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<?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/>.
/**
* Classes to enforce the various access rules that can apply to a quiz.
*
* @package mod_quiz
* @copyright 2009 Tim Hunt
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* This class keeps track of the various access rules that apply to a particular
* quiz, with convinient methods for seeing whether access is allowed.
*
* @copyright 2009 Tim Hunt
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
* @since Moodle 2.2
*/
class quiz_access_manager {
/** @var quiz the quiz settings object. */
protected $quizobj;
/** @var int the time to be considered as 'now'. */
protected $timenow;
/** @var array of quiz_access_rule_base. */
protected $rules = array();
/**
* Create an instance for a particular quiz.
* @param object $quizobj An instance of the class quiz from attemptlib.php.
* The quiz we will be controlling access to.
* @param int $timenow The time to use as 'now'.
* @param bool $canignoretimelimits Whether this user is exempt from time
* limits (has_capability('mod/quiz:ignoretimelimits', ...)).
*/
public function __construct($quizobj, $timenow, $canignoretimelimits) {
$this->quizobj = $quizobj;
$this->timenow = $timenow;
$this->rules = $this->make_rules($quizobj, $timenow, $canignoretimelimits);
}
/**
* Make all the rules relevant to a particular quiz.
* @param quiz $quizobj information about the quiz in question.
* @param int $timenow the time that should be considered as 'now'.
* @param bool $canignoretimelimits whether the current user is exempt from
* time limits by the mod/quiz:ignoretimelimits capability.
* @return array of {@link quiz_access_rule_base}s.
*/
protected function make_rules($quizobj, $timenow, $canignoretimelimits) {
$rules = array();
foreach (self::get_rule_classes() as $ruleclass) {
$rule = $ruleclass::make($quizobj, $timenow, $canignoretimelimits);
if ($rule) {
$rules[$ruleclass] = $rule;
}
}
$superceededrules = array();
foreach ($rules as $rule) {
$superceededrules += $rule->get_superceded_rules();
}
foreach ($superceededrules as $superceededrule) {
unset($rules['quizaccess_' . $superceededrule]);
}
return $rules;
}
/**
* @return array of all the installed rule class names.
*/
protected static function get_rule_classes() {
return core_component::get_plugin_list_with_class('quizaccess', '', 'rule.php');
}
/**
* Add any form fields that the access rules require to the settings form.
*
* Note that the standard plugins do not use this mechanism, becuase all their
* settings are stored in the quiz table.
*
* @param mod_quiz_mod_form $quizform the quiz settings form that is being built.
* @param MoodleQuickForm $mform the wrapped MoodleQuickForm.
*/
public static function add_settings_form_fields(
mod_quiz_mod_form $quizform, MoodleQuickForm $mform) {
foreach (self::get_rule_classes() as $rule) {
$rule::add_settings_form_fields($quizform, $mform);
}
}
/**
* The the options for the Browser security settings menu.
*
* @return array key => lang string.
*/
public static function get_browser_security_choices() {
$options = array('-' => get_string('none', 'quiz'));
foreach (self::get_rule_classes() as $rule) {
$options += $rule::get_browser_security_choices();
}
return $options;
}
/**
* Validate the data from any form fields added using {@link add_settings_form_fields()}.
* @param array $errors the errors found so far.
* @param array $data the submitted form data.
* @param array $files information about any uploaded files.
* @param mod_quiz_mod_form $quizform the quiz form object.
* @return array $errors the updated $errors array.
*/
public static function validate_settings_form_fields(array $errors,
array $data, $files, mod_quiz_mod_form $quizform) {
foreach (self::get_rule_classes() as $rule) {
$errors = $rule::validate_settings_form_fields($errors, $data, $files, $quizform);
}
return $errors;
}
/**
* Save any submitted settings when the quiz settings form is submitted.
*
* Note that the standard plugins do not use this mechanism because their
* settings are stored in the quiz table.
*
* @param object $quiz the data from the quiz form, including $quiz->id
* which is the id of the quiz being saved.
*/
public static function save_settings($quiz) {
foreach (self::get_rule_classes() as $rule) {
$rule::save_settings($quiz);
}
}
/**
* Delete any rule-specific settings when the quiz is deleted.
*
* Note that the standard plugins do not use this mechanism because their
* settings are stored in the quiz table.
*
* @param object $quiz the data from the database, including $quiz->id
* which is the id of the quiz being deleted.
* @since Moodle 2.7.1, 2.6.4, 2.5.7
*/
public static function delete_settings($quiz) {
foreach (self::get_rule_classes() as $rule) {
$rule::delete_settings($quiz);
}
}
/**
* Build the SQL for loading all the access settings in one go.
* @param int $quizid the quiz id.
* @param string $basefields initial part of the select list.
* @return array with two elements, the sql and the placeholder values.
* If $basefields is '' then you must allow for the possibility that
* there is no data to load, in which case this method returns $sql = ''.
*/
protected static function get_load_sql($quizid, $rules, $basefields) {
$allfields = $basefields;
$alljoins = '{quiz} quiz';
$allparams = array('quizid' => $quizid);
foreach ($rules as $rule) {
list($fields, $joins, $params) = $rule::get_settings_sql($quizid);
if ($fields) {
if ($allfields) {
$allfields .= ', ';
}
$allfields .= $fields;
}
if ($joins) {
$alljoins .= ' ' . $joins;
}
if ($params) {
$allparams += $params;
}
}
if ($allfields === '') {
return array('', array());
}
return array("SELECT $allfields FROM $alljoins WHERE quiz.id = :quizid", $allparams);
}
/**
* Load any settings required by the access rules. We try to do this with
* a single DB query.
*
* Note that the standard plugins do not use this mechanism, becuase all their
* settings are stored in the quiz table.
*
* @param int $quizid the quiz id.
* @return array setting value name => value. The value names should all
* start with the name of the corresponding plugin to avoid collisions.
*/
public static function load_settings($quizid) {
global $DB;
$rules = self::get_rule_classes();
list($sql, $params) = self::get_load_sql($quizid, $rules, '');
if ($sql) {
$data = (array) $DB->get_record_sql($sql, $params);
} else {
$data = array();
}
foreach ($rules as $rule) {
$data += $rule::get_extra_settings($quizid);
}
return $data;
}
/**
* Load the quiz settings and any settings required by the access rules.
* We try to do this with a single DB query.
*
* Note that the standard plugins do not use this mechanism, becuase all their
* settings are stored in the quiz table.
*
* @param int $quizid the quiz id.
* @return object mdl_quiz row with extra fields.
*/
public static function load_quiz_and_settings($quizid) {
global $DB;
$rules = self::get_rule_classes();
list($sql, $params) = self::get_load_sql($quizid, $rules, 'quiz.*');
$quiz = $DB->get_record_sql($sql, $params, MUST_EXIST);
foreach ($rules as $rule) {
foreach ($rule::get_extra_settings($quizid) as $name => $value) {
$quiz->$name = $value;
}
}
return $quiz;
}
/**
* @return array the class names of all the active rules. Mainly useful for
* debugging.
*/
public function get_active_rule_names() {
$classnames = array();
foreach ($this->rules as $rule) {
$classnames[] = get_class($rule);
}
return $classnames;
}
/**
* Accumulates an array of messages.
* @param array $messages the current list of messages.
* @param string|array $new the new messages or messages.
* @return array the updated array of messages.
*/
protected function accumulate_messages($messages, $new) {
if (is_array($new)) {
$messages = array_merge($messages, $new);
} else if (is_string($new) && $new) {
$messages[] = $new;
}
return $messages;
}
/**
* Provide a description of the rules that apply to this quiz, such
* as is shown at the top of the quiz view page. Note that not all
* rules consider themselves important enough to output a description.
*
* @return array an array of description messages which may be empty. It
* would be sensible to output each one surrounded by <p> tags.
*/
public function describe_rules() {
$result = array();
foreach ($this->rules as $rule) {
$result = $this->accumulate_messages($result, $rule->description());
}
return $result;
}
/**
* Whether or not a user should be allowed to start a new attempt at this quiz now.
* If there are any restrictions in force now, return an array of reasons why access
* should be blocked. If access is OK, return false.
*
* @param int $numattempts the number of previous attempts this user has made.
* @param object|false $lastattempt information about the user's last completed attempt.
* if there is not a previous attempt, the false is passed.
* @return mixed An array of reason why access is not allowed, or an empty array
* (== false) if access should be allowed.
*/
public function prevent_new_attempt($numprevattempts, $lastattempt) {
$reasons = array();
foreach ($this->rules as $rule) {
$reasons = $this->accumulate_messages($reasons,
$rule->prevent_new_attempt($numprevattempts, $lastattempt));
}
return $reasons;
}
/**
* Whether the user should be blocked from starting a new attempt or continuing
* an attempt now. If there are any restrictions in force now, return an array
* of reasons why access should be blocked. If access is OK, return false.
*
* @return mixed An array of reason why access is not allowed, or an empty array
* (== false) if access should be allowed.
*/
public function prevent_access() {
$reasons = array();
foreach ($this->rules as $rule) {
$reasons = $this->accumulate_messages($reasons, $rule->prevent_access());
}
return $reasons;
}
/**
* @param int|null $attemptid the id of the current attempt, if there is one,
* otherwise null.
* @return bool whether a check is required before the user starts/continues
* their attempt.
*/
public function is_preflight_check_required($attemptid) {
foreach ($this->rules as $rule) {
if ($rule->is_preflight_check_required($attemptid)) {
return true;
}
}
return false;
}
/**
* Build the form required to do the pre-flight checks.
* @param moodle_url $url the form action URL.
* @param int|null $attemptid the id of the current attempt, if there is one,
* otherwise null.
* @return mod_quiz_preflight_check_form the form.
*/
public function get_preflight_check_form(moodle_url $url, $attemptid) {
// This form normally wants POST submissins. However, it also needs to
// accept GET submissions. Since formslib is strict, we have to detect
// which case we are in, and set the form property appropriately.
$method = 'post';
if (!empty($_GET['_qf__mod_quiz_preflight_check_form'])) {
$method = 'get';
}
return new mod_quiz_preflight_check_form($url->out_omit_querystring(),
array('rules' => $this->rules, 'quizobj' => $this->quizobj,
'attemptid' => $attemptid, 'hidden' => $url->params()), $method);
}
/**
* The pre-flight check has passed. This is a chance to record that fact in
* some way.
* @param int|null $attemptid the id of the current attempt, if there is one,
* otherwise null.
*/
public function notify_preflight_check_passed($attemptid) {
foreach ($this->rules as $rule) {
$rule->notify_preflight_check_passed($attemptid);
}
}
/**
* Inform the rules that the current attempt is finished. This is use, for example
* by the password rule, to clear the flag in the session.
*/
public function current_attempt_finished() {
foreach ($this->rules as $rule) {
$rule->current_attempt_finished();
}
}
/**
* Do any of the rules mean that this student will no be allowed any further attempts at this
* quiz. Used, for example, to change the label by the grade displayed on the view page from
* 'your current grade is' to 'your final grade is'.
*
* @param int $numattempts the number of previous attempts this user has made.
* @param object $lastattempt information about the user's last completed attempt.
* @return bool true if there is no way the user will ever be allowed to attempt
* this quiz again.
*/
public function is_finished($numprevattempts, $lastattempt) {
foreach ($this->rules as $rule) {
if ($rule->is_finished($numprevattempts, $lastattempt)) {
return true;
}
}
return false;
}
/**
* Sets up the attempt (review or summary) page with any properties required
* by the access rules.
*
* @param moodle_page $page the page object to initialise.
*/
public function setup_attempt_page($page) {
foreach ($this->rules as $rule) {
$rule->setup_attempt_page($page);
}
}
/**
* Compute when the attempt must be submitted.
*
* @param object $attempt the data from the relevant quiz_attempts row.
* @return int|false the attempt close time.
* False if there is no limit.
*/
public function get_end_time($attempt) {
$timeclose = false;
foreach ($this->rules as $rule) {
$ruletimeclose = $rule->end_time($attempt);
if ($ruletimeclose !== false && ($timeclose === false || $ruletimeclose < $timeclose)) {
$timeclose = $ruletimeclose;
}
}
return $timeclose;
}
/**
* Compute what should be displayed to the user for time remaining in this attempt.
*
* @param object $attempt the data from the relevant quiz_attempts row.
* @param int $timenow the time to consider as 'now'.
* @return int|false the number of seconds remaining for this attempt.
* False if no limit should be displayed.
*/
public function get_time_left_display($attempt, $timenow) {
$timeleft = false;
foreach ($this->rules as $rule) {
$ruletimeleft = $rule->time_left_display($attempt, $timenow);
if ($ruletimeleft !== false && ($timeleft === false || $ruletimeleft < $timeleft)) {
$timeleft = $ruletimeleft;
}
}
return $timeleft;
}
/**
* @return bolean if this quiz should only be shown to students in a popup window.
*/
public function attempt_must_be_in_popup() {
foreach ($this->rules as $rule) {
if ($rule->attempt_must_be_in_popup()) {
return true;
}
}
return false;
}
/**
* @return array any options that are required for showing the attempt page
* in a popup window.
*/
public function get_popup_options() {
$options = array();
foreach ($this->rules as $rule) {
$options += $rule->get_popup_options();
}
return $options;
}
/**
* Send the user back to the quiz view page. Normally this is just a redirect, but
* If we were in a secure window, we close this window, and reload the view window we came from.
*
* This method does not return;
*
* @param mod_quiz_renderer $output the quiz renderer.
* @param string $message optional message to output while redirecting.
*/
public function back_to_view_page($output, $message = '') {
if ($this->attempt_must_be_in_popup()) {
echo $output->close_attempt_popup($this->quizobj->view_url(), $message);
die();
} else {
redirect($this->quizobj->view_url(), $message);
}
}
/**
* Make some text into a link to review the quiz, if that is appropriate.
*
* @param string $linktext some text.
* @param object $attempt the attempt object
* @return string some HTML, the $linktext either unmodified or wrapped in a
* link to the review page.
*/
public function make_review_link($attempt, $reviewoptions, $output) {
// If the attempt is still open, don't link.
if (in_array($attempt->state, array(quiz_attempt::IN_PROGRESS, quiz_attempt::OVERDUE))) {
return $output->no_review_message('');
}
$when = quiz_attempt_state($this->quizobj->get_quiz(), $attempt);
$reviewoptions = mod_quiz_display_options::make_from_quiz(
$this->quizobj->get_quiz(), $when);
if (!$reviewoptions->attempt) {
return $output->no_review_message($this->quizobj->cannot_review_message($when, true));
} else {
return $output->review_link($this->quizobj->review_url($attempt->id),
$this->attempt_must_be_in_popup(), $this->get_popup_options());
}
}
/**
* Run the preflight checks using the given data in all the rules supporting them.
*
* @param array $data passed data for validation
* @param array $files un-used, Moodle seems to not support it anymore
* @param int|null $attemptid the id of the current attempt, if there is one,
* otherwise null.
* @return array of errors, empty array means no erros
* @since Moodle 3.1
*/
public function validate_preflight_check($data, $files, $attemptid) {
$errors = array();
foreach ($this->rules as $rule) {
if ($rule->is_preflight_check_required($attemptid)) {
$errors = $rule->validate_preflight_check($data, $files, $errors, $attemptid);
}
}
return $errors;
}
}