// 零依赖本地热重载静态服务器 — pangolin 原型单源预览
// 用法: node design/prototype/serve.mjs [port]   默认 5180
// 评审给 URL,不截图(ds-flow L3)。
import http from 'node:http';
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { spawn } from 'node:child_process';

const ROOT = path.dirname(fileURLToPath(import.meta.url));
const PORT = Number(process.argv[2]) || 5180;

const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.mjs': 'text/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.svg': 'image/svg+xml',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.woff2': 'font/woff2',
  '.otf': 'font/otf',
  '.ttf': 'font/ttf',
};

const clients = new Set();
const RELOAD_SNIPPET = `\n<script>
(function(){ try{
  var es=new EventSource('/__reload');
  es.onmessage=function(){ location.reload(); };
}catch(e){} })();
</script>\n`;

const server = http.createServer((req, res) => {
  if (req.url === '/__reload') {
    res.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      Connection: 'keep-alive',
    });
    res.write('retry: 500\n\n');
    clients.add(res);
    req.on('close', () => clients.delete(res));
    return;
  }

  let urlPath = decodeURIComponent(req.url.split('?')[0]);
  if (urlPath === '/') urlPath = '/index.html';
  const filePath = path.join(ROOT, urlPath);
  if (!filePath.startsWith(ROOT)) { res.writeHead(403); res.end('forbidden'); return; }

  fs.readFile(filePath, (err, data) => {
    if (err) { res.writeHead(404, { 'Content-Type': 'text/html; charset=utf-8' }); res.end('<h1>404</h1>'); return; }
    const ext = path.extname(filePath).toLowerCase();
    const mime = MIME[ext] || 'application/octet-stream';
    const noCache = { 'Cache-Control': 'no-store, no-cache, must-revalidate', 'Pragma': 'no-cache', 'Expires': '0' };
    if (ext === '.html') {
      const html = data.toString('utf8').replace('</body>', RELOAD_SNIPPET + '</body>');
      res.writeHead(200, { 'Content-Type': mime, ...noCache });
      res.end(html);
    } else {
      res.writeHead(200, { 'Content-Type': mime, ...noCache });
      res.end(data);
    }
  });
});

// 设计系统守门:启动 + 每次改动自动跑 check-ds.mjs(Phase 5 建立后生效)。
const CHECK_DS = path.join(ROOT, 'tools', 'check-ds.mjs');
function runDsCheck() {
  if (!fs.existsSync(CHECK_DS)) return; // Phase 5 前无闸,静默跳过
  const p = spawn(process.execPath, [CHECK_DS], { cwd: ROOT });
  let out = '';
  p.stdout.on('data', d => out += d);
  p.stderr.on('data', d => out += d);
  p.on('close', code => {
    const t = new Date().toLocaleTimeString();
    if (code === 0) console.log(`\x1b[32m[设计系统 ✓ ${t}] 颜色全部走 token、变量均已定义\x1b[0m`);
    else console.log(`\x1b[31m[设计系统 ✗ ${t}] 存在违规 —— 运行 node tools/check-ds.mjs 看详情\x1b[0m`);
  });
}

let debounce;
fs.watch(ROOT, { recursive: true }, (_ev, file) => {
  if (file && file.endsWith('serve.mjs')) return;
  clearTimeout(debounce);
  debounce = setTimeout(() => {
    for (const c of clients) c.write('data: reload\n\n');
    if (file && /\.(html|css|js)$/.test(file)) runDsCheck();
  }, 80);
});

server.listen(PORT, () => {
  console.log(`prototype live at http://localhost:${PORT}/  (watching ${ROOT})`);
  runDsCheck();
});