<?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/>.

/**
 * External badge renderable.
 *
 * @package    core
 * @subpackage badges
 * @copyright  2012 onwards Totara Learning Solutions Ltd {@link http://www.totaralms.com/}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @author     Yuliya Bozhko <yuliya.bozhko@totaralms.com>
 */

namespace core_badges\output;

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

require_once($CFG->libdir . '/badgeslib.php');

use renderable;

/**
 * An external badges for external.php page
 *
 * @copyright  2012 onwards Totara Learning Solutions Ltd {@link http://www.totaralms.com/}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class external_badge implements renderable {
    /** @var issued badge */
    public $issued;

    /** @var User ID */
    public $recipient;

    /** @var validation of external badge */
    public $valid = true;

    /**
     * Initializes the badge to display
     *
     * @param object $badge External badge information.
     * @param int $recipient User id.
     */
    public function __construct($badge, $recipient) {
        global $DB;
        // At this point a user has connected a backpack. So, we are going to get
        // their backpack email rather than their account email.
        $namefields = get_all_user_name_fields(true, 'u');
        $user = $DB->get_record_sql("SELECT {$namefields}, b.email
                    FROM {user} u INNER JOIN {badge_backpack} b ON u.id = b.userid
                    WHERE b.userid = :userid", array('userid' => $recipient), IGNORE_MISSING);

        $this->issued = $badge;
        $this->recipient = $user;

        // Check if recipient is valid.
        // There is no way to be 100% sure that a badge belongs to a user.
        // Backpack does not return any recipient information.
        // All we can do is compare that backpack email hashed using salt
        // provided in the assertion matches a badge recipient from the assertion.
        if ($user) {
            if (isset($badge->assertion->recipient->identity)) {
                $badge->assertion->salt = $badge->assertion->recipient->salt;
                $badge->assertion->recipient = $badge->assertion->recipient->identity;
            }
            // Open Badges V2 does not even include a recipient.
            if (!isset($badge->assertion->recipient)) {
                $this->valid = false;
            } else if (validate_email($badge->assertion->recipient) && $badge->assertion->recipient == $user->email) {
                // If we have email, compare emails.
                $this->valid = true;
            } else if ($badge->assertion->recipient == 'sha256$' . hash('sha256', $user->email)) {
                // If recipient is hashed, but no salt, compare hashes without salt.
                $this->valid = true;
            } else if ($badge->assertion->recipient == 'sha256$' . hash('sha256', $user->email . $badge->assertion->salt)) {
                // If recipient is hashed, compare hashes.
                $this->valid = true;
            } else {
                // Otherwise, we cannot be sure that this user is a recipient.
                $this->valid = false;
            }
        } else {
            $this->valid = false;
        }
    }
}