/**
 * dev/server.mjs — Orbit's dev static server.
 *
 *   node dev/server.mjs [port]     (default 8080)
 *
 * Why not `python3 -m http.server`? That server sends `Last-Modified`
 * with no `Cache-Control`, so browsers apply HEURISTIC caching to the
 * ES modules. During iterative development the browser then keeps
 * running an OLD js/*.js module graph (stale GameScene.js, stale
 * BuildWindow.js, …) long after the files on disk changed — while
 * re-fetched JSON data is fresh. New data + old JS is exactly how you
 * get "the build console behaves like an older version" no matter how
 * often you clear the JSON cache or hard-reset the game.
 *
 * This server sends `Cache-Control: no-store` on every response, so a
 * normal reload always runs what's on disk. Zero dependencies (node).
 */
import http from 'node:http';
import { promises as fs } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const PORT = Number(process.argv[2] ?? 8080);

const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.mjs': 'text/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.mp4': 'video/mp4',
  '.webm': 'video/webm',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif': 'image/gif',
  '.webp': 'image/webp',
  '.svg': 'image/svg+xml',
  '.otf': 'font/otf',
  '.ttf': 'font/ttf',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
  '.md': 'text/markdown; charset=utf-8',
  '.txt': 'text/plain; charset=utf-8',
};

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://${req.headers.host ?? 'localhost'}`);
  let p = decodeURIComponent(url.pathname);
  if (p.endsWith('/')) p += 'index.html';
  const file = path.normalize(path.join(ROOT, p));
  if (!file.startsWith(ROOT + path.sep) && file !== ROOT) {
    res.writeHead(403).end('forbidden');
    return;
  }
  try {
    const data = await fs.readFile(file);
    res.writeHead(200, {
      'Content-Type': MIME[path.extname(file).toLowerCase()] ?? 'application/octet-stream',
      'Content-Length': data.length,
      // The whole point: browsers must never cache these.
      'Cache-Control': 'no-store, no-cache, must-revalidate',
      Pragma: 'no-cache',
      Expires: '0',
    });
    res.end(data);
  } catch {
    res.writeHead(404, { 'Content-Type': 'text/plain; charset=utf-8', 'Cache-Control': 'no-store' });
    res.end(`404 — not found: ${url.pathname}\n(serving ${ROOT})`);
  }
});

server.listen(PORT, '127.0.0.1', () => {
  console.log(`orbit dev server → http://127.0.0.1:${PORT}  (no-store caching; root ${ROOT})`);
});