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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; } }