import http from 'http';
import os   from 'os';
import fs   from 'fs';

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 server = http.createServer((req, res) => {
  if (req.method === 'GET' && req.url === '/health') {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({
      ok:       true,
      hostname: os.hostname(),
      uptime:   Math.round(process.uptime()),
      version:  VERSION,
      role:     NODE_ROLE,
    }));
  } else {
    res.writeHead(404);
    res.end();
  }
});

// ── 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;
}

// ── Hardware detection ────────────────────────────────────────────────────
// GPU_COUNT / BMD_COUNT env vars override filesystem detection when /dev isn't mapped
function detectHardware() {
  const capabilities = { gpus: [], blackmagic: [] };

  const gpuOverride = parseInt(process.env.GPU_COUNT || '-1', 10);
  if (gpuOverride >= 0) {
    for (let i = 0; i < gpuOverride; i++) {
      capabilities.gpus.push({ device: `/dev/nvidia${i}`, type: 'nvidia', index: i });
    }
  } else {
    for (let i = 0; i < 16; i++) {
      try {
        fs.accessSync(`/dev/nvidia${i}`, fs.constants.F_OK);
        capabilities.gpus.push({ device: `/dev/nvidia${i}`, type: 'nvidia', index: i });
      } catch (_) { break; }
    }
  }

  const bmdOverride = parseInt(process.env.BMD_COUNT || '-1', 10);
  if (bmdOverride >= 0) {
    for (let i = 0; i < bmdOverride; i++) {
      capabilities.blackmagic.push({ device: `/dev/blackmagic/dv${i}`, index: i });
    }
  } else {
    try {
      const bmdEntries = fs.readdirSync('/dev/blackmagic');
      capabilities.blackmagic = bmdEntries.map(d => ({ device: `/dev/blackmagic/${d}` }));
    } catch (_) {}
  }

  return capabilities;
}

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

  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),
    capabilities,
  };

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

  try {
    const res = await fetch(`${MAM_API_URL}/api/v1/cluster/heartbeat`, {
      method:  'POST',
      headers,
      body:    JSON.stringify(payload),
      signal:  AbortSignal.timeout(8000),
    });
    if (res.ok) {
      const gpuStr = capabilities.gpus.length ? `  gpu=${capabilities.gpus.length}` : '';
      const bmdStr = capabilities.blackmagic.length ? `  bmd=${capabilities.blackmagic.length}` : '';
      process.stdout.write(
        `[hb] ${payload.hostname}  cpu=${cpu_usage}%  ` +
        `mem=${payload.mem_used_mb}/${payload.mem_total_mb}MB${gpuStr}${bmdStr}\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);

server.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`);
});