<?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/>.

/**
 * Implementaton of the quizaccess_safebrowser plugin.
 *
 * @package    quizaccess
 * @subpackage safebrowser
 * @copyright  2011 The Open University
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


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

require_once($CFG->dirroot . '/mod/quiz/accessrule/accessrulebase.php');


/**
 * A rule representing the safe browser check.
 *
 * @copyright  2009 Oliver Rahs
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class quizaccess_safebrowser extends quiz_access_rule_base {

    public static function make(quiz $quizobj, $timenow, $canignoretimelimits) {

        if ($quizobj->get_quiz()->browsersecurity !== 'safebrowser') {
            return null;
        }

        return new self($quizobj, $timenow);
    }

    public function prevent_access() {
        if (!$this->check_safe_browser()) {
            return get_string('safebrowsererror', 'quizaccess_safebrowser');
        } else {
            return false;
        }
    }

    public function description() {
        return get_string('safebrowsernotice', 'quizaccess_safebrowser');
    }

    public function setup_attempt_page($page) {
        $page->set_title($this->quizobj->get_course()->shortname . ': ' . $page->title);
        $page->set_cacheable(false);
    }

    /**
     * Checks if browser is safe browser
     *
     * @return true, if browser is safe browser else false
     */
    public function check_safe_browser() {
        return strpos($_SERVER['HTTP_USER_AGENT'], 'SEB') !== false;
    }

    /**
     * @return array key => lang string any choices to add to the quiz Browser
     *      security settings menu.
     */
    public static function get_browser_security_choices() {
        global $CFG;

        if (empty($CFG->enablesafebrowserintegration)) {
            return array();
        }

        return array('safebrowser' =>
                get_string('requiresafeexambrowser', 'quizaccess_safebrowser'));
    }
}