<?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/>.

/**
 * Redirect the user to registration with token and openid config url as query params.
 *
 * @package mod_lti
 * @copyright  2020 Cengage
 * @author     Claude Vervoort
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

use Firebase\JWT\JWT;

use mod_lti\local\ltiopenid\jwks_helper;
use mod_lti\local\ltiopenid\registration_helper;

require_once(__DIR__ . '/../../config.php');
require_once($CFG->libdir.'/weblib.php');
require_once($CFG->dirroot . '/mod/lti/locallib.php');

require_login();
$context = context_system::instance();
require_capability('moodle/site:config', $context);

$starturl = required_param('url', PARAM_URL);
$typeid = optional_param('type', -1, PARAM_INT);

$types = lti_get_tools_by_url($starturl, null);

if (!empty($types) && $typeid == -1) {
    // There are matching types for the registration domain, let's prompt the user to upgrade.
    $pageurl = new moodle_url('/mod/lti/startltiadvregistration.php');
    $PAGE->set_context($context);
    $PAGE->set_url($pageurl);
    $PAGE->set_pagelayout('maintenance');
    $output = $PAGE->get_renderer('mod_lti');
    $page = new \mod_lti\output\registration_upgrade_choice_page($types, $starturl);
    echo $output->header();
    echo $output->render($page);
    echo $output->footer();
} else {
    // Let's actually start the registration process by launching the tool registration
    // endpoint with the registration token and the site config url.
    require_sesskey();
    $sub = registration_helper::get()->new_clientid();
    $scope = registration_helper::REG_TOKEN_OP_NEW_REG;
    if ($typeid > 0) {
        // In the context of an update, the sub is the id of the type.
        $sub = strval($typeid);
        $scope = registration_helper::REG_TOKEN_OP_UPDATE_REG;
    }
    $now = time();
    $token = [
        "sub" => $sub,
        "scope" => $scope,
        "iat" => $now,
        "exp" => $now + HOURSECS
    ];
    $privatekey = jwks_helper::get_private_key();
    $regtoken = JWT::encode($token, $privatekey['key'], 'RS256', $privatekey['kid']);
    $confurl = new moodle_url('/mod/lti/openid-configuration.php');
    $url = new moodle_url($starturl);
    $url->param('openid_configuration', $confurl->out(false));
    $url->param('registration_token', $regtoken);
    header("Location: ".$url->out(false));
}