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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Cohort related management functions, this file needs to be included manually.
  19   *
  20   * @package    core_cohort
  21   * @copyright  2010 Petr Skoda  {@link http://skodak.org}
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  defined('MOODLE_INTERNAL') || die();
  26  
  27  define('COHORT_ALL', 0);
  28  define('COHORT_COUNT_MEMBERS', 1);
  29  define('COHORT_COUNT_ENROLLED_MEMBERS', 3);
  30  define('COHORT_WITH_MEMBERS_ONLY', 5);
  31  define('COHORT_WITH_ENROLLED_MEMBERS_ONLY', 17);
  32  define('COHORT_WITH_NOTENROLLED_MEMBERS_ONLY', 23);
  33  
  34  /**
  35   * Add new cohort.
  36   *
  37   * @param  stdClass $cohort
  38   * @return int new cohort id
  39   */
  40  function cohort_add_cohort($cohort) {
  41      global $DB;
  42  
  43      if (!isset($cohort->name)) {
  44          throw new coding_exception('Missing cohort name in cohort_add_cohort().');
  45      }
  46      if (!isset($cohort->idnumber)) {
  47          $cohort->idnumber = NULL;
  48      }
  49      if (!isset($cohort->description)) {
  50          $cohort->description = '';
  51      }
  52      if (!isset($cohort->descriptionformat)) {
  53          $cohort->descriptionformat = FORMAT_HTML;
  54      }
  55      if (!isset($cohort->visible)) {
  56          $cohort->visible = 1;
  57      }
  58      if (empty($cohort->component)) {
  59          $cohort->component = '';
  60      }
  61      if (!isset($cohort->timecreated)) {
  62          $cohort->timecreated = time();
  63      }
  64      if (!isset($cohort->timemodified)) {
  65          $cohort->timemodified = $cohort->timecreated;
  66      }
  67  
  68      $cohort->id = $DB->insert_record('cohort', $cohort);
  69  
  70      $event = \core\event\cohort_created::create(array(
  71          'context' => context::instance_by_id($cohort->contextid),
  72          'objectid' => $cohort->id,
  73      ));
  74      $event->add_record_snapshot('cohort', $cohort);
  75      $event->trigger();
  76  
  77      return $cohort->id;
  78  }
  79  
  80  /**
  81   * Update existing cohort.
  82   * @param  stdClass $cohort
  83   * @return void
  84   */
  85  function cohort_update_cohort($cohort) {
  86      global $DB;
  87      if (property_exists($cohort, 'component') and empty($cohort->component)) {
  88          // prevent NULLs
  89          $cohort->component = '';
  90      }
  91      $cohort->timemodified = time();
  92      $DB->update_record('cohort', $cohort);
  93  
  94      $event = \core\event\cohort_updated::create(array(
  95          'context' => context::instance_by_id($cohort->contextid),
  96          'objectid' => $cohort->id,
  97      ));
  98      $event->trigger();
  99  }
 100  
 101  /**
 102   * Delete cohort.
 103   * @param  stdClass $cohort
 104   * @return void
 105   */
 106  function cohort_delete_cohort($cohort) {
 107      global $DB;
 108  
 109      if ($cohort->component) {
 110          // TODO: add component delete callback
 111      }
 112  
 113      $DB->delete_records('cohort_members', array('cohortid'=>$cohort->id));
 114      $DB->delete_records('cohort', array('id'=>$cohort->id));
 115  
 116      $event = \core\event\cohort_deleted::create(array(
 117          'context' => context::instance_by_id($cohort->contextid),
 118          'objectid' => $cohort->id,
 119      ));
 120      $event->add_record_snapshot('cohort', $cohort);
 121      $event->trigger();
 122  }
 123  
 124  /**
 125   * Somehow deal with cohorts when deleting course category,
 126   * we can not just delete them because they might be used in enrol
 127   * plugins or referenced in external systems.
 128   * @param  stdClass|coursecat $category
 129   * @return void
 130   */
 131  function cohort_delete_category($category) {
 132      global $DB;
 133      // TODO: make sure that cohorts are really, really not used anywhere and delete, for now just move to parent or system context
 134  
 135      $oldcontext = context_coursecat::instance($category->id);
 136  
 137      if ($category->parent and $parent = $DB->get_record('course_categories', array('id'=>$category->parent))) {
 138          $parentcontext = context_coursecat::instance($parent->id);
 139          $sql = "UPDATE {cohort} SET contextid = :newcontext WHERE contextid = :oldcontext";
 140          $params = array('oldcontext'=>$oldcontext->id, 'newcontext'=>$parentcontext->id);
 141      } else {
 142          $syscontext = context_system::instance();
 143          $sql = "UPDATE {cohort} SET contextid = :newcontext WHERE contextid = :oldcontext";
 144          $params = array('oldcontext'=>$oldcontext->id, 'newcontext'=>$syscontext->id);
 145      }
 146  
 147      $DB->execute($sql, $params);
 148  }
 149  
 150  /**
 151   * Add cohort member
 152   * @param  int $cohortid
 153   * @param  int $userid
 154   * @return void
 155   */
 156  function cohort_add_member($cohortid, $userid) {
 157      global $DB;
 158      if ($DB->record_exists('cohort_members', array('cohortid'=>$cohortid, 'userid'=>$userid))) {
 159          // No duplicates!
 160          return;
 161      }
 162      $record = new stdClass();
 163      $record->cohortid  = $cohortid;
 164      $record->userid    = $userid;
 165      $record->timeadded = time();
 166      $DB->insert_record('cohort_members', $record);
 167  
 168      $cohort = $DB->get_record('cohort', array('id' => $cohortid), '*', MUST_EXIST);
 169  
 170      $event = \core\event\cohort_member_added::create(array(
 171          'context' => context::instance_by_id($cohort->contextid),
 172          'objectid' => $cohortid,
 173          'relateduserid' => $userid,
 174      ));
 175      $event->add_record_snapshot('cohort', $cohort);
 176      $event->trigger();
 177  }
 178  
 179  /**
 180   * Remove cohort member
 181   * @param  int $cohortid
 182   * @param  int $userid
 183   * @return void
 184   */
 185  function cohort_remove_member($cohortid, $userid) {
 186      global $DB;
 187      $DB->delete_records('cohort_members', array('cohortid'=>$cohortid, 'userid'=>$userid));
 188  
 189      $cohort = $DB->get_record('cohort', array('id' => $cohortid), '*', MUST_EXIST);
 190  
 191      $event = \core\event\cohort_member_removed::create(array(
 192          'context' => context::instance_by_id($cohort->contextid),
 193          'objectid' => $cohortid,
 194          'relateduserid' => $userid,
 195      ));
 196      $event->add_record_snapshot('cohort', $cohort);
 197      $event->trigger();
 198  }
 199  
 200  /**
 201   * Is this user a cohort member?
 202   * @param int $cohortid
 203   * @param int $userid
 204   * @return bool
 205   */
 206  function cohort_is_member($cohortid, $userid) {
 207      global $DB;
 208  
 209      return $DB->record_exists('cohort_members', array('cohortid'=>$cohortid, 'userid'=>$userid));
 210  }
 211  
 212  /**
 213   * Returns the list of cohorts visible to the current user in the given course.
 214   *
 215   * The following fields are returned in each record: id, name, contextid, idnumber, visible
 216   * Fields memberscnt and enrolledcnt will be also returned if requested
 217   *
 218   * @param context $currentcontext
 219   * @param int $withmembers one of the COHORT_XXX constants that allows to return non empty cohorts only
 220   *      or cohorts with enroled/not enroled users, or just return members count
 221   * @param int $offset
 222   * @param int $limit
 223   * @param string $search
 224   * @return array
 225   */
 226  function cohort_get_available_cohorts($currentcontext, $withmembers = 0, $offset = 0, $limit = 25, $search = '') {
 227      global $DB;
 228  
 229      $params = array();
 230  
 231      // Build context subquery. Find the list of parent context where user is able to see any or visible-only cohorts.
 232      // Since this method is normally called for the current course all parent contexts are already preloaded.
 233      $contextsany = array_filter($currentcontext->get_parent_context_ids(),
 234          create_function('$a', 'return has_capability("moodle/cohort:view", context::instance_by_id($a));'));
 235      $contextsvisible = array_diff($currentcontext->get_parent_context_ids(), $contextsany);
 236      if (empty($contextsany) && empty($contextsvisible)) {
 237          // User does not have any permissions to view cohorts.
 238          return array();
 239      }
 240      $subqueries = array();
 241      if (!empty($contextsany)) {
 242          list($parentsql, $params1) = $DB->get_in_or_equal($contextsany, SQL_PARAMS_NAMED, 'ctxa');
 243          $subqueries[] = 'c.contextid ' . $parentsql;
 244          $params = array_merge($params, $params1);
 245      }
 246      if (!empty($contextsvisible)) {
 247          list($parentsql, $params1) = $DB->get_in_or_equal($contextsvisible, SQL_PARAMS_NAMED, 'ctxv');
 248          $subqueries[] = '(c.visible = 1 AND c.contextid ' . $parentsql. ')';
 249          $params = array_merge($params, $params1);
 250      }
 251      $wheresql = '(' . implode(' OR ', $subqueries) . ')';
 252  
 253      // Build the rest of the query.
 254      $fromsql = "";
 255      $fieldssql = 'c.id, c.name, c.contextid, c.idnumber, c.visible';
 256      $groupbysql = '';
 257      $havingsql = '';
 258      if ($withmembers) {
 259          $groupbysql = " GROUP BY $fieldssql";
 260          $fromsql = " LEFT JOIN {cohort_members} cm ON cm.cohortid = c.id ";
 261          $fieldssql .= ', COUNT(DISTINCT cm.userid) AS memberscnt';
 262          if (in_array($withmembers,
 263                  array(COHORT_COUNT_ENROLLED_MEMBERS, COHORT_WITH_ENROLLED_MEMBERS_ONLY, COHORT_WITH_NOTENROLLED_MEMBERS_ONLY))) {
 264              list($esql, $params2) = get_enrolled_sql($currentcontext);
 265              $fromsql .= " LEFT JOIN ($esql) u ON u.id = cm.userid ";
 266              $params = array_merge($params2, $params);
 267              $fieldssql .= ', COUNT(DISTINCT u.id) AS enrolledcnt';
 268          }
 269          if ($withmembers == COHORT_WITH_MEMBERS_ONLY) {
 270              $havingsql = " HAVING COUNT(DISTINCT cm.userid) > 0";
 271          } else if ($withmembers == COHORT_WITH_ENROLLED_MEMBERS_ONLY) {
 272              $havingsql = " HAVING COUNT(DISTINCT u.id) > 0";
 273          } else if ($withmembers == COHORT_WITH_NOTENROLLED_MEMBERS_ONLY) {
 274              $havingsql = " HAVING COUNT(DISTINCT cm.userid) > COUNT(DISTINCT u.id)";
 275          }
 276      }
 277      if ($search) {
 278          list($searchsql, $searchparams) = cohort_get_search_query($search);
 279          $wheresql .= ' AND ' . $searchsql;
 280          $params = array_merge($params, $searchparams);
 281      }
 282  
 283      $sql = "SELECT $fieldssql
 284                FROM {cohort} c
 285                $fromsql
 286               WHERE $wheresql
 287               $groupbysql
 288               $havingsql
 289            ORDER BY c.name, c.idnumber";
 290  
 291      return $DB->get_records_sql($sql, $params, $offset, $limit);
 292  }
 293  
 294  /**
 295   * Check if cohort exists and user is allowed to access it from the given context.
 296   *
 297   * @param stdClass|int $cohortorid cohort object or id
 298   * @param context $currentcontext current context (course) where visibility is checked
 299   * @return boolean
 300   */
 301  function cohort_can_view_cohort($cohortorid, $currentcontext) {
 302      global $DB;
 303      if (is_numeric($cohortorid)) {
 304          $cohort = $DB->get_record('cohort', array('id' => $cohortorid), 'id, contextid, visible');
 305      } else {
 306          $cohort = $cohortorid;
 307      }
 308  
 309      if ($cohort && in_array($cohort->contextid, $currentcontext->get_parent_context_ids())) {
 310          if ($cohort->visible) {
 311              return true;
 312          }
 313          $cohortcontext = context::instance_by_id($cohort->contextid);
 314          if (has_capability('moodle/cohort:view', $cohortcontext)) {
 315              return true;
 316          }
 317      }
 318      return false;
 319  }
 320  
 321  /**
 322   * Produces a part of SQL query to filter cohorts by the search string
 323   *
 324   * Called from {@link cohort_get_cohorts()}, {@link cohort_get_all_cohorts()} and {@link cohort_get_available_cohorts()}
 325   *
 326   * @access private
 327   *
 328   * @param string $search search string
 329   * @param string $tablealias alias of cohort table in the SQL query (highly recommended if other tables are used in query)
 330   * @return array of two elements - SQL condition and array of named parameters
 331   */
 332  function cohort_get_search_query($search, $tablealias = '') {
 333      global $DB;
 334      $params = array();
 335      if (empty($search)) {
 336          // This function should not be called if there is no search string, just in case return dummy query.
 337          return array('1=1', $params);
 338      }
 339      if ($tablealias && substr($tablealias, -1) !== '.') {
 340          $tablealias .= '.';
 341      }
 342      $searchparam = '%' . $DB->sql_like_escape($search) . '%';
 343      $conditions = array();
 344      $fields = array('name', 'idnumber', 'description');
 345      $cnt = 0;
 346      foreach ($fields as $field) {
 347          $conditions[] = $DB->sql_like($tablealias . $field, ':csearch' . $cnt, false);
 348          $params['csearch' . $cnt] = $searchparam;
 349          $cnt++;
 350      }
 351      $sql = '(' . implode(' OR ', $conditions) . ')';
 352      return array($sql, $params);
 353  }
 354  
 355  /**
 356   * Get all the cohorts defined in given context.
 357   *
 358   * The function does not check user capability to view/manage cohorts in the given context
 359   * assuming that it has been already verified.
 360   *
 361   * @param int $contextid
 362   * @param int $page number of the current page
 363   * @param int $perpage items per page
 364   * @param string $search search string
 365   * @return array    Array(totalcohorts => int, cohorts => array, allcohorts => int)
 366   */
 367  function cohort_get_cohorts($contextid, $page = 0, $perpage = 25, $search = '') {
 368      global $DB;
 369  
 370      $fields = "SELECT *";
 371      $countfields = "SELECT COUNT(1)";
 372      $sql = " FROM {cohort}
 373               WHERE contextid = :contextid";
 374      $params = array('contextid' => $contextid);
 375      $order = " ORDER BY name ASC, idnumber ASC";
 376  
 377      if (!empty($search)) {
 378          list($searchcondition, $searchparams) = cohort_get_search_query($search);
 379          $sql .= ' AND ' . $searchcondition;
 380          $params = array_merge($params, $searchparams);
 381      }
 382  
 383      $totalcohorts = $allcohorts = $DB->count_records('cohort', array('contextid' => $contextid));
 384      if (!empty($search)) {
 385          $totalcohorts = $DB->count_records_sql($countfields . $sql, $params);
 386      }
 387      $cohorts = $DB->get_records_sql($fields . $sql . $order, $params, $page*$perpage, $perpage);
 388  
 389      return array('totalcohorts' => $totalcohorts, 'cohorts' => $cohorts, 'allcohorts' => $allcohorts);
 390  }
 391  
 392  /**
 393   * Get all the cohorts defined anywhere in system.
 394   *
 395   * The function assumes that user capability to view/manage cohorts on system level
 396   * has already been verified. This function only checks if such capabilities have been
 397   * revoked in child (categories) contexts.
 398   *
 399   * @param int $page number of the current page
 400   * @param int $perpage items per page
 401   * @param string $search search string
 402   * @return array    Array(totalcohorts => int, cohorts => array, allcohorts => int)
 403   */
 404  function cohort_get_all_cohorts($page = 0, $perpage = 25, $search = '') {
 405      global $DB;
 406  
 407      $fields = "SELECT c.*, ".context_helper::get_preload_record_columns_sql('ctx');
 408      $countfields = "SELECT COUNT(*)";
 409      $sql = " FROM {cohort} c
 410               JOIN {context} ctx ON ctx.id = c.contextid ";
 411      $params = array();
 412      $wheresql = '';
 413  
 414      if ($excludedcontexts = cohort_get_invisible_contexts()) {
 415          list($excludedsql, $excludedparams) = $DB->get_in_or_equal($excludedcontexts, SQL_PARAMS_NAMED, 'excl', false);
 416          $wheresql = ' WHERE c.contextid '.$excludedsql;
 417          $params = array_merge($params, $excludedparams);
 418      }
 419  
 420      $totalcohorts = $allcohorts = $DB->count_records_sql($countfields . $sql . $wheresql, $params);
 421  
 422      if (!empty($search)) {
 423          list($searchcondition, $searchparams) = cohort_get_search_query($search, 'c');
 424          $wheresql .= ($wheresql ? ' AND ' : ' WHERE ') . $searchcondition;
 425          $params = array_merge($params, $searchparams);
 426          $totalcohorts = $DB->count_records_sql($countfields . $sql . $wheresql, $params);
 427      }
 428  
 429      $order = " ORDER BY c.name ASC, c.idnumber ASC";
 430      $cohorts = $DB->get_records_sql($fields . $sql . $wheresql . $order, $params, $page*$perpage, $perpage);
 431  
 432      // Preload used contexts, they will be used to check view/manage/assign capabilities and display categories names.
 433      foreach (array_keys($cohorts) as $key) {
 434          context_helper::preload_from_record($cohorts[$key]);
 435      }
 436  
 437      return array('totalcohorts' => $totalcohorts, 'cohorts' => $cohorts, 'allcohorts' => $allcohorts);
 438  }
 439  
 440  /**
 441   * Returns list of contexts where cohorts are present but current user does not have capability to view/manage them.
 442   *
 443   * This function is called from {@link cohort_get_all_cohorts()} to ensure correct pagination in rare cases when user
 444   * is revoked capability in child contexts. It assumes that user's capability to view/manage cohorts on system
 445   * level has already been verified.
 446   *
 447   * @access private
 448   *
 449   * @return array array of context ids
 450   */
 451  function cohort_get_invisible_contexts() {
 452      global $DB;
 453      if (is_siteadmin()) {
 454          // Shortcut, admin can do anything and can not be prohibited from any context.
 455          return array();
 456      }
 457      $records = $DB->get_recordset_sql("SELECT DISTINCT ctx.id, ".context_helper::get_preload_record_columns_sql('ctx')." ".
 458          "FROM {context} ctx JOIN {cohort} c ON ctx.id = c.contextid ");
 459      $excludedcontexts = array();
 460      foreach ($records as $ctx) {
 461          context_helper::preload_from_record($ctx);
 462          if (!has_any_capability(array('moodle/cohort:manage', 'moodle/cohort:view'), context::instance_by_id($ctx->id))) {
 463              $excludedcontexts[] = $ctx->id;
 464          }
 465      }
 466      return $excludedcontexts;
 467  }
 468  
 469  /**
 470   * Returns navigation controls (tabtree) to be displayed on cohort management pages
 471   *
 472   * @param context $context system or category context where cohorts controls are about to be displayed
 473   * @param moodle_url $currenturl
 474   * @return null|renderable
 475   */
 476  function cohort_edit_controls(context $context, moodle_url $currenturl) {
 477      $tabs = array();
 478      $currenttab = 'view';
 479      $viewurl = new moodle_url('/cohort/index.php', array('contextid' => $context->id));
 480      if (($searchquery = $currenturl->get_param('search'))) {
 481          $viewurl->param('search', $searchquery);
 482      }
 483      if ($context->contextlevel == CONTEXT_SYSTEM) {
 484          $tabs[] = new tabobject('view', new moodle_url($viewurl, array('showall' => 0)), get_string('systemcohorts', 'cohort'));
 485          $tabs[] = new tabobject('viewall', new moodle_url($viewurl, array('showall' => 1)), get_string('allcohorts', 'cohort'));
 486          if ($currenturl->get_param('showall')) {
 487              $currenttab = 'viewall';
 488          }
 489      } else {
 490          $tabs[] = new tabobject('view', $viewurl, get_string('cohorts', 'cohort'));
 491      }
 492      if (has_capability('moodle/cohort:manage', $context)) {
 493          $addurl = new moodle_url('/cohort/edit.php', array('contextid' => $context->id));
 494          $tabs[] = new tabobject('addcohort', $addurl, get_string('addcohort', 'cohort'));
 495          if ($currenturl->get_path() === $addurl->get_path() && !$currenturl->param('id')) {
 496              $currenttab = 'addcohort';
 497          }
 498  
 499          $uploadurl = new moodle_url('/cohort/upload.php', array('contextid' => $context->id));
 500          $tabs[] = new tabobject('uploadcohorts', $uploadurl, get_string('uploadcohorts', 'cohort'));
 501          if ($currenturl->get_path() === $uploadurl->get_path()) {
 502              $currenttab = 'uploadcohorts';
 503          }
 504      }
 505      if (count($tabs) > 1) {
 506          return new tabtree($tabs, $currenttab);
 507      }
 508      return null;
 509  }