import 'dotenv/config';
import express from 'express';
import cors from 'cors';
import session from 'express-session';
import ConnectPgSimple from 'connect-pg-simple';
import os from 'node:os';
import { exec } from 'node:child_process';
import pool from './db/pool.js';
import { errorHandler } from './middleware/errors.js';
import { loadS3ConfigFromDb } from './s3/client.js';

// Routes
import authRouter from './routes/auth.js';
import assetsRouter from './routes/assets.js';
import projectsRouter from './routes/projects.js';
import binsRouter from './routes/bins.js';
import jobsRouter from './routes/jobs.js';
import captureRouter from './routes/capture.js';
import uploadRouter from './routes/upload.js';
import recordersRouter from './routes/recorders.js';
import settingsRouter from './routes/settings.js';
import amppRouter from './routes/ampp.js';
import usersRouter    from './routes/users.js';
import groupsRouter   from './routes/groups.js';
import tokensRouter   from './routes/tokens.js';
import sequencesRouter from './routes/sequences.js';
import systemRouter  from './routes/system.js';
import clusterRouter from './routes/cluster.js';
import sdkRouter     from './routes/sdk.js';
import schedulesRouter from './routes/schedules.js';
import metricsRouter  from './routes/metrics.js';
import commentsRouter from './routes/comments.js';
import importsRouter  from './routes/imports.js';
import storageRouter  from './routes/storage.js';
import { startSchedulerLoop, stopSchedulerLoop } from './scheduler.js';
import { startCleanupLoop } from './tasks/cleanupTempSegments.js';

const app  = express();
const PORT = process.env.PORT || 3000;

// ── Middleware ────────────────────────────────────────────────────────────────
// Trust the first proxy (nginx in front of us) so req.ip, req.secure, and
// req.protocol reflect the real client request — required for both the
// login rate-limiter's IP keying and `cookie.secure` cookie issuance.
app.set('trust proxy', 1);

app.use(cors({ origin: true, credentials: true }));
app.use(express.json({ limit: '50mb' }));

const PgSession = ConnectPgSimple(session);

// Session security knobs.
//
// - `secure` is set from SESSION_COOKIE_SECURE (default: true when AUTH_ENABLED).
//   `trust proxy` above tells express-session that x-forwarded-proto can be
//   trusted, so it issues Secure cookies on HTTPS requests forwarded by
//   nginx/Cloudflare even though the proxy → mam-api hop is plain HTTP.
//   Set SESSION_COOKIE_SECURE=false explicitly for local-only HTTP testing.
// - `sameSite: 'lax'` ships the cookie on top-level navigations (including
//   the post-login redirect from /login.html) but blocks cross-site POSTs.
// - Renamed from default `connect.sid` to `df.sid` so it's obvious in DevTools.
// - `rolling: true` refreshes maxAge on every request so an active user
//   doesn't get bounced to login after the 7-day TTL.
const authEnabled = process.env.AUTH_ENABLED === 'true';
const SESSION_SECRET = process.env.SESSION_SECRET
  || (authEnabled
        ? (() => { throw new Error('SESSION_SECRET is required when AUTH_ENABLED=true'); })()
        : 'dev-only-not-for-production');

const SESSION_COOKIE_SECURE = process.env.SESSION_COOKIE_SECURE
  ? process.env.SESSION_COOKIE_SECURE === 'true'
  : authEnabled;   // default: secure cookies whenever auth is on

app.use(
  session({
    name: 'df.sid',
    store: new PgSession({
      pool,
      tableName: 'sessions',
      pruneSessionInterval: 3600,
    }),
    secret:            SESSION_SECRET,
    resave:            false,
    saveUninitialized: false,
    rolling:           true,
    cookie: {
      secure:   SESSION_COOKIE_SECURE,
      httpOnly: true,
      sameSite: 'lax',
      maxAge:   1000 * 60 * 60 * 24 * 7,   // 7 days
    },
  })
);

// ── Health (no auth) ──────────────────────────────────────────────────────────
app.get('/health', (_req, res) => res.json({ status: 'ok' }));

// ── API Routes ────────────────────────────────────────────────────────────────
app.use('/api/v1/auth',      authRouter);
app.use('/api/v1/assets',    assetsRouter);
app.use('/api/v1/projects',  projectsRouter);
app.use('/api/v1/bins',      binsRouter);
app.use('/api/v1/jobs',      jobsRouter);
app.use('/api/v1/capture',   captureRouter);
app.use('/api/v1/upload',    uploadRouter);
app.use('/api/v1/recorders', recordersRouter);
app.use('/api/v1/settings',  settingsRouter);
app.use('/api/v1/ampp',      amppRouter);
app.use('/api/v1/users',     usersRouter);
app.use('/api/v1/groups',    groupsRouter);
app.use('/api/v1/tokens',    tokensRouter);
app.use('/api/v1/sequences', sequencesRouter);
app.use('/api/v1/system',    systemRouter);
app.use('/api/v1/cluster',   clusterRouter);
app.use('/api/v1/sdk',       sdkRouter);
app.use('/api/v1/schedules', schedulesRouter);
app.use('/api/v1/metrics',   metricsRouter);
app.use('/api/v1/assets/:assetId/comments', commentsRouter);
app.use('/api/v1/imports',   importsRouter);
app.use('/api/v1/storage',   storageRouter);

// ── Error handler ─────────────────────────────────────────────────────────────
app.use(errorHandler);

// ── Start ────────────────────────────────────────────────────────────────────
import { readdirSync, readFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';

const __dirnameMig = dirname(fileURLToPath(import.meta.url));
async function runMigrations() {
  // Issue #107 — previously the loop swallowed errors and let the server boot
  // on a half-migrated schema. Now: track applied migrations in a table, run
  // every pending one inside a transaction, and exit non-zero on failure so
  // the orchestrator restarts (and so an operator notices) instead of serving
  // 500s for the next month.
  const dir = join(__dirnameMig, 'db', 'migrations');
  let files = [];
  try { files = readdirSync(dir).filter(f => f.endsWith('.sql')).sort(); } catch { return; }

  await pool.query(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      filename     TEXT PRIMARY KEY,
      applied_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
      checksum_sha TEXT
    )
  `);

  // Allow forcing a re-run via env when iterating locally.
  const force = process.env.MIGRATIONS_FORCE === '1';
  const allowFailures = process.env.MIGRATIONS_ALLOW_FAILURES === '1';

  const appliedRes = await pool.query('SELECT filename FROM schema_migrations');
  const applied = new Set(appliedRes.rows.map(r => r.filename));

  for (const f of files) {
    if (!force && applied.has(f)) continue;
    const sql = readFileSync(join(dir, f), 'utf8');
    const client = await pool.connect();
    try {
      await client.query('BEGIN');
      await client.query(sql);
      await client.query(
        `INSERT INTO schema_migrations (filename) VALUES ($1)
         ON CONFLICT (filename) DO UPDATE SET applied_at = NOW()`,
        [f]
      );
      await client.query('COMMIT');
      console.log('[migration] applied ' + f);
    } catch (err) {
      await client.query('ROLLBACK').catch(() => {});
      console.error('[migration] FAILED ' + f + ': ' + err.message);
      client.release();
      if (allowFailures) continue;
      // Hard fail — better to crash now than serve traffic on a broken schema.
      console.error('[migration] aborting startup. Set MIGRATIONS_ALLOW_FAILURES=1 to override.');
      process.exit(1);
    }
    client.release();
  }
}
await runMigrations();

// Load S3 config from DB so any settings saved via the Settings page override env vars
await loadS3ConfigFromDb();

// ── Cluster self-heartbeat ────────────────────────────────────────────────────
function getLocalIp() {
  // Prefer an explicit override — useful when running inside Docker where
  // os.networkInterfaces() returns container bridge IPs, not the host LAN IP.
  if (process.env.NODE_IP) return process.env.NODE_IP;

  const ifaces = os.networkInterfaces();
  for (const name of Object.keys(ifaces)) {
    for (const iface of (ifaces[name] || [])) {
      if (iface.family === 'IPv4' && !iface.internal) return iface.address;
    }
  }
  return '127.0.0.1';
}

// Detect NVIDIA GPUs available to this container via nvidia-smi.
// Returns an array like [{ index: 0, name: 'Tesla P4', memory_mb: 7680 }, ...]
// or an empty array if nvidia-smi is unavailable or no GPUs found.
function detectGpus() {
  return new Promise(resolve => {
    exec(
      'nvidia-smi --query-gpu=index,name,memory.total --format=csv,noheader,nounits',
      { timeout: 5000 },
      (err, stdout) => {
        if (err || !stdout.trim()) return resolve([]);
        const gpus = stdout.trim().split('\n').map(line => {
          const parts = line.split(',').map(s => s.trim());
          return {
            index:     parseInt(parts[0], 10),
            name:      parts[1] || 'Unknown GPU',
            memory_mb: parseInt(parts[2], 10) || 0,
          };
        }).filter(g => !isNaN(g.index));
        resolve(gpus);
      }
    );
  });
}

async function selfHeartbeat() {
  const load  = os.loadavg()[0];
  const total = os.totalmem();
  const used  = total - os.freemem();
  const gpus  = await detectGpus();

  const capabilities = { gpus, blackmagic: [] };

  pool.query(
    `INSERT INTO cluster_nodes
       (hostname, ip_address, role, version, api_url,
        cpu_usage, mem_used_mb, mem_total_mb, capabilities, last_seen)
     VALUES ($1,$2,'primary',$3,$4,$5,$6,$7,$8,NOW())
     ON CONFLICT (hostname) DO UPDATE SET
       ip_address   = EXCLUDED.ip_address,
       cpu_usage    = EXCLUDED.cpu_usage,
       mem_used_mb  = EXCLUDED.mem_used_mb,
       mem_total_mb = EXCLUDED.mem_total_mb,
       capabilities = EXCLUDED.capabilities,
       last_seen    = NOW()`,
    [
      process.env.NODE_HOSTNAME || os.hostname(),
      getLocalIp(),
      process.env.npm_package_version || null,
      `http://${getLocalIp()}:${PORT}`,
      parseFloat(load.toFixed(2)),
      Math.round(used  / 1024 / 1024),
      Math.round(total / 1024 / 1024),
      JSON.stringify(capabilities),
    ]
  ).catch(err => console.error('[cluster] heartbeat failed:', err.message));
}

setInterval(selfHeartbeat, 30_000);
selfHeartbeat();

const server = app.listen(PORT, () => {
  const authMode = process.env.AUTH_ENABLED === 'true' ? 'ENABLED' : 'DISABLED (set AUTH_ENABLED=true for production)';
  console.log(`MAM API listening on port ${PORT}`);
  console.log(`Authentication: ${authMode}`);
  // Boot the recorder scheduler tick loop after the HTTP server is live so
  // the loop's self-calls to /recorders/:id/start|stop reach a ready socket.
  startSchedulerLoop();

  // Boot the temp-segment cleanup loop (runs hourly).
  startCleanupLoop();
});

// Issue #100 — graceful shutdown. Without this, `docker stop` (SIGTERM) killed
// the process mid-scheduler-tick, leaving Redis connections and Docker
// sockets dangling and producing partial DB writes. Now: stop the scheduler,
// finish in-flight HTTP requests, close PG/Redis pools, and exit cleanly
// (or hard-exit after 25 s if something is stuck).
let _shuttingDown = false;
async function gracefulShutdown(signal) {
  if (_shuttingDown) return;
  _shuttingDown = true;
  console.log(`[shutdown] received ${signal} — closing gracefully…`);

  // Stop accepting new requests + wind down the scheduler tick.
  try { stopSchedulerLoop(); } catch (_) {}

  // Force-exit watchdog so a hung connection can't keep us alive forever.
  const killSwitch = setTimeout(() => {
    console.error('[shutdown] forced exit after 25s timeout');
    process.exit(1);
  }, 25_000);
  killSwitch.unref();

  // Stop the HTTP server (waits for in-flight requests to finish).
  await new Promise(resolve => server.close(resolve));

  // Close DB pool + S3 client + any other resources. Best-effort.
  try { await pool.end(); } catch (e) { console.warn('[shutdown] pool.end:', e.message); }

  console.log('[shutdown] clean exit');
  process.exit(0);
}

process.on('SIGTERM', () => gracefulShutdown('SIGTERM'));
process.on('SIGINT',  () => gracefulShutdown('SIGINT'));
process.on('uncaughtException', (err) => {
  console.error('[fatal] uncaughtException:', err);
  gracefulShutdown('uncaughtException');
});
process.on('unhandledRejection', (reason) => {
  console.error('[fatal] unhandledRejection:', reason);
});