import { createReadStream, existsSync, statSync } from 'node:fs';
import { dirname, extname, join, normalize } from 'node:path';
import { createServer } from 'node:http';
import { fileURLToPath } from 'node:url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);
const root = normalize(join(__dirname, '../../userfront/build/web'));

if (!existsSync(root) || !statSync(root).isDirectory()) {
  console.error(
    '[userfront-e2e] userfront/build/web not found. Run: cd userfront && flutter build web --wasm --release',
  );
  process.exit(1);
}

const port = Number.parseInt(process.env.PORT ?? '4173', 10);

const contentTypes = {
  '.css': 'text/css; charset=utf-8',
  '.html': 'text/html; charset=utf-8',
  '.ico': 'image/x-icon',
  '.js': 'application/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.mjs': 'application/javascript; charset=utf-8',
  '.png': 'image/png',
  '.svg': 'image/svg+xml; charset=utf-8',
  '.txt': 'text/plain; charset=utf-8',
  '.wasm': 'application/wasm',
  '.webmanifest': 'application/manifest+json; charset=utf-8',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
};

const server = createServer((req, res) => {
  const url = new URL(req.url ?? '/', 'http://localhost');
  const pathname = decodeURIComponent(url.pathname);
  if (pathname === '/' && url.search === '') {
    res.statusCode = 302;
    res.setHeader('Location', '/ko/signin');
    res.setHeader('Cache-Control', 'no-cache, max-age=0, must-revalidate');
    res.end();
    return;
  }
  const relative = pathname === '/' ? '/index.html' : pathname;
  const candidate = normalize(join(root, relative));

  if (!candidate.startsWith(root)) {
    res.statusCode = 403;
    res.end('Forbidden');
    return;
  }

  let filePath = candidate;
  let servesAppShellFallback = false;

  if (!existsSync(filePath) || statSync(filePath).isDirectory()) {
    if (extname(pathname)) {
      res.statusCode = 404;
      res.setHeader('Cache-Control', 'no-cache, max-age=0, must-revalidate');
      res.end('Not Found');
      return;
    }

    // Flutter web 라우팅 경로(`/ko`, `/ko/signin`)도 index.html로 fallback 처리
    filePath = join(root, 'index.html');
    servesAppShellFallback = true;
  }

  const acceptsBrotli = /\bbr\b/.test(req.headers['accept-encoding'] ?? '');
  const brotliPath = `${filePath}.br`;
  const servedPath = acceptsBrotli && existsSync(brotliPath) ? brotliPath : filePath;
  const ext = extname(filePath);
  const contentType = contentTypes[ext] ?? 'application/octet-stream';
  const stats = statSync(servedPath);
  const etag = `"${stats.size.toString(16)}-${Math.trunc(stats.mtimeMs).toString(16)}"`;
  const cacheControl = cacheControlFor(pathname, filePath, servesAppShellFallback);

  res.setHeader('Content-Type', contentType);
  res.setHeader('ETag', etag);
  res.setHeader('Last-Modified', stats.mtime.toUTCString());
  res.setHeader('Cache-Control', cacheControl);
  res.setHeader('Vary', 'Accept-Encoding');

  // Flutter WASM requires SharedArrayBuffer which needs these COOP/COEP headers
  // to be cross-origin isolated in most modern browsers (WebKit, Firefox, etc.)
  res.setHeader('Cross-Origin-Opener-Policy', 'same-origin');
  res.setHeader('Cross-Origin-Embedder-Policy', 'require-corp');

  if (servedPath === brotliPath) {
    res.setHeader('Content-Encoding', 'br');
  }

  if (req.headers['if-none-match'] === etag) {
    res.statusCode = 304;
    res.end();
    return;
  }

  createReadStream(servedPath)
    .on('error', () => {
      res.statusCode = 500;
      res.end('Internal Server Error');
    })
    .pipe(res);
});

function cacheControlFor(pathname, filePath, servesAppShellFallback) {
  const basename = filePath.split('/').pop() ?? '';

  if (
    servesAppShellFallback ||
    basename === 'index.html' ||
    basename === 'flutter_bootstrap.js' ||
    basename === 'flutter_service_worker.js' ||
    basename === 'version.json' ||
    basename === 'manifest.json'
  ) {
    return 'no-cache, max-age=0, must-revalidate';
  }

  if (/^\/canvaskit\/.*\.(?:js|wasm)$/i.test(pathname)) {
    return 'public, max-age=31536000, immutable';
  }

  if (/^\/main\.dart\.[0-9a-f]{12}\.(?:js|mjs|wasm)$/i.test(pathname)) {
    return 'public, max-age=31536000, immutable';
  }

  if (/\.(?:png|ico|svg|webp|woff|woff2)$/i.test(pathname)) {
    return 'public, max-age=31536000, immutable';
  }

  if (/\.(?:js|css|json|mjs|wasm)$/i.test(pathname)) {
    return 'no-cache, max-age=0, must-revalidate';
  }

  return 'no-cache, max-age=0, must-revalidate';
}

server.listen(port, '127.0.0.1', () => {
  console.log(`[userfront-e2e] serving ${root} at http://127.0.0.1:${port}`);
});