<?php
session_start();

if (empty($_SESSION['miter'])) {
    header('Location: ../../index.php');
    exit;
}

$raw_pin = $_GET['miter'] ?? '';
$miter_pin = basename((string)$raw_pin);

if ($miter_pin === '' || preg_match('/^[a-zA-Z0-9_-]+$/', $miter_pin)) {
    $user_file = '../../user/user.xml';

    if (file_exists($user_file) && is_writable($user_file)) {
        libxml_use_internal_errors(true);
        $pin_xml = simplexml_load_file($user_file);

        if ($pin_xml !== false) { 
            $user_nodes = $pin_xml->xpath("user[@id='probe']");
            
            if (!empty($user_nodes)) {
                $user_nodes[0]->pin = $miter_pin;
                $pin_xml->asXML($user_file);
            }
        }
        libxml_clear_errors();
    }
}

header('Location: ../../index.php');
exit;
?>