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Differences Between: [Versions 310 and 311] [Versions 310 and 400] [Versions 310 and 401] [Versions 310 and 402] [Versions 310 and 403]

   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   * Code for handling and processing questions
  19   *
  20   * This is code that is module independent, i.e., can be used by any module that
  21   * uses questions, like quiz, lesson, ..
  22   * This script also loads the questiontype classes
  23   * Code for handling the editing of questions is in {@link question/editlib.php}
  24   *
  25   * TODO: separate those functions which form part of the API
  26   *       from the helper functions.
  27   *
  28   * @package moodlecore
  29   * @subpackage questionbank
  30   * @copyright 1999 onwards Martin Dougiamas and others {@link http://moodle.com}
  31   * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  32   */
  33  
  34  
  35  defined('MOODLE_INTERNAL') || die();
  36  
  37  require_once($CFG->dirroot . '/question/engine/lib.php');
  38  require_once($CFG->dirroot . '/question/type/questiontypebase.php');
  39  
  40  
  41  
  42  /// CONSTANTS ///////////////////////////////////
  43  
  44  /**
  45   * Constant determines the number of answer boxes supplied in the editing
  46   * form for multiple choice and similar question types.
  47   */
  48  define("QUESTION_NUMANS", 10);
  49  
  50  /**
  51   * Constant determines the number of answer boxes supplied in the editing
  52   * form for multiple choice and similar question types to start with, with
  53   * the option of adding QUESTION_NUMANS_ADD more answers.
  54   */
  55  define("QUESTION_NUMANS_START", 3);
  56  
  57  /**
  58   * Constant determines the number of answer boxes to add in the editing
  59   * form for multiple choice and similar question types when the user presses
  60   * 'add form fields button'.
  61   */
  62  define("QUESTION_NUMANS_ADD", 3);
  63  
  64  /**
  65   * Move one question type in a list of question types. If you try to move one element
  66   * off of the end, nothing will change.
  67   *
  68   * @param array $sortedqtypes An array $qtype => anything.
  69   * @param string $tomove one of the keys from $sortedqtypes
  70   * @param integer $direction +1 or -1
  71   * @return array an array $index => $qtype, with $index from 0 to n in order, and
  72   *      the $qtypes in the same order as $sortedqtypes, except that $tomove will
  73   *      have been moved one place.
  74   */
  75  function question_reorder_qtypes($sortedqtypes, $tomove, $direction) {
  76      $neworder = array_keys($sortedqtypes);
  77      // Find the element to move.
  78      $key = array_search($tomove, $neworder);
  79      if ($key === false) {
  80          return $neworder;
  81      }
  82      // Work out the other index.
  83      $otherkey = $key + $direction;
  84      if (!isset($neworder[$otherkey])) {
  85          return $neworder;
  86      }
  87      // Do the swap.
  88      $swap = $neworder[$otherkey];
  89      $neworder[$otherkey] = $neworder[$key];
  90      $neworder[$key] = $swap;
  91      return $neworder;
  92  }
  93  
  94  /**
  95   * Save a new question type order to the config_plugins table.
  96   * @global object
  97   * @param $neworder An arra $index => $qtype. Indices should start at 0 and be in order.
  98   * @param $config get_config('question'), if you happen to have it around, to save one DB query.
  99   */
 100  function question_save_qtype_order($neworder, $config = null) {
 101      global $DB;
 102  
 103      if (is_null($config)) {
 104          $config = get_config('question');
 105      }
 106  
 107      foreach ($neworder as $index => $qtype) {
 108          $sortvar = $qtype . '_sortorder';
 109          if (!isset($config->$sortvar) || $config->$sortvar != $index + 1) {
 110              set_config($sortvar, $index + 1, 'question');
 111          }
 112      }
 113  }
 114  
 115  /// FUNCTIONS //////////////////////////////////////////////////////
 116  
 117  /**
 118   * @param array $questionids of question ids.
 119   * @return boolean whether any of these questions are being used by any part of Moodle.
 120   */
 121  function questions_in_use($questionids) {
 122  
 123      // Are they used by the core question system?
 124      if (question_engine::questions_in_use($questionids)) {
 125          return true;
 126      }
 127  
 128      // Check if any plugins are using these questions.
 129      $callbacksbytype = get_plugins_with_function('questions_in_use');
 130      foreach ($callbacksbytype as $callbacks) {
 131          foreach ($callbacks as $function) {
 132              if ($function($questionids)) {
 133                  return true;
 134              }
 135          }
 136      }
 137  
 138      // Finally check legacy callback.
 139      $legacycallbacks = get_plugin_list_with_function('mod', 'question_list_instances');
 140      foreach ($legacycallbacks as $plugin => $function) {
 141          debugging($plugin . ' implements deprecated method ' . $function .
 142                  '. ' . $plugin . '_questions_in_use should be implemented instead.', DEBUG_DEVELOPER);
 143  
 144          if (isset($callbacksbytype['mod'][substr($plugin, 4)])) {
 145              continue; // Already done.
 146          }
 147  
 148          foreach ($questionids as $questionid) {
 149              if (!empty($function($questionid))) {
 150                  return true;
 151              }
 152          }
 153      }
 154  
 155      return false;
 156  }
 157  
 158  /**
 159   * Determine whether there arey any questions belonging to this context, that is whether any of its
 160   * question categories contain any questions. This will return true even if all the questions are
 161   * hidden.
 162   *
 163   * @param mixed $context either a context object, or a context id.
 164   * @return boolean whether any of the question categories beloning to this context have
 165   *         any questions in them.
 166   */
 167  function question_context_has_any_questions($context) {
 168      global $DB;
 169      if (is_object($context)) {
 170          $contextid = $context->id;
 171      } else if (is_numeric($context)) {
 172          $contextid = $context;
 173      } else {
 174          print_error('invalidcontextinhasanyquestions', 'question');
 175      }
 176      return $DB->record_exists_sql("SELECT *
 177                                       FROM {question} q
 178                                       JOIN {question_categories} qc ON qc.id = q.category
 179                                      WHERE qc.contextid = ? AND q.parent = 0", array($contextid));
 180  }
 181  
 182  /**
 183   * Check whether a given grade is one of a list of allowed options. If not,
 184   * depending on $matchgrades, either return the nearest match, or return false
 185   * to signal an error.
 186   * @param array $gradeoptionsfull list of valid options
 187   * @param int $grade grade to be tested
 188   * @param string $matchgrades 'error' or 'nearest'
 189   * @return mixed either 'fixed' value or false if error.
 190   */
 191  function match_grade_options($gradeoptionsfull, $grade, $matchgrades = 'error') {
 192  
 193      if ($matchgrades == 'error') {
 194          // (Almost) exact match, or an error.
 195          foreach ($gradeoptionsfull as $value => $option) {
 196              // Slightly fuzzy test, never check floats for equality.
 197              if (abs($grade - $value) < 0.00001) {
 198                  return $value; // Be sure the return the proper value.
 199              }
 200          }
 201          // Didn't find a match so that's an error.
 202          return false;
 203  
 204      } else if ($matchgrades == 'nearest') {
 205          // Work out nearest value
 206          $best = false;
 207          $bestmismatch = 2;
 208          foreach ($gradeoptionsfull as $value => $option) {
 209              $newmismatch = abs($grade - $value);
 210              if ($newmismatch < $bestmismatch) {
 211                  $best = $value;
 212                  $bestmismatch = $newmismatch;
 213              }
 214          }
 215          return $best;
 216  
 217      } else {
 218          // Unknow option passed.
 219          throw new coding_exception('Unknown $matchgrades ' . $matchgrades .
 220                  ' passed to match_grade_options');
 221      }
 222  }
 223  
 224  /**
 225   * Remove stale questions from a category.
 226   *
 227   * While questions should not be left behind when they are not used any more,
 228   * it does happen, maybe via restore, or old logic, or uncovered scenarios. When
 229   * this happens, the users are unable to delete the question category unless
 230   * they move those stale questions to another one category, but to them the
 231   * category is empty as it does not contain anything. The purpose of this function
 232   * is to detect the questions that may have gone stale and remove them.
 233   *
 234   * You will typically use this prior to checking if the category contains questions.
 235   *
 236   * The stale questions (unused and hidden to the user) handled are:
 237   * - hidden questions
 238   * - random questions
 239   *
 240   * @param int $categoryid The category ID.
 241   */
 242  function question_remove_stale_questions_from_category($categoryid) {
 243      global $DB;
 244  
 245      $select = 'category = :categoryid AND (qtype = :qtype OR hidden = :hidden)';
 246      $params = ['categoryid' => $categoryid, 'qtype' => 'random', 'hidden' => 1];
 247      $questions = $DB->get_recordset_select("question", $select, $params, '', 'id');
 248      foreach ($questions as $question) {
 249          // The function question_delete_question does not delete questions in use.
 250          question_delete_question($question->id);
 251      }
 252      $questions->close();
 253  }
 254  
 255  /**
 256   * Category is about to be deleted,
 257   * 1/ All questions are deleted for this question category.
 258   * 2/ Any questions that can't be deleted are moved to a new category
 259   * NOTE: this function is called from lib/db/upgrade.php
 260   *
 261   * @param object|core_course_category $category course category object
 262   */
 263  function question_category_delete_safe($category) {
 264      global $DB;
 265      $criteria = array('category' => $category->id);
 266      $context = context::instance_by_id($category->contextid, IGNORE_MISSING);
 267      $rescue = null; // See the code around the call to question_save_from_deletion.
 268  
 269      // Deal with any questions in the category.
 270      if ($questions = $DB->get_records('question', $criteria, '', 'id,qtype')) {
 271  
 272          // Try to delete each question.
 273          foreach ($questions as $question) {
 274              question_delete_question($question->id);
 275          }
 276  
 277          // Check to see if there were any questions that were kept because
 278          // they are still in use somehow, even though quizzes in courses
 279          // in this category will already have been deleted. This could
 280          // happen, for example, if questions are added to a course,
 281          // and then that course is moved to another category (MDL-14802).
 282          $questionids = $DB->get_records_menu('question', $criteria, '', 'id, 1');
 283          if (!empty($questionids)) {
 284              $parentcontextid = SYSCONTEXTID;
 285              $name = get_string('unknown', 'question');
 286              if ($context !== false) {
 287                  $name = $context->get_context_name();
 288                  $parentcontext = $context->get_parent_context();
 289                  if ($parentcontext) {
 290                      $parentcontextid = $parentcontext->id;
 291                  }
 292              }
 293              question_save_from_deletion(array_keys($questionids), $parentcontextid, $name, $rescue);
 294          }
 295      }
 296  
 297      // Now delete the category.
 298      $DB->delete_records('question_categories', array('id' => $category->id));
 299  }
 300  
 301  /**
 302   * Tests whether any question in a category is used by any part of Moodle.
 303   *
 304   * @param integer $categoryid a question category id.
 305   * @param boolean $recursive whether to check child categories too.
 306   * @return boolean whether any question in this category is in use.
 307   */
 308  function question_category_in_use($categoryid, $recursive = false) {
 309      global $DB;
 310  
 311      //Look at each question in the category
 312      if ($questions = $DB->get_records_menu('question',
 313              array('category' => $categoryid), '', 'id, 1')) {
 314          if (questions_in_use(array_keys($questions))) {
 315              return true;
 316          }
 317      }
 318      if (!$recursive) {
 319          return false;
 320      }
 321  
 322      //Look under child categories recursively
 323      if ($children = $DB->get_records('question_categories',
 324              array('parent' => $categoryid), '', 'id, 1')) {
 325          foreach ($children as $child) {
 326              if (question_category_in_use($child->id, $recursive)) {
 327                  return true;
 328              }
 329          }
 330      }
 331  
 332      return false;
 333  }
 334  
 335  /**
 336   * Deletes question and all associated data from the database
 337   *
 338   * It will not delete a question if it is used somewhere.
 339   *
 340   * @param object $question  The question being deleted
 341   */
 342  function question_delete_question($questionid) {
 343      global $DB;
 344  
 345      $question = $DB->get_record_sql('
 346              SELECT q.*, ctx.id AS contextid
 347              FROM {question} q
 348              LEFT JOIN {question_categories} qc ON qc.id = q.category
 349              LEFT JOIN {context} ctx ON ctx.id = qc.contextid
 350              WHERE q.id = ?', array($questionid));
 351      if (!$question) {
 352          // In some situations, for example if this was a child of a
 353          // Cloze question that was previously deleted, the question may already
 354          // have gone. In this case, just do nothing.
 355          return;
 356      }
 357  
 358      // Do not delete a question if it is used by an activity module
 359      if (questions_in_use(array($questionid))) {
 360          return;
 361      }
 362  
 363      // This sometimes happens in old sites with bad data.
 364      if (!$question->contextid) {
 365          debugging('Deleting question ' . $question->id . ' which is no longer linked to a context. ' .
 366                  'Assuming system context to avoid errors, but this may mean that some data like files, ' .
 367                  'tags, are not cleaned up.');
 368          $question->contextid = context_system::instance()->id;
 369      }
 370  
 371      // Delete previews of the question.
 372      $dm = new question_engine_data_mapper();
 373      $dm->delete_previews($questionid);
 374  
 375      // delete questiontype-specific data
 376      question_bank::get_qtype($question->qtype, false)->delete_question(
 377              $questionid, $question->contextid);
 378  
 379      // Delete all tag instances.
 380      core_tag_tag::remove_all_item_tags('core_question', 'question', $question->id);
 381  
 382      // Now recursively delete all child questions
 383      if ($children = $DB->get_records('question',
 384              array('parent' => $questionid), '', 'id, qtype')) {
 385          foreach ($children as $child) {
 386              if ($child->id != $questionid) {
 387                  question_delete_question($child->id);
 388              }
 389          }
 390      }
 391  
 392      // Finally delete the question record itself
 393      $DB->delete_records('question', array('id' => $questionid));
 394      question_bank::notify_question_edited($questionid);
 395  
 396      // Log the deletion of this question.
 397      $event = \core\event\question_deleted::create_from_question_instance($question);
 398      $event->add_record_snapshot('question', $question);
 399      $event->trigger();
 400  }
 401  
 402  /**
 403   * All question categories and their questions are deleted for this context id.
 404   *
 405   * @param int $contextid The contextid to delete question categories from
 406   * @return array only returns an empty array for backwards compatibility.
 407   */
 408  function question_delete_context($contextid) {
 409      global $DB;
 410  
 411      $fields = 'id, parent, name, contextid';
 412      if ($categories = $DB->get_records('question_categories', array('contextid' => $contextid), 'parent', $fields)) {
 413          //Sort categories following their tree (parent-child) relationships
 414          //this will make the feedback more readable
 415          $categories = sort_categories_by_tree($categories);
 416  
 417          foreach ($categories as $category) {
 418              question_category_delete_safe($category);
 419          }
 420      }
 421      return [];
 422  }
 423  
 424  /**
 425   * All question categories and their questions are deleted for this course.
 426   *
 427   * @param stdClass $course an object representing the activity
 428   * @param bool $notused this argument is not used any more. Kept for backwards compatibility.
 429   * @return bool always true.
 430   */
 431  function question_delete_course($course, $notused = false) {
 432      $coursecontext = context_course::instance($course->id);
 433      question_delete_context($coursecontext->id);
 434      return true;
 435  }
 436  
 437  /**
 438   * Category is about to be deleted,
 439   * 1/ All question categories and their questions are deleted for this course category.
 440   * 2/ All questions are moved to new category
 441   *
 442   * @param stdClass|core_course_category $category course category object
 443   * @param stdClass|core_course_category $newcategory empty means everything deleted, otherwise id of
 444   *      category where content moved
 445   * @param bool $notused this argument is no longer used. Kept for backwards compatibility.
 446   * @return boolean
 447   */
 448  function question_delete_course_category($category, $newcategory, $notused=false) {
 449      global $DB;
 450  
 451      $context = context_coursecat::instance($category->id);
 452      if (empty($newcategory)) {
 453          question_delete_context($context->id);
 454  
 455      } else {
 456          // Move question categories to the new context.
 457          if (!$newcontext = context_coursecat::instance($newcategory->id)) {
 458              return false;
 459          }
 460  
 461          // Only move question categories if there is any question category at all!
 462          if ($topcategory = question_get_top_category($context->id)) {
 463              $newtopcategory = question_get_top_category($newcontext->id, true);
 464  
 465              question_move_category_to_context($topcategory->id, $context->id, $newcontext->id);
 466              $DB->set_field('question_categories', 'parent', $newtopcategory->id, array('parent' => $topcategory->id));
 467              // Now delete the top category.
 468              $DB->delete_records('question_categories', array('id' => $topcategory->id));
 469          }
 470      }
 471  
 472      return true;
 473  }
 474  
 475  /**
 476   * Enter description here...
 477   *
 478   * @param array $questionids of question ids
 479   * @param object $newcontextid the context to create the saved category in.
 480   * @param string $oldplace a textual description of the think being deleted,
 481   *      e.g. from get_context_name
 482   * @param object $newcategory
 483   * @return mixed false on
 484   */
 485  function question_save_from_deletion($questionids, $newcontextid, $oldplace,
 486          $newcategory = null) {
 487      global $DB;
 488  
 489      // Make a category in the parent context to move the questions to.
 490      if (is_null($newcategory)) {
 491          $newcategory = new stdClass();
 492          $newcategory->parent = question_get_top_category($newcontextid, true)->id;
 493          $newcategory->contextid = $newcontextid;
 494          // Max length of column name in question_categories is 255.
 495          $newcategory->name = shorten_text(get_string('questionsrescuedfrom', 'question', $oldplace), 255);
 496          $newcategory->info = get_string('questionsrescuedfrominfo', 'question', $oldplace);
 497          $newcategory->sortorder = 999;
 498          $newcategory->stamp = make_unique_id_code();
 499          $newcategory->id = $DB->insert_record('question_categories', $newcategory);
 500      }
 501  
 502      // Move any remaining questions to the 'saved' category.
 503      if (!question_move_questions_to_category($questionids, $newcategory->id)) {
 504          return false;
 505      }
 506      return $newcategory;
 507  }
 508  
 509  /**
 510   * All question categories and their questions are deleted for this activity.
 511   *
 512   * @param object $cm the course module object representing the activity
 513   * @param bool $notused the argument is not used any more. Kept for backwards compatibility.
 514   * @return boolean
 515   */
 516  function question_delete_activity($cm, $notused = false) {
 517      global $DB;
 518  
 519      $modcontext = context_module::instance($cm->id);
 520      question_delete_context($modcontext->id);
 521      return true;
 522  }
 523  
 524  /**
 525   * This function will handle moving all tag instances to a new context for a
 526   * given list of questions.
 527   *
 528   * Questions can be tagged in up to two contexts:
 529   * 1.) The context the question exists in.
 530   * 2.) The course context (if the question context is a higher context.
 531   *     E.g. course category context or system context.
 532   *
 533   * This means a question that exists in a higher context (e.g. course cat or
 534   * system context) may have multiple groups of tags in any number of child
 535   * course contexts.
 536   *
 537   * Questions in the course category context can be move "down" a context level
 538   * into one of their child course contexts or activity contexts which affects the
 539   * availability of that question in other courses / activities.
 540   *
 541   * In this case it makes the questions no longer available in the other course or
 542   * activity contexts so we need to make sure that the tag instances in those other
 543   * contexts are removed.
 544   *
 545   * @param stdClass[] $questions The list of question being moved (must include
 546   *                              the id and contextid)
 547   * @param context $newcontext The Moodle context the questions are being moved to
 548   */
 549  function question_move_question_tags_to_new_context(array $questions, context $newcontext) {
 550      // If the questions are moving to a new course/activity context then we need to
 551      // find any existing tag instances from any unavailable course contexts and
 552      // delete them because they will no longer be applicable (we don't support
 553      // tagging questions across courses).
 554      $instancestodelete = [];
 555      $instancesfornewcontext = [];
 556      $newcontextparentids = $newcontext->get_parent_context_ids();
 557      $questionids = array_map(function($question) {
 558          return $question->id;
 559      }, $questions);
 560      $questionstagobjects = core_tag_tag::get_items_tags('core_question', 'question', $questionids);
 561  
 562      foreach ($questions as $question) {
 563          $tagobjects = $questionstagobjects[$question->id] ?? [];
 564  
 565          foreach ($tagobjects as $tagobject) {
 566              $tagid = $tagobject->taginstanceid;
 567              $tagcontextid = $tagobject->taginstancecontextid;
 568              $istaginnewcontext = $tagcontextid == $newcontext->id;
 569              $istaginquestioncontext = $tagcontextid == $question->contextid;
 570  
 571              if ($istaginnewcontext) {
 572                  // This tag instance is already in the correct context so we can
 573                  // ignore it.
 574                  continue;
 575              }
 576  
 577              if ($istaginquestioncontext) {
 578                  // This tag instance is in the question context so it needs to be
 579                  // updated.
 580                  $instancesfornewcontext[] = $tagid;
 581                  continue;
 582              }
 583  
 584              // These tag instances are in neither the new context nor the
 585              // question context so we need to determine what to do based on
 586              // the context they are in and the new question context.
 587              $tagcontext = context::instance_by_id($tagcontextid);
 588              $tagcoursecontext = $tagcontext->get_course_context(false);
 589              // The tag is in a course context if get_course_context() returns
 590              // itself.
 591              $istaginstancecontextcourse = !empty($tagcoursecontext)
 592                  && $tagcontext->id == $tagcoursecontext->id;
 593  
 594              if ($istaginstancecontextcourse) {
 595                  // If the tag instance is in a course context we need to add some
 596                  // special handling.
 597                  $tagcontextparentids = $tagcontext->get_parent_context_ids();
 598                  $isnewcontextaparent = in_array($newcontext->id, $tagcontextparentids);
 599                  $isnewcontextachild = in_array($tagcontext->id, $newcontextparentids);
 600  
 601                  if ($isnewcontextaparent) {
 602                      // If the tag instance is a course context tag and the new
 603                      // context is still a parent context to the tag context then
 604                      // we can leave this tag where it is.
 605                      continue;
 606                  } else if ($isnewcontextachild) {
 607                      // If the new context is a child context (e.g. activity) of this
 608                      // tag instance then we should move all of this tag instance
 609                      // down into the activity context along with the question.
 610                      $instancesfornewcontext[] = $tagid;
 611                  } else {
 612                      // If the tag is in a course context that is no longer a parent
 613                      // or child of the new context then this tag instance should be
 614                      // removed.
 615                      $instancestodelete[] = $tagid;
 616                  }
 617              } else {
 618                  // This is a catch all for any tag instances not in the question
 619                  // context or a course context. These tag instances should be
 620                  // updated to the new context id. This will clean up old invalid
 621                  // data.
 622                  $instancesfornewcontext[] = $tagid;
 623              }
 624          }
 625      }
 626  
 627      if (!empty($instancestodelete)) {
 628          // Delete any course context tags that may no longer be valid.
 629          core_tag_tag::delete_instances_by_id($instancestodelete);
 630      }
 631  
 632      if (!empty($instancesfornewcontext)) {
 633          // Update the tag instances to the new context id.
 634          core_tag_tag::change_instances_context($instancesfornewcontext, $newcontext);
 635      }
 636  }
 637  
 638  /**
 639   * This function should be considered private to the question bank, it is called from
 640   * question/editlib.php question/contextmoveq.php and a few similar places to to the
 641   * work of actually moving questions and associated data. However, callers of this
 642   * function also have to do other work, which is why you should not call this method
 643   * directly from outside the questionbank.
 644   *
 645   * @param array $questionids of question ids.
 646   * @param integer $newcategoryid the id of the category to move to.
 647   */
 648  function question_move_questions_to_category($questionids, $newcategoryid) {
 649      global $DB;
 650  
 651      $newcontextid = $DB->get_field('question_categories', 'contextid',
 652              array('id' => $newcategoryid));
 653      list($questionidcondition, $params) = $DB->get_in_or_equal($questionids);
 654      $questions = $DB->get_records_sql("
 655              SELECT q.id, q.qtype, qc.contextid, q.idnumber, q.category
 656                FROM {question} q
 657                JOIN {question_categories} qc ON q.category = qc.id
 658               WHERE  q.id $questionidcondition", $params);
 659      foreach ($questions as $question) {
 660          if ($newcontextid != $question->contextid) {
 661              question_bank::get_qtype($question->qtype)->move_files(
 662                      $question->id, $question->contextid, $newcontextid);
 663          }
 664          // Check whether there could be a clash of idnumbers in the new category.
 665          if (((string) $question->idnumber !== '') &&
 666                  $DB->record_exists('question', ['idnumber' => $question->idnumber, 'category' => $newcategoryid])) {
 667              $rec = $DB->get_records_select('question', "category = ? AND idnumber LIKE ?",
 668                      [$newcategoryid, $question->idnumber . '_%'], 'idnumber DESC', 'id, idnumber', 0, 1);
 669              $unique = 1;
 670              if (count($rec)) {
 671                  $rec = reset($rec);
 672                  $idnumber = $rec->idnumber;
 673                  if (strpos($idnumber, '_') !== false) {
 674                      $unique = substr($idnumber, strpos($idnumber, '_') + 1) + 1;
 675                  }
 676              }
 677              // For the move process, add a numerical increment to the idnumber. This means that if a question is
 678              // mistakenly moved then the idnumber will not be completely lost.
 679              $q = new stdClass();
 680              $q->id = $question->id;
 681              $q->category = $newcategoryid;
 682              $q->idnumber = $question->idnumber . '_' . $unique;
 683              $DB->update_record('question', $q);
 684          }
 685  
 686          // Log this question move.
 687          $event = \core\event\question_moved::create_from_question_instance($question, context::instance_by_id($question->contextid),
 688                  ['oldcategoryid' => $question->category, 'newcategoryid' => $newcategoryid]);
 689          $event->trigger();
 690      }
 691  
 692      // Move the questions themselves.
 693      $DB->set_field_select('question', 'category', $newcategoryid,
 694              "id $questionidcondition", $params);
 695  
 696      // Move any subquestions belonging to them.
 697      $DB->set_field_select('question', 'category', $newcategoryid,
 698              "parent $questionidcondition", $params);
 699  
 700      $newcontext = context::instance_by_id($newcontextid);
 701      question_move_question_tags_to_new_context($questions, $newcontext);
 702  
 703      // TODO Deal with datasets.
 704  
 705      // Purge these questions from the cache.
 706      foreach ($questions as $question) {
 707          question_bank::notify_question_edited($question->id);
 708      }
 709  
 710      return true;
 711  }
 712  
 713  /**
 714   * This function helps move a question cateogry to a new context by moving all
 715   * the files belonging to all the questions to the new context.
 716   * Also moves subcategories.
 717   * @param integer $categoryid the id of the category being moved.
 718   * @param integer $oldcontextid the old context id.
 719   * @param integer $newcontextid the new context id.
 720   */
 721  function question_move_category_to_context($categoryid, $oldcontextid, $newcontextid) {
 722      global $DB;
 723  
 724      $questions = [];
 725      $questionids = $DB->get_records_menu('question',
 726              array('category' => $categoryid), '', 'id,qtype');
 727      foreach ($questionids as $questionid => $qtype) {
 728          question_bank::get_qtype($qtype)->move_files(
 729                  $questionid, $oldcontextid, $newcontextid);
 730          // Purge this question from the cache.
 731          question_bank::notify_question_edited($questionid);
 732  
 733          $questions[] = (object) [
 734              'id' => $questionid,
 735              'contextid' => $oldcontextid
 736          ];
 737      }
 738  
 739      $newcontext = context::instance_by_id($newcontextid);
 740      question_move_question_tags_to_new_context($questions, $newcontext);
 741  
 742      $subcatids = $DB->get_records_menu('question_categories',
 743              array('parent' => $categoryid), '', 'id,1');
 744      foreach ($subcatids as $subcatid => $notused) {
 745          $DB->set_field('question_categories', 'contextid', $newcontextid,
 746                  array('id' => $subcatid));
 747          question_move_category_to_context($subcatid, $oldcontextid, $newcontextid);
 748      }
 749  }
 750  
 751  /**
 752   * Generate the URL for starting a new preview of a given question with the given options.
 753   * @param integer $questionid the question to preview.
 754   * @param string $preferredbehaviour the behaviour to use for the preview.
 755   * @param float $maxmark the maximum to mark the question out of.
 756   * @param question_display_options $displayoptions the display options to use.
 757   * @param int $variant the variant of the question to preview. If null, one will
 758   *      be picked randomly.
 759   * @param object $context context to run the preview in (affects things like
 760   *      filter settings, theme, lang, etc.) Defaults to $PAGE->context.
 761   * @return moodle_url the URL.
 762   */
 763  function question_preview_url($questionid, $preferredbehaviour = null,
 764          $maxmark = null, $displayoptions = null, $variant = null, $context = null) {
 765  
 766      $params = array('id' => $questionid);
 767  
 768      if (is_null($context)) {
 769          global $PAGE;
 770          $context = $PAGE->context;
 771      }
 772      if ($context->contextlevel == CONTEXT_MODULE) {
 773          $params['cmid'] = $context->instanceid;
 774      } else if ($context->contextlevel == CONTEXT_COURSE) {
 775          $params['courseid'] = $context->instanceid;
 776      }
 777  
 778      if (!is_null($preferredbehaviour)) {
 779          $params['behaviour'] = $preferredbehaviour;
 780      }
 781  
 782      if (!is_null($maxmark)) {
 783          $params['maxmark'] = format_float($maxmark, -1);
 784      }
 785  
 786      if (!is_null($displayoptions)) {
 787          $params['correctness']     = $displayoptions->correctness;
 788          $params['marks']           = $displayoptions->marks;
 789          $params['markdp']          = $displayoptions->markdp;
 790          $params['feedback']        = (bool) $displayoptions->feedback;
 791          $params['generalfeedback'] = (bool) $displayoptions->generalfeedback;
 792          $params['rightanswer']     = (bool) $displayoptions->rightanswer;
 793          $params['history']         = (bool) $displayoptions->history;
 794      }
 795  
 796      if ($variant) {
 797          $params['variant'] = $variant;
 798      }
 799  
 800      return new moodle_url('/question/preview.php', $params);
 801  }
 802  
 803  /**
 804   * @return array that can be passed as $params to the {@link popup_action} constructor.
 805   */
 806  function question_preview_popup_params() {
 807      return array(
 808          'height' => 600,
 809          'width' => 800,
 810      );
 811  }
 812  
 813  /**
 814   * Given a list of ids, load the basic information about a set of questions from
 815   * the questions table. The $join and $extrafields arguments can be used together
 816   * to pull in extra data. See, for example, the usage in mod/quiz/attemptlib.php, and
 817   * read the code below to see how the SQL is assembled. Throws exceptions on error.
 818   *
 819   * @param array $questionids array of question ids to load. If null, then all
 820   * questions matched by $join will be loaded.
 821   * @param string $extrafields extra SQL code to be added to the query.
 822   * @param string $join extra SQL code to be added to the query.
 823   * @param array $extraparams values for any placeholders in $join.
 824   * You must use named placeholders.
 825   * @param string $orderby what to order the results by. Optional, default is unspecified order.
 826   *
 827   * @return array partially complete question objects. You need to call get_question_options
 828   * on them before they can be properly used.
 829   */
 830  function question_preload_questions($questionids = null, $extrafields = '', $join = '',
 831          $extraparams = array(), $orderby = '') {
 832      global $DB;
 833  
 834      if ($questionids === null) {
 835          $where = '';
 836          $params = array();
 837      } else {
 838          if (empty($questionids)) {
 839              return array();
 840          }
 841  
 842          list($questionidcondition, $params) = $DB->get_in_or_equal(
 843                  $questionids, SQL_PARAMS_NAMED, 'qid0000');
 844          $where = 'WHERE q.id ' . $questionidcondition;
 845      }
 846  
 847      if ($join) {
 848          $join = 'JOIN ' . $join;
 849      }
 850  
 851      if ($extrafields) {
 852          $extrafields = ', ' . $extrafields;
 853      }
 854  
 855      if ($orderby) {
 856          $orderby = 'ORDER BY ' . $orderby;
 857      }
 858  
 859      $sql = "SELECT q.*, qc.contextid{$extrafields}
 860                FROM {question} q
 861                JOIN {question_categories} qc ON q.category = qc.id
 862                {$join}
 863               {$where}
 864            {$orderby}";
 865  
 866      // Load the questions.
 867      $questions = $DB->get_records_sql($sql, $extraparams + $params);
 868      foreach ($questions as $question) {
 869          $question->_partiallyloaded = true;
 870      }
 871  
 872      return $questions;
 873  }
 874  
 875  /**
 876   * Load a set of questions, given a list of ids. The $join and $extrafields arguments can be used
 877   * together to pull in extra data. See, for example, the usage in mod/quiz/attempt.php, and
 878   * read the code below to see how the SQL is assembled. Throws exceptions on error.
 879   *
 880   * @param array $questionids array of question ids.
 881   * @param string $extrafields extra SQL code to be added to the query.
 882   * @param string $join extra SQL code to be added to the query.
 883   * @param array $extraparams values for any placeholders in $join.
 884   * You are strongly recommended to use named placeholder.
 885   *
 886   * @return array question objects.
 887   */
 888  function question_load_questions($questionids, $extrafields = '', $join = '') {
 889      $questions = question_preload_questions($questionids, $extrafields, $join);
 890  
 891      // Load the question type specific information
 892      if (!get_question_options($questions)) {
 893          return 'Could not load the question options';
 894      }
 895  
 896      return $questions;
 897  }
 898  
 899  /**
 900   * Private function to factor common code out of get_question_options().
 901   *
 902   * @param object $question the question to tidy.
 903   * @param stdClass $category The question_categories record for the given $question.
 904   * @param stdClass[]|null $tagobjects The tags for the given $question.
 905   * @param stdClass[]|null $filtercourses The courses to filter the course tags by.
 906   */
 907  function _tidy_question($question, $category, array $tagobjects = null, array $filtercourses = null) {
 908      // Load question-type specific fields.
 909      if (!question_bank::is_qtype_installed($question->qtype)) {
 910          $question->questiontext = html_writer::tag('p', get_string('warningmissingtype',
 911                  'qtype_missingtype')) . $question->questiontext;
 912      }
 913      question_bank::get_qtype($question->qtype)->get_question_options($question);
 914  
 915      // Convert numeric fields to float. (Prevents these being displayed as 1.0000000.)
 916      $question->defaultmark += 0;
 917      $question->penalty += 0;
 918  
 919      if (isset($question->_partiallyloaded)) {
 920          unset($question->_partiallyloaded);
 921      }
 922  
 923      $question->categoryobject = $category;
 924  
 925      if (!is_null($tagobjects)) {
 926          $categorycontext = context::instance_by_id($category->contextid);
 927          $sortedtagobjects = question_sort_tags($tagobjects, $categorycontext, $filtercourses);
 928          $question->coursetagobjects = $sortedtagobjects->coursetagobjects;
 929          $question->coursetags = $sortedtagobjects->coursetags;
 930          $question->tagobjects = $sortedtagobjects->tagobjects;
 931          $question->tags = $sortedtagobjects->tags;
 932      }
 933  }
 934  
 935  /**
 936   * Updates the question objects with question type specific
 937   * information by calling {@link get_question_options()}
 938   *
 939   * Can be called either with an array of question objects or with a single
 940   * question object.
 941   *
 942   * @param mixed $questions Either an array of question objects to be updated
 943   *         or just a single question object
 944   * @param bool $loadtags load the question tags from the tags table. Optional, default false.
 945   * @param stdClass[] $filtercourses The courses to filter the course tags by.
 946   * @return bool Indicates success or failure.
 947   */
 948  function get_question_options(&$questions, $loadtags = false, $filtercourses = null) {
 949      global $DB;
 950  
 951      $questionlist = is_array($questions) ? $questions : [$questions];
 952      $categoryids = [];
 953      $questionids = [];
 954  
 955      if (empty($questionlist)) {
 956          return true;
 957      }
 958  
 959      foreach ($questionlist as $question) {
 960          $questionids[] = $question->id;
 961  
 962          if (!in_array($question->category, $categoryids)) {
 963              $categoryids[] = $question->category;
 964          }
 965      }
 966  
 967      $categories = $DB->get_records_list('question_categories', 'id', $categoryids);
 968  
 969      if ($loadtags && core_tag_tag::is_enabled('core_question', 'question')) {
 970          $tagobjectsbyquestion = core_tag_tag::get_items_tags('core_question', 'question', $questionids);
 971      } else {
 972          $tagobjectsbyquestion = null;
 973      }
 974  
 975      foreach ($questionlist as $question) {
 976          if (is_null($tagobjectsbyquestion)) {
 977              $tagobjects = null;
 978          } else {
 979              $tagobjects = $tagobjectsbyquestion[$question->id];
 980          }
 981  
 982          _tidy_question($question, $categories[$question->category], $tagobjects, $filtercourses);
 983      }
 984  
 985      return true;
 986  }
 987  
 988  /**
 989   * Sort question tags by course or normal tags.
 990   *
 991   * This function also search tag instances that may have a context id that don't match either a course or
 992   * question context and fix the data setting the correct context id.
 993   *
 994   * @param stdClass[] $tagobjects The tags for the given $question.
 995   * @param stdClass $categorycontext The question categories context.
 996   * @param stdClass[]|null $filtercourses The courses to filter the course tags by.
 997   * @return stdClass $sortedtagobjects Sorted tag objects.
 998   */
 999  function question_sort_tags($tagobjects, $categorycontext, $filtercourses = null) {
1000  
1001      // Questions can have two sets of tag instances. One set at the
1002      // course context level and another at the context the question
1003      // belongs to (e.g. course category, system etc).
1004      $sortedtagobjects = new stdClass();
1005      $sortedtagobjects->coursetagobjects = [];
1006      $sortedtagobjects->coursetags = [];
1007      $sortedtagobjects->tagobjects = [];
1008      $sortedtagobjects->tags = [];
1009      $taginstanceidstonormalise = [];
1010      $filtercoursecontextids = [];
1011      $hasfiltercourses = !empty($filtercourses);
1012  
1013      if ($hasfiltercourses) {
1014          // If we're being asked to filter the course tags by a set of courses
1015          // then get the context ids to filter below.
1016          $filtercoursecontextids = array_map(function($course) {
1017              $coursecontext = context_course::instance($course->id);
1018              return $coursecontext->id;
1019          }, $filtercourses);
1020      }
1021  
1022      foreach ($tagobjects as $tagobject) {
1023          $tagcontextid = $tagobject->taginstancecontextid;
1024          $tagcontext = context::instance_by_id($tagcontextid);
1025          $tagcoursecontext = $tagcontext->get_course_context(false);
1026          // This is a course tag if the tag context is a course context which
1027          // doesn't match the question's context. Any tag in the question context
1028          // is not considered a course tag, it belongs to the question.
1029          $iscoursetag = $tagcoursecontext
1030              && $tagcontext->id == $tagcoursecontext->id
1031              && $tagcontext->id != $categorycontext->id;
1032  
1033          if ($iscoursetag) {
1034              // Any tag instance in a course context level is considered a course tag.
1035              if (!$hasfiltercourses || in_array($tagcontextid, $filtercoursecontextids)) {
1036                  // Add the tag to the list of course tags if we aren't being
1037                  // asked to filter or if this tag is in the list of courses
1038                  // we're being asked to filter by.
1039                  $sortedtagobjects->coursetagobjects[] = $tagobject;
1040                  $sortedtagobjects->coursetags[$tagobject->id] = $tagobject->get_display_name();
1041              }
1042          } else {
1043              // All non course context level tag instances or tags in the question
1044              // context belong to the context that the question was created in.
1045              $sortedtagobjects->tagobjects[] = $tagobject;
1046              $sortedtagobjects->tags[$tagobject->id] = $tagobject->get_display_name();
1047  
1048              // Due to legacy tag implementations that don't force the recording
1049              // of a context id, some tag instances may have context ids that don't
1050              // match either a course context or the question context. In this case
1051              // we should take the opportunity to fix up the data and set the correct
1052              // context id.
1053              if ($tagcontext->id != $categorycontext->id) {
1054                  $taginstanceidstonormalise[] = $tagobject->taginstanceid;
1055                  // Update the object properties to reflect the DB update that will
1056                  // happen below.
1057                  $tagobject->taginstancecontextid = $categorycontext->id;
1058              }
1059          }
1060      }
1061  
1062      if (!empty($taginstanceidstonormalise)) {
1063          // If we found any tag instances with incorrect context id data then we can
1064          // correct those values now by setting them to the question context id.
1065          core_tag_tag::change_instances_context($taginstanceidstonormalise, $categorycontext);
1066      }
1067  
1068      return $sortedtagobjects;
1069  }
1070  
1071  /**
1072   * Print the icon for the question type
1073   *
1074   * @param object $question The question object for which the icon is required.
1075   *       Only $question->qtype is used.
1076   * @return string the HTML for the img tag.
1077   */
1078  function print_question_icon($question) {
1079      global $PAGE;
1080      return $PAGE->get_renderer('question', 'bank')->qtype_icon($question->qtype);
1081  }
1082  
1083  /**
1084   * Creates a stamp that uniquely identifies this version of the question
1085   *
1086   * In future we want this to use a hash of the question data to guarantee that
1087   * identical versions have the same version stamp.
1088   *
1089   * @param object $question
1090   * @return string A unique version stamp
1091   */
1092  function question_hash($question) {
1093      return make_unique_id_code();
1094  }
1095  
1096  /// CATEGORY FUNCTIONS /////////////////////////////////////////////////////////////////
1097  
1098  /**
1099   * returns the categories with their names ordered following parent-child relationships
1100   * finally it tries to return pending categories (those being orphaned, whose parent is
1101   * incorrect) to avoid missing any category from original array.
1102   */
1103  function sort_categories_by_tree(&$categories, $id = 0, $level = 1) {
1104      global $DB;
1105  
1106      $children = array();
1107      $keys = array_keys($categories);
1108  
1109      foreach ($keys as $key) {
1110          if (!isset($categories[$key]->processed) && $categories[$key]->parent == $id) {
1111              $children[$key] = $categories[$key];
1112              $categories[$key]->processed = true;
1113              $children = $children + sort_categories_by_tree(
1114                      $categories, $children[$key]->id, $level+1);
1115          }
1116      }
1117      //If level = 1, we have finished, try to look for non processed categories
1118      // (bad parent) and sort them too
1119      if ($level == 1) {
1120          foreach ($keys as $key) {
1121              // If not processed and it's a good candidate to start (because its
1122              // parent doesn't exist in the course)
1123              if (!isset($categories[$key]->processed) && !$DB->record_exists('question_categories',
1124                      array('contextid' => $categories[$key]->contextid,
1125                              'id' => $categories[$key]->parent))) {
1126                  $children[$key] = $categories[$key];
1127                  $categories[$key]->processed = true;
1128                  $children = $children + sort_categories_by_tree(
1129                          $categories, $children[$key]->id, $level + 1);
1130              }
1131          }
1132      }
1133      return $children;
1134  }
1135  
1136  /**
1137   * Private method, only for the use of add_indented_names().
1138   *
1139   * Recursively adds an indentedname field to each category, starting with the category
1140   * with id $id, and dealing with that category and all its children, and
1141   * return a new array, with those categories in the right order.
1142   *
1143   * @param array $categories an array of categories which has had childids
1144   *          fields added by flatten_category_tree(). Passed by reference for
1145   *          performance only. It is not modfied.
1146   * @param int $id the category to start the indenting process from.
1147   * @param int $depth the indent depth. Used in recursive calls.
1148   * @return array a new array of categories, in the right order for the tree.
1149   */
1150  function flatten_category_tree(&$categories, $id, $depth = 0, $nochildrenof = -1) {
1151  
1152      // Indent the name of this category.
1153      $newcategories = array();
1154      $newcategories[$id] = $categories[$id];
1155      $newcategories[$id]->indentedname = str_repeat('&nbsp;&nbsp;&nbsp;', $depth) .
1156              $categories[$id]->name;
1157  
1158      // Recursively indent the children.
1159      foreach ($categories[$id]->childids as $childid) {
1160          if ($childid != $nochildrenof) {
1161              $newcategories = $newcategories + flatten_category_tree(
1162                      $categories, $childid, $depth + 1, $nochildrenof);
1163          }
1164      }
1165  
1166      // Remove the childids array that were temporarily added.
1167      unset($newcategories[$id]->childids);
1168  
1169      return $newcategories;
1170  }
1171  
1172  /**
1173   * Format categories into an indented list reflecting the tree structure.
1174   *
1175   * @param array $categories An array of category objects, for example from the.
1176   * @return array The formatted list of categories.
1177   */
1178  function add_indented_names($categories, $nochildrenof = -1) {
1179  
1180      // Add an array to each category to hold the child category ids. This array
1181      // will be removed again by flatten_category_tree(). It should not be used
1182      // outside these two functions.
1183      foreach (array_keys($categories) as $id) {
1184          $categories[$id]->childids = array();
1185      }
1186  
1187      // Build the tree structure, and record which categories are top-level.
1188      // We have to be careful, because the categories array may include published
1189      // categories from other courses, but not their parents.
1190      $toplevelcategoryids = array();
1191      foreach (array_keys($categories) as $id) {
1192          if (!empty($categories[$id]->parent) &&
1193                  array_key_exists($categories[$id]->parent, $categories)) {
1194              $categories[$categories[$id]->parent]->childids[] = $id;
1195          } else {
1196              $toplevelcategoryids[] = $id;
1197          }
1198      }
1199  
1200      // Flatten the tree to and add the indents.
1201      $newcategories = array();
1202      foreach ($toplevelcategoryids as $id) {
1203          $newcategories = $newcategories + flatten_category_tree(
1204                  $categories, $id, 0, $nochildrenof);
1205      }
1206  
1207      return $newcategories;
1208  }
1209  
1210  /**
1211   * Output a select menu of question categories.
1212   *
1213   * Categories from this course and (optionally) published categories from other courses
1214   * are included. Optionally, only categories the current user may edit can be included.
1215   *
1216   * @param integer $courseid the id of the course to get the categories for.
1217   * @param integer $published if true, include publised categories from other courses.
1218   * @param integer $only_editable if true, exclude categories this user is not allowed to edit.
1219   * @param integer $selected optionally, the id of a category to be selected by
1220   *      default in the dropdown.
1221   */
1222  function question_category_select_menu($contexts, $top = false, $currentcat = 0,
1223          $selected = "", $nochildrenof = -1) {
1224      $categoriesarray = question_category_options($contexts, $top, $currentcat,
1225              false, $nochildrenof, false);
1226      if ($selected) {
1227          $choose = '';
1228      } else {
1229          $choose = 'choosedots';
1230      }
1231      $options = array();
1232      foreach ($categoriesarray as $group => $opts) {
1233          $options[] = array($group => $opts);
1234      }
1235      echo html_writer::label(get_string('questioncategory', 'core_question'), 'id_movetocategory', false, array('class' => 'accesshide'));
1236      $attrs = array(
1237          'id' => 'id_movetocategory',
1238          'class' => 'custom-select',
1239          'data-action' => 'toggle',
1240          'data-togglegroup' => 'qbank',
1241          'data-toggle' => 'action',
1242          'disabled' => true,
1243      );
1244      echo html_writer::select($options, 'category', $selected, $choose, $attrs);
1245  }
1246  
1247  /**
1248   * @param integer $contextid a context id.
1249   * @return object the default question category for that context, or false if none.
1250   */
1251  function question_get_default_category($contextid) {
1252      global $DB;
1253      $category = $DB->get_records_select('question_categories', 'contextid = ? AND parent <> 0',
1254              array($contextid), 'id', '*', 0, 1);
1255      if (!empty($category)) {
1256          return reset($category);
1257      } else {
1258          return false;
1259      }
1260  }
1261  
1262  /**
1263   * Gets the top category in the given context.
1264   * This function can optionally create the top category if it doesn't exist.
1265   *
1266   * @param int $contextid A context id.
1267   * @param bool $create Whether create a top category if it doesn't exist.
1268   * @return bool|stdClass The top question category for that context, or false if none.
1269   */
1270  function question_get_top_category($contextid, $create = false) {
1271      global $DB;
1272      $category = $DB->get_record('question_categories',
1273              array('contextid' => $contextid, 'parent' => 0));
1274  
1275      if (!$category && $create) {
1276          // We need to make one.
1277          $category = new stdClass();
1278          $category->name = 'top'; // A non-real name for the top category. It will be localised at the display time.
1279          $category->info = '';
1280          $category->contextid = $contextid;
1281          $category->parent = 0;
1282          $category->sortorder = 0;
1283          $category->stamp = make_unique_id_code();
1284          $category->id = $DB->insert_record('question_categories', $category);
1285      }
1286  
1287      return $category;
1288  }
1289  
1290  /**
1291   * Gets the list of top categories in the given contexts in the array("categoryid,categorycontextid") format.
1292   *
1293   * @param array $contextids List of context ids
1294   * @return array
1295   */
1296  function question_get_top_categories_for_contexts($contextids) {
1297      global $DB;
1298  
1299      $concatsql = $DB->sql_concat_join("','", ['id', 'contextid']);
1300      list($insql, $params) = $DB->get_in_or_equal($contextids);
1301      $sql = "SELECT $concatsql FROM {question_categories} WHERE contextid $insql AND parent = 0";
1302      $topcategories = $DB->get_fieldset_sql($sql, $params);
1303  
1304      return $topcategories;
1305  }
1306  
1307  /**
1308   * Gets the default category in the most specific context.
1309   * If no categories exist yet then default ones are created in all contexts.
1310   *
1311   * @param array $contexts  The context objects for this context and all parent contexts.
1312   * @return object The default category - the category in the course context
1313   */
1314  function question_make_default_categories($contexts) {
1315      global $DB;
1316      static $preferredlevels = array(
1317          CONTEXT_COURSE => 4,
1318          CONTEXT_MODULE => 3,
1319          CONTEXT_COURSECAT => 2,
1320          CONTEXT_SYSTEM => 1,
1321      );
1322  
1323      $toreturn = null;
1324      $preferredness = 0;
1325      // If it already exists, just return it.
1326      foreach ($contexts as $key => $context) {
1327          $topcategory = question_get_top_category($context->id, true);
1328          if (!$exists = $DB->record_exists("question_categories",
1329                  array('contextid' => $context->id, 'parent' => $topcategory->id))) {
1330              // Otherwise, we need to make one
1331              $category = new stdClass();
1332              $contextname = $context->get_context_name(false, true);
1333              // Max length of name field is 255.
1334              $category->name = shorten_text(get_string('defaultfor', 'question', $contextname), 255);
1335              $category->info = get_string('defaultinfofor', 'question', $contextname);
1336              $category->contextid = $context->id;
1337              $category->parent = $topcategory->id;
1338              // By default, all categories get this number, and are sorted alphabetically.
1339              $category->sortorder = 999;
1340              $category->stamp = make_unique_id_code();
1341              $category->id = $DB->insert_record('question_categories', $category);
1342          } else {
1343              $category = question_get_default_category($context->id);
1344          }
1345          $thispreferredness = $preferredlevels[$context->contextlevel];
1346          if (has_any_capability(array('moodle/question:usemine', 'moodle/question:useall'), $context)) {
1347              $thispreferredness += 10;
1348          }
1349          if ($thispreferredness > $preferredness) {
1350              $toreturn = $category;
1351              $preferredness = $thispreferredness;
1352          }
1353      }
1354  
1355      if (!is_null($toreturn)) {
1356          $toreturn = clone($toreturn);
1357      }
1358      return $toreturn;
1359  }
1360  
1361  /**
1362   * Get all the category objects, including a count of the number of questions in that category,
1363   * for all the categories in the lists $contexts.
1364   *
1365   * @param mixed $contexts either a single contextid, or a comma-separated list of context ids.
1366   * @param string $sortorder used as the ORDER BY clause in the select statement.
1367   * @param bool $top Whether to return the top categories or not.
1368   * @return array of category objects.
1369   */
1370  function get_categories_for_contexts($contexts, $sortorder = 'parent, sortorder, name ASC', $top = false) {
1371      global $DB;
1372      $topwhere = $top ? '' : 'AND c.parent <> 0';
1373      return $DB->get_records_sql("
1374              SELECT c.*, (SELECT count(1) FROM {question} q
1375                          WHERE c.id = q.category AND q.hidden='0' AND q.parent='0') AS questioncount
1376                FROM {question_categories} c
1377               WHERE c.contextid IN ($contexts) $topwhere
1378            ORDER BY $sortorder");
1379  }
1380  
1381  /**
1382   * Output an array of question categories.
1383   *
1384   * @param array $contexts The list of contexts.
1385   * @param bool $top Whether to return the top categories or not.
1386   * @param int $currentcat
1387   * @param bool $popupform
1388   * @param int $nochildrenof
1389   * @param boolean $escapecontextnames Whether the returned name of the thing is to be HTML escaped or not.
1390   * @return array
1391   */
1392  function question_category_options($contexts, $top = false, $currentcat = 0,
1393          $popupform = false, $nochildrenof = -1, $escapecontextnames = true) {
1394      global $CFG;
1395      $pcontexts = array();
1396      foreach ($contexts as $context) {
1397          $pcontexts[] = $context->id;
1398      }
1399      $contextslist = join(', ', $pcontexts);
1400  
1401      $categories = get_categories_for_contexts($contextslist, 'parent, sortorder, name ASC', $top);
1402  
1403      if ($top) {
1404          $categories = question_fix_top_names($categories);
1405      }
1406  
1407      $categories = question_add_context_in_key($categories);
1408      $categories = add_indented_names($categories, $nochildrenof);
1409  
1410      // sort cats out into different contexts
1411      $categoriesarray = array();
1412      foreach ($pcontexts as $contextid) {
1413          $context = context::instance_by_id($contextid);
1414          $contextstring = $context->get_context_name(true, true, $escapecontextnames);
1415          foreach ($categories as $category) {
1416              if ($category->contextid == $contextid) {
1417                  $cid = $category->id;
1418                  if ($currentcat != $cid || $currentcat == 0) {
1419                      $a = new stdClass;
1420                      $a->name = format_string($category->indentedname, true,
1421                              array('context' => $context));
1422                      if ($category->idnumber !== null && $category->idnumber !== '') {
1423                          $a->idnumber = s($category->idnumber);
1424                      }
1425                      if (!empty($category->questioncount)) {
1426                          $a->questioncount = $category->questioncount;
1427                      }
1428                      if (isset($a->idnumber) && isset($a->questioncount)) {
1429                          $formattedname = get_string('categorynamewithidnumberandcount', 'question', $a);
1430                      } else if (isset($a->idnumber)) {
1431                          $formattedname = get_string('categorynamewithidnumber', 'question', $a);
1432                      } else if (isset($a->questioncount)) {
1433                          $formattedname = get_string('categorynamewithcount', 'question', $a);
1434                      } else {
1435                          $formattedname = $a->name;
1436                      }
1437                      $categoriesarray[$contextstring][$cid] = $formattedname;
1438                  }
1439              }
1440          }
1441      }
1442      if ($popupform) {
1443          $popupcats = array();
1444          foreach ($categoriesarray as $contextstring => $optgroup) {
1445              $group = array();
1446              foreach ($optgroup as $key => $value) {
1447                  $key = str_replace($CFG->wwwroot, '', $key);
1448                  $group[$key] = $value;
1449              }
1450              $popupcats[] = array($contextstring => $group);
1451          }
1452          return $popupcats;
1453      } else {
1454          return $categoriesarray;
1455      }
1456  }
1457  
1458  function question_add_context_in_key($categories) {
1459      $newcatarray = array();
1460      foreach ($categories as $id => $category) {
1461          $category->parent = "$category->parent,$category->contextid";
1462          $category->id = "$category->id,$category->contextid";
1463          $newcatarray["$id,$category->contextid"] = $category;
1464      }
1465      return $newcatarray;
1466  }
1467  
1468  /**
1469   * Finds top categories in the given categories hierarchy and replace their name with a proper localised string.
1470   *
1471   * @param array $categories An array of question categories.
1472   * @param boolean $escape Whether the returned name of the thing is to be HTML escaped or not.
1473   * @return array The same question category list given to the function, with the top category names being translated.
1474   */
1475  function question_fix_top_names($categories, $escape = true) {
1476  
1477      foreach ($categories as $id => $category) {
1478          if ($category->parent == 0) {
1479              $context = context::instance_by_id($category->contextid);
1480              $categories[$id]->name = get_string('topfor', 'question', $context->get_context_name(false, false, $escape));
1481          }
1482      }
1483  
1484      return $categories;
1485  }
1486  
1487  /**
1488   * @return array of question category ids of the category and all subcategories.
1489   */
1490  function question_categorylist($categoryid) {
1491      global $DB;
1492  
1493      // final list of category IDs
1494      $categorylist = array();
1495  
1496      // a list of category IDs to check for any sub-categories
1497      $subcategories = array($categoryid);
1498  
1499      while ($subcategories) {
1500          foreach ($subcategories as $subcategory) {
1501              // if anything from the temporary list was added already, then we have a loop
1502              if (isset($categorylist[$subcategory])) {
1503                  throw new coding_exception("Category id=$subcategory is already on the list - loop of categories detected.");
1504              }
1505              $categorylist[$subcategory] = $subcategory;
1506          }
1507  
1508          list ($in, $params) = $DB->get_in_or_equal($subcategories);
1509  
1510          $subcategories = $DB->get_records_select_menu('question_categories',
1511                  "parent $in", $params, NULL, 'id,id AS id2');
1512      }
1513  
1514      return $categorylist;
1515  }
1516  
1517  /**
1518   * Get all parent categories of a given question category in decending order.
1519   * @param int $categoryid for which you want to find the parents.
1520   * @return array of question category ids of all parents categories.
1521   */
1522  function question_categorylist_parents(int $categoryid) {
1523      global $DB;
1524      $parent = $DB->get_field('question_categories', 'parent', array('id' => $categoryid));
1525      if (!$parent) {
1526          return [];
1527      }
1528      $categorylist = [$parent];
1529      $currentid = $parent;
1530      while ($currentid) {
1531          $currentid = $DB->get_field('question_categories', 'parent', array('id' => $currentid));
1532          if ($currentid) {
1533              $categorylist[] = $currentid;
1534          }
1535      }
1536      // Present the list in decending order (the top category at the top).
1537      $categorylist = array_reverse($categorylist);
1538      return $categorylist;
1539  }
1540  
1541  //===========================
1542  // Import/Export Functions
1543  //===========================
1544  
1545  /**
1546   * Get list of available import or export formats
1547   * @param string $type 'import' if import list, otherwise export list assumed
1548   * @return array sorted list of import/export formats available
1549   */
1550  function get_import_export_formats($type) {
1551      global $CFG;
1552      require_once($CFG->dirroot . '/question/format.php');
1553  
1554      $formatclasses = core_component::get_plugin_list_with_class('qformat', '', 'format.php');
1555  
1556      $fileformatname = array();
1557      foreach ($formatclasses as $component => $formatclass) {
1558  
1559          $format = new $formatclass();
1560          if ($type == 'import') {
1561              $provided = $format->provide_import();
1562          } else {
1563              $provided = $format->provide_export();
1564          }
1565  
1566          if ($provided) {
1567              list($notused, $fileformat) = explode('_', $component, 2);
1568              $fileformatnames[$fileformat] = get_string('pluginname', $component);
1569          }
1570      }
1571  
1572      core_collator::asort($fileformatnames);
1573      return $fileformatnames;
1574  }
1575  
1576  
1577  /**
1578   * Create a reasonable default file name for exporting questions from a particular
1579   * category.
1580   * @param object $course the course the questions are in.
1581   * @param object $category the question category.
1582   * @return string the filename.
1583   */
1584  function question_default_export_filename($course, $category) {
1585      // We build a string that is an appropriate name (questions) from the lang pack,
1586      // then the corse shortname, then the question category name, then a timestamp.
1587  
1588      $base = clean_filename(get_string('exportfilename', 'question'));
1589  
1590      $dateformat = str_replace(' ', '_', get_string('exportnameformat', 'question'));
1591      $timestamp = clean_filename(userdate(time(), $dateformat, 99, false));
1592  
1593      $shortname = clean_filename($course->shortname);
1594      if ($shortname == '' || $shortname == '_' ) {
1595          $shortname = $course->id;
1596      }
1597  
1598      $categoryname = clean_filename(format_string($category->name));
1599  
1600      return "{$base}-{$shortname}-{$categoryname}-{$timestamp}";
1601  
1602      return $export_name;
1603  }
1604  
1605  /**
1606   * Converts contextlevels to strings and back to help with reading/writing contexts
1607   * to/from import/export files.
1608   *
1609   * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
1610   * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
1611   */
1612  class context_to_string_translator{
1613      /**
1614       * @var array used to translate between contextids and strings for this context.
1615       */
1616      protected $contexttostringarray = array();
1617  
1618      public function __construct($contexts) {
1619          $this->generate_context_to_string_array($contexts);
1620      }
1621  
1622      public function context_to_string($contextid) {
1623          return $this->contexttostringarray[$contextid];
1624      }
1625  
1626      public function string_to_context($contextname) {
1627          $contextid = array_search($contextname, $this->contexttostringarray);
1628          return $contextid;
1629      }
1630  
1631      protected function generate_context_to_string_array($contexts) {
1632          if (!$this->contexttostringarray) {
1633              $catno = 1;
1634              foreach ($contexts as $context) {
1635                  switch ($context->contextlevel) {
1636                      case CONTEXT_MODULE :
1637                          $contextstring = 'module';
1638                          break;
1639                      case CONTEXT_COURSE :
1640                          $contextstring = 'course';
1641                          break;
1642                      case CONTEXT_COURSECAT :
1643                          $contextstring = "cat$catno";
1644                          $catno++;
1645                          break;
1646                      case CONTEXT_SYSTEM :
1647                          $contextstring = 'system';
1648                          break;
1649                  }
1650                  $this->contexttostringarray[$context->id] = $contextstring;
1651              }
1652          }
1653      }
1654  
1655  }
1656  
1657  /**
1658   * Check capability on category
1659   *
1660   * @param int|stdClass|question_definition $questionorid object or id.
1661   *      If an object is passed, it should include ->contextid and ->createdby.
1662   * @param string $cap 'add', 'edit', 'view', 'use', 'move' or 'tag'.
1663   * @param int $notused no longer used.
1664   * @return bool this user has the capability $cap for this question $question?
1665   * @throws coding_exception
1666   */
1667  function question_has_capability_on($questionorid, $cap, $notused = -1) {
1668      global $USER, $DB;
1669  
1670      if (is_numeric($questionorid)) {
1671          $questionid = (int)$questionorid;
1672      } else if (is_object($questionorid)) {
1673          // All we really need in this function is the contextid and author of the question.
1674          // We won't bother fetching other details of the question if these 2 fields are provided.
1675          if (isset($questionorid->contextid) && isset($questionorid->createdby)) {
1676              $question = $questionorid;
1677          } else if (!empty($questionorid->id)) {
1678              $questionid = $questionorid->id;
1679          }
1680      }
1681  
1682      // At this point, either $question or $questionid is expected to be set.
1683      if (isset($questionid)) {
1684          try {
1685              $question = question_bank::load_question_data($questionid);
1686          } catch (Exception $e) {
1687              // Let's log the exception for future debugging,
1688              // but not during Behat, or we can't test these cases.
1689              if (!defined('BEHAT_SITE_RUNNING')) {
1690                  debugging($e->getMessage(), DEBUG_NORMAL, $e->getTrace());
1691              }
1692  
1693              // Well, at least we tried. Seems that we really have to read from DB.
1694              $question = $DB->get_record_sql('SELECT q.id, q.createdby, qc.contextid
1695                                                 FROM {question} q
1696                                                 JOIN {question_categories} qc ON q.category = qc.id
1697                                                WHERE q.id = :id', ['id' => $questionid]);
1698          }
1699      }
1700  
1701      if (!isset($question)) {
1702          throw new coding_exception('$questionorid parameter needs to be an integer or an object.');
1703      }
1704  
1705      $context = context::instance_by_id($question->contextid);
1706  
1707      // These are existing questions capabilities that are set per category.
1708      // Each of these has a 'mine' and 'all' version that is appended to the capability name.
1709      $capabilitieswithallandmine = ['edit' => 1, 'view' => 1, 'use' => 1, 'move' => 1, 'tag' => 1];
1710  
1711      if (!isset($capabilitieswithallandmine[$cap])) {
1712          return has_capability('moodle/question:' . $cap, $context);
1713      } else {
1714          return has_capability('moodle/question:' . $cap . 'all', $context) ||
1715              ($question->createdby == $USER->id && has_capability('moodle/question:' . $cap . 'mine', $context));
1716      }
1717  }
1718  
1719  /**
1720   * Require capability on question.
1721   */
1722  function question_require_capability_on($question, $cap) {
1723      if (!question_has_capability_on($question, $cap)) {
1724          print_error('nopermissions', '', '', $cap);
1725      }
1726      return true;
1727  }
1728  
1729  /**
1730   * @param object $context a context
1731   * @return string A URL for editing questions in this context.
1732   */
1733  function question_edit_url($context) {
1734      global $CFG, $SITE;
1735      if (!has_any_capability(question_get_question_capabilities(), $context)) {
1736          return false;
1737      }
1738      $baseurl = $CFG->wwwroot . '/question/edit.php?';
1739      $defaultcategory = question_get_default_category($context->id);
1740      if ($defaultcategory) {
1741          $baseurl .= 'cat=' . $defaultcategory->id . ',' . $context->id . '&amp;';
1742      }
1743      switch ($context->contextlevel) {
1744          case CONTEXT_SYSTEM:
1745              return $baseurl . 'courseid=' . $SITE->id;
1746          case CONTEXT_COURSECAT:
1747              // This is nasty, becuase we can only edit questions in a course
1748              // context at the moment, so for now we just return false.
1749              return false;
1750          case CONTEXT_COURSE:
1751              return $baseurl . 'courseid=' . $context->instanceid;
1752          case CONTEXT_MODULE:
1753              return $baseurl . 'cmid=' . $context->instanceid;
1754      }
1755  
1756  }
1757  
1758  /**
1759   * Adds question bank setting links to the given navigation node if caps are met.
1760   *
1761   * @param navigation_node $navigationnode The navigation node to add the question branch to
1762   * @param object $context
1763   * @return navigation_node Returns the question branch that was added
1764   */
1765  function question_extend_settings_navigation(navigation_node $navigationnode, $context) {
1766      global $PAGE;
1767  
1768      if ($context->contextlevel == CONTEXT_COURSE) {
1769          $params = array('courseid'=>$context->instanceid);
1770      } else if ($context->contextlevel == CONTEXT_MODULE) {
1771          $params = array('cmid'=>$context->instanceid);
1772      } else {
1773          return;
1774      }
1775  
1776      if (($cat = $PAGE->url->param('cat')) && preg_match('~\d+,\d+~', $cat)) {
1777          $params['cat'] = $cat;
1778      }
1779  
1780      $questionnode = $navigationnode->add(get_string('questionbank', 'question'),
1781              new moodle_url('/question/edit.php', $params), navigation_node::TYPE_CONTAINER, null, 'questionbank');
1782  
1783      $contexts = new question_edit_contexts($context);
1784      if ($contexts->have_one_edit_tab_cap('questions')) {
1785          $questionnode->add(get_string('questions', 'question'), new moodle_url(
1786                  '/question/edit.php', $params), navigation_node::TYPE_SETTING, null, 'questions');
1787      }
1788      if ($contexts->have_one_edit_tab_cap('categories')) {
1789          $questionnode->add(get_string('categories', 'question'), new moodle_url(
1790                  '/question/category.php', $params), navigation_node::TYPE_SETTING, null, 'categories');
1791      }
1792      if ($contexts->have_one_edit_tab_cap('import')) {
1793          $questionnode->add(get_string('import', 'question'), new moodle_url(
1794                  '/question/import.php', $params), navigation_node::TYPE_SETTING, null, 'import');
1795      }
1796      if ($contexts->have_one_edit_tab_cap('export')) {
1797          $questionnode->add(get_string('export', 'question'), new moodle_url(
1798                  '/question/export.php', $params), navigation_node::TYPE_SETTING, null, 'export');
1799      }
1800  
1801      return $questionnode;
1802  }
1803  
1804  /**
1805   * @return array all the capabilities that relate to accessing particular questions.
1806   */
1807  function question_get_question_capabilities() {
1808      return array(
1809          'moodle/question:add',
1810          'moodle/question:editmine',
1811          'moodle/question:editall',
1812          'moodle/question:viewmine',
1813          'moodle/question:viewall',
1814          'moodle/question:usemine',
1815          'moodle/question:useall',
1816          'moodle/question:movemine',
1817          'moodle/question:moveall',
1818          'moodle/question:tagmine',
1819          'moodle/question:tagall',
1820      );
1821  }
1822  
1823  /**
1824   * @return array all the question bank capabilities.
1825   */
1826  function question_get_all_capabilities() {
1827      $caps = question_get_question_capabilities();
1828      $caps[] = 'moodle/question:managecategory';
1829      $caps[] = 'moodle/question:flag';
1830      return $caps;
1831  }
1832  
1833  
1834  /**
1835   * Tracks all the contexts related to the one where we are currently editing
1836   * questions, and provides helper methods to check permissions.
1837   *
1838   * @copyright 2007 Jamie Pratt me@jamiep.org
1839   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
1840   */
1841  class question_edit_contexts {
1842  
1843      public static $caps = array(
1844          'editq' => array('moodle/question:add',
1845              'moodle/question:editmine',
1846              'moodle/question:editall',
1847              'moodle/question:viewmine',
1848              'moodle/question:viewall',
1849              'moodle/question:usemine',
1850              'moodle/question:useall',
1851              'moodle/question:movemine',
1852              'moodle/question:moveall'),
1853          'questions'=>array('moodle/question:add',
1854              'moodle/question:editmine',
1855              'moodle/question:editall',
1856              'moodle/question:viewmine',
1857              'moodle/question:viewall',
1858              'moodle/question:movemine',
1859              'moodle/question:moveall'),
1860          'categories'=>array('moodle/question:managecategory'),
1861          'import'=>array('moodle/question:add'),
1862          'export'=>array('moodle/question:viewall', 'moodle/question:viewmine'));
1863  
1864      protected $allcontexts;
1865  
1866      /**
1867       * Constructor
1868       * @param context the current context.
1869       */
1870      public function __construct(context $thiscontext) {
1871          $this->allcontexts = array_values($thiscontext->get_parent_contexts(true));
1872      }
1873  
1874      /**
1875       * @return context[] all parent contexts
1876       */
1877      public function all() {
1878          return $this->allcontexts;
1879      }
1880  
1881      /**
1882       * @return context lowest context which must be either the module or course context
1883       */
1884      public function lowest() {
1885          return $this->allcontexts[0];
1886      }
1887  
1888      /**
1889       * @param string $cap capability
1890       * @return context[] parent contexts having capability, zero based index
1891       */
1892      public function having_cap($cap) {
1893          $contextswithcap = array();
1894          foreach ($this->allcontexts as $context) {
1895              if (has_capability($cap, $context)) {
1896                  $contextswithcap[] = $context;
1897              }
1898          }
1899          return $contextswithcap;
1900      }
1901  
1902      /**
1903       * @param array $caps capabilities
1904       * @return context[] parent contexts having at least one of $caps, zero based index
1905       */
1906      public function having_one_cap($caps) {
1907          $contextswithacap = array();
1908          foreach ($this->allcontexts as $context) {
1909              foreach ($caps as $cap) {
1910                  if (has_capability($cap, $context)) {
1911                      $contextswithacap[] = $context;
1912                      break; //done with caps loop
1913                  }
1914              }
1915          }
1916          return $contextswithacap;
1917      }
1918  
1919      /**
1920       * @param string $tabname edit tab name
1921       * @return context[] parent contexts having at least one of $caps, zero based index
1922       */
1923      public function having_one_edit_tab_cap($tabname) {
1924          return $this->having_one_cap(self::$caps[$tabname]);
1925      }
1926  
1927      /**
1928       * @return context[] those contexts where a user can add a question and then use it.
1929       */
1930      public function having_add_and_use() {
1931          $contextswithcap = array();
1932          foreach ($this->allcontexts as $context) {
1933              if (!has_capability('moodle/question:add', $context)) {
1934                  continue;
1935              }
1936              if (!has_any_capability(array('moodle/question:useall', 'moodle/question:usemine'), $context)) {
1937                              continue;
1938              }
1939              $contextswithcap[] = $context;
1940          }
1941          return $contextswithcap;
1942      }
1943  
1944      /**
1945       * Has at least one parent context got the cap $cap?
1946       *
1947       * @param string $cap capability
1948       * @return boolean
1949       */
1950      public function have_cap($cap) {
1951          return (count($this->having_cap($cap)));
1952      }
1953  
1954      /**
1955       * Has at least one parent context got one of the caps $caps?
1956       *
1957       * @param array $caps capability
1958       * @return boolean
1959       */
1960      public function have_one_cap($caps) {
1961          foreach ($caps as $cap) {
1962              if ($this->have_cap($cap)) {
1963                  return true;
1964              }
1965          }
1966          return false;
1967      }
1968  
1969      /**
1970       * Has at least one parent context got one of the caps for actions on $tabname
1971       *
1972       * @param string $tabname edit tab name
1973       * @return boolean
1974       */
1975      public function have_one_edit_tab_cap($tabname) {
1976          return $this->have_one_cap(self::$caps[$tabname]);
1977      }
1978  
1979      /**
1980       * Throw error if at least one parent context hasn't got the cap $cap
1981       *
1982       * @param string $cap capability
1983       */
1984      public function require_cap($cap) {
1985          if (!$this->have_cap($cap)) {
1986              print_error('nopermissions', '', '', $cap);
1987          }
1988      }
1989  
1990      /**
1991       * Throw error if at least one parent context hasn't got one of the caps $caps
1992       *
1993       * @param array $caps capabilities
1994       */
1995      public function require_one_cap($caps) {
1996          if (!$this->have_one_cap($caps)) {
1997              $capsstring = join(', ', $caps);
1998              print_error('nopermissions', '', '', $capsstring);
1999          }
2000      }
2001  
2002      /**
2003       * Throw error if at least one parent context hasn't got one of the caps $caps
2004       *
2005       * @param string $tabname edit tab name
2006       */
2007      public function require_one_edit_tab_cap($tabname) {
2008          if (!$this->have_one_edit_tab_cap($tabname)) {
2009              print_error('nopermissions', '', '', 'access question edit tab '.$tabname);
2010          }
2011      }
2012  }
2013  
2014  
2015  /**
2016   * Helps call file_rewrite_pluginfile_urls with the right parameters.
2017   *
2018   * @package  core_question
2019   * @category files
2020   * @param string $text text being processed
2021   * @param string $file the php script used to serve files
2022   * @param int $contextid context ID
2023   * @param string $component component
2024   * @param string $filearea filearea
2025   * @param array $ids other IDs will be used to check file permission
2026   * @param int $itemid item ID
2027   * @param array $options options
2028   * @return string
2029   */
2030  function question_rewrite_question_urls($text, $file, $contextid, $component,
2031          $filearea, array $ids, $itemid, array $options=null) {
2032  
2033      $idsstr = '';
2034      if (!empty($ids)) {
2035          $idsstr .= implode('/', $ids);
2036      }
2037      if ($itemid !== null) {
2038          $idsstr .= '/' . $itemid;
2039      }
2040      return file_rewrite_pluginfile_urls($text, $file, $contextid, $component,
2041              $filearea, $idsstr, $options);
2042  }
2043  
2044  /**
2045   * Rewrite the PLUGINFILE urls in part of the content of a question, for use when
2046   * viewing the question outside an attempt (for example, in the question bank
2047   * listing or in the quiz statistics report).
2048   *
2049   * @param string $text the question text.
2050   * @param int $questionid the question id.
2051   * @param int $filecontextid the context id of the question being displayed.
2052   * @param string $filecomponent the component that owns the file area.
2053   * @param string $filearea the file area name.
2054   * @param int|null $itemid the file's itemid
2055   * @param int $previewcontextid the context id where the preview is being displayed.
2056   * @param string $previewcomponent component responsible for displaying the preview.
2057   * @param array $options text and file options ('forcehttps'=>false)
2058   * @return string $questiontext with URLs rewritten.
2059   */
2060  function question_rewrite_question_preview_urls($text, $questionid,
2061          $filecontextid, $filecomponent, $filearea, $itemid,
2062          $previewcontextid, $previewcomponent, $options = null) {
2063  
2064      $path = "preview/$previewcontextid/$previewcomponent/$questionid";
2065      if ($itemid) {
2066          $path .= '/' . $itemid;
2067      }
2068  
2069      return file_rewrite_pluginfile_urls($text, 'pluginfile.php', $filecontextid,
2070              $filecomponent, $filearea, $path, $options);
2071  }
2072  
2073  /**
2074   * Called by pluginfile.php to serve files related to the 'question' core
2075   * component and for files belonging to qtypes.
2076   *
2077   * For files that relate to questions in a question_attempt, then we delegate to
2078   * a function in the component that owns the attempt (for example in the quiz,
2079   * or in core question preview) to get necessary inforation.
2080   *
2081   * (Note that, at the moment, all question file areas relate to questions in
2082   * attempts, so the If at the start of the last paragraph is always true.)
2083   *
2084   * Does not return, either calls send_file_not_found(); or serves the file.
2085   *
2086   * @package  core_question
2087   * @category files
2088   * @param stdClass $course course settings object
2089   * @param stdClass $context context object
2090   * @param string $component the name of the component we are serving files for.
2091   * @param string $filearea the name of the file area.
2092   * @param array $args the remaining bits of the file path.
2093   * @param bool $forcedownload whether the user must be forced to download the file.
2094   * @param array $options additional options affecting the file serving
2095   */
2096  function question_pluginfile($course, $context, $component, $filearea, $args, $forcedownload, array $options=array()) {
2097      global $DB, $CFG;
2098  
2099      // Special case, sending a question bank export.
2100      if ($filearea === 'export') {
2101          list($context, $course, $cm) = get_context_info_array($context->id);
2102          require_login($course, false, $cm);
2103  
2104          require_once($CFG->dirroot . '/question/editlib.php');
2105          $contexts = new question_edit_contexts($context);
2106          // check export capability
2107          $contexts->require_one_edit_tab_cap('export');
2108          $category_id = (int)array_shift($args);
2109          $format      = array_shift($args);
2110          $cattofile   = array_shift($args);
2111          $contexttofile = array_shift($args);
2112          $filename    = array_shift($args);
2113  
2114          // load parent class for import/export
2115          require_once($CFG->dirroot . '/question/format.php');
2116          require_once($CFG->dirroot . '/question/editlib.php');
2117          require_once($CFG->dirroot . '/question/format/' . $format . '/format.php');
2118  
2119          $classname = 'qformat_' . $format;
2120          if (!class_exists($classname)) {
2121              send_file_not_found();
2122          }
2123  
2124          $qformat = new $classname();
2125  
2126          if (!$category = $DB->get_record('question_categories', array('id' => $category_id))) {
2127              send_file_not_found();
2128          }
2129  
2130          $qformat->setCategory($category);
2131          $qformat->setContexts($contexts->having_one_edit_tab_cap('export'));
2132          $qformat->setCourse($course);
2133  
2134          if ($cattofile == 'withcategories') {
2135              $qformat->setCattofile(true);
2136          } else {
2137              $qformat->setCattofile(false);
2138          }
2139  
2140          if ($contexttofile == 'withcontexts') {
2141              $qformat->setContexttofile(true);
2142          } else {
2143              $qformat->setContexttofile(false);
2144          }
2145  
2146          if (!$qformat->exportpreprocess()) {
2147              send_file_not_found();
2148              print_error('exporterror', 'question', $thispageurl->out());
2149          }
2150  
2151          // export data to moodle file pool
2152          if (!$content = $qformat->exportprocess()) {
2153              send_file_not_found();
2154          }
2155  
2156          send_file($content, $filename, 0, 0, true, true, $qformat->mime_type());
2157      }
2158  
2159      // Normal case, a file belonging to a question.
2160      $qubaidorpreview = array_shift($args);
2161  
2162      // Two sub-cases: 1. A question being previewed outside an attempt/usage.
2163      if ($qubaidorpreview === 'preview') {
2164          $previewcontextid = (int)array_shift($args);
2165          $previewcomponent = array_shift($args);
2166          $questionid = (int) array_shift($args);
2167          $previewcontext = context_helper::instance_by_id($previewcontextid);
2168  
2169          $result = component_callback($previewcomponent, 'question_preview_pluginfile', array(
2170                  $previewcontext, $questionid,
2171                  $context, $component, $filearea, $args,
2172                  $forcedownload, $options), 'callbackmissing');
2173  
2174          if ($result === 'callbackmissing') {
2175              throw new coding_exception("Component {$previewcomponent} does not define the callback " .
2176                      "{$previewcomponent}_question_preview_pluginfile callback. " .
2177                      "Which is required if you are using question_rewrite_question_preview_urls.", DEBUG_DEVELOPER);
2178          }
2179  
2180          send_file_not_found();
2181      }
2182  
2183      // 2. A question being attempted in the normal way.
2184      $qubaid = (int)$qubaidorpreview;
2185      $slot = (int)array_shift($args);
2186  
2187      $module = $DB->get_field('question_usages', 'component',
2188              array('id' => $qubaid));
2189      if (!$module) {
2190          send_file_not_found();
2191      }
2192  
2193      if ($module === 'core_question_preview') {
2194          require_once($CFG->dirroot . '/question/previewlib.php');
2195          return question_preview_question_pluginfile($course, $context,
2196                  $component, $filearea, $qubaid, $slot, $args, $forcedownload, $options);
2197  
2198      } else {
2199          $dir = core_component::get_component_directory($module);
2200          if (!file_exists("$dir/lib.php")) {
2201              send_file_not_found();
2202          }
2203          include_once("$dir/lib.php");
2204  
2205          $filefunction = $module . '_question_pluginfile';
2206          if (function_exists($filefunction)) {
2207              $filefunction($course, $context, $component, $filearea, $qubaid, $slot,
2208                  $args, $forcedownload, $options);
2209          }
2210  
2211          // Okay, we're here so lets check for function without 'mod_'.
2212          if (strpos($module, 'mod_') === 0) {
2213              $filefunctionold  = substr($module, 4) . '_question_pluginfile';
2214              if (function_exists($filefunctionold)) {
2215                  $filefunctionold($course, $context, $component, $filearea, $qubaid, $slot,
2216                      $args, $forcedownload, $options);
2217              }
2218          }
2219  
2220          send_file_not_found();
2221      }
2222  }
2223  
2224  /**
2225   * Serve questiontext files in the question text when they are displayed in this report.
2226   *
2227   * @package  core_files
2228   * @category files
2229   * @param context $previewcontext the context in which the preview is happening.
2230   * @param int $questionid the question id.
2231   * @param context $filecontext the file (question) context.
2232   * @param string $filecomponent the component the file belongs to.
2233   * @param string $filearea the file area.
2234   * @param array $args remaining file args.
2235   * @param bool $forcedownload.
2236   * @param array $options additional options affecting the file serving.
2237   */
2238  function core_question_question_preview_pluginfile($previewcontext, $questionid,
2239          $filecontext, $filecomponent, $filearea, $args, $forcedownload, $options = array()) {
2240      global $DB;
2241  
2242      // Verify that contextid matches the question.
2243      $question = $DB->get_record_sql('
2244              SELECT q.*, qc.contextid
2245                FROM {question} q
2246                JOIN {question_categories} qc ON qc.id = q.category
2247               WHERE q.id = :id AND qc.contextid = :contextid',
2248              array('id' => $questionid, 'contextid' => $filecontext->id), MUST_EXIST);
2249  
2250      // Check the capability.
2251      list($context, $course, $cm) = get_context_info_array($previewcontext->id);
2252      require_login($course, false, $cm);
2253  
2254      question_require_capability_on($question, 'use');
2255  
2256      $fs = get_file_storage();
2257      $relativepath = implode('/', $args);
2258      $fullpath = "/{$filecontext->id}/{$filecomponent}/{$filearea}/{$relativepath}";
2259      if (!$file = $fs->get_file_by_hash(sha1($fullpath)) or $file->is_directory()) {
2260          send_file_not_found();
2261      }
2262  
2263      send_stored_file($file, 0, 0, $forcedownload, $options);
2264  }
2265  
2266  /**
2267   * Create url for question export
2268   *
2269   * @param int $contextid, current context
2270   * @param int $categoryid, categoryid
2271   * @param string $format
2272   * @param string $withcategories
2273   * @param string $ithcontexts
2274   * @param moodle_url export file url
2275   */
2276  function question_make_export_url($contextid, $categoryid, $format, $withcategories,
2277          $withcontexts, $filename) {
2278      global $CFG;
2279      $urlbase = "$CFG->wwwroot/pluginfile.php";
2280      return moodle_url::make_file_url($urlbase,
2281              "/$contextid/question/export/{$categoryid}/{$format}/{$withcategories}" .
2282              "/{$withcontexts}/{$filename}", true);
2283  }
2284  
2285  /**
2286   * Get the URL to export a single question (exportone.php).
2287   *
2288   * @param stdClass|question_definition $question the question definition as obtained from
2289   *      question_bank::load_question_data() or question_bank::make_question().
2290   *      (Only ->id and ->contextid are used.)
2291   * @return moodle_url the requested URL.
2292   */
2293  function question_get_export_single_question_url($question) {
2294      $params = ['id' => $question->id, 'sesskey' => sesskey()];
2295      $context = context::instance_by_id($question->contextid);
2296      switch ($context->contextlevel) {
2297          case CONTEXT_MODULE:
2298              $params['cmid'] = $context->instanceid;
2299              break;
2300  
2301          case CONTEXT_COURSE:
2302              $params['courseid'] = $context->instanceid;
2303              break;
2304  
2305          default:
2306              $params['courseid'] = SITEID;
2307      }
2308  
2309      return new moodle_url('/question/exportone.php', $params);
2310  }
2311  
2312  /**
2313   * Return a list of page types
2314   * @param string $pagetype current page type
2315   * @param stdClass $parentcontext Block's parent context
2316   * @param stdClass $currentcontext Current context of block
2317   */
2318  function question_page_type_list($pagetype, $parentcontext, $currentcontext) {
2319      global $CFG;
2320      $types = array(
2321          'question-*'=>get_string('page-question-x', 'question'),
2322          'question-edit'=>get_string('page-question-edit', 'question'),
2323          'question-category'=>get_string('page-question-category', 'question'),
2324          'question-export'=>get_string('page-question-export', 'question'),
2325          'question-import'=>get_string('page-question-import', 'question')
2326      );
2327      if ($currentcontext->contextlevel == CONTEXT_COURSE) {
2328          require_once($CFG->dirroot . '/course/lib.php');
2329          return array_merge(course_page_type_list($pagetype, $parentcontext, $currentcontext), $types);
2330      } else {
2331          return $types;
2332      }
2333  }
2334  
2335  /**
2336   * Does an activity module use the question bank?
2337   *
2338   * @param string $modname The name of the module (without mod_ prefix).
2339   * @return bool true if the module uses questions.
2340   */
2341  function question_module_uses_questions($modname) {
2342      if (plugin_supports('mod', $modname, FEATURE_USES_QUESTIONS)) {
2343          return true;
2344      }
2345  
2346      $component = 'mod_'.$modname;
2347      if (component_callback_exists($component, 'question_pluginfile')) {
2348          debugging("{$component} uses questions but doesn't declare FEATURE_USES_QUESTIONS", DEBUG_DEVELOPER);
2349          return true;
2350      }
2351  
2352      return false;
2353  }
2354  
2355  /**
2356   * If $oldidnumber ends in some digits then return the next available idnumber of the same form.
2357   *
2358   * So idnum -> null (no digits at the end) idnum0099 -> idnum0100 (if that is unused,
2359   * else whichever of idnum0101, idnume0102, ... is unused. idnum9 -> idnum10.
2360   *
2361   * @param string|null $oldidnumber a question idnumber, or can be null.
2362   * @param int $categoryid a question category id.
2363   * @return string|null suggested new idnumber for a question in that category, or null if one cannot be found.
2364   */
2365  function core_question_find_next_unused_idnumber(?string $oldidnumber, int $categoryid): ?string {
2366      global $DB;
2367  
2368      // The the old idnumber is not of the right form, bail now.
2369      if (!preg_match('~\d+$~', $oldidnumber, $matches)) {
2370          return null;
2371      }
2372  
2373      // Find all used idnumbers in one DB query.
2374      $usedidnumbers = $DB->get_records_select_menu('question', 'category = ? AND idnumber IS NOT NULL',
2375              [$categoryid], '', 'idnumber, 1');
2376  
2377      // Find the next unused idnumber.
2378      $numberbit = 'X' . $matches[0]; // Need a string here so PHP does not do '0001' + 1 = 2.
2379      $stem = substr($oldidnumber, 0, -strlen($matches[0]));
2380      do {
2381  
2382          // If we have got to something9999, insert an extra digit before incrementing.
2383          if (preg_match('~^(.*[^0-9])(9+)$~', $numberbit, $matches)) {
2384              $numberbit = $matches[1] . '0' . $matches[2];
2385          }
2386          $numberbit++;
2387          $newidnumber = $stem . substr($numberbit, 1);
2388      } while (isset($usedidnumbers[$newidnumber]));
2389  
2390      return (string) $newidnumber;
2391  }