<?php

declare(strict_types=1);

$uriPath = parse_url($_SERVER['REQUEST_URI'] ?? '/', PHP_URL_PATH) ?: '/';
$root = __DIR__;

if (str_starts_with($uriPath, '/backend/')) {
    return false;
}

$frontendPath = $uriPath === '/' ? '/index.html' : $uriPath;
$file = realpath($root . '/frontend' . $frontendPath);
$frontendRoot = realpath($root . '/frontend');

if (
    $file !== false
    && $frontendRoot !== false
    && str_starts_with($file, $frontendRoot)
    && is_file($file)
) {
    $extension = strtolower(pathinfo($file, PATHINFO_EXTENSION));
    $contentTypes = [
        'css' => 'text/css; charset=utf-8',
        'html' => 'text/html; charset=utf-8',
        'js' => 'text/javascript; charset=utf-8',
        'json' => 'application/json; charset=utf-8',
        'svg' => 'image/svg+xml',
    ];

    header('Content-Type: ' . ($contentTypes[$extension] ?? 'application/octet-stream'));
    readfile($file);
    return true;
}

http_response_code(404);
header('Content-Type: text/plain; charset=utf-8');
echo "Not found\n";