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Developer Documentation

See Release Notes

  • Bug fixes for general core bugs in 4.2.x will end 22 April 2024 (12 months).
  • Bug fixes for security issues in 4.2.x will end 7 October 2024 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.1.x is supported too.

Differences Between: [Versions 310 and 402] [Versions 311 and 402] [Versions 39 and 402] [Versions 400 and 402] [Versions 401 and 402] [Versions 402 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   * Quiz statistics report class.
  19   *
  20   * @package   quiz_statistics
  21   * @copyright 2014 Open University
  22   * @author    James Pratt <me@jamiep.org>
  23   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24   */
  25  
  26  defined('MOODLE_INTERNAL') || die();
  27  
  28  use mod_quiz\local\reports\report_base;
  29  use core_question\statistics\responses\analyser;
  30  use core_question\statistics\questions\all_calculated_for_qubaid_condition;
  31  
  32  require_once($CFG->dirroot . '/mod/quiz/report/reportlib.php');
  33  require_once($CFG->dirroot . '/mod/quiz/report/statistics/statistics_form.php');
  34  require_once($CFG->dirroot . '/mod/quiz/report/statistics/statistics_table.php');
  35  require_once($CFG->dirroot . '/mod/quiz/report/statistics/statistics_question_table.php');
  36  require_once($CFG->dirroot . '/mod/quiz/report/statistics/statisticslib.php');
  37  
  38  /**
  39   * The quiz statistics report provides summary information about each question in
  40   * a quiz, compared to the whole quiz. It also provides a drill-down to more
  41   * detailed information about each question.
  42   *
  43   * @copyright 2008 Jamie Pratt
  44   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  45   */
  46  class quiz_statistics_report extends report_base {
  47  
  48      /** @var context_module context of this quiz.*/
  49      protected $context;
  50  
  51      /** @var quiz_statistics_table instance of table class used for main questions stats table. */
  52      protected $table;
  53  
  54      /** @var \core\progress\base|null $progress Handles progress reporting or not. */
  55      protected $progress = null;
  56  
  57      /**
  58       * Display the report.
  59       */
  60      public function display($quiz, $cm, $course) {
  61          global $OUTPUT, $DB;
  62  
  63          raise_memory_limit(MEMORY_HUGE);
  64  
  65          $this->context = context_module::instance($cm->id);
  66  
  67          if (!quiz_has_questions($quiz->id)) {
  68              $this->print_header_and_tabs($cm, $course, $quiz, 'statistics');
  69              echo quiz_no_questions_message($quiz, $cm, $this->context);
  70              return true;
  71          }
  72  
  73          // Work out the display options.
  74          $download = optional_param('download', '', PARAM_ALPHA);
  75          $everything = optional_param('everything', 0, PARAM_BOOL);
  76          $recalculate = optional_param('recalculate', 0, PARAM_BOOL);
  77          // A qid paramter indicates we should display the detailed analysis of a sub question.
  78          $qid = optional_param('qid', 0, PARAM_INT);
  79          $slot = optional_param('slot', 0, PARAM_INT);
  80          $variantno = optional_param('variant', null, PARAM_INT);
  81          $whichattempts = optional_param('whichattempts', $quiz->grademethod, PARAM_INT);
  82          $whichtries = optional_param('whichtries', question_attempt::LAST_TRY, PARAM_ALPHA);
  83  
  84          $pageoptions = [];
  85          $pageoptions['id'] = $cm->id;
  86          $pageoptions['mode'] = 'statistics';
  87  
  88          $reporturl = new moodle_url('/mod/quiz/report.php', $pageoptions);
  89  
  90          $mform = new quiz_statistics_settings_form($reporturl, compact('quiz'));
  91  
  92          $mform->set_data(['whichattempts' => $whichattempts, 'whichtries' => $whichtries]);
  93  
  94          if ($whichattempts != $quiz->grademethod) {
  95              $reporturl->param('whichattempts', $whichattempts);
  96          }
  97  
  98          if ($whichtries != question_attempt::LAST_TRY) {
  99              $reporturl->param('whichtries', $whichtries);
 100          }
 101  
 102          // Find out current groups mode.
 103          $currentgroup = $this->get_current_group($cm, $course, $this->context);
 104          $nostudentsingroup = false; // True if a group is selected and there is no one in it.
 105          if (empty($currentgroup)) {
 106              $currentgroup = 0;
 107              $groupstudentsjoins = new \core\dml\sql_join();
 108  
 109          } else if ($currentgroup == self::NO_GROUPS_ALLOWED) {
 110              $groupstudentsjoins = new \core\dml\sql_join();
 111              $nostudentsingroup = true;
 112  
 113          } else {
 114              // All users who can attempt quizzes and who are in the currently selected group.
 115              $groupstudentsjoins = get_enrolled_with_capabilities_join($this->context, '',
 116                      ['mod/quiz:reviewmyattempts', 'mod/quiz:attempt'], $currentgroup);
 117              if (!empty($groupstudentsjoins->joins)) {
 118                  $sql = "SELECT DISTINCT u.id
 119                      FROM {user} u
 120                      {$groupstudentsjoins->joins}
 121                      WHERE {$groupstudentsjoins->wheres}";
 122                  if (!$DB->record_exists_sql($sql, $groupstudentsjoins->params)) {
 123                      $nostudentsingroup = true;
 124                  }
 125              }
 126          }
 127  
 128          $qubaids = quiz_statistics_qubaids_condition($quiz->id, $groupstudentsjoins, $whichattempts);
 129  
 130          // If recalculate was requested, handle that.
 131          if ($recalculate && confirm_sesskey()) {
 132              $this->clear_cached_data($qubaids);
 133              redirect($reporturl);
 134          }
 135  
 136          // Set up the main table.
 137          $this->table = new quiz_statistics_table();
 138          if ($everything) {
 139              $report = get_string('completestatsfilename', 'quiz_statistics');
 140          } else {
 141              $report = get_string('questionstatsfilename', 'quiz_statistics');
 142          }
 143          $courseshortname = format_string($course->shortname, true,
 144                  ['context' => context_course::instance($course->id)]);
 145          $filename = quiz_report_download_filename($report, $courseshortname, $quiz->name);
 146          $this->table->is_downloading($download, $filename,
 147                  get_string('quizstructureanalysis', 'quiz_statistics'));
 148          $questions = $this->load_and_initialise_questions_for_calculations($quiz);
 149  
 150          // Print the page header stuff (if not downloading.
 151          if (!$this->table->is_downloading()) {
 152              $this->print_header_and_tabs($cm, $course, $quiz, 'statistics');
 153          }
 154  
 155          if (!$nostudentsingroup) {
 156              // Get the data to be displayed.
 157              $progress = $this->get_progress_trace_instance();
 158              list($quizstats, $questionstats) =
 159                  $this->get_all_stats_and_analysis($quiz, $whichattempts, $whichtries, $groupstudentsjoins, $questions, $progress);
 160              if (is_null($quizstats)) {
 161                  echo $OUTPUT->notification(get_string('nostats', 'quiz_statistics'), 'error');
 162                  return true;
 163              }
 164          } else {
 165              // Or create empty stats containers.
 166              $quizstats = new \quiz_statistics\calculated($whichattempts);
 167              $questionstats = new \core_question\statistics\questions\all_calculated_for_qubaid_condition();
 168          }
 169  
 170          // Set up the table.
 171          $this->table->statistics_setup($quiz, $cm->id, $reporturl, $quizstats->s());
 172  
 173          // Print the rest of the page header stuff (if not downloading.
 174          if (!$this->table->is_downloading()) {
 175  
 176              if (groups_get_activity_groupmode($cm)) {
 177                  groups_print_activity_menu($cm, $reporturl->out());
 178                  if ($currentgroup && $nostudentsingroup) {
 179                      $OUTPUT->notification(get_string('nostudentsingroup', 'quiz_statistics'));
 180                  }
 181              }
 182  
 183              if (!$this->table->is_downloading() && $quizstats->s() == 0) {
 184                  echo $OUTPUT->notification(get_string('nogradedattempts', 'quiz_statistics'));
 185              }
 186  
 187              foreach ($questionstats->any_error_messages() as $errormessage) {
 188                  echo $OUTPUT->notification($errormessage);
 189              }
 190  
 191              // Print display options form.
 192              $mform->display();
 193          }
 194  
 195          if ($everything) { // Implies is downloading.
 196              // Overall report, then the analysis of each question.
 197              $quizinfo = $quizstats->get_formatted_quiz_info_data($course, $cm, $quiz);
 198              $this->download_quiz_info_table($quizinfo);
 199  
 200              if ($quizstats->s()) {
 201                  $this->output_quiz_structure_analysis_table($questionstats);
 202  
 203                  if ($this->table->is_downloading() == 'html' && $quizstats->s() != 0) {
 204                      $this->output_statistics_graph($quiz, $qubaids);
 205                  }
 206  
 207                  $this->output_all_question_response_analysis($qubaids, $questions, $questionstats, $reporturl, $whichtries);
 208              }
 209  
 210              $this->table->export_class_instance()->finish_document();
 211  
 212          } else if ($qid) {
 213              // Report on an individual sub-question indexed questionid.
 214              if (!$questionstats->has_subq($qid, $variantno)) {
 215                  throw new \moodle_exception('questiondoesnotexist', 'question');
 216              }
 217  
 218              $this->output_individual_question_data($quiz, $questionstats->for_subq($qid, $variantno));
 219              $this->output_individual_question_response_analysis($questionstats->for_subq($qid, $variantno)->question,
 220                                                                  $variantno,
 221                                                                  $questionstats->for_subq($qid, $variantno)->s,
 222                                                                  $reporturl,
 223                                                                  $qubaids,
 224                                                                  $whichtries);
 225              // Back to overview link.
 226              echo $OUTPUT->box('<a href="' . $reporturl->out() . '">' .
 227                                get_string('backtoquizreport', 'quiz_statistics') . '</a>',
 228                                'boxaligncenter generalbox boxwidthnormal mdl-align');
 229          } else if ($slot) {
 230              // Report on an individual question indexed by position.
 231              if (!isset($questions[$slot])) {
 232                  throw new \moodle_exception('questiondoesnotexist', 'question');
 233              }
 234  
 235              if ($variantno === null &&
 236                                  ($questionstats->for_slot($slot)->get_sub_question_ids()
 237                                  || $questionstats->for_slot($slot)->get_variants())) {
 238                  if (!$this->table->is_downloading()) {
 239                      $number = $questionstats->for_slot($slot)->question->number;
 240                      echo $OUTPUT->heading(get_string('slotstructureanalysis', 'quiz_statistics', $number), 3);
 241                  }
 242                  $this->table->define_baseurl(new moodle_url($reporturl, ['slot' => $slot]));
 243                  $this->table->format_and_add_array_of_rows($questionstats->structure_analysis_for_one_slot($slot));
 244              } else {
 245                  $this->output_individual_question_data($quiz, $questionstats->for_slot($slot, $variantno));
 246                  $this->output_individual_question_response_analysis($questions[$slot],
 247                                                                      $variantno,
 248                                                                      $questionstats->for_slot($slot, $variantno)->s,
 249                                                                      $reporturl,
 250                                                                      $qubaids,
 251                                                                      $whichtries);
 252              }
 253              if (!$this->table->is_downloading()) {
 254                  // Back to overview link.
 255                  echo $OUTPUT->box('<a href="' . $reporturl->out() . '">' .
 256                          get_string('backtoquizreport', 'quiz_statistics') . '</a>',
 257                          'backtomainstats boxaligncenter generalbox boxwidthnormal mdl-align');
 258              } else {
 259                  $this->table->finish_output();
 260              }
 261  
 262          } else if ($this->table->is_downloading()) {
 263              // Downloading overview report.
 264              $quizinfo = $quizstats->get_formatted_quiz_info_data($course, $cm, $quiz);
 265              $this->download_quiz_info_table($quizinfo);
 266              if ($quizstats->s()) {
 267                  $this->output_quiz_structure_analysis_table($questionstats);
 268              }
 269              $this->table->export_class_instance()->finish_document();
 270  
 271          } else {
 272              // On-screen display of overview report.
 273              echo $OUTPUT->heading(get_string('quizinformation', 'quiz_statistics'), 3);
 274              echo $this->output_caching_info($quizstats->timemodified, $quiz->id, $groupstudentsjoins, $whichattempts, $reporturl);
 275              echo $this->everything_download_options($reporturl);
 276              $quizinfo = $quizstats->get_formatted_quiz_info_data($course, $cm, $quiz);
 277              echo $this->output_quiz_info_table($quizinfo);
 278              if ($quizstats->s()) {
 279                  echo $OUTPUT->heading(get_string('quizstructureanalysis', 'quiz_statistics'), 3);
 280                  $this->output_quiz_structure_analysis_table($questionstats);
 281                  $this->output_statistics_graph($quiz, $qubaids);
 282              }
 283          }
 284  
 285          return true;
 286      }
 287  
 288      /**
 289       * Display the statistical and introductory information about a question.
 290       * Only called when not downloading.
 291       *
 292       * @param stdClass                                         $quiz         the quiz settings.
 293       * @param \core_question\statistics\questions\calculated $questionstat the question to report on.
 294       */
 295      protected function output_individual_question_data($quiz, $questionstat) {
 296          global $OUTPUT;
 297  
 298          // On-screen display. Show a summary of the question's place in the quiz,
 299          // and the question statistics.
 300          $datumfromtable = $this->table->format_row($questionstat);
 301  
 302          // Set up the question info table.
 303          $questioninfotable = new html_table();
 304          $questioninfotable->align = ['center', 'center'];
 305          $questioninfotable->width = '60%';
 306          $questioninfotable->attributes['class'] = 'generaltable titlesleft';
 307  
 308          $questioninfotable->data = [];
 309          $questioninfotable->data[] = [get_string('modulename', 'quiz'), $quiz->name];
 310          $questioninfotable->data[] = [get_string('questionname', 'quiz_statistics'),
 311                  $questionstat->question->name.'&nbsp;'.$datumfromtable['actions']];
 312  
 313          if ($questionstat->variant !== null) {
 314              $questioninfotable->data[] = [get_string('variant', 'quiz_statistics'), $questionstat->variant];
 315  
 316          }
 317          $questioninfotable->data[] = [get_string('questiontype', 'quiz_statistics'),
 318                  $datumfromtable['icon'] . '&nbsp;' .
 319                  question_bank::get_qtype($questionstat->question->qtype, false)->menu_name() . '&nbsp;' .
 320                  $datumfromtable['icon']];
 321          $questioninfotable->data[] = [get_string('positions', 'quiz_statistics'),
 322                  $questionstat->positions];
 323  
 324          // Set up the question statistics table.
 325          $questionstatstable = new html_table();
 326          $questionstatstable->align = ['center', 'center'];
 327          $questionstatstable->width = '60%';
 328          $questionstatstable->attributes['class'] = 'generaltable titlesleft';
 329  
 330          unset($datumfromtable['number']);
 331          unset($datumfromtable['icon']);
 332          $actions = $datumfromtable['actions'];
 333          unset($datumfromtable['actions']);
 334          unset($datumfromtable['name']);
 335          $labels = [
 336              's' => get_string('attempts', 'quiz_statistics'),
 337              'facility' => get_string('facility', 'quiz_statistics'),
 338              'sd' => get_string('standarddeviationq', 'quiz_statistics'),
 339              'random_guess_score' => get_string('random_guess_score', 'quiz_statistics'),
 340              'intended_weight' => get_string('intended_weight', 'quiz_statistics'),
 341              'effective_weight' => get_string('effective_weight', 'quiz_statistics'),
 342              'discrimination_index' => get_string('discrimination_index', 'quiz_statistics'),
 343              'discriminative_efficiency' =>
 344                                  get_string('discriminative_efficiency', 'quiz_statistics')
 345          ];
 346          foreach ($datumfromtable as $item => $value) {
 347              $questionstatstable->data[] = [$labels[$item], $value];
 348          }
 349  
 350          // Display the various bits.
 351          echo $OUTPUT->heading(get_string('questioninformation', 'quiz_statistics'), 3);
 352          echo html_writer::table($questioninfotable);
 353          echo $this->render_question_text($questionstat->question);
 354          echo $OUTPUT->heading(get_string('questionstatistics', 'quiz_statistics'), 3);
 355          echo html_writer::table($questionstatstable);
 356      }
 357  
 358      /**
 359       * Output question text in a box with urls appropriate for a preview of the question.
 360       *
 361       * @param stdClass $question question data.
 362       * @return string HTML of question text, ready for display.
 363       */
 364      protected function render_question_text($question) {
 365          global $OUTPUT;
 366  
 367          $text = question_rewrite_question_preview_urls($question->questiontext, $question->id,
 368                  $question->contextid, 'question', 'questiontext', $question->id,
 369                  $this->context->id, 'quiz_statistics');
 370  
 371          return $OUTPUT->box(format_text($text, $question->questiontextformat,
 372                  ['noclean' => true, 'para' => false, 'overflowdiv' => true]),
 373                  'questiontext boxaligncenter generalbox boxwidthnormal mdl-align');
 374      }
 375  
 376      /**
 377       * Display the response analysis for a question.
 378       *
 379       * @param stdClass           $question  the question to report on.
 380       * @param int|null         $variantno the variant
 381       * @param int              $s
 382       * @param moodle_url       $reporturl the URL to redisplay this report.
 383       * @param qubaid_condition $qubaids
 384       * @param string           $whichtries
 385       */
 386      protected function output_individual_question_response_analysis($question, $variantno, $s, $reporturl, $qubaids,
 387                                                                      $whichtries = question_attempt::LAST_TRY) {
 388          global $OUTPUT;
 389  
 390          if (!question_bank::get_qtype($question->qtype, false)->can_analyse_responses()) {
 391              return;
 392          }
 393  
 394          $qtable = new quiz_statistics_question_table($question->id);
 395          $exportclass = $this->table->export_class_instance();
 396          $qtable->export_class_instance($exportclass);
 397          if (!$this->table->is_downloading()) {
 398              // Output an appropriate title.
 399              echo $OUTPUT->heading(get_string('analysisofresponses', 'quiz_statistics'), 3);
 400  
 401          } else {
 402              // Work out an appropriate title.
 403              $a = clone($question);
 404              $a->variant = $variantno;
 405  
 406              if (!empty($question->number) && !is_null($variantno)) {
 407                  $questiontabletitle = get_string('analysisnovariant', 'quiz_statistics', $a);
 408              } else if (!empty($question->number)) {
 409                  $questiontabletitle = get_string('analysisno', 'quiz_statistics', $a);
 410              } else if (!is_null($variantno)) {
 411                  $questiontabletitle = get_string('analysisvariant', 'quiz_statistics', $a);
 412              } else {
 413                  $questiontabletitle = get_string('analysisnameonly', 'quiz_statistics', $a);
 414              }
 415  
 416              if ($this->table->is_downloading() == 'html') {
 417                  $questiontabletitle = get_string('analysisofresponsesfor', 'quiz_statistics', $questiontabletitle);
 418              }
 419  
 420              // Set up the table.
 421              $exportclass->start_table($questiontabletitle);
 422  
 423              if ($this->table->is_downloading() == 'html') {
 424                  echo $this->render_question_text($question);
 425              }
 426          }
 427  
 428          $responesanalyser = new analyser($question, $whichtries);
 429          $responseanalysis = $responesanalyser->load_cached($qubaids, $whichtries);
 430  
 431          $qtable->question_setup($reporturl, $question, $s, $responseanalysis);
 432          if ($this->table->is_downloading()) {
 433              $exportclass->output_headers($qtable->headers);
 434          }
 435  
 436          // Where no variant no is specified the variant no is actually one.
 437          if ($variantno === null) {
 438              $variantno = 1;
 439          }
 440          foreach ($responseanalysis->get_subpart_ids($variantno) as $partid) {
 441              $subpart = $responseanalysis->get_analysis_for_subpart($variantno, $partid);
 442              foreach ($subpart->get_response_class_ids() as $responseclassid) {
 443                  $responseclass = $subpart->get_response_class($responseclassid);
 444                  $tabledata = $responseclass->data_for_question_response_table($subpart->has_multiple_response_classes(), $partid);
 445                  foreach ($tabledata as $row) {
 446                      $qtable->add_data_keyed($qtable->format_row($row));
 447                  }
 448              }
 449          }
 450  
 451          $qtable->finish_output(!$this->table->is_downloading());
 452      }
 453  
 454      /**
 455       * Output the table that lists all the questions in the quiz with their statistics.
 456       *
 457       * @param \core_question\statistics\questions\all_calculated_for_qubaid_condition $questionstats the stats for all questions in
 458       *                                                                                               the quiz including subqs and
 459       *                                                                                               variants.
 460       */
 461      protected function output_quiz_structure_analysis_table($questionstats) {
 462          $limitvariants = !$this->table->is_downloading();
 463          foreach ($questionstats->get_all_slots() as $slot) {
 464              // Output the data for these question statistics.
 465              $structureanalysis = $questionstats->structure_analysis_for_one_slot($slot, $limitvariants);
 466              if (is_null($structureanalysis)) {
 467                  $this->table->add_separator();
 468              } else {
 469                  foreach ($structureanalysis as $row) {
 470                      $bgcssclass = '';
 471                      // The only way to identify in this point of the report if a row is a summary row
 472                      // is checking if it's a instance of calculated_question_summary class.
 473                      if ($row instanceof \core_question\statistics\questions\calculated_question_summary) {
 474                          // Apply a custom css class to summary row to remove border and reduce paddings.
 475                          $bgcssclass = 'quiz_statistics-summaryrow';
 476  
 477                          // For question that contain a summary row, we add a "hidden" row in between so the report
 478                          // display both rows with same background color.
 479                          $this->table->add_data_keyed([], 'd-none hidden');
 480                      }
 481  
 482                      $this->table->add_data_keyed($this->table->format_row($row), $bgcssclass);
 483                  }
 484              }
 485          }
 486  
 487          $this->table->finish_output(!$this->table->is_downloading());
 488      }
 489  
 490      /**
 491       * Return HTML for table of overall quiz statistics.
 492       *
 493       * @param array $quizinfo as returned by {@link get_formatted_quiz_info_data()}.
 494       * @return string the HTML.
 495       */
 496      protected function output_quiz_info_table($quizinfo) {
 497  
 498          $quizinfotable = new html_table();
 499          $quizinfotable->align = ['center', 'center'];
 500          $quizinfotable->width = '60%';
 501          $quizinfotable->attributes['class'] = 'generaltable titlesleft';
 502          $quizinfotable->data = [];
 503  
 504          foreach ($quizinfo as $heading => $value) {
 505               $quizinfotable->data[] = [$heading, $value];
 506          }
 507  
 508          return html_writer::table($quizinfotable);
 509      }
 510  
 511      /**
 512       * Download the table of overall quiz statistics.
 513       *
 514       * @param array $quizinfo as returned by {@link get_formatted_quiz_info_data()}.
 515       */
 516      protected function download_quiz_info_table($quizinfo) {
 517          global $OUTPUT;
 518  
 519          // HTML download is a special case.
 520          if ($this->table->is_downloading() == 'html') {
 521              echo $OUTPUT->heading(get_string('quizinformation', 'quiz_statistics'), 3);
 522              echo $this->output_quiz_info_table($quizinfo);
 523              return;
 524          }
 525  
 526          // Reformat the data ready for output.
 527          $headers = [];
 528          $row = [];
 529          foreach ($quizinfo as $heading => $value) {
 530              $headers[] = $heading;
 531              $row[] = $value;
 532          }
 533  
 534          // Do the output.
 535          $exportclass = $this->table->export_class_instance();
 536          $exportclass->start_table(get_string('quizinformation', 'quiz_statistics'));
 537          $exportclass->output_headers($headers);
 538          $exportclass->add_data($row);
 539          $exportclass->finish_table();
 540      }
 541  
 542      /**
 543       * Output the HTML needed to show the statistics graph.
 544       *
 545       * @param stdClass $quiz the quiz.
 546       * @param qubaid_condition $qubaids the question usages whose responses to analyse.
 547       */
 548      protected function output_statistics_graph($quiz, $qubaids) {
 549          global $DB, $PAGE;
 550  
 551          // Load the rest of the required data.
 552          $questions = quiz_report_get_significant_questions($quiz);
 553  
 554          // Only load main question not sub questions.
 555          $questionstatistics = $DB->get_records_select('question_statistics',
 556                  'hashcode = ? AND slot IS NOT NULL AND variant IS NULL',
 557              [$qubaids->get_hash_code()]);
 558  
 559          // Configure what to display.
 560          $fieldstoplot = [
 561              'facility' => get_string('facility', 'quiz_statistics'),
 562              'discriminativeefficiency' => get_string('discriminative_efficiency', 'quiz_statistics')
 563          ];
 564          $fieldstoplotfactor = ['facility' => 100, 'discriminativeefficiency' => 1];
 565  
 566          // Prepare the arrays to hold the data.
 567          $xdata = [];
 568          foreach (array_keys($fieldstoplot) as $fieldtoplot) {
 569              $ydata[$fieldtoplot] = [];
 570          }
 571  
 572          // Fill in the data for each question.
 573          foreach ($questionstatistics as $questionstatistic) {
 574              $number = $questions[$questionstatistic->slot]->number;
 575              $xdata[$number] = $number;
 576  
 577              foreach ($fieldstoplot as $fieldtoplot => $notused) {
 578                  $value = $questionstatistic->$fieldtoplot;
 579                  if (is_null($value)) {
 580                      $value = 0;
 581                  }
 582                  $value *= $fieldstoplotfactor[$fieldtoplot];
 583                  $ydata[$fieldtoplot][$number] = number_format($value, 2);
 584              }
 585          }
 586  
 587          // Create the chart.
 588          sort($xdata);
 589          $chart = new \core\chart_bar();
 590          $chart->get_xaxis(0, true)->set_label(get_string('position', 'quiz_statistics'));
 591          $chart->set_labels(array_values($xdata));
 592  
 593          foreach ($fieldstoplot as $fieldtoplot => $notused) {
 594              ksort($ydata[$fieldtoplot]);
 595              $series = new \core\chart_series($fieldstoplot[$fieldtoplot], array_values($ydata[$fieldtoplot]));
 596              $chart->add_series($series);
 597          }
 598  
 599          // Find max.
 600          $max = 0;
 601          foreach ($fieldstoplot as $fieldtoplot => $notused) {
 602              $max = max($max, max($ydata[$fieldtoplot]));
 603          }
 604  
 605          // Set Y properties.
 606          $yaxis = $chart->get_yaxis(0, true);
 607          $yaxis->set_stepsize(10);
 608          $yaxis->set_label('%');
 609  
 610          $output = $PAGE->get_renderer('mod_quiz');
 611          $graphname = get_string('statisticsreportgraph', 'quiz_statistics');
 612          echo $output->chart($chart, $graphname);
 613      }
 614  
 615      /**
 616       * Get the quiz and question statistics, either by loading the cached results,
 617       * or by recomputing them.
 618       *
 619       * @param stdClass $quiz               the quiz settings.
 620       * @param string $whichattempts      which attempts to use, represented internally as one of the constants as used in
 621       *                                   $quiz->grademethod ie.
 622       *                                   QUIZ_GRADEAVERAGE, QUIZ_GRADEHIGHEST, QUIZ_ATTEMPTLAST or QUIZ_ATTEMPTFIRST
 623       *                                   we calculate stats based on which attempts would affect the grade for each student.
 624       * @param string $whichtries         which tries to analyse for response analysis. Will be one of
 625       *                                   question_attempt::FIRST_TRY, LAST_TRY or ALL_TRIES.
 626       * @param \core\dml\sql_join $groupstudentsjoins Contains joins, wheres, params for students in this group.
 627       * @param array  $questions          full question data.
 628       * @param \core\progress\base|null   $progress
 629       * @param bool $calculateifrequired  if true (the default) the stats will be calculated if not already stored.
 630       *                                   If false, [null, null] will be returned if the stats are not already available.
 631       * @param bool $performanalysis      if true (the default) and there are calculated stats, analysis will be performed
 632       *                                   for each question.
 633       * @return array with 2 elements:    - $quizstats The statistics for overall attempt scores.
 634       *                                   - $questionstats \core_question\statistics\questions\all_calculated_for_qubaid_condition
 635       *                                   Both may be null, if $calculateifrequired is false.
 636       */
 637      public function get_all_stats_and_analysis(
 638              $quiz, $whichattempts, $whichtries, \core\dml\sql_join $groupstudentsjoins,
 639              $questions, $progress = null, bool $calculateifrequired = true, bool $performanalysis = true) {
 640  
 641          if ($progress === null) {
 642              $progress = new \core\progress\none();
 643          }
 644  
 645          $qubaids = quiz_statistics_qubaids_condition($quiz->id, $groupstudentsjoins, $whichattempts);
 646  
 647          $qcalc = new \core_question\statistics\questions\calculator($questions, $progress);
 648  
 649          $quizcalc = new \quiz_statistics\calculator($progress);
 650  
 651          $progress->start_progress('', 4);
 652  
 653          // Get a lock on this set of qubaids before performing calculations. This prevents the same calculation running
 654          // concurrently and causing database deadlocks. We use a long timeout here as a big quiz with lots of attempts may
 655          // take a long time to process.
 656          $lockfactory = \core\lock\lock_config::get_lock_factory('quiz_statistics_get_stats');
 657          $lock = $lockfactory->get_lock($qubaids->get_hash_code(), 0);
 658          if (!$lock) {
 659              if (!$calculateifrequired) {
 660                  // We're not going to do the calculation in this request anyway, so just give up here.
 661                  $progress->progress(4);
 662                  $progress->end_progress();
 663                  return [null, null];
 664              }
 665              $locktimeout = get_config('quiz_statistics', 'getstatslocktimeout');
 666              $lock = \core\lock\lock_utils::wait_for_lock_with_progress(
 667                  $lockfactory,
 668                  $qubaids->get_hash_code(),
 669                  $progress,
 670                  $locktimeout,
 671                  get_string('getstatslockprogress', 'quiz_statistics'),
 672              );
 673              if (!$lock) {
 674                  // Lock attempt timed out.
 675                  $progress->progress(4);
 676                  $progress->end_progress();
 677                  debugging('Could not get lock on ' .
 678                          $qubaids->get_hash_code() . ' (Quiz ID ' . $quiz->id . ') after ' .
 679                          $locktimeout . ' seconds');
 680                  return [null, null];
 681              }
 682          }
 683  
 684          try {
 685              if ($quizcalc->get_last_calculated_time($qubaids) === false) {
 686                  if (!$calculateifrequired) {
 687                      $progress->progress(4);
 688                      $progress->end_progress();
 689                      $lock->release();
 690                      return [null, null];
 691                  }
 692  
 693                  // Recalculate now.
 694                  $questionstats = $qcalc->calculate($qubaids);
 695                  $progress->progress(2);
 696  
 697                  $quizstats = $quizcalc->calculate(
 698                      $quiz->id,
 699                      $whichattempts,
 700                      $groupstudentsjoins,
 701                      count($questions),
 702                      $qcalc->get_sum_of_mark_variance()
 703                  );
 704                  $progress->progress(3);
 705              } else {
 706                  $quizstats = $quizcalc->get_cached($qubaids);
 707                  $progress->progress(2);
 708                  $questionstats = $qcalc->get_cached($qubaids);
 709                  $progress->progress(3);
 710              }
 711  
 712              if ($quizstats->s() && $performanalysis) {
 713                  $subquestions = $questionstats->get_sub_questions();
 714                  $this->analyse_responses_for_all_questions_and_subquestions(
 715                      $questions,
 716                      $subquestions,
 717                      $qubaids,
 718                      $whichtries,
 719                      $progress
 720                  );
 721              }
 722              $progress->progress(4);
 723              $progress->end_progress();
 724          } finally {
 725              $lock->release();
 726          }
 727  
 728          return [$quizstats, $questionstats];
 729      }
 730  
 731      /**
 732       * Appropriate instance depending if we want html output for the user or not.
 733       *
 734       * @return \core\progress\base child of \core\progress\base to handle the display (or not) of task progress.
 735       */
 736      protected function get_progress_trace_instance() {
 737          if ($this->progress === null) {
 738              if (!$this->table->is_downloading()) {
 739                  $this->progress = new \core\progress\display_if_slow(get_string('calculatingallstats', 'quiz_statistics'));
 740                  $this->progress->set_display_names();
 741              } else {
 742                  $this->progress = new \core\progress\none();
 743              }
 744          }
 745          return $this->progress;
 746      }
 747  
 748      /**
 749       * Analyse responses for all questions and sub questions in this quiz.
 750       *
 751       * @param stdClass[] $questions as returned by self::load_and_initialise_questions_for_calculations
 752       * @param stdClass[] $subquestions full question objects.
 753       * @param qubaid_condition $qubaids the question usages whose responses to analyse.
 754       * @param string $whichtries which tries to analyse \question_attempt::FIRST_TRY, LAST_TRY or ALL_TRIES.
 755       * @param null|\core\progress\base $progress Used to indicate progress of task.
 756       */
 757      protected function analyse_responses_for_all_questions_and_subquestions($questions, $subquestions, $qubaids,
 758                                                                              $whichtries, $progress = null) {
 759          if ($progress === null) {
 760              $progress = new \core\progress\none();
 761          }
 762  
 763          // Starting response analysis tasks.
 764          $progress->start_progress('', count($questions) + count($subquestions));
 765  
 766          $done = $this->analyse_responses_for_questions($questions, $qubaids, $whichtries, $progress);
 767  
 768          $this->analyse_responses_for_questions($subquestions, $qubaids, $whichtries, $progress, $done);
 769  
 770          // Finished all response analysis tasks.
 771          $progress->end_progress();
 772      }
 773  
 774      /**
 775       * Analyse responses for an array of questions or sub questions.
 776       *
 777       * @param stdClass[] $questions  as returned by self::load_and_initialise_questions_for_calculations.
 778       * @param qubaid_condition $qubaids the question usages whose responses to analyse.
 779       * @param string $whichtries which tries to analyse \question_attempt::FIRST_TRY, LAST_TRY or ALL_TRIES.
 780       * @param null|\core\progress\base $progress Used to indicate progress of task.
 781       * @param int[] $done array keys are ids of questions that have been analysed before calling method.
 782       * @return array array keys are ids of questions that were analysed after this method call.
 783       */
 784      protected function analyse_responses_for_questions($questions, $qubaids, $whichtries, $progress = null, $done = []) {
 785          $countquestions = count($questions);
 786          if (!$countquestions) {
 787              return [];
 788          }
 789          if ($progress === null) {
 790              $progress = new \core\progress\none();
 791          }
 792          $progress->start_progress('', $countquestions, $countquestions);
 793          foreach ($questions as $question) {
 794              $progress->increment_progress();
 795              if (question_bank::get_qtype($question->qtype, false)->can_analyse_responses()  && !isset($done[$question->id])) {
 796                  $responesstats = new analyser($question, $whichtries);
 797                  $responesstats->calculate($qubaids, $whichtries);
 798              }
 799              $done[$question->id] = 1;
 800          }
 801          $progress->end_progress();
 802          return $done;
 803      }
 804  
 805      /**
 806       * Return a little form for the user to request to download the full report, including quiz stats and response analysis for
 807       * all questions and sub-questions.
 808       *
 809       * @param moodle_url $reporturl the base URL of the report.
 810       * @return string HTML.
 811       */
 812      protected function everything_download_options(moodle_url $reporturl) {
 813          global $OUTPUT;
 814          return $OUTPUT->download_dataformat_selector(get_string('downloadeverything', 'quiz_statistics'),
 815              $reporturl->out_omit_querystring(), 'download', $reporturl->params() + ['everything' => 1]);
 816      }
 817  
 818      /**
 819       * Return HTML for a message that says when the stats were last calculated and a 'recalculate now' button.
 820       *
 821       * @param int    $lastcachetime  the time the stats were last cached.
 822       * @param int    $quizid         the quiz id.
 823       * @param \core\dml\sql_join $groupstudentsjoins (joins, wheres, params) for students in the group
 824       *                                   or empty array if groups not used.
 825       * @param string $whichattempts which attempts to use, represented internally as one of the constants as used in
 826       *                                   $quiz->grademethod ie.
 827       *                                   QUIZ_GRADEAVERAGE, QUIZ_GRADEHIGHEST, QUIZ_ATTEMPTLAST or QUIZ_ATTEMPTFIRST
 828       *                                   we calculate stats based on which attempts would affect the grade for each student.
 829       * @param moodle_url $reporturl url for this report
 830       * @return string HTML.
 831       */
 832      protected function output_caching_info($lastcachetime, $quizid, $groupstudentsjoins, $whichattempts, $reporturl) {
 833          global $DB, $OUTPUT;
 834  
 835          if (empty($lastcachetime)) {
 836              return '';
 837          }
 838  
 839          // Find the number of attempts since the cached statistics were computed.
 840          list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $groupstudentsjoins, $whichattempts, true);
 841          $count = $DB->count_records_sql("
 842                  SELECT COUNT(1)
 843                  FROM $fromqa
 844                  WHERE $whereqa
 845                  AND quiza.timefinish > {$lastcachetime}", $qaparams);
 846  
 847          if (!$count) {
 848              $count = 0;
 849          }
 850  
 851          // Generate the output.
 852          $a = new stdClass();
 853          $a->lastcalculated = format_time(time() - $lastcachetime);
 854          $a->count = $count;
 855  
 856          $recalcualteurl = new moodle_url($reporturl,
 857                  ['recalculate' => 1, 'sesskey' => sesskey()]);
 858          $output = '';
 859          $output .= $OUTPUT->box_start(
 860                  'boxaligncenter generalbox boxwidthnormal mdl-align', 'cachingnotice');
 861          $output .= get_string('lastcalculated', 'quiz_statistics', $a);
 862          $output .= $OUTPUT->single_button($recalcualteurl,
 863                  get_string('recalculatenow', 'quiz_statistics'));
 864          $output .= $OUTPUT->box_end(true);
 865  
 866          return $output;
 867      }
 868  
 869      /**
 870       * Clear the cached data for a particular report configuration. This will trigger a re-computation the next time the report
 871       * is displayed.
 872       *
 873       * @param $qubaids qubaid_condition
 874       */
 875      public function clear_cached_data($qubaids) {
 876          global $DB;
 877          $DB->delete_records('quiz_statistics', ['hashcode' => $qubaids->get_hash_code()]);
 878          $DB->delete_records('question_statistics', ['hashcode' => $qubaids->get_hash_code()]);
 879          $DB->delete_records('question_response_analysis', ['hashcode' => $qubaids->get_hash_code()]);
 880      }
 881  
 882      /**
 883       * Load the questions in this quiz and add some properties to the objects needed in the reports.
 884       *
 885       * @param stdClass $quiz the quiz.
 886       * @return array of questions for this quiz.
 887       */
 888      public function load_and_initialise_questions_for_calculations($quiz) {
 889          // Load the questions.
 890          $questions = quiz_report_get_significant_questions($quiz);
 891          $questiondata = [];
 892          foreach ($questions as $qs => $question) {
 893              if ($question->qtype === 'random') {
 894                  $question->id = 0;
 895                  $question->name = get_string('random', 'quiz');
 896                  $question->questiontext = get_string('random', 'quiz');
 897                  $question->parenttype = 'random';
 898                  $questiondata[$question->slot] = $question;
 899              } else if ($question->qtype === 'missingtype') {
 900                  $question->id = is_numeric($question->id) ? (int) $question->id : 0;
 901                  $questiondata[$question->slot] = $question;
 902                  $question->name = get_string('deletedquestion', 'qtype_missingtype');
 903                  $question->questiontext = get_string('deletedquestiontext', 'qtype_missingtype');
 904              } else {
 905                  $q = question_bank::load_question_data($question->id);
 906                  $q->maxmark = $question->maxmark;
 907                  $q->slot = $question->slot;
 908                  $q->number = $question->number;
 909                  $q->parenttype = null;
 910                  $questiondata[$question->slot] = $q;
 911              }
 912          }
 913  
 914          return $questiondata;
 915      }
 916  
 917      /**
 918       * Output all response analysis for all questions, sub-questions and variants. For download in a number of formats.
 919       *
 920       * @param $qubaids
 921       * @param $questions
 922       * @param $questionstats
 923       * @param $reporturl
 924       * @param $whichtries string
 925       */
 926      protected function output_all_question_response_analysis($qubaids,
 927                                                               $questions,
 928                                                               $questionstats,
 929                                                               $reporturl,
 930                                                               $whichtries = question_attempt::LAST_TRY) {
 931          foreach ($questions as $slot => $question) {
 932              if (question_bank::get_qtype(
 933                  $question->qtype, false)->can_analyse_responses()
 934              ) {
 935                  if ($questionstats->for_slot($slot)->get_variants()) {
 936                      foreach ($questionstats->for_slot($slot)->get_variants() as $variantno) {
 937                          $this->output_individual_question_response_analysis($question,
 938                                                                              $variantno,
 939                                                                              $questionstats->for_slot($slot, $variantno)->s,
 940                                                                              $reporturl,
 941                                                                              $qubaids,
 942                                                                              $whichtries);
 943                      }
 944                  } else {
 945                      $this->output_individual_question_response_analysis($question,
 946                                                                          null,
 947                                                                          $questionstats->for_slot($slot)->s,
 948                                                                          $reporturl,
 949                                                                          $qubaids,
 950                                                                          $whichtries);
 951                  }
 952              } else if ($subqids = $questionstats->for_slot($slot)->get_sub_question_ids()) {
 953                  foreach ($subqids as $subqid) {
 954                      if ($variants = $questionstats->for_subq($subqid)->get_variants()) {
 955                          foreach ($variants as $variantno) {
 956                              $this->output_individual_question_response_analysis(
 957                                  $questionstats->for_subq($subqid, $variantno)->question,
 958                                  $variantno,
 959                                  $questionstats->for_subq($subqid, $variantno)->s,
 960                                  $reporturl,
 961                                  $qubaids,
 962                                  $whichtries);
 963                          }
 964                      } else {
 965                          $this->output_individual_question_response_analysis(
 966                              $questionstats->for_subq($subqid)->question,
 967                              null,
 968                              $questionstats->for_subq($subqid)->s,
 969                              $reporturl,
 970                              $qubaids,
 971                              $whichtries);
 972  
 973                      }
 974                  }
 975              }
 976          }
 977      }
 978  
 979      /**
 980       * Load question stats for a quiz
 981       *
 982       * @param int $quizid question usage
 983       * @param bool $calculateifrequired if true (the default) the stats will be calculated if not already stored.
 984       *     If false, null will be returned if the stats are not already available.
 985       * @param bool $performanalysis if true (the default) and there are calculated stats, analysis will be performed
 986       *     for each question.
 987       * @return ?all_calculated_for_qubaid_condition question stats
 988       */
 989      public function calculate_questions_stats_for_question_bank(
 990              int $quizid,
 991              bool $calculateifrequired = true,
 992              bool $performanalysis = true,
 993          ): ?all_calculated_for_qubaid_condition {
 994          global $DB;
 995          $quiz = $DB->get_record('quiz', ['id' => $quizid], '*', MUST_EXIST);
 996          $questions = $this->load_and_initialise_questions_for_calculations($quiz);
 997  
 998          [, $questionstats] = $this->get_all_stats_and_analysis($quiz,
 999              $quiz->grademethod, question_attempt::ALL_TRIES, new \core\dml\sql_join(),
1000              $questions, null, $calculateifrequired, $performanalysis);
1001  
1002          return $questionstats;
1003      }
1004  }