<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

namespace quiz_statistics\task;

use core\dml\sql_join;
use quiz_attempt;

< use quiz;


use quiz_statistics_report;

defined('MOODLE_INTERNAL') || die();

require_once($CFG->dirroot . '/mod/quiz/locallib.php');
require_once($CFG->dirroot . '/mod/quiz/report/statistics/statisticslib.php');
require_once($CFG->dirroot . '/mod/quiz/report/reportlib.php');
require_once($CFG->dirroot . '/mod/quiz/report/statistics/report.php');

/**
 * Re-calculate question statistics.
 *
 * @package    quiz_statistics
 * @copyright  2022 Catalyst IT Australia Pty Ltd
 * @author     Nathan Nguyen <nathannguyen@catalyst-au.net>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

< class recalculate extends \core\task\scheduled_task {
<     /** @var int the maximum length of time one instance of this task will run. */
<     const TIME_LIMIT = 3600;



> class recalculate extends \core\task\adhoc_task {
>     /**
>      * The time to delay queued runs by, to prevent repeated recalculations.
>      */
>     const DELAY = HOURSECS;
> 
>     /**
>      * Create a new instance of the task.
>      *
>      * This sets the properties so that only one task will be queued at a time for a given quiz.
>      *
>      * @param int $quizid
>      * @return recalculate
>      */
>     public static function instance(int $quizid): recalculate {
>         $task = new self();
>         $task->set_component('quiz_statistics');
>         $task->set_custom_data((object)[
>             'quizid' => $quizid,
>         ]);
>         return $task;
>     }
> 



    public function get_name(): string {
        return get_string('recalculatetask', 'quiz_statistics');
    }

    public function execute(): void {
        global $DB;

<         $stoptime = time() + self::TIME_LIMIT;


        $dateformat = get_string('strftimedatetimeshortaccurate', 'core_langconfig');

< 
<         // TODO: MDL-75197, add quizid in quiz_statistics so that it is simpler to find quizzes for stats calculation.
<         // Only calculate stats for quizzes which have recently finished attempt.
<         $latestattempts = $DB->get_records_sql("
<                 SELECT q.id AS quizid,
<                        q.name AS quizname,
<                        q.grademethod AS quizgrademethod,
<                        c.id AS courseid,
<                        c.shortname AS courseshortname,
<                        MAX(quiza.timefinish) AS mostrecentattempttime,
<                        COUNT(1) AS numberofattempts
< 
<                   FROM {quiz_attempts} quiza
<                   JOIN {quiz} q ON q.id = quiza.quiz
<                   JOIN {course} c ON c.id = q.course
< 
<                  WHERE quiza.preview = 0
<                    AND quiza.state = :quizstatefinished
< 
<               GROUP BY q.id, q.name, q.grademethod, c.id, c.shortname
<               ORDER BY MAX(quiza.timefinish) DESC
<             ", ["quizstatefinished" => quiz_attempt::FINISHED]);
< 
<         $anyexception = null;
<         foreach ($latestattempts as $latestattempt) {
<             if (time() >= $stoptime) {
<                 mtrace("This task has been running for more than " .
<                         format_time(self::TIME_LIMIT) . " so stopping this execution.");
<                 break;
<             }
< 
<             // Check if there is any existing question stats, and it has been calculated after latest quiz attempt.
<             $qubaids = quiz_statistics_qubaids_condition($latestattempt->quizid,
<                     new sql_join(), $latestattempt->quizgrademethod);
<             $lateststatstime = $DB->get_field('quiz_statistics', 'COALESCE(MAX(timemodified), 0)',
<                     ['hashcode' => $qubaids->get_hash_code()]);
< 
<             $quizinfo = "'$latestattempt->quizname' ($latestattempt->quizid) in course " .
<                     "$latestattempt->courseshortname ($latestattempt->courseid) has most recent attempt finished at " .
<                         userdate($latestattempt->mostrecentattempttime, $dateformat);
<             if ($lateststatstime) {
<                 $quizinfo .= " and statistics from " . userdate($lateststatstime, $dateformat);
<             }
< 
<             if ($lateststatstime >= $latestattempt->mostrecentattempttime) {
<                 mtrace("  " . $quizinfo . " so nothing to do.");
<                 continue;



>         $data = $this->get_custom_data();
>         $quiz = $DB->get_record('quiz', ['id' => $data->quizid]);
>         if (!$quiz) {
>             mtrace('Could not find quiz with ID ' . $data->quizid . '.');
>             return;
>         }
>         $course = $DB->get_record('course', ['id' => $quiz->course]);
>         if (!$course) {
>             mtrace('Could not find course with ID ' . $quiz->course . '.');
>             return;
>         }
>         $attemptcount = $DB->count_records('quiz_attempts', ['quiz' => $data->quizid, 'state' => quiz_attempt::FINISHED]);
>         if ($attemptcount === 0) {
>             mtrace('Could not find any finished attempts for course with ID ' . $data->quizid . '.');
>             return;


            }


<             // OK, so we need to calculate for this quiz.
<             mtrace("  " . $quizinfo . " so re-calculating statistics for $latestattempt->numberofattempts attempts, start time " .



>         mtrace("Re-calculating statistics for quiz {$quiz->name} ({$quiz->id}) " .
>             "from course {$course->shortname} ({$course->id}) with {$attemptcount} attempts, start time " .


                    userdate(time(), $dateformat) . " ...");


<             try {
<                 $quizobj = quiz::create($latestattempt->quizid);



>         $qubaids = quiz_statistics_qubaids_condition(
>             $quiz->id,
>             new sql_join(),
>             $quiz->grademethod
>         );
> 


                $report = new quiz_statistics_report();
                $report->clear_cached_data($qubaids);

<                 $report->calculate_questions_stats_for_question_bank($quizobj->get_quizid());
<                 mtrace("    Calculations completed at " . userdate(time(), $dateformat) . ".");
< 
<             } catch (\Throwable $e) {
<                 // We don't want an exception from one quiz to stop processing of other quizzes.
<                 mtrace_exception($e);
<                 $anyexception = $e;
<             }



>         $report->calculate_questions_stats_for_question_bank($quiz->id);
>         mtrace('    Calculations completed at ' . userdate(time(), $dateformat) . '.');


        }


<         if ($anyexception) {
<             // If there was any error, ensure the task fails.
<             throw $anyexception;
<         }



>     /**
>      * Queue an instance of this task to happen after a delay.
>      *
>      * Multiple events may happen over a short period that require a recalculation. Rather than
>      * run the recalculation each time, this will queue a single run of the task for a given quiz,
>      * within the delay period.
>      *
>      * @param int $quizid The quiz to run the recalculation for.
>      * @return bool true of the task was queued.
>      */
>     public static function queue_future_run(int $quizid): bool {
>         $task = self::instance($quizid);
>         $task->set_next_run_time(time() + self::DELAY);
>         return \core\task\manager::queue_adhoc_task($task, true);


    }
}