#!/usr/bin/env node
// dev-proxy.js — 本地开发反向代理
// localhost:3000  →  营销站 :3001 / Flutter Web :8888
// /app/* 路由到 Flutter，其余路由到 Eleventy
// 自动把 Flutter index.html 里的 base href="/" 改写为 /app/，使静态资源请求正确走代理

const http = require('http');
const net  = require('net');

const PROXY_PORT    = parseInt(process.env.PROXY_PORT    || '3000', 10);
const ELEVENTY_PORT = parseInt(process.env.ELEVENTY_PORT || '3001', 10);
const FLUTTER_PORT  = parseInt(process.env.FLUTTER_PORT  || '9090', 10);
const BACKEND_PORT  = parseInt(process.env.BACKEND_PORT  || '8080', 10);

function isFlutter(url) {
  return url === '/app' || url.startsWith('/app/');
}

function isBackend(url) {
  return url.startsWith('/api/') || url === '/health' || url.startsWith('/images/');
}

function stripApp(url) {
  return url.slice(4) || '/';
}

function proxyHttp(req, res, port, path) {
  const opts = {
    hostname: 'localhost',
    port,
    path,
    method: req.method,
    headers: { ...req.headers, host: `localhost:${port}` },
  };

  const pr = http.request(opts, (upstream) => {
    const ct = upstream.headers['content-type'] || '';

    if (port === FLUTTER_PORT && ct.includes('text/html')) {
      let body = '';
      upstream.setEncoding('utf8');
      upstream.on('data', (c) => { body += c; });
      upstream.on('end', () => {
        // rewrite base href so Flutter asset requests stay under /app/
        body = body.replace(/(<base\s+href=")[^"]*(")/i, '$1/app/$2');
        const headers = { ...upstream.headers };
        headers['content-length'] = Buffer.byteLength(body);
        delete headers['transfer-encoding'];
        res.writeHead(upstream.statusCode, headers);
        res.end(body);
      });
    } else {
      res.writeHead(upstream.statusCode, upstream.headers);
      upstream.pipe(res, { end: true });
    }
  });

  pr.on('error', () => res.writeHead(502).end('upstream error'));
  req.pipe(pr, { end: true });
}

const server = http.createServer((req, res) => {
  if (isFlutter(req.url)) {
    proxyHttp(req, res, FLUTTER_PORT, stripApp(req.url));
  } else if (isBackend(req.url)) {
    proxyHttp(req, res, BACKEND_PORT, req.url);
  } else {
    proxyHttp(req, res, ELEVENTY_PORT, req.url);
  }
});

// WebSocket 透传（Eleventy 热重载 / Flutter DevTools）
server.on('upgrade', (req, socket, head) => {
  const port = isFlutter(req.url) ? FLUTTER_PORT
    : isBackend(req.url) ? BACKEND_PORT
    : ELEVENTY_PORT;
  const path = isFlutter(req.url) ? stripApp(req.url) : req.url;

  const conn = net.createConnection(port, 'localhost', () => {
    conn.write(`${req.method} ${path} HTTP/1.1\r\n`);
    for (const [k, v] of Object.entries(req.headers)) {
      conn.write(`${k}: ${v}\r\n`);
    }
    conn.write('\r\n');
    if (head && head.length) conn.write(head);
    socket.pipe(conn);
    conn.pipe(socket);
  });

  conn.on('error', () => socket.destroy());
  socket.on('error', () => conn.destroy());
});

server.listen(PROXY_PORT, () => {
  console.log(`[proxy] http://localhost:${PROXY_PORT}`);
  console.log(`  /      → Eleventy   :${ELEVENTY_PORT}`);
  console.log(`  /app/  → Flutter Web :${FLUTTER_PORT}`);
});