import http from 'node:http';
import { readFileSync } from 'node:fs';
import { resolve, dirname } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = resolve(dirname(fileURLToPath(import.meta.url)), '..');
const port = Number(process.env.UI_PORT || 8856);
const upstream = process.env.UI_UPSTREAM || 'http://127.0.0.1:8855';
const files = new Map([
  ['/', ['AI团队协作台-统一面板-R7.html', 'text/html']],
  ['/index.html', ['AI团队协作台-统一面板-R7.html', 'text/html']],
  ['/ui/workspace.css', ['web/workspace/workspace.css', 'text/css']],
  ['/ui/lucide.min.js', ['web/workspace/lucide.min.js', 'text/javascript']],
]);

export function createUiServer({ target = upstream } = {}) {
  return http.createServer((req, res) => {
    const url = new URL(req.url, 'http://localhost');
    const file = files.get(url.pathname);
    if (file && req.method === 'GET') {
      try {
        const content = readFileSync(resolve(root, file[0]));
        res.writeHead(200, { 'content-type': file[1] + '; charset=utf-8', 'cache-control': 'no-store' });
        res.end(content);
      } catch {
        res.writeHead(500); res.end('UI asset unavailable');
      }
      return;
    }
    if (!url.pathname.startsWith('/api/') && !['/submit', '/xcr', '/xcrb'].includes(url.pathname)) {
      res.writeHead(404); res.end('Not found'); return;
    }
    // Preserve status and download headers from the existing gateway.
    const proxy = http.request(new URL(url.pathname + url.search, target), {
      method: req.method, headers: { ...req.headers, host: new URL(target).host },
    }, (response) => {
      res.writeHead(response.statusCode, response.headers);
      response.pipe(res);
    });
    proxy.setTimeout(120000, () => proxy.destroy(new Error('Upstream timeout')));
    proxy.on('error', () => {
      if (res.headersSent) { res.destroy(); return; }
      res.writeHead(502, { 'content-type': 'application/json; charset=utf-8' });
      res.end(JSON.stringify({ error: '服务暂时无法连接，请确认原协作台和任务引擎已启动。' }));
    });
    req.pipe(proxy);
  });
}

if (process.argv[1] && resolve(process.argv[1]) === fileURLToPath(import.meta.url)) {
  const server = createUiServer();
  server.on('error', (error) => { console.error(error.message); process.exitCode = 1; });
  server.listen(port, '127.0.0.1', () => console.log('Task workspace: http://127.0.0.1:' + port + '/'));
}