// 常驻 CDP 桥：只与 Chrome 建立一条长连接，对外提供本地 HTTP 接口
import http from 'node:http';
import { connect, evaluate, saveJson } from './lib.mjs';

const BRIDGE_PORT = 65177;
let cdp = null;
let sessionId = null;
let attachedTargetId = null;
let reconnects = 0;

async function ensureConnected() {
  if (cdp && cdp.ws && cdp.ws.readyState === 1) return cdp;
  console.log('[bridge] connecting to Chrome...');
  cdp = await connect({ timeoutMs: 45000 });
  sessionId = null;
  attachedTargetId = null;
  reconnects++;
  console.log(`[bridge] connected port=${cdp.port} reconnects=${reconnects}`);
  cdp.ws.addEventListener('close', () => {
    console.log('[bridge] ws closed');
    sessionId = null;
    attachedTargetId = null;
  });
  return cdp;
}

async function ensureAttached(urlMatch) {
  const c = await ensureConnected();
  if (sessionId && attachedTargetId) {
    // 验证 session 仍有效
    try {
      await c.send('Runtime.evaluate', { expression: '1', returnByValue: true }, sessionId);
      return sessionId;
    } catch {
      sessionId = null;
      attachedTargetId = null;
    }
  }
  const { targetInfos } = await c.send('Target.getTargets');
  let page = targetInfos.find(t => t.type === 'page' && t.url.includes(urlMatch));
  if (!page) {
    const created = await c.send('Target.createTarget', { url: 'https://' + urlMatch + '/', background: false });
    await new Promise(r => setTimeout(r, 3000));
    const t2 = await c.send('Target.getTargets');
    page = t2.targetInfos.find(t => t.targetId === created.targetId);
  }
  if (!page) throw new Error('no page matching ' + urlMatch);
  const res = await c.send('Target.attachToTarget', { targetId: page.targetId, flatten: true });
  sessionId = res.sessionId;
  attachedTargetId = page.targetId;
  await c.send('Runtime.enable', {}, sessionId).catch(() => {});
  return sessionId;
}

const server = http.createServer(async (req, res) => {
  const reply = (code, obj) => {
    res.writeHead(code, { 'content-type': 'application/json; charset=utf-8' });
    res.end(JSON.stringify(obj));
  };

  if (req.url === '/health') {
    try {
      const c = await ensureConnected();
      return reply(200, { ok: true, port: c.port, attached: !!sessionId, reconnects });
    } catch (e) {
      return reply(500, { ok: false, error: e.message });
    }
  }

  if (req.method === 'POST' && req.url === '/eval') {
    let body = '';
    for await (const chunk of req) body += chunk;
    try {
      const { expr, urlMatch = 'baijiahao.baidu.com', save } = JSON.parse(body);
      const sid = await ensureAttached(urlMatch);
      const value = await evaluate(cdp, sid, expr);
      if (save) saveJson(save, value);
      return reply(200, { ok: true, value });
    } catch (e) {
      return reply(500, { ok: false, error: e.message });
    }
  }

  reply(404, { ok: false, error: 'unknown endpoint' });
});

server.listen(BRIDGE_PORT, '127.0.0.1', () => {
  console.log(`[bridge] listening on http://127.0.0.1:${BRIDGE_PORT}`);
});

// 保持连接活跃
setInterval(async () => {
  try {
    if (cdp && cdp.ws && cdp.ws.readyState === 1) {
      await cdp.send('Target.getTargets').catch(() => {});
    } else {
      await ensureConnected();
    }
  } catch (e) {
    console.log('[bridge] keepalive error: ' + e.message);
  }
}, 25000);