<?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/>.

/**
 * @package    qtype_algebra
 * @copyright  2018 Jean-Michel Vedrine
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

define('AJAX_SCRIPT', true);

require_once(__DIR__ . '/../../../config.php');
require_once(__DIR__ . '/parser.php');

$p = new qtype_algebra_parser;

$vars  = required_param('vars', PARAM_RAW);
$expr  = required_param('expr', PARAM_RAW);
/*
if (!confirm_sesskey()) {
    header('HTTP/1.1 403 Forbidden');
    die();
}
*/
try {
    $vars = explode(',', $vars);
    if (empty($expr)) {
        $texexp = '';
    } else {
        $exp = $p->parse($expr, $vars);
        $texexp = $exp->tex();
    }
} catch (Exception $e) {
    $texexp = '';
}
if ($CFG->qtype_algebra_texdelimiters == 'old') {
    $texexp = '$$' . $texexp . '$$';
} else {
    $texexp = '\\[' . $texexp . '\\]';
}
header('Content-Type: application/json; charset: utf-8');
echo json_encode($texexp);