import express from 'express';
import os      from 'os';

const MAM_API_URL  = (process.env.MAM_API_URL  || 'http://localhost:3000').replace(/\/$/, '');
const NODE_TOKEN   =  process.env.NODE_TOKEN   || '';
const NODE_ROLE    =  process.env.NODE_ROLE    || 'worker';
const AGENT_PORT   = parseInt(process.env.AGENT_PORT   || '3002',  10);
const HEARTBEAT_MS = parseInt(process.env.HEARTBEAT_MS || '30000', 10);
const VERSION      = '1.0.0';

const app = express();
app.use(express.json());

// ── Health ────────────────────────────────────────────────────────────────
app.get('/health', (_req, res) => {
  res.json({
    ok:       true,
    hostname: os.hostname(),
    uptime:   Math.round(process.uptime()),
    version:  VERSION,
    role:     NODE_ROLE,
  });
});

// ── CPU sampling (500ms window) ───────────────────────────────────────────
function sampleCpu() {
  return new Promise(resolve => {
    const s1 = os.cpus();
    setTimeout(() => {
      const s2 = os.cpus();
      let idle = 0, total = 0;
      s2.forEach((cpu, i) => {
        for (const t of Object.keys(cpu.times)) {
          const d = cpu.times[t] - (s1[i]?.times[t] ?? 0);
          total += d;
          if (t === 'idle') idle += d;
        }
      });
      resolve(total > 0 ? Math.round((1 - idle / total) * 10000) / 100 : 0);
    }, 500);
  });
}

function getIp() {
  for (const ifaces of Object.values(os.networkInterfaces())) {
    const hit = (ifaces || []).find(a => a.family === 'IPv4' && !a.internal);
    if (hit) return hit.address;
  }
  return null;
}

// ── Heartbeat ─────────────────────────────────────────────────────────────
async function heartbeat() {
  const cpu_usage  = await sampleCpu();
  const totalMem   = os.totalmem();
  const freeMem    = os.freemem();
  const ip_address = getIp();

  const payload = {
    hostname:     os.hostname(),
    ip_address,
    role:         NODE_ROLE,
    version:      VERSION,
    api_url:      `http://${ip_address || os.hostname()}:${AGENT_PORT}`,
    cpu_usage,
    mem_used_mb:  Math.round((totalMem - freeMem) / 1048576),
    mem_total_mb: Math.round(totalMem / 1048576),
  };

  const headers = { 'Content-Type': 'application/json' };
  if (NODE_TOKEN) headers['Authorization'] = `Bearer ${NODE_TOKEN}`;

  try {
    const res = await fetch(`${MAM_API_URL}/api/v1/cluster/heartbeat`, {
      method:  'POST',
      headers,
      body:    JSON.stringify(payload),
      signal:  AbortSignal.timeout(8000),
    });
    if (res.ok) {
      process.stdout.write(
        `[hb] ${payload.hostname}  cpu=${cpu_usage}%  ` +
        `mem=${payload.mem_used_mb}/${payload.mem_total_mb}MB\n`
      );
    } else {
      const txt = await res.text().catch(() => '');
      console.error(`[hb] ${res.status}  ${txt.slice(0, 120)}`);
    }
  } catch (err) {
    console.error(`[hb] failed — ${err.message}`);
  }
}

heartbeat();
setInterval(heartbeat, HEARTBEAT_MS);

app.listen(AGENT_PORT, () => {
  console.log(`wild-dragon-node-agent v${VERSION}`);
  console.log(`  Listening  :${AGENT_PORT}`);
  console.log(`  Primary    ${MAM_API_URL}`);
  console.log(`  Role       ${NODE_ROLE}`);
  console.log(`  Heartbeat  every ${HEARTBEAT_MS / 1000}s`);
});