// frontend-server.js
import dotenv from 'dotenv';
import express from 'express';
import path from 'path';
import { fileURLToPath } from 'url';
import { createProxyMiddleware } from 'http-proxy-middleware';
import logger from './common/logger.js';

dotenv.config({ quiet: true });

const frontendApp = express();
const backEndPort = parseInt(process.env.BACKEND_PORT || 11966, 10);
const frontEndPort = parseInt(process.env.FRONTEND_PORT || 18966, 10);

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

// API Proxy to backend server
frontendApp.use('/api', createProxyMiddleware({ 
  target: `http://localhost:${backEndPort}/api`,
  changeOrigin: true
}));

// Set static file directory.
// Cache-Control is set per-asset class so the static layer behaves well
// even when no CDN sits in front of it (CF in production sets its own
// Browser TTL on top of these, so the longer values are upper bounds):
//   - dist/assets/**       Vite-hashed JS/CSS/images — content-addressed → 1y immutable
//   - dist/fonts/**        non-hashed but essentially never change → 1y immutable
//   - favicons/**          connectivity-target icons → 30d; not hashed,
//                          but a changed icon ships under a new member id
//                          (= new filename), so long caching is safe
//   - non-hashed images    favicon / logos / achievements / … → 7d
//                          (any depth; not content-hashed, so changing one
//                          of these images requires renaming the file)
//   - HTML + manifest +    24h at the edge (s-maxage), zero in browsers — the
//     SEO surfaces         build's postbuild purge evicts them on deploy, so
//                          the TTL only caps drift between deploys and no
//                          browser copy outlives a purge; manifest references
//                          only stable /logos/* paths, so a stale copy never
//                          points at dead assets
//   - everything else      (ads.txt, …) → 1h
const distDir = path.join(__dirname, './dist');

// Root-level SEO / AI-engine surfaces
const SEO_SURFACES = new Set(['llms.txt', 'llms-full.txt', 'sitemap.xml', 'robots.txt']);

function setStaticHeaders(res, filePath) {
  const rel = path.relative(distDir, filePath).replaceAll(path.sep, '/');

  if (rel.startsWith('assets/') || rel.startsWith('fonts/')) {
    res.setHeader('Cache-Control', `public, max-age=${24 * 60 * 60 * 365}, immutable`);
  } else if (rel.startsWith('favicons/')) {
    res.setHeader('Cache-Control', `public, max-age=${30 * 24 * 60 * 60}`);
  } else if (/\.(png|jpg|jpeg|webp|svg|ico)$/i.test(rel)) {
    res.setHeader('Cache-Control', `public, max-age=${7 * 24 * 60 * 60}`);
  } else if (rel.endsWith('.html') || rel === 'manifest.webmanifest' || SEO_SURFACES.has(rel)) {
    res.setHeader('Cache-Control', `public, max-age=0, s-maxage=${24 * 60 * 60}, must-revalidate`);
  } else {
    res.setHeader('Cache-Control', `public, max-age=${60 * 60}`);
  }
}

frontendApp.use(express.static(distDir, { setHeaders: setStaticHeaders }));

// SPA history fallback. The app uses HTML5 history routing (e.g. /tools/whois),
// so a hard load / new-tab of a client route reaches this server as a real
// path with no matching file. Serve index.html for navigation requests and let
// vue-router resolve the route. Mounted after the /api proxy and the static
// layer, so real assets and API calls are untouched.
//   - GET only; other methods fall through.
//   - `req.accepts('html')` gates on navigations: browsers asking for a page
//     send `Accept: text/html`.
//   - A path whose final segment has a file extension (e.g. /assets/x.js) is an
//     asset request, not a client route — let it 404 rather than return an HTML
//     body, which would break a missing JS/CSS chunk's importer after a deploy
//     (`*/*` requests otherwise match `accepts('html')`).
//   - Client-route loads stay uncached (unlike / and /index.html on the
//     static layer): only those two URLs live at the edge, so a deploy-time
//     purge stays a two-URL operation.
frontendApp.use((req, res, next) => {
  if (req.method !== 'GET' || !req.accepts('html')) return next();
  if (req.path.split('/').pop().includes('.')) return next();
  res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
  res.sendFile(path.join(distDir, 'index.html'));
});

// Start static file server
frontendApp.listen(frontEndPort, () => {
  logger.info(`🚀 Static file server ready on http://localhost:${frontEndPort}`);
});