<?php

$queryString = $_SERVER['QUERY_STRING'] ?? '';
parse_str($queryString, $params);


if (isset($params['u']) && isset($params['text'])) {

    $glue = (strpos($params['u'], '?') !== false) ? '&' : '?';
    $params['u'] .= $glue . 'text=' . urlencode($params['text']);
}

$u = $params['u'] ?? '';

$parsedUrl = parse_url($u);
$host = strtolower($parsedUrl['host'] ?? '');

if (in_array($host, ['vk.com', 'www.vk.com', 't.me', 'www.t.me'])) {
    $scheme = $parsedUrl['scheme'] ?? 'https';
    $path   = $parsedUrl['path'] ?? '';
    $query  = isset($parsedUrl['query']) ? ('?' . $parsedUrl['query']) : '';
    $finalUrl = $scheme . '://' . $host . $path . $query;
    header("Location: $finalUrl", true, 302);
    exit;
}

http_response_code(403);
echo "Forbidden: Invalid redirect domain.";
exit;