lib/datalib.php

   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  * Library of functions for database manipulation.
  19  *
  20  * Other main libraries:
  21  * - weblib.php - functions that produce web output
  22  * - moodlelib.php - general-purpose Moodle functions
  23  *
  24  * @package    core
  25  * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  26  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  27  */
  28
  29 defined('MOODLE_INTERNAL') || die();
  30
  31 /**
  32  * The maximum courses in a category
  33  * MAX_COURSES_IN_CATEGORY * MAX_COURSE_CATEGORIES must not be more than max integer!
  34  */
  35 define('MAX_COURSES_IN_CATEGORY', 10000);
  36
  37 /**
  38   * The maximum number of course categories
  39   * MAX_COURSES_IN_CATEGORY * MAX_COURSE_CATEGORIES must not be more than max integer!
  40   */
  41 define('MAX_COURSE_CATEGORIES', 10000);
  42
  43 /**
  44  * Number of seconds to wait before updating lastaccess information in DB.
  45  *
  46  * We allow overwrites from config.php, useful to ensure coherence in performance
  47  * tests results.
  48  *
  49  * Note: For web service requests in the external_tokens field, we use a different constant
  50  * webservice::TOKEN_LASTACCESS_UPDATE_SECS.
  51  */
  52 if (!defined('LASTACCESS_UPDATE_SECS')) {
  53     define('LASTACCESS_UPDATE_SECS', 60);
  54 }
  55
  56 /**
  57  * Returns $user object of the main admin user
  58  *
  59  * @static stdClass $mainadmin
  60  * @return stdClass {@link $USER} record from DB, false if not found
  61  */
  62 function get_admin() {
  63     global $CFG, $DB;
  64
  65     static $mainadmin = null;
  66     static $prevadmins = null;
  67
  68     if (empty($CFG->siteadmins)) {
  69         // Should not happen on an ordinary site.
  70         // It does however happen during unit tests.
  71         return false;
  72     }
  73
  74     if (isset($mainadmin) and $prevadmins === $CFG->siteadmins) {
  75         return clone($mainadmin);
  76     }
  77
  78     $mainadmin = null;
  79
  80     foreach (explode(',', $CFG->siteadmins) as $id) {
  81         if ($user = $DB->get_record('user', array('id'=>$id, 'deleted'=>0))) {
  82             $mainadmin = $user;
  83             break;
  84         }
  85     }
  86
  87     if ($mainadmin) {
  88         $prevadmins = $CFG->siteadmins;
  89         return clone($mainadmin);
  90     } else {
  91         // this should not happen
  92         return false;
  93     }
  94 }
  95
  96 /**
  97  * Returns list of all admins, using 1 DB query
  98  *
  99  * @return array
 100  */
 101 function get_admins() {
 102     global $DB, $CFG;
 103
 104     if (empty($CFG->siteadmins)) {  // Should not happen on an ordinary site
 105         return array();
 106     }
 107
 108     $sql = "SELECT u.*
 109               FROM {user} u
 110              WHERE u.deleted = 0 AND u.id IN ($CFG->siteadmins)";
 111
 112     // We want the same order as in $CFG->siteadmins.
 113     $records = $DB->get_records_sql($sql);
 114     $admins = array();
 115     foreach (explode(',', $CFG->siteadmins) as $id) {
 116         $id = (int)$id;
 117         if (!isset($records[$id])) {
 118             // User does not exist, this should not happen.
 119             continue;
 120         }
 121         $admins[$records[$id]->id] = $records[$id];
 122     }
 123
 124     return $admins;
 125 }
 126
 127 /**
 128  * Search through course users
 129  *
 130  * If $coursid specifies the site course then this function searches
 131  * through all undeleted and confirmed users
 132  *
 133  * @global object
 134  * @uses SITEID
 135  * @uses SQL_PARAMS_NAMED
 136  * @uses CONTEXT_COURSE
 137  * @param int $courseid The course in question.
 138  * @param int $groupid The group in question.
 139  * @param string $searchtext The string to search for
 140  * @param string $sort A field to sort by
 141  * @param array $exceptions A list of IDs to ignore, eg 2,4,5,8,9,10
 142  * @return array
 143  */
 144 function search_users($courseid, $groupid, $searchtext, $sort='', array $exceptions=null) {
 145     global $DB;
 146
 147     $fullname  = $DB->sql_fullname('u.firstname', 'u.lastname');
 148
 149     if (!empty($exceptions)) {
 150         list($exceptions, $params) = $DB->get_in_or_equal($exceptions, SQL_PARAMS_NAMED, 'ex', false);
 151         $except = "AND u.id $exceptions";
 152     } else {
 153         $except = "";
 154         $params = array();
 155     }
 156
 157     if (!empty($sort)) {
 158         $order = "ORDER BY $sort";
 159     } else {
 160         $order = "";
 161     }
 162
 163     $select = "u.deleted = 0 AND u.confirmed = 1 AND (".$DB->sql_like($fullname, ':search1', false)." OR ".$DB->sql_like('u.email', ':search2', false).")";
 164     $params['search1'] = "%$searchtext%";
 165     $params['search2'] = "%$searchtext%";
 166
 167     if (!$courseid or $courseid == SITEID) {
 168         $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 169                   FROM {user} u
 170                  WHERE $select
 171                        $except
 172                 $order";
 173         return $DB->get_records_sql($sql, $params);
 174
 175     } else {
 176         if ($groupid) {
 177             $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 178                       FROM {user} u
 179                       JOIN {groups_members} gm ON gm.userid = u.id
 180                      WHERE $select AND gm.groupid = :groupid
 181                            $except
 182                      $order";
 183             $params['groupid'] = $groupid;
 184             return $DB->get_records_sql($sql, $params);
 185
 186         } else {
 187             $context = context_course::instance($courseid);
 188
 189             // We want to query both the current context and parent contexts.
 190             list($relatedctxsql, $relatedctxparams) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'relatedctx');
 191
 192             $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 193                       FROM {user} u
 194                       JOIN {role_assignments} ra ON ra.userid = u.id
 195                      WHERE $select AND ra.contextid $relatedctxsql
 196                            $except
 197                     $order";
 198             $params = array_merge($params, $relatedctxparams);
 199             return $DB->get_records_sql($sql, $params);
 200         }
 201     }
 202 }
 203
 204 /**
 205  * Returns SQL used to search through user table to find users (in a query
 206  * which may also join and apply other conditions).
 207  *
 208  * You can combine this SQL with an existing query by adding 'AND $sql' to the
 209  * WHERE clause of your query (where $sql is the first element in the array
 210  * returned by this function), and merging in the $params array to the parameters
 211  * of your query (where $params is the second element). Your query should use
 212  * named parameters such as :param, rather than the question mark style.
 213  *
 214  * There are examples of basic usage in the unit test for this function.
 215  *
 216  * @param string $search the text to search for (empty string = find all)
 217  * @param string $u the table alias for the user table in the query being
 218  *     built. May be ''.
 219  * @param bool $searchanywhere If true (default), searches in the middle of
 220  *     names, otherwise only searches at start
 221  * @param array $extrafields Array of extra user fields to include in search, must be prefixed with table alias if they are not in
 222  *     the user table.
 223  * @param array $exclude Array of user ids to exclude (empty = don't exclude)
 224  * @param array $includeonly If specified, only returns users that have ids
 225  *     incldued in this array (empty = don't restrict)
 226  * @return array an array with two elements, a fragment of SQL to go in the
 227  *     where clause the query, and an associative array containing any required
 228  *     parameters (using named placeholders).
 229  */
 230 function users_search_sql(string $search, string $u = 'u', bool $searchanywhere = true, array $extrafields = [],
 231         array $exclude = null, array $includeonly = null): array {
 232     global $DB, $CFG;
 233     $params = array();
 234     $tests = array();
 235
 236     if ($u) {
 237         $u .= '.';
 238     }
 239
 240     // If we have a $search string, put a field LIKE '$search%' condition on each field.
 241     if ($search) {
 242         $conditions = array(
 243             $DB->sql_fullname($u . 'firstname', $u . 'lastname'),
 244             $conditions[] = $u . 'lastname'
 245         );
 246         foreach ($extrafields as $field) {
 247             // Add the table alias for the user table if the field doesn't already have an alias.
 248             $conditions[] = strpos($field, '.') !== false ? $field : $u . $field;
 249         }
 250         if ($searchanywhere) {
 251             $searchparam = '%' . $search . '%';
 252         } else {
 253             $searchparam = $search . '%';
 254         }
 255         $i = 0;
 256         foreach ($conditions as $key => $condition) {
 257             $conditions[$key] = $DB->sql_like($condition, ":con{$i}00", false, false);
 258             $params["con{$i}00"] = $searchparam;
 259             $i++;
 260         }
 261         $tests[] = '(' . implode(' OR ', $conditions) . ')';
 262     }
 263
 264     // Add some additional sensible conditions.
 265     $tests[] = $u . "id <> :guestid";
 266     $params['guestid'] = $CFG->siteguest;
 267     $tests[] = $u . 'deleted = 0';
 268     $tests[] = $u . 'confirmed = 1';
 269
 270     // If we are being asked to exclude any users, do that.
 271     if (!empty($exclude)) {
 272         list($usertest, $userparams) = $DB->get_in_or_equal($exclude, SQL_PARAMS_NAMED, 'ex', false);
 273         $tests[] = $u . 'id ' . $usertest;
 274         $params = array_merge($params, $userparams);
 275     }
 276
 277     // If we are validating a set list of userids, add an id IN (...) test.
 278     if (!empty($includeonly)) {
 279         list($usertest, $userparams) = $DB->get_in_or_equal($includeonly, SQL_PARAMS_NAMED, 'val');
 280         $tests[] = $u . 'id ' . $usertest;
 281         $params = array_merge($params, $userparams);
 282     }
 283
 284     // In case there are no tests, add one result (this makes it easier to combine
 285     // this with an existing query as you can always add AND $sql).
 286     if (empty($tests)) {
 287         $tests[] = '1 = 1';
 288     }
 289
 290     // Combing the conditions and return.
 291     return array(implode(' AND ', $tests), $params);
 292 }
 293
 294
 295 /**
 296  * This function generates the standard ORDER BY clause for use when generating
 297  * lists of users. If you don't have a reason to use a different order, then
 298  * you should use this method to generate the order when displaying lists of users.
 299  *
 300  * If the optional $search parameter is passed, then exact matches to the search
 301  * will be sorted first. For example, suppose you have two users 'Al Zebra' and
 302  * 'Alan Aardvark'. The default sort is Alan, then Al. If, however, you search for
 303  * 'Al', then Al will be listed first. (With two users, this is not a big deal,
 304  * but with thousands of users, it is essential.)
 305  *
 306  * The list of fields scanned for exact matches are:
 307  *  - firstname
 308  *  - lastname
 309  *  - $DB->sql_fullname
 310  *  - those returned by \core_user\fields::get_identity_fields or those included in $customfieldmappings
 311  *
 312  * If named parameters are used (which is the default, and highly recommended),
 313  * then the parameter names are like :usersortexactN, where N is an int.
 314  *
 315  * The simplest possible example use is:
 316  * list($sort, $params) = users_order_by_sql();
 317  * $sql = 'SELECT * FROM {users} ORDER BY ' . $sort;
 318  *
 319  * A more complex example, showing that this sort can be combined with other sorts:
 320  * list($sort, $sortparams) = users_order_by_sql('u');
 321  * $sql = "SELECT g.id AS groupid, gg.groupingid, u.id AS userid, u.firstname, u.lastname, u.idnumber, u.username
 322  *           FROM {groups} g
 323  *      LEFT JOIN {groupings_groups} gg ON g.id = gg.groupid
 324  *      LEFT JOIN {groups_members} gm ON g.id = gm.groupid
 325  *      LEFT JOIN {user} u ON gm.userid = u.id
 326  *          WHERE g.courseid = :courseid $groupwhere $groupingwhere
 327  *       ORDER BY g.name, $sort";
 328  * $params += $sortparams;
 329  *
 330  * An example showing the use of $search:
 331  * list($sort, $sortparams) = users_order_by_sql('u', $search, $this->get_context());
 332  * $order = ' ORDER BY ' . $sort;
 333  * $params += $sortparams;
 334  * $availableusers = $DB->get_records_sql($fields . $sql . $order, $params, $page*$perpage, $perpage);
 335  *
 336  * @param string $usertablealias (optional) any table prefix for the {users} table. E.g. 'u'.
 337  * @param string $search (optional) a current search string. If given,
 338  *      any exact matches to this string will be sorted first.
 339  * @param context|null $context the context we are in. Used by \core_user\fields::get_identity_fields.
 340  *      Defaults to $PAGE->context.
 341  * @param array $customfieldmappings associative array of mappings for custom fields returned by \core_user\fields::get_sql.
 342  * @return array with two elements:
 343  *      string SQL fragment to use in the ORDER BY clause. For example, "firstname, lastname".
 344  *      array of parameters used in the SQL fragment. If $search is not given, this is guaranteed to be an empty array.
 345  */
 346 function users_order_by_sql(string $usertablealias = '', string $search = null, context $context = null,
 347         array $customfieldmappings = []) {
 348     global $DB, $PAGE;
 349
 350     if ($usertablealias) {
 351         $tableprefix = $usertablealias . '.';
 352     } else {
 353         $tableprefix = '';
 354     }
 355
 356     $sort = "{$tableprefix}lastname, {$tableprefix}firstname, {$tableprefix}id";
 357     $params = array();
 358
 359     if (!$search) {
 360         return array($sort, $params);
 361     }
 362
 363     if (!$context) {
 364         $context = $PAGE->context;
 365     }
 366
 367     $exactconditions = array();
 368     $paramkey = 'usersortexact1';
 369
 370     $exactconditions[] = $DB->sql_fullname($tableprefix . 'firstname', $tableprefix  . 'lastname') .
 371             ' = :' . $paramkey;
 372     $params[$paramkey] = $search;
 373     $paramkey++;
 374
 375     if ($customfieldmappings) {
 376         $fieldstocheck = array_merge([$tableprefix . 'firstname', $tableprefix . 'lastname'], array_values($customfieldmappings));
 377     } else {
 378         $fieldstocheck = array_merge(['firstname', 'lastname'], \core_user\fields::get_identity_fields($context, false));
 379         $fieldstocheck = array_map(function($field) use ($tableprefix) {
 380             return $tableprefix . $field;
 381         }, $fieldstocheck);
 382     }
 383
 384     foreach ($fieldstocheck as $key => $field) {
 385         $exactconditions[] = 'LOWER(' . $field . ') = LOWER(:' . $paramkey . ')';
 386         $params[$paramkey] = $search;
 387         $paramkey++;
 388     }
 389
 390     $sort = 'CASE WHEN ' . implode(' OR ', $exactconditions) .
 391             ' THEN 0 ELSE 1 END, ' . $sort;
 392
 393     return array($sort, $params);
 394 }
 395
 396 /**
 397  * Returns a subset of users
 398  *
 399  * @global object
 400  * @uses DEBUG_DEVELOPER
 401  * @uses SQL_PARAMS_NAMED
 402  * @param bool $get If false then only a count of the records is returned
 403  * @param string $search A simple string to search for
 404  * @param bool $confirmed A switch to allow/disallow unconfirmed users
 405  * @param array $exceptions A list of IDs to ignore, eg 2,4,5,8,9,10
 406  * @param string $sort A SQL snippet for the sorting criteria to use
 407  * @param string $firstinitial Users whose first name starts with $firstinitial
 408  * @param string $lastinitial Users whose last name starts with $lastinitial
 409  * @param string $page The page or records to return
 410  * @param string $recordsperpage The number of records to return per page
 411  * @param string $fields A comma separated list of fields to be returned from the chosen table.
 412  * @return array|int|bool  {@link $USER} records unless get is false in which case the integer count of the records found is returned.
 413  *                        False is returned if an error is encountered.
 414  */
 415 function get_users($get=true, $search='', $confirmed=false, array $exceptions=null, $sort='firstname ASC',
 416                    $firstinitial='', $lastinitial='', $page='', $recordsperpage='', $fields='*', $extraselect='', array $extraparams=null) {
 417     global $DB, $CFG;
 418
 419     if ($get && !$recordsperpage) {
 420         debugging('Call to get_users with $get = true no $recordsperpage limit. ' .
 421                 'On large installations, this will probably cause an out of memory error. ' .
 422                 'Please think again and change your code so that it does not try to ' .
 423                 'load so much data into memory.', DEBUG_DEVELOPER);
 424     }
 425
 426     $fullname  = $DB->sql_fullname();
 427
 428     $select = " id <> :guestid AND deleted = 0";
 429     $params = array('guestid'=>$CFG->siteguest);
 430
 431     if (!empty($search)){
 432         $search = trim($search);
 433         $select .= " AND (".$DB->sql_like($fullname, ':search1', false)." OR ".$DB->sql_like('email', ':search2', false)." OR username = :search3)";
 434         $params['search1'] = "%$search%";
 435         $params['search2'] = "%$search%";
 436         $params['search3'] = "$search";
 437     }
 438
 439     if ($confirmed) {
 440         $select .= " AND confirmed = 1";
 441     }
 442
 443     if ($exceptions) {
 444         list($exceptions, $eparams) = $DB->get_in_or_equal($exceptions, SQL_PARAMS_NAMED, 'ex', false);
 445         $params = $params + $eparams;
 446         $select .= " AND id $exceptions";
 447     }
 448
 449     if ($firstinitial) {
 450         $select .= " AND ".$DB->sql_like('firstname', ':fni', false, false);
 451         $params['fni'] = "$firstinitial%";
 452     }
 453     if ($lastinitial) {
 454         $select .= " AND ".$DB->sql_like('lastname', ':lni', false, false);
 455         $params['lni'] = "$lastinitial%";
 456     }
 457
 458     if ($extraselect) {
 459         $select .= " AND $extraselect";
 460         $params = $params + (array)$extraparams;
 461     }
 462
 463     if ($get) {
 464         return $DB->get_records_select('user', $select, $params, $sort, $fields, $page, $recordsperpage);
 465     } else {
 466         return $DB->count_records_select('user', $select, $params);
 467     }
 468 }
 469
 470
 471 /**
 472  * Return filtered (if provided) list of users in site, except guest and deleted users.
 473  *
 474  * @param string $sort An SQL field to sort by
 475  * @param string $dir The sort direction ASC|DESC
 476  * @param int $page The page or records to return
 477  * @param int $recordsperpage The number of records to return per page
 478  * @param string $search A simple string to search for
 479  * @param string $firstinitial Users whose first name starts with $firstinitial
 480  * @param string $lastinitial Users whose last name starts with $lastinitial
 481  * @param string $extraselect An additional SQL select statement to append to the query
 482  * @param array $extraparams Additional parameters to use for the above $extraselect
 483  * @param stdClass $extracontext If specified, will include user 'extra fields'
 484  *   as appropriate for current user and given context
 485  * @return array Array of {@link $USER} records
 486  */
 487 function get_users_listing($sort='lastaccess', $dir='ASC', $page=0, $recordsperpage=0,
 488                            $search='', $firstinitial='', $lastinitial='', $extraselect='',
 489                            array $extraparams=null, $extracontext = null) {
 490     global $DB, $CFG;
 491
 492     $fullname  = $DB->sql_fullname();
 493
 494     $select = "deleted <> 1 AND u.id <> :guestid";
 495     $params = array('guestid' => $CFG->siteguest);
 496
 497     if (!empty($search)) {
 498         $search = trim($search);
 499         $select .= " AND (". $DB->sql_like($fullname, ':search1', false, false).
 500                    " OR ". $DB->sql_like('email', ':search2', false, false).
 501                    " OR username = :search3)";
 502         $params['search1'] = "%$search%";
 503         $params['search2'] = "%$search%";
 504         $params['search3'] = "$search";
 505     }
 506
 507     if ($firstinitial) {
 508         $select .= " AND ". $DB->sql_like('firstname', ':fni', false, false);
 509         $params['fni'] = "$firstinitial%";
 510     }
 511     if ($lastinitial) {
 512         $select .= " AND ". $DB->sql_like('lastname', ':lni', false, false);
 513         $params['lni'] = "$lastinitial%";
 514     }
 515
 516     if ($extraselect) {
 517         // The extra WHERE clause may refer to the 'id' column which can now be ambiguous because we
 518         // changed the query to include joins, so replace any 'id' that is on its own (no alias)
 519         // with 'u.id'.
 520         $extraselect = preg_replace('~([ =]|^)id([ =]|$)~', '$1u.id$2', $extraselect);
 521         $select .= " AND $extraselect";
 522         $params = $params + (array)$extraparams;
 523     }
 524
 525     // If a context is specified, get extra user fields that the current user
 526     // is supposed to see, otherwise just get the name fields.
 527     $userfields = \core_user\fields::for_name();
 528     if ($extracontext) {
 529         $userfields->with_identity($extracontext, true);
 530     }
 531
 532     $userfields->excluding('id');
 533     $userfields->including('username', 'email', 'city', 'country', 'lastaccess', 'confirmed', 'mnethostid', 'suspended');
 534     ['selects' => $selects, 'joins' => $joins, 'params' => $joinparams, 'mappings' => $mappings] =
 535             (array)$userfields->get_sql('u', true);
 536
 537     if ($sort) {
 538         $orderbymap = $mappings;
 539         $orderbymap['default'] = 'lastaccess';
 540         $sort = get_safe_orderby($orderbymap, $sort, $dir);
 541     }
 542
 543     // warning: will return UNCONFIRMED USERS
 544     return $DB->get_records_sql("SELECT u.id $selects
 545                                    FROM {user} u
 546                                         $joins
 547                                   WHERE $select
 548                                   $sort", array_merge($params, $joinparams), $page, $recordsperpage);
 549
 550 }
 551
 552
 553 /**
 554  * Full list of users that have confirmed their accounts.
 555  *
 556  * @global object
 557  * @return array of unconfirmed users
 558  */
 559 function get_users_confirmed() {
 560     global $DB, $CFG;
 561     return $DB->get_records_sql("SELECT *
 562                                    FROM {user}
 563                                   WHERE confirmed = 1 AND deleted = 0 AND id <> ?", array($CFG->siteguest));
 564 }
 565
 566
 567 /// OTHER SITE AND COURSE FUNCTIONS /////////////////////////////////////////////
 568
 569
 570 /**
 571  * Returns $course object of the top-level site.
 572  *
 573  * @return object A {@link $COURSE} object for the site, exception if not found
 574  */
 575 function get_site() {
 576     global $SITE, $DB;
 577
 578     if (!empty($SITE->id)) {   // We already have a global to use, so return that
 579         return $SITE;
 580     }
 581
 582     if ($course = $DB->get_record('course', array('category'=>0))) {
 583         return $course;
 584     } else {
 585         // course table exists, but the site is not there,
 586         // unfortunately there is no automatic way to recover
 587         throw new moodle_exception('nosite', 'error');
 588     }
 589 }
 590
 591 /**
 592  * Gets a course object from database. If the course id corresponds to an
 593  * already-loaded $COURSE or $SITE object, then the loaded object will be used,
 594  * saving a database query.
 595  *
 596  * If it reuses an existing object, by default the object will be cloned. This
 597  * means you can modify the object safely without affecting other code.
 598  *
 599  * @param int $courseid Course id
 600  * @param bool $clone If true (default), makes a clone of the record
 601  * @return stdClass A course object
 602  * @throws dml_exception If not found in database
 603  */
 604 function get_course($courseid, $clone = true) {
 605     global $DB, $COURSE, $SITE;
 606     if (!empty($COURSE->id) && $COURSE->id == $courseid) {
 607         return $clone ? clone($COURSE) : $COURSE;
 608     } else if (!empty($SITE->id) && $SITE->id == $courseid) {
 609         return $clone ? clone($SITE) : $SITE;
 610     } else {
 611         return $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
 612     }
 613 }
 614
 615 /**
 616  * Returns list of courses, for whole site, or category
 617  *
 618  * Returns list of courses, for whole site, or category
 619  * Important: Using c.* for fields is extremely expensive because
 620  *            we are using distinct. You almost _NEVER_ need all the fields
 621  *            in such a large SELECT
 622  *
 623  * Consider using core_course_category::get_courses()
 624  * or core_course_category::search_courses() instead since they use caching.
 625  *
 626  * @global object
 627  * @global object
 628  * @global object
 629  * @uses CONTEXT_COURSE
 630  * @param string|int $categoryid Either a category id or 'all' for everything
 631  * @param string $sort A field and direction to sort by
 632  * @param string $fields The additional fields to return (note that "id, category, visible" are always present)
 633  * @return array Array of courses
 634  */
 635 function get_courses($categoryid="all", $sort="c.sortorder ASC", $fields="c.*") {
 636
 637     global $USER, $CFG, $DB;
 638
 639     $params = array();
 640
 641     if ($categoryid !== "all" && is_numeric($categoryid)) {
 642         $categoryselect = "WHERE c.category = :catid";
 643         $params['catid'] = $categoryid;
 644     } else {
 645         $categoryselect = "";
 646     }
 647
 648     if (empty($sort)) {
 649         $sortstatement = "";
 650     } else {
 651         $sortstatement = "ORDER BY $sort";
 652     }
 653
 654     $visiblecourses = array();
 655
 656     $ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
 657     $ccjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = c.id AND ctx.contextlevel = :contextlevel)";
 658     $params['contextlevel'] = CONTEXT_COURSE;
 659
 660     // The fields "id, category, visible" are required in the subsequent loop and must always be present.
 661     if ($fields !== 'c.*') {
 662         $fieldarray = array_merge(
 663             // Split fields on comma + zero or more whitespace, merge with required fields.
 664             preg_split('/,\s*/', $fields), [
 665                 'c.id',
 666                 'c.category',
 667                 'c.visible',
 668             ]
 669         );
 670         $fields = implode(',', array_unique($fieldarray));
 671     }
 672
 673     $sql = "SELECT $fields $ccselect
 674               FROM {course} c
 675            $ccjoin
 676               $categoryselect
 677               $sortstatement";
 678
 679     // pull out all course matching the cat
 680     if ($courses = $DB->get_records_sql($sql, $params)) {
 681
 682         // loop throught them
 683         foreach ($courses as $course) {
 684             context_helper::preload_from_record($course);
 685             if (core_course_category::can_view_course_info($course)) {
 686                 $visiblecourses [$course->id] = $course;
 687             }
 688         }
 689     }
 690     return $visiblecourses;
 691 }
 692
 693 /**
 694  * A list of courses that match a search
 695  *
 696  * @global object
 697  * @global object
 698  * @param array $searchterms An array of search criteria
 699  * @param string $sort A field and direction to sort by
 700  * @param int $page The page number to get
 701  * @param int $recordsperpage The number of records per page
 702  * @param int $totalcount Passed in by reference.
 703  * @param array $requiredcapabilities Extra list of capabilities used to filter courses
 704  * @param array $searchcond additional search conditions, for example ['c.enablecompletion = :p1']
 705  * @param array $params named parameters for additional search conditions, for example ['p1' => 1]
 706  * @return stdClass[] {@link $COURSE} records
 707  */
 708 function get_courses_search($searchterms, $sort, $page, $recordsperpage, &$totalcount,
 709                             $requiredcapabilities = array(), $searchcond = [], $params = []) {
 710     global $CFG, $DB;
 711
 712     if ($DB->sql_regex_supported()) {
 713         $REGEXP    = $DB->sql_regex(true);
 714         $NOTREGEXP = $DB->sql_regex(false);
 715     }
 716
 717     $i = 0;
 718
 719     // Thanks Oracle for your non-ansi concat and type limits in coalesce. MDL-29912
 720     if ($DB->get_dbfamily() == 'oracle') {
 721         $concat = "(c.summary|| ' ' || c.fullname || ' ' || c.idnumber || ' ' || c.shortname)";
 722     } else {
 723         $concat = $DB->sql_concat("COALESCE(c.summary, '')", "' '", 'c.fullname', "' '", 'c.idnumber', "' '", 'c.shortname');
 724     }
 725
 726     foreach ($searchterms as $searchterm) {
 727         $i++;
 728
 729         $NOT = false; /// Initially we aren't going to perform NOT LIKE searches, only MSSQL and Oracle
 730                    /// will use it to simulate the "-" operator with LIKE clause
 731
 732     /// Under Oracle and MSSQL, trim the + and - operators and perform
 733     /// simpler LIKE (or NOT LIKE) queries
 734         if (!$DB->sql_regex_supported()) {
 735             if (substr($searchterm, 0, 1) == '-') {
 736                 $NOT = true;
 737             }
 738             $searchterm = trim($searchterm, '+-');
 739         }
 740
 741         // TODO: +- may not work for non latin languages
 742
 743         if (substr($searchterm,0,1) == '+') {
 744             $searchterm = trim($searchterm, '+-');
 745             $searchterm = preg_quote($searchterm, '|');
 746             $searchcond[] = "$concat $REGEXP :ss$i";
 747             $params['ss'.$i] = "(^|[^a-zA-Z0-9])$searchterm([^a-zA-Z0-9]|$)";
 748
 749         } else if ((substr($searchterm,0,1) == "-") && (core_text::strlen($searchterm) > 1)) {
 750             $searchterm = trim($searchterm, '+-');
 751             $searchterm = preg_quote($searchterm, '|');
 752             $searchcond[] = "$concat $NOTREGEXP :ss$i";
 753             $params['ss'.$i] = "(^|[^a-zA-Z0-9])$searchterm([^a-zA-Z0-9]|$)";
 754
 755         } else {
 756             $searchcond[] = $DB->sql_like($concat,":ss$i", false, true, $NOT);
 757             $params['ss'.$i] = "%$searchterm%";
 758         }
 759     }
 760
 761     if (empty($searchcond)) {
 762         $searchcond = array('1 = 1');
 763     }
 764
 765     $searchcond = implode(" AND ", $searchcond);
 766
 767     $courses = array();
 768     $c = 0; // counts how many visible courses we've seen
 769
 770     // Tiki pagination
 771     $limitfrom = $page * $recordsperpage;
 772     $limitto   = $limitfrom + $recordsperpage;
 773
 774     $ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
 775     $ccjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = c.id AND ctx.contextlevel = :contextlevel)";
 776     $params['contextlevel'] = CONTEXT_COURSE;
 777
 778     $sql = "SELECT c.* $ccselect
 779               FROM {course} c
 780            $ccjoin
 781              WHERE $searchcond AND c.id <> ".SITEID."
 782           ORDER BY $sort";
 783
 784     $mycourses = enrol_get_my_courses();
 785     $rs = $DB->get_recordset_sql($sql, $params);
 786     foreach($rs as $course) {
 787         // Preload contexts only for hidden courses or courses we need to return.
 788         context_helper::preload_from_record($course);
 789         $coursecontext = context_course::instance($course->id);
 790         if (!array_key_exists($course->id, $mycourses) && !core_course_category::can_view_course_info($course)) {
 791             continue;
 792         }
 793         if (!empty($requiredcapabilities)) {
 794             if (!has_all_capabilities($requiredcapabilities, $coursecontext)) {
 795                 continue;
 796             }
 797         }
 798         // Don't exit this loop till the end
 799         // we need to count all the visible courses
 800         // to update $totalcount
 801         if ($c >= $limitfrom && $c < $limitto) {
 802             $courses[$course->id] = $course;
 803         }
 804         $c++;
 805     }
 806     $rs->close();
 807
 808     // our caller expects 2 bits of data - our return
 809     // array, and an updated $totalcount
 810     $totalcount = $c;
 811     return $courses;
 812 }
 813
 814 /**
 815  * Fixes course category and course sortorder, also verifies category and course parents and paths.
 816  * (circular references are not fixed)
 817  *
 818  * @global object
 819  * @global object
 820  * @uses MAX_COURSE_CATEGORIES
 821  * @uses SITEID
 822  * @uses CONTEXT_COURSE
 823  * @return void
 824  */
 825 function fix_course_sortorder() {
 826     global $DB, $SITE;
 827
 828     //WARNING: this is PHP5 only code!
 829
 830     // if there are any changes made to courses or categories we will trigger
 831     // the cache events to purge all cached courses/categories data
 832     $cacheevents = array();
 833
 834     if ($unsorted = $DB->get_records('course_categories', array('sortorder'=>0))) {
 835         //move all categories that are not sorted yet to the end
 836         $DB->set_field('course_categories', 'sortorder',
 837             get_max_courses_in_category() * MAX_COURSE_CATEGORIES, array('sortorder' => 0));
 838         $cacheevents['changesincoursecat'] = true;
 839     }
 840
 841     $allcats = $DB->get_records('course_categories', null, 'sortorder, id', 'id, sortorder, parent, depth, path');
 842     $topcats    = array();
 843     $brokencats = array();
 844     foreach ($allcats as $cat) {
 845         $sortorder = (int)$cat->sortorder;
 846         if (!$cat->parent) {
 847             while(isset($topcats[$sortorder])) {
 848                 $sortorder++;
 849             }
 850             $topcats[$sortorder] = $cat;
 851             continue;
 852         }
 853         if (!isset($allcats[$cat->parent])) {
 854             $brokencats[] = $cat;
 855             continue;
 856         }
 857         if (!isset($allcats[$cat->parent]->children)) {
 858             $allcats[$cat->parent]->children = array();
 859         }
 860         while(isset($allcats[$cat->parent]->children[$sortorder])) {
 861             $sortorder++;
 862         }
 863         $allcats[$cat->parent]->children[$sortorder] = $cat;
 864     }
 865     unset($allcats);
 866
 867     // add broken cats to category tree
 868     if ($brokencats) {
 869         $defaultcat = reset($topcats);
 870         foreach ($brokencats as $cat) {
 871             $topcats[] = $cat;
 872         }
 873     }
 874
 875     // now walk recursively the tree and fix any problems found
 876     $sortorder = 0;
 877     $fixcontexts = array();
 878     if (_fix_course_cats($topcats, $sortorder, 0, 0, '', $fixcontexts)) {
 879         $cacheevents['changesincoursecat'] = true;
 880     }
 881
 882     // detect if there are "multiple" frontpage courses and fix them if needed
 883     $frontcourses = $DB->get_records('course', array('category'=>0), 'id');
 884     if (count($frontcourses) > 1) {
 885         if (isset($frontcourses[SITEID])) {
 886             $frontcourse = $frontcourses[SITEID];
 887             unset($frontcourses[SITEID]);
 888         } else {
 889             $frontcourse = array_shift($frontcourses);
 890         }
 891         $defaultcat = reset($topcats);
 892         foreach ($frontcourses as $course) {
 893             $DB->set_field('course', 'category', $defaultcat->id, array('id'=>$course->id));
 894             $context = context_course::instance($course->id);
 895             $fixcontexts[$context->id] = $context;
 896             $cacheevents['changesincourse'] = true;
 897         }
 898         unset($frontcourses);
 899     } else {
 900         $frontcourse = reset($frontcourses);
 901     }
 902
 903     // now fix the paths and depths in context table if needed
 904     if ($fixcontexts) {
 905         foreach ($fixcontexts as $fixcontext) {
 906             $fixcontext->reset_paths(false);
 907         }
 908         context_helper::build_all_paths(false);
 909         unset($fixcontexts);
 910         $cacheevents['changesincourse'] = true;
 911         $cacheevents['changesincoursecat'] = true;
 912     }
 913
 914     // release memory
 915     unset($topcats);
 916     unset($brokencats);
 917     unset($fixcontexts);
 918
 919     // fix frontpage course sortorder
 920     if ($frontcourse->sortorder != 1) {
 921         $DB->set_field('course', 'sortorder', 1, array('id'=>$frontcourse->id));
 922         $cacheevents['changesincourse'] = true;
 923     }
 924
 925     // now fix the course counts in category records if needed
 926     $sql = "SELECT cc.id, cc.coursecount, COUNT(c.id) AS newcount
 927               FROM {course_categories} cc
 928               LEFT JOIN {course} c ON c.category = cc.id
 929           GROUP BY cc.id, cc.coursecount
 930             HAVING cc.coursecount <> COUNT(c.id)";
 931
 932     if ($updatecounts = $DB->get_records_sql($sql)) {
 933         // categories with more courses than MAX_COURSES_IN_CATEGORY
 934         $categories = array();
 935         foreach ($updatecounts as $cat) {
 936             $cat->coursecount = $cat->newcount;
 937             if ($cat->coursecount >= get_max_courses_in_category()) {
 938                 $categories[] = $cat->id;
 939             }
 940             unset($cat->newcount);
 941             $DB->update_record_raw('course_categories', $cat, true);
 942         }
 943         if (!empty($categories)) {
 944             $str = implode(', ', $categories);
 945             debugging("The number of courses (category id: $str) has reached max number of courses " .
 946                 "in a category (" . get_max_courses_in_category() . "). It will cause a sorting performance issue. " .
 947                 "Please set higher value for \$CFG->maxcoursesincategory in config.php. " .
 948                 "Please also make sure \$CFG->maxcoursesincategory * MAX_COURSE_CATEGORIES less than max integer. " .
 949                 "See tracker issues: MDL-25669 and MDL-69573", DEBUG_DEVELOPER);
 950         }
 951         $cacheevents['changesincoursecat'] = true;
 952     }
 953
 954     // now make sure that sortorders in course table are withing the category sortorder ranges
 955     $sql = "SELECT DISTINCT cc.id, cc.sortorder
 956               FROM {course_categories} cc
 957               JOIN {course} c ON c.category = cc.id
 958              WHERE c.sortorder < cc.sortorder OR c.sortorder > cc.sortorder + " . get_max_courses_in_category();
 959
 960     if ($fixcategories = $DB->get_records_sql($sql)) {
 961         //fix the course sortorder ranges
 962         foreach ($fixcategories as $cat) {
 963             $sql = "UPDATE {course}
 964                        SET sortorder = ".$DB->sql_modulo('sortorder', get_max_courses_in_category())." + ?
 965                      WHERE category = ?";
 966             $DB->execute($sql, array($cat->sortorder, $cat->id));
 967         }
 968         $cacheevents['changesincoursecat'] = true;
 969     }
 970     unset($fixcategories);
 971
 972     // categories having courses with sortorder duplicates or having gaps in sortorder
 973     $sql = "SELECT DISTINCT c1.category AS id , cc.sortorder
 974               FROM {course} c1
 975               JOIN {course} c2 ON c1.sortorder = c2.sortorder
 976               JOIN {course_categories} cc ON (c1.category = cc.id)
 977              WHERE c1.id <> c2.id";
 978     $fixcategories = $DB->get_records_sql($sql);
 979
 980     $sql = "SELECT cc.id, cc.sortorder, cc.coursecount, MAX(c.sortorder) AS maxsort, MIN(c.sortorder) AS minsort
 981               FROM {course_categories} cc
 982               JOIN {course} c ON c.category = cc.id
 983           GROUP BY cc.id, cc.sortorder, cc.coursecount
 984             HAVING (MAX(c.sortorder) <>  cc.sortorder + cc.coursecount) OR (MIN(c.sortorder) <>  cc.sortorder + 1)";
 985     $gapcategories = $DB->get_records_sql($sql);
 986
 987     foreach ($gapcategories as $cat) {
 988         if (isset($fixcategories[$cat->id])) {
 989             // duplicates detected already
 990
 991         } else if ($cat->minsort == $cat->sortorder and $cat->maxsort == $cat->sortorder + $cat->coursecount - 1) {
 992             // easy - new course inserted with sortorder 0, the rest is ok
 993             $sql = "UPDATE {course}
 994                        SET sortorder = sortorder + 1
 995                      WHERE category = ?";
 996             $DB->execute($sql, array($cat->id));
 997
 998         } else {
 999             // it needs full resorting
1000             $fixcategories[$cat->id] = $cat;
1001         }
1002         $cacheevents['changesincourse'] = true;
1003     }
1004     unset($gapcategories);
1005
1006     // fix course sortorders in problematic categories only
1007     foreach ($fixcategories as $cat) {
1008         $i = 1;
1009         $courses = $DB->get_records('course', array('category'=>$cat->id), 'sortorder ASC, id DESC', 'id, sortorder');
1010         foreach ($courses as $course) {
1011             if ($course->sortorder != $cat->sortorder + $i) {
1012                 $course->sortorder = $cat->sortorder + $i;
1013                 $DB->update_record_raw('course', $course, true);
1014                 $cacheevents['changesincourse'] = true;
1015             }
1016             $i++;
1017         }
1018     }
1019
1020     // advise all caches that need to be rebuilt
1021     foreach (array_keys($cacheevents) as $event) {
1022         cache_helper::purge_by_event($event);
1023     }
1024 }
1025
1026 /**
1027  * Internal recursive category verification function, do not use directly!
1028  *
1029  * @todo Document the arguments of this function better
1030  *
1031  * @global object
1032  * @uses CONTEXT_COURSECAT
1033  * @param array $children
1034  * @param int $sortorder
1035  * @param string $parent
1036  * @param int $depth
1037  * @param string $path
1038  * @param array $fixcontexts
1039  * @return bool if changes were made
1040  */
1041 function _fix_course_cats($children, &$sortorder, $parent, $depth, $path, &$fixcontexts) {
1042     global $DB;
1043
1044     $depth++;
1045     $changesmade = false;
1046
1047     foreach ($children as $cat) {
1048         $sortorder = $sortorder + get_max_courses_in_category();
1049         $update = false;
1050         if ($parent != $cat->parent or $depth != $cat->depth or $path.'/'.$cat->id != $cat->path) {
1051             $cat->parent = $parent;
1052             $cat->depth  = $depth;
1053             $cat->path   = $path.'/'.$cat->id;
1054             $update = true;
1055
1056             // make sure context caches are rebuild and dirty contexts marked
1057             $context = context_coursecat::instance($cat->id);
1058             $fixcontexts[$context->id] = $context;
1059         }
1060         if ($cat->sortorder != $sortorder) {
1061             $cat->sortorder = $sortorder;
1062             $update = true;
1063         }
1064         if ($update) {
1065             $DB->update_record('course_categories', $cat, true);
1066             $changesmade = true;
1067         }
1068         if (isset($cat->children)) {
1069             if (_fix_course_cats($cat->children, $sortorder, $cat->id, $cat->depth, $cat->path, $fixcontexts)) {
1070                 $changesmade = true;
1071             }
1072         }
1073     }
1074     return $changesmade;
1075 }
1076
1077 /**
1078  * List of remote courses that a user has access to via MNET.
1079  * Works only on the IDP
1080  *
1081  * @global object
1082  * @global object
1083  * @param int @userid The user id to get remote courses for
1084  * @return array Array of {@link $COURSE} of course objects
1085  */
1086 function get_my_remotecourses($userid=0) {
1087     global $DB, $USER;
1088
1089     if (empty($userid)) {
1090         $userid = $USER->id;
1091     }
1092
1093     // we can not use SELECT DISTINCT + text field (summary) because of MS SQL and Oracle, subselect used therefore
1094     $sql = "SELECT c.id, c.remoteid, c.shortname, c.fullname,
1095                    c.hostid, c.summary, c.summaryformat, c.categoryname AS cat_name,
1096                    h.name AS hostname
1097               FROM {mnetservice_enrol_courses} c
1098               JOIN (SELECT DISTINCT hostid, remotecourseid
1099                       FROM {mnetservice_enrol_enrolments}
1100                      WHERE userid = ?
1101                    ) e ON (e.hostid = c.hostid AND e.remotecourseid = c.remoteid)
1102               JOIN {mnet_host} h ON h.id = c.hostid";
1103
1104     return $DB->get_records_sql($sql, array($userid));
1105 }
1106
1107 /**
1108  * List of remote hosts that a user has access to via MNET.
1109  * Works on the SP
1110  *
1111  * @global object
1112  * @global object
1113  * @return array|bool Array of host objects or false
1114  */
1115 function get_my_remotehosts() {
1116     global $CFG, $USER;
1117
1118     if ($USER->mnethostid == $CFG->mnet_localhost_id) {
1119         return false; // Return nothing on the IDP
1120     }
1121     if (!empty($USER->mnet_foreign_host_array) && is_array($USER->mnet_foreign_host_array)) {
1122         return $USER->mnet_foreign_host_array;
1123     }
1124     return false;
1125 }
1126
1127
1128 /**
1129  * Returns a menu of all available scales from the site as well as the given course
1130  *
1131  * @global object
1132  * @param int $courseid The id of the course as found in the 'course' table.
1133  * @return array
1134  */
1135 function get_scales_menu($courseid=0) {
1136     global $DB;
1137
1138     $sql = "SELECT id, name, courseid
1139               FROM {scale}
1140              WHERE courseid = 0 or courseid = ?
1141           ORDER BY courseid ASC, name ASC";
1142     $params = array($courseid);
1143     $scales = array();
1144     $results = $DB->get_records_sql($sql, $params);
1145     foreach ($results as $index => $record) {
1146         $context = empty($record->courseid) ? context_system::instance() : context_course::instance($record->courseid);
1147         $scales[$index] = format_string($record->name, false, ["context" => $context]);
1148     }
1149     // Format: [id => 'scale name'].
1150     return $scales;
1151 }
1152
1153 /**
1154  * Increment standard revision field.
1155  *
1156  * The revision are based on current time and are incrementing.
1157  * There is a protection for runaway revisions, it may not go further than
1158  * one hour into future.
1159  *
1160  * The field has to be XMLDB_TYPE_INTEGER with size 10.
1161  *
1162  * @param string $table
1163  * @param string $field name of the field containing revision
1164  * @param string $select use empty string when updating all records
1165  * @param array $params optional select parameters
1166  */
1167 function increment_revision_number($table, $field, $select, array $params = null) {
1168     global $DB;
1169
1170     $now = time();
1171     $sql = "UPDATE {{$table}}
1172                    SET $field = (CASE
1173                        WHEN $field IS NULL THEN $now
1174                        WHEN $field < $now THEN $now
1175                        WHEN $field > $now + 3600 THEN $now
1176                        ELSE $field + 1 END)";
1177     if ($select) {
1178         $sql = $sql . " WHERE $select";
1179     }
1180     $DB->execute($sql, $params);
1181 }
1182
1183
1184 /// MODULE FUNCTIONS /////////////////////////////////////////////////
1185
1186 /**
1187  * Just gets a raw list of all modules in a course
1188  *
1189  * @global object
1190  * @param int $courseid The id of the course as found in the 'course' table.
1191  * @return array
1192  */
1193 function get_course_mods($courseid) {
1194     global $DB;
1195
1196     if (empty($courseid)) {
1197         return false; // avoid warnings
1198     }
1199
1200     return $DB->get_records_sql("SELECT cm.*, m.name as modname
1201                                    FROM {modules} m, {course_modules} cm
1202                                   WHERE cm.course = ? AND cm.module = m.id AND m.visible = 1",
1203                                 array($courseid)); // no disabled mods
1204 }
1205
1206
1207 /**
1208  * Given an id of a course module, finds the coursemodule description
1209  *
1210  * Please note that this function performs 1-2 DB queries. When possible use cached
1211  * course modinfo. For example get_fast_modinfo($courseorid)->get_cm($cmid)
1212  * See also {@link cm_info::get_course_module_record()}
1213  *
1214  * @global object
1215  * @param string $modulename name of module type, eg. resource, assignment,... (optional, slower and less safe if not specified)
1216  * @param int $cmid course module id (id in course_modules table)
1217  * @param int $courseid optional course id for extra validation
1218  * @param bool $sectionnum include relative section number (0,1,2 ...)
1219  * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
1220  *                        IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
1221  *                        MUST_EXIST means throw exception if no record or multiple records found
1222  * @return stdClass
1223  */
1224 function get_coursemodule_from_id($modulename, $cmid, $courseid=0, $sectionnum=false, $strictness=IGNORE_MISSING) {
1225     global $DB;
1226
1227     $params = array('cmid'=>$cmid);
1228
1229     if (!$modulename) {
1230         if (!$modulename = $DB->get_field_sql("SELECT md.name
1231                                                  FROM {modules} md
1232                                                  JOIN {course_modules} cm ON cm.module = md.id
1233                                                 WHERE cm.id = :cmid", $params, $strictness)) {
1234             return false;
1235         }
1236     } else {
1237         if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1238             throw new coding_exception('Invalid modulename parameter');
1239         }
1240     }
1241
1242     $params['modulename'] = $modulename;
1243
1244     $courseselect = "";
1245     $sectionfield = "";
1246     $sectionjoin  = "";
1247
1248     if ($courseid) {
1249         $courseselect = "AND cm.course = :courseid";
1250         $params['courseid'] = $courseid;
1251     }
1252
1253     if ($sectionnum) {
1254         $sectionfield = ", cw.section AS sectionnum";
1255         $sectionjoin  = "LEFT JOIN {course_sections} cw ON cw.id = cm.section";
1256     }
1257
1258     $sql = "SELECT cm.*, m.name, md.name AS modname $sectionfield
1259               FROM {course_modules} cm
1260                    JOIN {modules} md ON md.id = cm.module
1261                    JOIN {".$modulename."} m ON m.id = cm.instance
1262                    $sectionjoin
1263              WHERE cm.id = :cmid AND md.name = :modulename
1264                    $courseselect";
1265
1266     return $DB->get_record_sql($sql, $params, $strictness);
1267 }
1268
1269 /**
1270  * Given an instance number of a module, finds the coursemodule description
1271  *
1272  * Please note that this function performs DB query. When possible use cached course
1273  * modinfo. For example get_fast_modinfo($courseorid)->instances[$modulename][$instance]
1274  * See also {@link cm_info::get_course_module_record()}
1275  *
1276  * @global object
1277  * @param string $modulename name of module type, eg. resource, assignment,...
1278  * @param int $instance module instance number (id in resource, assignment etc. table)
1279  * @param int $courseid optional course id for extra validation
1280  * @param bool $sectionnum include relative section number (0,1,2 ...)
1281  * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
1282  *                        IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
1283  *                        MUST_EXIST means throw exception if no record or multiple records found
1284  * @return stdClass
1285  */
1286 function get_coursemodule_from_instance($modulename, $instance, $courseid=0, $sectionnum=false, $strictness=IGNORE_MISSING) {
1287     global $DB;
1288
1289     if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1290         throw new coding_exception('Invalid modulename parameter');
1291     }
1292
1293     $params = array('instance'=>$instance, 'modulename'=>$modulename);
1294
1295     $courseselect = "";
1296     $sectionfield = "";
1297     $sectionjoin  = "";
1298
1299     if ($courseid) {
1300         $courseselect = "AND cm.course = :courseid";
1301         $params['courseid'] = $courseid;
1302     }
1303
1304     if ($sectionnum) {
1305         $sectionfield = ", cw.section AS sectionnum";
1306         $sectionjoin  = "LEFT JOIN {course_sections} cw ON cw.id = cm.section";
1307     }
1308
1309     $sql = "SELECT cm.*, m.name, md.name AS modname $sectionfield
1310               FROM {course_modules} cm
1311                    JOIN {modules} md ON md.id = cm.module
1312                    JOIN {".$modulename."} m ON m.id = cm.instance
1313                    $sectionjoin
1314              WHERE m.id = :instance AND md.name = :modulename
1315                    $courseselect";
1316
1317     return $DB->get_record_sql($sql, $params, $strictness);
1318 }
1319
1320 /**
1321  * Returns all course modules of given activity in course
1322  *
1323  * @param string $modulename The module name (forum, quiz, etc.)
1324  * @param int $courseid The course id to get modules for
1325  * @param string $extrafields extra fields starting with m.
1326  * @return array Array of results
1327  */
1328 function get_coursemodules_in_course($modulename, $courseid, $extrafields='') {
1329     global $DB;
1330
1331     if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1332         throw new coding_exception('Invalid modulename parameter');
1333     }
1334
1335     if (!empty($extrafields)) {
1336         $extrafields = ", $extrafields";
1337     }
1338     $params = array();
1339     $params['courseid'] = $courseid;
1340     $params['modulename'] = $modulename;
1341
1342
1343     return $DB->get_records_sql("SELECT cm.*, m.name, md.name as modname $extrafields
1344                                    FROM {course_modules} cm, {modules} md, {".$modulename."} m
1345                                   WHERE cm.course = :courseid AND
1346                                         cm.instance = m.id AND
1347                                         md.name = :modulename AND
1348                                         md.id = cm.module", $params);
1349 }
1350
1351 /**
1352  * Returns an array of all the active instances of a particular module in given courses, sorted in the order they are defined
1353  *
1354  * Returns an array of all the active instances of a particular
1355  * module in given courses, sorted in the order they are defined
1356  * in the course. Returns an empty array on any errors.
1357  *
1358  * The returned objects includle the columns cw.section, cm.visible,
1359  * cm.groupmode, cm.groupingid and cm.lang and are indexed by cm.id.
1360  *
1361  * @global object
1362  * @global object
1363  * @param string $modulename The name of the module to get instances for
1364  * @param array $courses an array of course objects.
1365  * @param int $userid
1366  * @param int $includeinvisible
1367  * @return array of module instance objects, including some extra fields from the course_modules
1368  *          and course_sections tables, or an empty array if an error occurred.
1369  */
1370 function get_all_instances_in_courses($modulename, $courses, $userid=NULL, $includeinvisible=false) {
1371     global $CFG, $DB;
1372
1373     if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1374         throw new coding_exception('Invalid modulename parameter');
1375     }
1376
1377     $outputarray = array();
1378
1379     if (empty($courses) || !is_array($courses) || count($courses) == 0) {
1380         return $outputarray;
1381     }
1382
1383     list($coursessql, $params) = $DB->get_in_or_equal(array_keys($courses), SQL_PARAMS_NAMED, 'c0');
1384     $params['modulename'] = $modulename;
1385
1386     if (!$rawmods = $DB->get_records_sql("SELECT cm.id AS coursemodule, m.*, cw.section, cm.visible AS visible,
1387                                                  cm.groupmode, cm.groupingid, cm.lang
1388                                             FROM {course_modules} cm, {course_sections} cw, {modules} md,
1389                                                  {".$modulename."} m
1390                                            WHERE cm.course $coursessql AND
1391                                                  cm.instance = m.id AND
1392                                                  cm.section = cw.id AND
1393                                                  md.name = :modulename AND
1394                                                  md.id = cm.module", $params)) {
1395         return $outputarray;
1396     }
1397
1398     foreach ($courses as $course) {
1399         $modinfo = get_fast_modinfo($course, $userid);
1400
1401         if (empty($modinfo->instances[$modulename])) {
1402             continue;
1403         }
1404
1405         foreach ($modinfo->instances[$modulename] as $cm) {
1406             if (!$includeinvisible and !$cm->uservisible) {
1407                 continue;
1408             }
1409             if (!isset($rawmods[$cm->id])) {
1410                 continue;
1411             }
1412             $instance = $rawmods[$cm->id];
1413             if (!empty($cm->extra)) {
1414                 $instance->extra = $cm->extra;
1415             }
1416             $outputarray[] = $instance;
1417         }
1418     }
1419
1420     return $outputarray;
1421 }
1422
1423 /**
1424  * Returns an array of all the active instances of a particular module in a given course,
1425  * sorted in the order they are defined.
1426  *
1427  * Returns an array of all the active instances of a particular
1428  * module in a given course, sorted in the order they are defined
1429  * in the course. Returns an empty array on any errors.
1430  *
1431  * The returned objects includle the columns cw.section, cm.visible,
1432  * cm.groupmode, and cm.groupingid, and are indexed by cm.id.
1433  *
1434  * Simply calls {@link all_instances_in_courses()} with a single provided course
1435  *
1436  * @param string $modulename The name of the module to get instances for
1437  * @param object $course The course obect.
1438  * @return array of module instance objects, including some extra fields from the course_modules
1439  *          and course_sections tables, or an empty array if an error occurred.
1440  * @param int $userid
1441  * @param int $includeinvisible
1442  */
1443 function get_all_instances_in_course($modulename, $course, $userid=NULL, $includeinvisible=false) {
1444     return get_all_instances_in_courses($modulename, array($course->id => $course), $userid, $includeinvisible);
1445 }
1446
1447
1448 /**
1449  * Determine whether a module instance is visible within a course
1450  *
1451  * Given a valid module object with info about the id and course,
1452  * and the module's type (eg "forum") returns whether the object
1453  * is visible or not according to the 'eye' icon only.
1454  *
1455  * NOTE: This does NOT take into account visibility to a particular user.
1456  * To get visibility access for a specific user, use get_fast_modinfo, get a
1457  * cm_info object from this, and check the ->uservisible property; or use
1458  * the \core_availability\info_module::is_user_visible() static function.
1459  *
1460  * @global object
1461
1462  * @param $moduletype Name of the module eg 'forum'
1463  * @param $module Object which is the instance of the module
1464  * @return bool Success
1465  */
1466 function instance_is_visible($moduletype, $module) {
1467     global $DB;
1468
1469     if (!empty($module->id)) {
1470         $params = array('courseid'=>$module->course, 'moduletype'=>$moduletype, 'moduleid'=>$module->id);
1471         if ($records = $DB->get_records_sql("SELECT cm.instance, cm.visible, cm.groupingid, cm.id, cm.course
1472                                                FROM {course_modules} cm, {modules} m
1473                                               WHERE cm.course = :courseid AND
1474                                                     cm.module = m.id AND
1475                                                     m.name = :moduletype AND
1476                                                     cm.instance = :moduleid", $params)) {
1477
1478             foreach ($records as $record) { // there should only be one - use the first one
1479                 return $record->visible;
1480             }
1481         }
1482     }
1483     return true;  // visible by default!
1484 }
1485
1486
1487 /// LOG FUNCTIONS /////////////////////////////////////////////////////
1488
1489 /**
1490  * Get instance of log manager.
1491  *
1492  * @param bool $forcereload
1493  * @return \core\log\manager
1494  */
1495 function get_log_manager($forcereload = false) {
1496     /** @var \core\log\manager $singleton */
1497     static $singleton = null;
1498
1499     if ($forcereload and isset($singleton)) {
1500         $singleton->dispose();
1501         $singleton = null;
1502     }
1503
1504     if (isset($singleton)) {
1505         return $singleton;
1506     }
1507
1508     $classname = '\tool_log\log\manager';
1509     if (defined('LOG_MANAGER_CLASS')) {
1510         $classname = LOG_MANAGER_CLASS;
1511     }
1512
1513     if (!class_exists($classname)) {
1514         if (!empty($classname)) {
1515             debugging("Cannot find log manager class '$classname'.", DEBUG_DEVELOPER);
1516         }
1517         $classname = '\core\log\dummy_manager';
1518     }
1519
1520     $singleton = new $classname();
1521     return $singleton;
1522 }
1523
1524 /**
1525  * Add an entry to the config log table.
1526  *
1527  * These are "action" focussed rather than web server hits,
1528  * and provide a way to easily reconstruct changes to Moodle configuration.
1529  *
1530  * @package core
1531  * @category log
1532  * @global moodle_database $DB
1533  * @global stdClass $USER
1534  * @param    string  $name     The name of the configuration change action
1535                                For example 'filter_active' when activating or deactivating a filter
1536  * @param    string  $oldvalue The config setting's previous value
1537  * @param    string  $value    The config setting's new value
1538  * @param    string  $plugin   Plugin name, for example a filter name when changing filter configuration
1539  * @return void
1540  */
1541 function add_to_config_log($name, $oldvalue, $value, $plugin) {
1542     global $USER, $DB;
1543
1544     $log = new stdClass();
1545     // Use 0 as user id during install.
1546     $log->userid       = during_initial_install() ? 0 : $USER->id;
1547     $log->timemodified = time();
1548     $log->name         = $name;
1549     $log->oldvalue  = $oldvalue;
1550     $log->value     = $value;
1551     $log->plugin    = $plugin;
1552
1553     $id = $DB->insert_record('config_log', $log);
1554
1555     $event = core\event\config_log_created::create(array(
1556             'objectid' => $id,
1557             'userid' => $log->userid,
1558             'context' => \context_system::instance(),
1559             'other' => array(
1560                 'name' => $log->name,
1561                 'oldvalue' => $log->oldvalue,
1562                 'value' => $log->value,
1563                 'plugin' => $log->plugin
1564             )
1565         ));
1566     $event->trigger();
1567 }
1568
1569 /**
1570  * Store user last access times - called when use enters a course or site
1571  *
1572  * @package core
1573  * @category log
1574  * @global stdClass $USER
1575  * @global stdClass $CFG
1576  * @global moodle_database $DB
1577  * @uses LASTACCESS_UPDATE_SECS
1578  * @uses SITEID
1579  * @param int $courseid  empty courseid means site
1580  * @return void
1581  */
1582 function user_accesstime_log($courseid=0) {
1583     global $USER, $CFG, $DB;
1584
1585     if (!isloggedin() or \core\session\manager::is_loggedinas()) {
1586         // no access tracking
1587         return;
1588     }
1589
1590     if (isguestuser()) {
1591         // Do not update guest access times/ips for performance.
1592         return;
1593     }
1594
1595     if (empty($courseid)) {
1596         $courseid = SITEID;
1597     }
1598
1599     $timenow = time();
1600
1601 /// Store site lastaccess time for the current user
1602     if ($timenow - $USER->lastaccess > LASTACCESS_UPDATE_SECS) {
1603     /// Update $USER->lastaccess for next checks
1604         $USER->lastaccess = $timenow;
1605
1606         $last = new stdClass();
1607         $last->id         = $USER->id;
1608         $last->lastip     = getremoteaddr();
1609         $last->lastaccess = $timenow;
1610
1611         $DB->update_record_raw('user', $last);
1612     }
1613
1614     if ($courseid == SITEID) {
1615     ///  no user_lastaccess for frontpage
1616         return;
1617     }
1618
1619 /// Store course lastaccess times for the current user
1620     if (empty($USER->currentcourseaccess[$courseid]) or ($timenow - $USER->currentcourseaccess[$courseid] > LASTACCESS_UPDATE_SECS)) {
1621
1622         $lastaccess = $DB->get_field('user_lastaccess', 'timeaccess', array('userid'=>$USER->id, 'courseid'=>$courseid));
1623
1624         if ($lastaccess === false) {
1625             // Update course lastaccess for next checks
1626             $USER->currentcourseaccess[$courseid] = $timenow;
1627
1628             $last = new stdClass();
1629             $last->userid     = $USER->id;
1630             $last->courseid   = $courseid;
1631             $last->timeaccess = $timenow;
1632             try {
1633                 $DB->insert_record_raw('user_lastaccess', $last, false);
1634             } catch (dml_write_exception $e) {
1635                 // During a race condition we can fail to find the data, then it appears.
1636                 // If we still can't find it, rethrow the exception.
1637                 $lastaccess = $DB->get_field('user_lastaccess', 'timeaccess', array('userid' => $USER->id,
1638                                                                                     'courseid' => $courseid));
1639                 if ($lastaccess === false) {
1640                     throw $e;
1641                 }
1642                 // If we did find it, the race condition was true and another thread has inserted the time for us.
1643                 // We can just continue without having to do anything.
1644             }
1645
1646         } else if ($timenow - $lastaccess <  LASTACCESS_UPDATE_SECS) {
1647             // no need to update now, it was updated recently in concurrent login ;-)
1648
1649         } else {
1650             // Update course lastaccess for next checks
1651             $USER->currentcourseaccess[$courseid] = $timenow;
1652
1653             $DB->set_field('user_lastaccess', 'timeaccess', $timenow, array('userid'=>$USER->id, 'courseid'=>$courseid));
1654         }
1655     }
1656 }
1657
1658 /// GENERAL HELPFUL THINGS  ///////////////////////////////////
1659
1660 /**
1661  * Dumps a given object's information for debugging purposes
1662  *
1663  * When used in a CLI script, the object's information is written to the standard
1664  * error output stream. When used in a web script, the object is dumped to a
1665  * pre-formatted block with the "notifytiny" CSS class.
1666  *
1667  * @param mixed $object The data to be printed
1668  * @return void output is echo'd
1669  */
1670 function print_object($object) {
1671
1672     // we may need a lot of memory here
1673     raise_memory_limit(MEMORY_EXTRA);
1674
1675     if (CLI_SCRIPT) {
1676         fwrite(STDERR, print_r($object, true));
1677         fwrite(STDERR, PHP_EOL);
1678     } else if (AJAX_SCRIPT) {
1679         foreach (explode("\n", print_r($object, true)) as $line) {
1680             error_log($line);
1681         }
1682     } else {
1683         echo html_writer::tag('pre', s(print_r($object, true)), array('class' => 'notifytiny'));
1684     }
1685 }
1686
1687 /**
1688  * This function is the official hook inside XMLDB stuff to delegate its debug to one
1689  * external function.
1690  *
1691  * Any script can avoid calls to this function by defining XMLDB_SKIP_DEBUG_HOOK before
1692  * using XMLDB classes. Obviously, also, if this function doesn't exist, it isn't invoked ;-)
1693  *
1694  * @uses DEBUG_DEVELOPER
1695  * @param string $message string contains the error message
1696  * @param object $object object XMLDB object that fired the debug
1697  */
1698 function xmldb_debug($message, $object) {
1699
1700     debugging($message, DEBUG_DEVELOPER);
1701 }
1702
1703 /**
1704  * @global object
1705  * @uses CONTEXT_COURSECAT
1706  * @return boolean Whether the user can create courses in any category in the system.
1707  */
1708 function user_can_create_courses() {
1709     global $DB;
1710     $catsrs = $DB->get_recordset('course_categories');
1711     foreach ($catsrs as $cat) {
1712         if (has_capability('moodle/course:create', context_coursecat::instance($cat->id))) {
1713             $catsrs->close();
1714             return true;
1715         }
1716     }
1717     $catsrs->close();
1718     return false;
1719 }
1720
1721 /**
1722  * This method can update the values in mulitple database rows for a colum with
1723  * a unique index, without violating that constraint.
1724  *
1725  * Suppose we have a table with a unique index on (otherid, sortorder), and
1726  * for a particular value of otherid, we want to change all the sort orders.
1727  * You have to do this carefully or you will violate the unique index at some time.
1728  * This method takes care of the details for you.
1729  *
1730  * Note that, it is the responsibility of the caller to make sure that the
1731  * requested rename is legal. For example, if you ask for [1 => 2, 2 => 2]
1732  * then you will get a unique key violation error from the database.
1733  *
1734  * @param string $table The database table to modify.
1735  * @param string $field the field that contains the values we are going to change.
1736  * @param array $newvalues oldvalue => newvalue how to change the values.
1737  *      E.g. [1 => 4, 2 => 1, 3 => 3, 4 => 2].
1738  * @param array $otherconditions array fieldname => requestedvalue extra WHERE clause
1739  *      conditions to restrict which rows are affected. E.g. array('otherid' => 123).
1740  * @param int $unusedvalue (defaults to -1) a value that is never used in $ordercol.
1741  */
1742 function update_field_with_unique_index($table, $field, array $newvalues,
1743         array $otherconditions, $unusedvalue = -1) {
1744     global $DB;
1745     $safechanges = decompose_update_into_safe_changes($newvalues, $unusedvalue);
1746
1747     $transaction = $DB->start_delegated_transaction();
1748     foreach ($safechanges as $change) {
1749         list($from, $to) = $change;
1750         $otherconditions[$field] = $from;
1751         $DB->set_field($table, $field, $to, $otherconditions);
1752     }
1753     $transaction->allow_commit();
1754 }
1755
1756 /**
1757  * Helper used by {@link update_field_with_unique_index()}. Given a desired
1758  * set of changes, break them down into single udpates that can be done one at
1759  * a time without breaking any unique index constraints.
1760  *
1761  * Suppose the input is array(1 => 2, 2 => 1) and -1. Then the output will be
1762  * array (array(1, -1), array(2, 1), array(-1, 2)). This function solves this
1763  * problem in the general case, not just for simple swaps. The unit tests give
1764  * more examples.
1765  *
1766  * Note that, it is the responsibility of the caller to make sure that the
1767  * requested rename is legal. For example, if you ask for something impossible
1768  * like array(1 => 2, 2 => 2) then the results are undefined. (You will probably
1769  * get a unique key violation error from the database later.)
1770  *
1771  * @param array $newvalues The desired re-ordering.
1772  *      E.g. array(1 => 4, 2 => 1, 3 => 3, 4 => 2).
1773  * @param int $unusedvalue A value that is not currently used.
1774  * @return array A safe way to perform the re-order. An array of two-element
1775  *      arrays array($from, $to).
1776  *      E.g. array(array(1, -1), array(2, 1), array(4, 2), array(-1, 4)).
1777  */
1778 function decompose_update_into_safe_changes(array $newvalues, $unusedvalue) {
1779     $nontrivialmap = array();
1780     foreach ($newvalues as $from => $to) {
1781         if ($from == $unusedvalue || $to == $unusedvalue) {
1782             throw new \coding_exception('Supposedly unused value ' . $unusedvalue . ' is actually used!');
1783         }
1784         if ($from != $to) {
1785             $nontrivialmap[$from] = $to;
1786         }
1787     }
1788
1789     if (empty($nontrivialmap)) {
1790         return array();
1791     }
1792
1793     // First we deal with all renames that are not part of cycles.
1794     // This bit is O(n^2) and it ought to be possible to do better,
1795     // but it does not seem worth the effort.
1796     $safechanges = array();
1797     $nontrivialmapchanged = true;
1798     while ($nontrivialmapchanged) {
1799         $nontrivialmapchanged = false;
1800
1801         foreach ($nontrivialmap as $from => $to) {
1802             if (array_key_exists($to, $nontrivialmap)) {
1803                 continue; // Cannot currenly do this rename.
1804             }
1805             // Is safe to do this rename now.
1806             $safechanges[] = array($from, $to);
1807             unset($nontrivialmap[$from]);
1808             $nontrivialmapchanged = true;
1809         }
1810     }
1811
1812     // Are we done?
1813     if (empty($nontrivialmap)) {
1814         return $safechanges;
1815     }
1816
1817     // Now what is left in $nontrivialmap must be a permutation,
1818     // which must be a combination of disjoint cycles. We need to break them.
1819     while (!empty($nontrivialmap)) {
1820         // Extract the first cycle.
1821         reset($nontrivialmap);
1822         $current = $cyclestart = key($nontrivialmap);
1823         $cycle = array();
1824         do {
1825             $cycle[] = $current;
1826             $next = $nontrivialmap[$current];
1827             unset($nontrivialmap[$current]);
1828             $current = $next;
1829         } while ($current != $cyclestart);
1830
1831         // Now convert it to a sequence of safe renames by using a temp.
1832         $safechanges[] = array($cyclestart, $unusedvalue);
1833         $cycle[0] = $unusedvalue;
1834         $to = $cyclestart;
1835         while ($from = array_pop($cycle)) {
1836             $safechanges[] = array($from, $to);
1837             $to = $from;
1838         }
1839     }
1840
1841     return $safechanges;
1842 }
1843
1844 /**
1845  * Return maximum number of courses in a category
1846  *
1847  * @uses MAX_COURSES_IN_CATEGORY
1848  * @return int number of courses
1849  */
1850 function get_max_courses_in_category() {
1851     global $CFG;
1852     // Use default MAX_COURSES_IN_CATEGORY if $CFG->maxcoursesincategory is not set or invalid.
1853     if (!isset($CFG->maxcoursesincategory) || clean_param($CFG->maxcoursesincategory, PARAM_INT) == 0) {
1854         return MAX_COURSES_IN_CATEGORY;
1855     } else {
1856         return $CFG->maxcoursesincategory;
1857     }
1858 }
1859
1860 /**
1861  * Prepare a safe ORDER BY statement from user interactable requests.
1862  *
1863  * This allows safe user specified sorting (ORDER BY), by abstracting the SQL from the value being requested by the user.
1864  * A standard string (and optional direction) can be specified, which will be mapped to a predefined allow list of SQL ordering.
1865  * The mapping can optionally include a 'default', which will be used if the key provided is invalid.
1866  *
1867  * Example usage:
1868  *      -If $orderbymap = [
1869  *              'courseid' => 'c.id',
1870  *              'somecustomvalue'=> 'c.startdate, c.shortname',
1871  *              'default' => 'c.fullname',
1872  *       ]
1873  *      -A value from the map array's keys can be passed in by a user interaction (eg web service) along with an optional direction.
1874  *      -get_safe_orderby($orderbymap, 'courseid', 'DESC') would return: ORDER BY c.id DESC
1875  *      -get_safe_orderby($orderbymap, 'somecustomvalue') would return: ORDER BY c.startdate, c.shortname
1876  *      -get_safe_orderby($orderbymap, 'invalidblah', 'DESC') would return: ORDER BY c.fullname DESC
1877  *      -If no default key was specified in $orderbymap, the invalidblah example above would return empty string.
1878  *
1879  * @param array $orderbymap An array in the format [keystring => sqlstring]. A default fallback can be set with the key 'default'.
1880  * @param string $orderbykey A string to be mapped to a key in $orderbymap.
1881  * @param string $direction Optional ORDER BY direction (ASC/DESC, case insensitive).
1882  * @param bool $useprefix Whether ORDER BY is prefixed to the output (true by default). This should not be modified in most cases.
1883  *                        It is included to enable get_safe_orderby_multiple() to use this function multiple times.
1884  * @return string The ORDER BY statement, or empty string if $orderbykey is invalid and no default is mapped.
1885  */
1886 function get_safe_orderby(array $orderbymap, string $orderbykey, string $direction = '', bool $useprefix = true): string {
1887     $orderby = $useprefix ? ' ORDER BY ' : '';
1888     $output = '';
1889
1890     // Only include an order direction if ASC/DESC is explicitly specified (case insensitive).
1891     $direction = strtoupper($direction);
1892     if (!in_array($direction, ['ASC', 'DESC'], true)) {
1893         $direction = '';
1894     } else {
1895         $direction = " {$direction}";
1896     }
1897
1898     // Prepare the statement if the key maps to a defined sort parameter.
1899     if (isset($orderbymap[$orderbykey])) {
1900         $output = "{$orderby}{$orderbymap[$orderbykey]}{$direction}";
1901     } else if (array_key_exists('default', $orderbymap)) {
1902         // Fall back to use the default if one is specified.
1903         $output = "{$orderby}{$orderbymap['default']}{$direction}";
1904     }
1905
1906     return $output;
1907 }
1908
1909 /**
1910  * Prepare a safe ORDER BY statement from user interactable requests using multiple values.
1911  *
1912  * This allows safe user specified sorting (ORDER BY) similar to get_safe_orderby(), but supports multiple keys and directions.
1913  * This is useful in cases where combinations of columns are needed and/or each item requires a specified direction (ASC/DESC).
1914  * The mapping can optionally include a 'default', which will be used if the key provided is invalid.
1915  *
1916  * Example usage:
1917  *      -If $orderbymap = [
1918  *              'courseid' => 'c.id',
1919  *              'fullname'=> 'c.fullname',
1920  *              'default' => 'c.startdate',
1921  *          ]
1922  *      -An array of values from the map's keys can be passed in by a user interaction (eg web service), with optional directions.
1923  *      -get_safe_orderby($orderbymap, ['courseid', 'fullname'], ['DESC', 'ASC']) would return: ORDER BY c.id DESC, c.fullname ASC
1924  *      -get_safe_orderby($orderbymap, ['courseid', 'invalidblah'], ['aaa', 'DESC']) would return: ORDER BY c.id, c.startdate DESC
1925  *      -If no default key was specified in $orderbymap, the invalidblah example above would return: ORDER BY c.id
1926  *
1927  * @param array $orderbymap An array in the format [keystring => sqlstring]. A default fallback can be set with the key 'default'.
1928  * @param array $orderbykeys An array of strings to be mapped to keys in $orderbymap.
1929  * @param array $directions Optional array of ORDER BY direction (ASC/DESC, case insensitive).
1930  *                          The array keys should match array keys in $orderbykeys.
1931  * @return string The ORDER BY statement, or empty string if $orderbykeys contains no valid items and no default is mapped.
1932  */
1933 function get_safe_orderby_multiple(array $orderbymap, array $orderbykeys, array $directions = []): string {
1934     $output = '';
1935
1936     // Check each key for a valid mapping and add to the ORDER BY statement (invalid entries will be empty strings).
1937     foreach ($orderbykeys as $index => $orderbykey) {
1938         $direction = $directions[$index] ?? '';
1939         $safeorderby = get_safe_orderby($orderbymap, $orderbykey, $direction, false);
1940
1941         if (!empty($safeorderby)) {
1942             $output .= ", {$safeorderby}";
1943         }
1944     }
1945
1946     // Prefix with ORDER BY if any valid ordering is specified (and remove comma from the start).
1947     if (!empty($output)) {
1948         $output = ' ORDER BY' . ltrim($output, ',');
1949     }
1950
1951     return $output;
1952 }