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   || '7436', 10);
const HEARTBEAT_MS = parseInt(process.env.HEARTBEAT_MS || '30000', 10);
const LIVE_DIR     = process.env.LIVE_DIR || '/mnt/NVME/MAM/wild-dragon-live';
const VERSION      = '1.2.0';

// Pick the host's LAN IP. Inside a bridge-mode container,
// os.networkInterfaces() returns the container's docker-bridge IP (172.x),
// not the host's LAN address. Two strategies:
//   1. honour an explicit NODE_IP override (set by onboard-node.sh)
//   2. filter out interfaces that obviously belong to container/virtual
//      bridges and down-rank the docker bridge range so real LAN IPs win
//
// Combine with `network_mode: host` in docker-compose.worker.yml for the
// most reliable result — that lets os.networkInterfaces() see the host's
// real adapters directly.
function getIp() {
  if (process.env.NODE_IP) return process.env.NODE_IP;

  const SKIP_IFACE = /^(lo|docker\d*|br-|veth|cni|flannel|cali|tun|tap|virbr|kube)/i;
  const isContainerBridge = (ip) => /^172\.(1[6-9]|2\d|3[01])\./.test(ip);

  const candidates = [];
  for (const [name, addrs] of Object.entries(os.networkInterfaces())) {
    if (SKIP_IFACE.test(name)) continue;
    for (const a of (addrs || [])) {
      if (a.family !== 'IPv4' || a.internal) continue;
      candidates.push({ name, address: a.address, rank: isContainerBridge(a.address) ? 1 : 0 });
    }
  }
  candidates.sort((a, b) => a.rank - b.rank);
  return candidates.length ? candidates[0].address : null;
}

// ── Docker API helper (talks to local /var/run/docker.sock) ───────────────
function dockerApi(method, path, body = null) {
  return new Promise((resolve, reject) => {
    const options = {
      socketPath: '/var/run/docker.sock',
      path: `/v1.43${path}`,
      method,
      headers: { 'Content-Type': 'application/json' },
    };
    const req = http.request(options, (res) => {
      let data = '';
      res.on('data', chunk => data += chunk);
      res.on('end', () => {
        try { resolve({ status: res.statusCode, data: data ? JSON.parse(data) : {} }); }
        catch { resolve({ status: res.statusCode, data }); }
      });
    });
    req.on('error', reject);
    if (body) req.write(JSON.stringify(body));
    req.end();
  });
}

function readBody(req) {
  return new Promise((resolve, reject) => {
    let data = '';
    req.on('data', chunk => data += chunk);
    req.on('end', () => {
      try { resolve(JSON.parse(data || '{}')); }
      catch { reject(new Error('Invalid JSON')); }
    });
    req.on('error', reject);
  });
}

function jsonResponse(res, status, body) {
  res.writeHead(status, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(body));
}

// ── Sidecar: spawn a capture container on this node ───────────────────────

async function handleSidecarStart(body, res) {
  try {
    const {
      image = 'wild-dragon-capture:latest',
      env = [],
      capturePort = 3001,
      sourceType = 'sdi',
    } = body;

    const binds = [`${LIVE_DIR}:/live`];
    if (sourceType === 'sdi') binds.unshift('/dev/blackmagic:/dev/blackmagic');

    const spec = {
      Image: image,
      Env: [...env, `PORT=${capturePort}`],
      HostConfig: {
        NetworkMode: 'host',
        Privileged: true,
        Binds: binds,
      },
    };

    const createRes = await dockerApi('POST', '/containers/create', spec);
    if (createRes.status !== 201) {
      return jsonResponse(res, 502, { error: 'Failed to create container', details: createRes.data });
    }

    const containerId = createRes.data.Id;
    const startRes = await dockerApi('POST', `/containers/${containerId}/start`);
    if (startRes.status !== 204) {
      await dockerApi('DELETE', `/containers/${containerId}?force=true`).catch(() => {});
      return jsonResponse(res, 502, { error: 'Failed to start container', details: startRes.data });
    }

    jsonResponse(res, 201, { containerId, capturePort });
  } catch (err) {
    jsonResponse(res, 500, { error: err.message });
  }
}

async function handleSidecarStop(containerId, res) {
  try {
    await dockerApi('POST', `/containers/${containerId}/stop`).catch(() => {});
    await dockerApi('DELETE', `/containers/${containerId}?force=true`).catch(() => {});
    jsonResponse(res, 200, { ok: true });
  } catch (err) {
    jsonResponse(res, 500, { error: err.message });
  }
}

async function handleSidecarStatus(containerId, res) {
  try {
    const inspectRes = await dockerApi('GET', `/containers/${containerId}/json`);
    if (inspectRes.status !== 200) {
      return jsonResponse(res, 200, { running: false });
    }

    const container = inspectRes.data;
    const running = container.State?.Running || false;
    const startedAt = container.State?.StartedAt;

    // Derive capturePort from the container's env so we know where to poll.
    const portEnv = (container.Config?.Env || []).find(e => e.startsWith('PORT='));
    const capturePort = portEnv ? parseInt(portEnv.split('=')[1], 10) : 3001;

    let live = null;
    if (running) {
      try {
        const captureRes = await fetch(`http://127.0.0.1:${capturePort}/capture/status`, {
          signal: AbortSignal.timeout(2000),
        });
        if (captureRes.ok) live = await captureRes.json();
      } catch (_) {}
    }

    jsonResponse(res, 200, { running, startedAt, live });
  } catch (err) {
    jsonResponse(res, 500, { error: err.message });
  }
}

// ── 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);
  });
}

// ── Hardware detection ────────────────────────────────────────────────────
// GPU_COUNT / BMD_COUNT env vars override filesystem detection when /dev isn't mapped
function detectGpusViaSmi() {
  // Run nvidia-smi in the host's mount namespace via nsenter so it uses the
  // host's glibc and NVIDIA driver libs (not the container's Alpine libc).
  // Requires pid: host in docker-compose so we can access /proc/1/ns/mnt.
  // Falls back to direct nvidia-smi call (works if container has glibc).
  // Returns null if nvidia-smi isn't available — caller falls back to /dev scan.
  const { execFileSync } = require('child_process');
  const QUERY = '--query-gpu=index,name,memory.total,driver_version';
  const FMT   = '--format=csv,noheader,nounits';

  const attempts = [
    // nsenter into host mount ns (preferred — uses host glibc)
    () => execFileSync('nsenter', ['--mount=/proc/1/ns/mnt', '--', 'nvidia-smi', QUERY, FMT],
                       { timeout: 8000, encoding: 'utf8' }),
    // Direct call (works if container has compatible glibc)
    () => execFileSync('nvidia-smi', [QUERY, FMT],
                       { timeout: 5000, encoding: 'utf8' }),
  ];

  for (const attempt of attempts) {
    try {
      const out = attempt();
      return out.trim().split('\n').filter(Boolean).map(line => {
        const [idx, name, memMiB, driver] = line.split(',').map(s => s.trim());
        return {
          index:     parseInt(idx, 10),
          name:      name,
          memory_mb: parseInt(memMiB, 10),
          driver:    driver,
          device:    `/dev/nvidia${idx}`,
          type:      'nvidia',
        };
      });
    } catch (_) {}
  }
  return null; // all attempts failed — caller falls back to /dev scan
}

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${i}`, type: 'nvidia', index: i });
    }
  } else {
    // Try nvidia-smi first for full GPU details; fall back to /dev file scan
    const smiGpus = detectGpusViaSmi();
    if (smiGpus !== null) {
      capabilities.gpus = smiGpus;
    } else {
      for (let i = 0; i < 16; i++) {
        try {
          fs.accessSync(`/dev/nvidia${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${i}`, index: i });
    }
  } else {
    try {
      const bmdEntries = fs.readdirSync('/dev/blackmagic');
      capabilities.blackmagic = bmdEntries.map((d, i) => ({ device: `/dev/blackmagic/${d}`, index: i }));
    } catch (_) {}
  }

  // Best-effort model name from BMD_MODEL env (set manually) — used by the UI
  // to render the correct card layout (Duo 2, Quad 2, Mini Recorder, ...).
  if (process.env.BMD_MODEL) capabilities.blackmagic_model = process.env.BMD_MODEL;

  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] ${payload.hostname}  ip=${ip_address || '?'}  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);

// ── HTTP server ───────────────────────────────────────────────────────────
const server = http.createServer((req, res) => {
  const { pathname } = new URL(req.url, 'http://localhost');

  if (req.method === 'GET' && pathname === '/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,
      ip:       getIp(),
    }));

  } else if (req.method === 'POST' && pathname === '/sidecar/start') {
    readBody(req)
      .then(body => handleSidecarStart(body, res))
      .catch(() => jsonResponse(res, 400, { error: 'Invalid request body' }));

  } else if (req.method === 'DELETE' && pathname.startsWith('/sidecar/')) {
    const id = pathname.slice('/sidecar/'.length);
    if (!id || id.includes('/')) { res.writeHead(404); return res.end(); }
    handleSidecarStop(id, res);

  } else if (req.method === 'GET' && /^\/sidecar\/[^/]+\/status$/.test(pathname)) {
    const id = pathname.slice('/sidecar/'.length, -'/status'.length);
    handleSidecarStatus(id, res);

  } else {
    res.writeHead(404);
    res.end();
  }
});

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