     // force cleanup of all broken enrolments
 712     $DB->delete_records('user_enrolments', array('userid'=>$user->id));
 713 }
 714
 715 /**
 716  * Called when course is about to be deleted.
 717  * @param stdClass $object
 718  * @return void
 719  */
 720 function enrol_course_delete($course) {
 721     global $DB;
 722
 723     $instances = enrol_get_instances($course->id, false);
 724     $plugins = enrol_get_plugins(true);
 725     foreach ($instances as $instance) {
 726         if (isset($plugins[$instance->enrol])) {
 727             $plugins[$instance->enrol]->delete_instance($instance);
 728         }
 729         // low level delete in case plugin did not do it
 730         $DB->delete_records('user_enrolments', array('enrolid'=>$instance->id));
 731         $DB->delete_records('role_assignments', array('itemid'=>$instance->id, 'component'=>'enrol_'.$instance->enrol));
 732         $DB->delete_records('user_enrolments', array('enrolid'=>$instance->id));
 733         $DB->delete_records('enrol', array('id'=>$instance->id));
 734     }
 735 }
 736
 737 /**
 738  * Try to enrol user via default internal auth plugin.
 739  *
 740  * For now this is always using the manual enrol plugin...
 741  *
 742  * @param $courseid
 743  * @param $userid
 744  * @param $roleid
 745  * @param $timestart
 746  * @param $timeend
 747  * @return bool success
 748  */
 749 function enrol_try_internal_enrol($courseid, $userid, $roleid = null, $timestart = 0, $timeend = 0) {
 750     global $DB;
 751
 752     //note: this is hardcoded to manual plugin for now
 753
 754     if (!enrol_is_enabled('manual')) {
 755         return false;
 756     }
 757
 758     if (!$enrol = enrol_get_plugin('manual')) {
 759         return false;
 760     }
 761     if (!$instances = $DB->get_records('enrol', array('enrol'=>'manual', 'courseid'=>$courseid, 'status'=>ENROL_INSTANCE_ENABLED), 'sortorder,id ASC')) {
 762         return false;
 763     }
 764     $instance = reset($instances);
 765
 766     $enrol->enrol_user($instance, $userid, $roleid, $timestart, $timeend);
 767
 768     return true;
 769 }
 770
 771 /**
 772  * All enrol plugins should be based on this class,
 773  * this is also the main source of documentation.
 774  */
 775 abstract class enrol_plugin {
 776     protected $config = null;
 777
 778     /**
 779      * Returns name of this enrol plugin
 780      * @return string
 781      */
 782     public function get_name() {
 783         // second word in class is always enrol name, sorry, no fancy plugin names with _
 784         $words = explode('_', get_class($this));
 785         return $words[1];
 786     }
 787
 788     /**
 789      * Returns localised name of enrol instance
 790      *
 791      * @param object $instance (null is accepted too)
 792      * @return string
 793      */
 794     public function get_instance_name($instance) {
 795         if (empty($instance->name)) {
 796             $enrol = $this->get_name();
 797             return get_string('pluginname', 'enrol_'.$enrol);
 798         } else {
 799             $context = get_context_instance(CONTEXT_COURSE, $instance->courseid);
 800             return format_string($instance->name, true, array('context'=>$context));
 801         }
 802     }
 803
 804     /**
 805      * Returns optional enrolment information icons.
 806      *
 807      * This is used in course list for quick overview of enrolment options.
 808      *
 809      * We are not using single instance parameter because sometimes
 810      * we might want to prevent icon repetition when multiple instances
 811      * of one type exist. One instance may also produce several icons.
 812      *
 813      * @param array $instances all enrol instances of this type in one course
 814      * @return array of pix_icon
 815      */
 816     public function get_info_icons(array $instances) {
 817         return array();
 818     }
 819
 820     /**
 821      * Returns optional enrolment instance description text.
 822      *
 823      * This is used in detailed course information.
 824      *
 825      *
 826      * @param object $instance
 827      * @return string short html text
 828      */
 829     public function get_description_text($instance) {
 830         return null;
 831     }
 832
 833     /**
 834      * Makes sure config is loaded and cached.
 835      * @return void
 836      */
 837     protected function load_config() {
 838         if (!isset($this->config)) {
 839             $name = $this->get_name();
 840             if (!$config = get_config("enrol_$name")) {
 841                 $config = new stdClass();
 842             }
 843             $this->config = $config;
 844         }
 845     }
 846
 847     /**
 848      * Returns plugin config value
 849      * @param  string $name
 850      * @param  string $default value if config does not exist yet
 851      * @return string value or default
 852      */
 853     public function get_config($name, $default = NULL) {
 854         $this->load_config();
 855         return isset($this->config->$name) ? $this->config->$name : $default;
 856     }
 857
 858     /**
 859      * Sets plugin config value
 860      * @param  string $name name of config
 861      * @param  string $value string config value, null means delete
 862      * @return string value
 863      */
 864     public function set_config($name, $value) {
 865         $pluginname = $this->get_name();
 866         $this->load_config();
 867         if ($value === NULL) {
 868             unset($this->config->$name);
 869         } else {
 870             $this->config->$name = $value;
 871         }
 872         set_config($name, $value, "enrol_$pluginname");
 873     }
 874
 875     /**
 876      * Does this plugin assign protected roles are can they be manually removed?
 877      * @return bool - false means anybody may tweak roles, it does not use itemid and component when assigning roles
 878      */
 879     public function roles_protected() {
 880         return true;
 881     }
 882
 883     /**
 884      * Does this plugin allow manual enrolments?
 885      *
 886      * @param stdClass $instance course enrol instance
 887      * All plugins allowing this must implement 'enrol/xxx:enrol' capability
 888      *
 889      * @return bool - true means user with 'enrol/xxx:enrol' may enrol others freely, trues means nobody may add more enrolments manually
 890      */
 891     public function allow_enrol(stdClass $instance) {
 892         return false;
 893     }
 894
 895     /**
 896      * Does this plugin allow manual unenrolments?
 897      *
 898      * @param stdClass $instance course enrol instance
 899      * All plugins allowing this must implement 'enrol/xxx:unenrol' capability
 900      *
 901      * @return bool - true means user with 'enrol/xxx:unenrol' may unenrol others freely, trues means nobody may touch user_enrolments
 902      */
 903     public function allow_unenrol(stdClass $instance) {
 904         return false;
 905     }
 906
 907     /**
 908      * Does this plugin allow manual changes in user_enrolments table?
 909      *
 910      * All plugins allowing this must implement 'enrol/xxx:manage' capability
 911      *
 912      * @param stdClass $instance course enrol instance
 913      * @return bool - true means it is possible to change enrol period and status in user_enrolments table
 914      */
 915     public function allow_manage(stdClass $instance) {
 916         return false;
 917     }
 918
 919     /**
 920      * Does this plugin support some way to user to self enrol?
 921      *
 922      * @param stdClass $instance course enrol instance
 923      *
 924      * @return bool - true means show "Enrol me in this course" link in course UI
 925      */
 926     public function show_enrolme_link(stdClass $instance) {
 927         return false;
 928     }
 929
 930     /**
 931      * Attempt to automatically enrol current user in course without any interaction,
 932      * calling code has to make sure the plugin and instance are active.
 933      *
 934      * @param stdClass $instance course enrol instance
 935      * @param stdClass $user record
 936      * @return bool|int false means not enrolled, integer means timeend
 937      */
 938     public function try_autoenrol(stdClass $instance) {
 939         global $USER;
 940
 941         return false;
 942     }
 943
 944     /**
 945      * Attempt to automatically gain temporary guest access to course,
 946      * calling code has to make sure the plugin and instance are active.
 947      *
 948      * @param stdClass $instance course enrol instance
 949      * @param stdClass $user record
 950      * @return bool|int false means no guest access, integer means timeend
 951      */
 952     public function try_guestaccess(stdClass $instance) {
 953         global $USER;
 954
 955         return false;
 956     }
 957
 958     /**
 959      * Enrol user into course via enrol instance.
 960      *
 961      * @param stdClass $instance
 962      * @param int $userid
 963      * @param int $roleid optional role id
 964      * @param int $timestart 0 means unknown
 965      * @param int $timeend 0 means forever
 966      * @param int $status default to ENROL_USER_ACTIVE for new enrolments, no change by default in updates
 967      * @return void
 968      */
 969     public function enrol_user(stdClass $instance, $userid, $roleid = NULL, $timestart = 0, $timeend = 0, $status = NULL) {
 970         global $DB, $USER, $CFG; // CFG necessary!!!
 971
 972         if ($instance->courseid == SITEID) {
 973             throw new coding_exception('invalid attempt to enrol into frontpage course!');
 974         }
 975
 976         $name = $this->get_name();
 977         $courseid = $instance->courseid;
 978
 979         if ($instance->enrol !== $name) {
 980             throw new coding_exception('invalid enrol instance!');
 981         }
 982         $context = get_context_instance(CONTEXT_COURSE, $instance->courseid, MUST_EXIST);
 983
 984         $inserted = false;
 985         if ($ue = $DB->get_record('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$userid))) {
 986             if ($ue->timestart != $timestart or $ue->timeend != $timeend) {
 987                 $ue->timestart    = $timestart;
 988                 $ue->timeend      = $timeend;
 989                 $ue->modifier     = $USER->id;
 990                 $ue->timemodified = time();
 991                 $DB->update_record('user_enrolments', $ue);
 992             }
 993         } else {
 994             $ue = new stdClass();
 995             $ue->enrolid      = $instance->id;
 996             $ue->status       = ENROL_USER_ACTIVE;
 997             $ue->userid       = $userid;
 998             $ue->timestart    = $timestart;
 999             $ue->timeend      = $timeend;
1000             $ue->modifier     = $USER->id;
1001             $ue->timecreated  = time();
1002             $ue->timemodified = $ue->timecreated;
1003             $ue->id = $DB->insert_record('user_enrolments', $ue);
1004
1005             $inserted = true;
1006         }
1007
1008         if ($roleid) {
1009             if ($this->roles_protected()) {
1010                 role_assign($roleid, $userid, $context->id, 'enrol_'.$name, $instance->id);
1011             } else {
1012                 role_assign($roleid, $userid, $context->id);
1013             }
1014         }
1015
1016         if ($inserted) {
1017             // add extra info and trigger event
1018             $ue->courseid  = $courseid;
1019             $ue->enrol     = $name;
1020             events_trigger('user_enrolled', $ue);
1021         }
1022
1023         // reset primitive require_login() caching
1024         if ($userid == $USER->id) {
1025             if (isset($USER->enrol['enrolled'][$courseid])) {
1026                 unset($USER->enrol['enrolled'][$courseid]);
1027             }
1028             if (isset($USER->enrol['tempguest'][$courseid])) {
1029                 unset($USER->enrol['tempguest'][$courseid]);
1030                 $USER->access = remove_temp_roles($context, $USER->access);
1031             }
1032         }
1033     }
1034
1035     /**
1036      * Store user_enrolments changes and trigger event.
1037      *
1038      * @param object $ue
1039      * @param int $user id
1040      * @param int $status
1041      * @param int $timestart
1042      * @param int $timeend
1043      * @return void
1044      */
1045     public function update_user_enrol(stdClass $instance, $userid, $status = NULL, $timestart = NULL, $timeend = NULL) {
1046         global $DB, $USER;
1047
1048         $name = $this->get_name();
1049
1050         if ($instance->enrol !== $name) {
1051             throw new coding_exception('invalid enrol instance!');
1052         }
1053
1054         if (!$ue = $DB->get_record('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$userid))) {
1055             // weird, user not enrolled
1056             return;
1057         }
1058
1059         $modified = false;
1060         if (isset($status) and $ue->status != $status) {
1061             $ue->status = $status;
1062             $modified = true;
1063         }
1064         if (isset($timestart) and $ue->timestart != $timestart) {
1065             $ue->timestart = $timestart;
1066             $modified = true;
1067         }
1068         if (isset($timeend) and $ue->timeend != $timeend) {
1069             $ue->timeend = $timeend;
1070             $modified = true;
1071         }
1072
1073         if (!$modified) {
1074             // no change
1075             return;
1076         }
1077
1078         $ue->modifierid = $USER->id;
1079         $DB->update_record('user_enrolments', $ue);
1080
1081         // trigger event
1082         $ue->courseid  = $instance->courseid;
1083         $ue->enrol     = $instance->name;
1084         events_trigger('user_unenrol_modified', $ue);
1085     }
1086
1087     /**
1088      * Unenrol user from course,
1089      * the last unenrolment removes all remaining roles.
1090      *
1091      * @param stdClass $instance
1092      * @param int $userid
1093      * @return void
1094      */
1095     public function unenrol_user(stdClass $instance, $userid) {
1096         global $CFG, $USER, $DB;
1097
1098         $name = $this->get_name();
1099         $courseid = $instance->courseid;
1100
1101         if ($instance->enrol !== $name) {
1102             throw new coding_exception('invalid enrol instance!');
1103         }
1104         $context = get_context_instance(CONTEXT_COURSE, $instance->courseid, MUST_EXIST);
1105
1106         if (!$ue = $DB->get_record('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$userid))) {
1107             // weird, user not enrolled
1108             return;
1109         }
1110
1111         role_unassign_all(array('userid'=>$userid, 'contextid'=>$context->id, 'component'=>'enrol_'.$name, 'itemid'=>$instance->id));
1112         $DB->delete_records('user_enrolments', array('id'=>$ue->id));
1113
1114         // add extra info and trigger event
1115         $ue->courseid  = $courseid;
1116         $ue->enrol     = $name;
1117
1118         $sql = "SELECT 'x'
1119                   FROM {user_enrolments} ue
1120                   JOIN {enrol} e ON (e.id = ue.enrolid)
1121                   WHERE ue.userid = :userid AND e.courseid = :courseid";
1122         if ($DB->record_exists_sql($sql, array('userid'=>$userid, 'courseid'=>$courseid))) {
1123             $ue->lastenrol = false;
1124             events_trigger('user_unenrolled', $ue);
1125             // user still has some enrolments, no big cleanup yet
1126         } else {
1127             // the big cleanup IS necessary!
1128
1129             require_once("$CFG->dirroot/group/lib.php");
1130             require_once("$CFG->libdir/gradelib.php");
1131
1132             // remove all remaining roles
1133             role_unassign_all(array('userid'=>$userid, 'contextid'=>$context->id), true, false);
1134
1135             //clean up ALL invisible user data from course if this is the last enrolment - groups, grades, etc.
1136             groups_delete_group_members($courseid, $userid);
1137
1138             grade_user_unenrol($courseid, $userid);
1139
1140             $DB->delete_records('user_lastaccess', array('userid'=>$userid, 'courseid'=>$courseid));
1141
1142             $ue->lastenrol = true; // means user not enrolled any more
1143             events_trigger('user_unenrolled', $ue);
1144         }
1145         // reset primitive require_login() caching
1146         if ($userid == $USER->id) {
1147             if (isset($USER->enrol['enrolled'][$courseid])) {
1148                 unset($USER->enrol['enrolled'][$courseid]);
1149             }
1150             if (isset($USER->enrol['tempguest'][$courseid])) {
1151                 unset($USER->enrol['tempguest'][$courseid]);
1152                 $USER->access = remove_temp_roles($context, $USER->access);
1153             }
1154         }
1155     }
1156
1157     /**
1158      * Forces synchronisation of user enrolments.
1159      *
1160      * This is important especially for external enrol plugins,
1161      * this function is called for all enabled enrol plugins
1162      * right after every user login.
1163      *
1164      * @param object $user user record
1165      * @return void
1166      */
1167     public function sync_user_enrolments($user) {
1168         // override if necessary
1169     }
1170
1171     /**
1172      * Returns link to page which may be used to add new instance of enrolment plugin in course.
1173      * @param int $courseid
1174      * @return moodle_url page url
1175      */
1176     public function get_newinstance_link($courseid) {
1177         // override for most plugins, check if instance already exists in cases only one instance is supported
1178         return NULL;
1179     }
1180
1181     /**
1182      * Is it possible to delete enrol instance via standard UI?
1183      *
1184      * @param object $instance
1185      * @return bool
1186      */
1187     public function instance_deleteable($instance) {
1188         return true;
1189     }
1190
1191     /**
1192      * Returns link to manual enrol UI if exists.
1193      * Does the access control tests automatically.
1194      *
1195      * @param object $instance
1196      * @return moodle_url
1197      */
1198     public function get_manual_enrol_link($instance) {
1199         return NULL;
1200     }
1201
1202     /**
1203      * Returns list of unenrol links for all enrol instances in course.
1204      *
1205      * @param int $instance
1206      * @return moodle_url or NULL if self unenrolment not supported
1207      */
1208     public function get_unenrolself_link($instance) {
1209         global $USER, $CFG, $DB;
1210
1211         $name = $this->get_name();
1212         if ($instance->enrol !== $name) {
1213             throw new coding_exception('invalid enrol instance!');
1214         }
1215
1216         if ($instance->courseid == SITEID) {
1217             return NULL;
1218         }
1219
1220         if (!enrol_is_enabled($name)) {
1221             return NULL;
1222         }
1223
1224         if ($instance->status != ENROL_INSTANCE_ENABLED) {
1225             return NULL;
1226         }
1227
1228         if (!file_exists("$CFG->dirroot/enrol/$name/unenrolself.php")) {
1229             return NULL;
1230         }
1231
1232         $context = get_context_instance(CONTEXT_COURSE, $instance->courseid, MUST_EXIST);
1233
1234         if (!has_capability("enrol/$name:unenrolself", $context)) {
1235             return NULL;
1236         }
1237
1238         if (!$DB->record_exists('user_enrolments', array('enrolid'=>$instance->id, 'userid'=>$USER->id, 'status'=>ENROL_USER_ACTIVE))) {
1239             return NULL;
1240         }
1241
1242         return new moodle_url("/enrol/$name/unenrolself.php", array('enrolid'=>$instance->id));;
1243     }
1244
1245     /**
1246      * Adds enrol instance UI to course edit form
1247      *
1248      * @param object $instance enrol instance or null if does not exist yet
1249      * @param MoodleQuickForm $mform
1250      * @param object $data
1251      * @param object $context context of existing course or parent category if course does not exist
1252      * @return void
1253      */
1254     public function course_edit_form($instance, MoodleQuickForm $mform, $data, $context) {
1255         // override - usually at least enable/disable switch, has to add own form header
1256     }
1257
1258     /**
1259      * Validates course edit form data
1260      *
1261      * @param object $instance enrol instance or null if does not exist yet
1262      * @param array $data
1263      * @param object $context context of existing course or parent category if course does not exist
1264      * @return array errors array
1265      */
1266     public function course_edit_validation($instance, array $data, $context) {
1267         return array();
1268     }
1269
1270     /**
1271      * Called after updating/inserting course.
1272      *
1273      * @param bool $inserted true if course just inserted
1274      * @param object $course
1275      * @param object $data form data
1276      * @return void
1277      */
1278     public function course_updated($inserted, $course, $data) {
1279         if ($inserted) {
1280             if ($this->get_config('defaultenrol')) {
1281                 $this->add_default_instance($course);
1282             }
1283         }
1284     }
1285
1286     /**
1287      * Add new instance of enrol plugin.
1288      * @param object $course
1289      * @param array instance fields
1290      * @return int id of new instance, null if can not be created
1291      */
1292     public function add_instance($course, array $fields = NULL) {
1293         global $DB;
1294
1295         if ($course->id == SITEID) {
1296             throw new coding_exception('Invalid request to add enrol instance to frontpage.');
1297         }
1298
1299         $instance = new stdClass();
1300         $instance->enrol          = $this->get_name();
1301         $instance->status         = ENROL_INSTANCE_ENABLED;
1302         $instance->courseid       = $course->id;
1303         $instance->enrolstartdate = 0;
1304         $instance->enrolenddate   = 0;
1305         $instance->timemodified   = time();
1306         $instance->timecreated    = $instance->timemodified;
1307         $instance->sortorder      = $DB->get_field('enrol', 'COALESCE(MAX(sortorder), -1) + 1', array('courseid'=>$course->id));
1308
1309         $fields = (array)$fields;
1310         unset($fields['enrol']);
1311         unset($fields['courseid']);
1312         unset($fields['sortorder']);
1313         foreach($fields as $field=>$value) {
1314             $instance->$field = $value;
1315         }
1316
1317         return $DB->insert_record('enrol', $instance);
1318     }
1319
1320     /**
1321      * Add new instance of enrol plugin with default settings,
1322      * called when adding new instance manually or when adding new course.
1323      *
1324      * Not all plugins support this.
1325      *
1326      * @param object $course
1327      * @return int id of new instance or null if no default supported
1328      */
1329     public function add_default_instance($course) {
1330         return null;
1331     }
1332
1333     /**
1334      * Delete course enrol plugin instance, unenrol all users.
1335      * @param object $instance
1336      * @return void
1337      */
1338     public function delete_instance($instance) {
1339         global $DB;
1340
1341         $name = $this->get_name();
1342         if ($instance->enrol !== $name) {
1343             throw new coding_exception('invalid enrol instance!');
1344         }
1345
1346         //first unenrol all users
1347         $participants = $DB->get_recordset('user_enrolments', array('enrolid'=>$instance->id));
1348         foreach ($participants as $participant) {
1349             $this->unenrol_user($instance, $participant->userid);
1350         }
1351         $participants->close();
1352
1353         // now clean up all remainders that were not removed correctly
1354         $DB->delete_records('role_assignments', array('itemid'=>$instance->id, 'component'=>$name));
1355         $DB->delete_records('user_enrolments', array('enrolid'=>$instance->id));
1356
1357         // finally drop the enrol row
1358         $DB->delete_records('enrol', array('id'=>$instance->id));
1359     }
1360
1361     /**
1362      * Creates course enrol form, checks if form submitted
1363      * and enrols user if necessary. It can also redirect.
1364      *
1365      * @param stdClass $instance
1366      * @return string html text, usually a form in a text box
1367      */
1368     public function enrol_page_hook(stdClass $instance) {
1369         return null;
1370     }
1371
1372     /**
1373      * Adds navigation links into course admin block.
1374      *
1375      * By defaults looks for manage links only.
1376      *
1377      * @param navigation_node $instancesnode
1378      * @param object $instance
1379      * @return void
1380      */
1381     public function add_course_navigation($instancesnode, stdClass $instance) {
1382         // usually adds manage users
1383     }
1384
1385     /**
1386      * Returns edit icons for the page with list of instances
1387      * @param stdClass $instance
1388      * @return array
1389      */
1390     public function get_action_icons(stdClass $instance) {
1391         return array();
1392     }
1393
1394     /**
1395      * Reads version.php and determines if it is necessary
1396      * to execute the cron job now.
1397      * @return bool
1398      */
1399     public function is_cron_required() {
1400         global $CFG;
1401
1402         $name = $this->get_name();
1403         $versionfile = "$CFG->dirroot/enrol/$name/version.php";
1404         $plugin = new stdClass();
1405         include($versionfile);
1406         if (empty($plugin->cron)) {
1407             return false;
1408         }
1409         $lastexecuted = $this->get_config('lastcron', 0);
1410         if ($lastexecuted + $plugin->cron < time()) {
1411             return true;
1412         } else {
1413             return false;
1414         }
1415     }
1416
1417     /**
1418      * Called for all enabled enrol plugins that returned true from is_cron_required().
1419      * @return void
1420      */
1421     public function cron() {
1422     }
1423
1424     /**
1425      * Called when user is about to be deleted
1426      * @param object $user
1427      * @return void
1428      */
1429     public function user_delete($user) {
1430         global $DB;
1431
1432         $sql = "SELECT e.*
1433                   FROM {enrol} e
1434                   JOIN {user_enrolments} ue ON (ue.courseid = e.courseid)
1435                  WHERE e.enrol = :meta AND ue.userid = :userid";
1436         $params = array('name'=>$this->get_name(), 'userid'=>$user->id);
1437
1438         $rs = $DB->get_records_recordset($sql, $params);
1439         foreach($rs as $instance) {
1440             $this->unenrol_user($instance, $user->id);
1441         }
1442         $rs->close();
1443     }
1444 }
1445