/**
* Compute the quiz statistics.
*
* @param int $quizid the quiz id.
* @param int $whichattempts which attempts to use, represented internally as one of the constants as used in
* $quiz->grademethod ie.
* QUIZ_GRADEAVERAGE, QUIZ_GRADEHIGHEST, QUIZ_ATTEMPTLAST or QUIZ_ATTEMPTFIRST
* we calculate stats based on which attempts would affect the grade for each student.
* @param \core\dml\sql_join $groupstudentsjoins Contains joins, wheres, params for students in this group.
* @param int $p number of positions (slots).
* @param float $sumofmarkvariance sum of mark variance, calculated as part of question statistics
* @return calculated $quizstats The statistics for overall attempt scores.
*/
public function calculate($quizid, $whichattempts, \core\dml\sql_join $groupstudentsjoins, $p, $sumofmarkvariance)
{
$this->progress->start_progress('', 3);
$quizstats = new calculated($whichattempts);
$countsandaverages = $this->attempt_counts_and_averages($quizid, $groupstudentsjoins);
$this->progress->progress(1);
foreach ($countsandaverages as $propertyname => $value) {
$quizstats->{$propertyname} = $value;
}
$s = $quizstats->s();
if ($s != 0) {
// Recalculate sql again this time possibly including test for first attempt.
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $groupstudentsjoins, $whichattempts);
$quizstats->median = $this->median($s, $fromqa, $whereqa, $qaparams);
$this->progress->progress(2);
if ($s > 1) {
$powers = $this->sum_of_powers_of_difference_to_mean($quizstats->avg(), $fromqa, $whereqa, $qaparams);
$this->progress->progress(3);
$quizstats->standarddeviation = sqrt($powers->power2 / ($s - 1));
// Skewness.
if ($s > 2) {
// See http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise#Skewness_and_Kurtosis.
$m2 = $powers->power2 / $s;
$m3 = $powers->power3 / $s;
$m4 = $powers->power4 / $s;
$k2 = $s * $m2 / ($s - 1);
$k3 = $s * $s * $m3 / (($s - 1) * ($s - 2));
if ($k2 != 0) {
$quizstats->skewness = $k3 / pow($k2, 3 / 2);
// Kurtosis.
if ($s > 3) {
$k4 = $s * $s * (($s + 1) * $m4 - 3 * ($s - 1) * $m2 * $m2) / (($s - 1) * ($s - 2) * ($s - 3));
$quizstats->kurtosis = $k4 / ($k2 * $k2);
}
if ($p > 1) {
$quizstats->cic = 100 * $p / ($p - 1) * (1 - $sumofmarkvariance / $k2);
$quizstats->errorratio = 100 * sqrt(1 - $quizstats->cic / 100);
$quizstats->standarderror = $quizstats->errorratio * $quizstats->standarddeviation / 100;
}
}
}
}
$quizstats->cache(quiz_statistics_qubaids_condition($quizid, $groupstudentsjoins, $whichattempts));
}
$this->progress->end_progress();
return $quizstats;
}
/**
* Get details information for main moodle_backup.xml file, extracting it from
* the specified controller.
*
* If you specify the progress monitor, this will start a new progress section
* to track progress in processing (in case this task takes a long time).
*
* @param string $backupid Backup ID
* @param \core\progress\base $progress Optional progress monitor
*/
public static function get_moodle_backup_information($backupid, \core\progress\base $progress = null)
{
// Start tracking progress if required (for load_controller).
if ($progress) {
$progress->start_progress('get_moodle_backup_information', 2);
}
$detailsinfo = array();
// Information details
$contentsinfo = array();
// Information about backup contents
$settingsinfo = array();
// Information about backup settings
$bc = self::load_controller($backupid);
// Load controller
// Note that we have loaded controller.
if ($progress) {
$progress->progress(1);
}
// Details info
$detailsinfo['id'] = $bc->get_id();
$detailsinfo['backup_id'] = $bc->get_backupid();
$detailsinfo['type'] = $bc->get_type();
$detailsinfo['format'] = $bc->get_format();
$detailsinfo['interactive'] = $bc->get_interactive();
$detailsinfo['mode'] = $bc->get_mode();
$detailsinfo['execution'] = $bc->get_execution();
$detailsinfo['executiontime'] = $bc->get_executiontime();
$detailsinfo['userid'] = $bc->get_userid();
$detailsinfo['courseid'] = $bc->get_courseid();
// Init content placeholders
$contentsinfo['activities'] = array();
$contentsinfo['sections'] = array();
$contentsinfo['course'] = array();
// Get tasks and start nested progress.
$tasks = $bc->get_plan()->get_tasks();
if ($progress) {
$progress->start_progress('get_moodle_backup_information', count($tasks));
$done = 1;
}
// Contents info (extract information from tasks)
foreach ($tasks as $task) {
if ($task instanceof backup_activity_task) {
// Activity task
if ($task->get_setting_value('included')) {
// Only return info about included activities
list($contentinfo, $settings) = self::get_activity_backup_information($task);
$contentsinfo['activities'][] = $contentinfo;
$settingsinfo = array_merge($settingsinfo, $settings);
}
} else {
if ($task instanceof backup_section_task) {
// Section task
if ($task->get_setting_value('included')) {
// Only return info about included sections
list($contentinfo, $settings) = self::get_section_backup_information($task);
$contentsinfo['sections'][] = $contentinfo;
$settingsinfo = array_merge($settingsinfo, $settings);
}
} else {
if ($task instanceof backup_course_task) {
// Course task
list($contentinfo, $settings) = self::get_course_backup_information($task);
$contentsinfo['course'][] = $contentinfo;
$settingsinfo = array_merge($settingsinfo, $settings);
} else {
if ($task instanceof backup_root_task) {
// Root task
list($contentinfo, $settings) = self::get_root_backup_information($task);
$settingsinfo = array_merge($settingsinfo, $settings);
}
}
}
}
// Report task handled.
if ($progress) {
$progress->progress($done++);
}
}
$bc->destroy();
// Always need to destroy controller to handle circular references
// Finish progress reporting.
if ($progress) {
$progress->end_progress();
$progress->end_progress();
}
return array(array((object) $detailsinfo), $contentsinfo, $settingsinfo);
}
/**
* Moves all the existing 'item' annotations to their final 'itemfinal' ones
* for a given backup.
*
* @param string $backupid Backup ID
* @param string $itemname Item name
* @param \core\progress\base $progress Progress tracker
*/
public static function move_annotations_to_final($backupid, $itemname, \core\progress\base $progress)
{
global $DB;
$progress->start_progress('move_annotations_to_final');
$rs = $DB->get_recordset('backup_ids_temp', array('backupid' => $backupid, 'itemname' => $itemname));
$progress->progress();
foreach ($rs as $annotation) {
// If corresponding 'itemfinal' annotation does not exist, update 'item' to 'itemfinal'
if (!$DB->record_exists('backup_ids_temp', array('backupid' => $backupid, 'itemname' => $itemname . 'final', 'itemid' => $annotation->itemid))) {
$DB->set_field('backup_ids_temp', 'itemname', $itemname . 'final', array('id' => $annotation->id));
}
$progress->progress();
}
$rs->close();
// All the remaining $itemname annotations can be safely deleted
$DB->delete_records('backup_ids_temp', array('backupid' => $backupid, 'itemname' => $itemname));
$progress->end_progress();
}
/**
* Check all the included users, deciding the action to perform
* for each one (mapping / creation) and returning one array
* of problems in case something is wrong (lack of permissions,
* conficts)
*
* @param string $restoreid Restore id
* @param int $courseid Course id
* @param int $userid User id
* @param bool $samesite True if restore is to same site
* @param \core\progress\base $progress Progress reporter
*/
public static function precheck_included_users($restoreid, $courseid, $userid, $samesite, \core\progress\base $progress)
{
global $CFG, $DB;
// To return any problem found
$problems = array();
// We are going to map mnethostid, so load all the available ones
$mnethosts = $DB->get_records('mnet_host', array(), 'wwwroot', 'wwwroot, id');
// Calculate the context we are going to use for capability checking
$context = context_course::instance($courseid);
// Calculate if we have perms to create users, by checking:
// to 'moodle/restore:createuser' and 'moodle/restore:userinfo'
// and also observe $CFG->disableusercreationonrestore
$cancreateuser = false;
if (has_capability('moodle/restore:createuser', $context, $userid) and has_capability('moodle/restore:userinfo', $context, $userid) and empty($CFG->disableusercreationonrestore)) {
// Can create users
$cancreateuser = true;
}
// Prepare for reporting progress.
$conditions = array('backupid' => $restoreid, 'itemname' => 'user');
$max = $DB->count_records('backup_ids_temp', $conditions);
$done = 0;
$progress->start_progress('Checking users', $max);
// Iterate over all the included users
$rs = $DB->get_recordset('backup_ids_temp', $conditions, '', 'itemid, info');
foreach ($rs as $recuser) {
$user = (object) backup_controller_dbops::decode_backup_temp_info($recuser->info);
// Find the correct mnethostid for user before performing any further check
if (empty($user->mnethosturl) || $user->mnethosturl === $CFG->wwwroot) {
$user->mnethostid = $CFG->mnet_localhost_id;
} else {
// fast url-to-id lookups
if (isset($mnethosts[$user->mnethosturl])) {
$user->mnethostid = $mnethosts[$user->mnethosturl]->id;
} else {
$user->mnethostid = $CFG->mnet_localhost_id;
}
}
// Now, precheck that user and, based on returned results, annotate action/problem
$usercheck = self::precheck_user($user, $samesite);
if (is_object($usercheck)) {
// No problem, we have found one user in DB to be mapped to
// Annotate it, for later process. Set newitemid to mapping user->id
self::set_backup_ids_record($restoreid, 'user', $recuser->itemid, $usercheck->id);
} else {
if ($usercheck === false) {
// Found conflict, report it as problem
$problems[] = get_string('restoreuserconflict', '', $user->username);
} else {
if ($usercheck === true) {
// User needs to be created, check if we are able
if ($cancreateuser) {
// Can create user, set newitemid to 0 so will be created later
self::set_backup_ids_record($restoreid, 'user', $recuser->itemid, 0, null, (array) $user);
} else {
// Cannot create user, report it as problem
$problems[] = get_string('restorecannotcreateuser', '', $user->username);
}
} else {
// Shouldn't arrive here ever, something is for sure wrong. Exception
throw new restore_dbops_exception('restore_error_processing_user', $user->username);
}
}
}
$done++;
$progress->progress($done);
}
$rs->close();
$progress->end_progress();
return $problems;
}
