import express from 'express';
import https from 'https';
import { Readable } from 'node:stream';
import path from 'path';
import fs from 'fs';
import fsPromises from 'fs/promises';
import { fileURLToPath } from 'url';
import process from 'process';
import { spawn } from 'child_process';
import { WebcamClient } from './webcamClient.js';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
app.use(express.json({ limit: '20mb' }));

const PORT = parseInt(process.env.PORT || process.env.HTTPS_PORT || '2093', 10);
const publicDir = path.join(__dirname, '..', 'public');
const snapshotsDir = path.join(publicDir, 'snapshots');
const WEBCAM_URL = process.env.WEBCAM_URL || '';
const BODYTRACKER_URL = process.env.BODYTRACKER_URL || '';
const HTTPS_KEY_PATH = process.env.HTTPS_KEY_PATH || path.join(__dirname, '..', 'https', 'localhost.key');
const HTTPS_CERT_PATH = process.env.HTTPS_CERT_PATH || path.join(__dirname, '..', 'https', 'localhost.pem');
const HTTPS_PASSPHRASE = process.env.HTTPS_PASSPHRASE || 'abcd';

app.use(express.static(publicDir));

app.get('/api/health', (req, res) => {
  res.json({ ok: true, mode: 'backend-proxy', webcamUrl: WEBCAM_URL || null, bodyTrackerUrl: BODYTRACKER_URL || null });
});

// ── WebCam-Proxy ─────────────────────────────────────────────────────────────

/** Kameraliste mit Metadaten (inkl. calibrationUrl falls Kalibrierung vorhanden). */
app.get('/api/webcam/cameras', async (req, res) => {
  if (!WEBCAM_URL) return res.status(501).json({ error: 'WEBCAM_URL ist nicht konfiguriert' });
  try {
    const wc = new WebcamClient(WEBCAM_URL);
    const data = await wc.getCameras();
    return res.json(data);
  } catch (err) {
    console.error('webcam/cameras error:', err);
    return res.status(502).json({ error: 'WebCam-Fehler', details: String(err) });
  }
});

/**
 * HD-JPEG einer Kamera (per Default hires).
 * Streamt die JPEG-Antwort direkt durch — kein Buffering im Backend.
 * Query-Parameter: ?hires=false für Live-Auflösung.
 */
app.get('/api/webcam/snapshot/:id', async (req, res) => {
  if (!WEBCAM_URL) return res.status(501).json({ error: 'WEBCAM_URL ist nicht konfiguriert' });
  const hires = req.query.hires !== 'false';
  try {
    const wc = new WebcamClient(WEBCAM_URL);
    const upstream = await wc.getSnapshot(req.params.id, hires);

    // Relevante Response-Header durchreichen
    res.setHeader('Content-Type', upstream.headers.get('content-type') || 'image/jpeg');
    res.setHeader('Cache-Control', 'no-store');
    for (const header of ['x-camera-id', 'x-frame-width', 'x-timestamp', 'content-length']) {
      const val = upstream.headers.get(header);
      if (val) res.setHeader(header, val);
    }

    const nodeStream = Readable.fromWeb(upstream.body);
    nodeStream.on('error', (err) => {
      console.error(`webcam/snapshot/${req.params.id} stream error:`, err);
      if (!res.headersSent) res.status(502).json({ error: 'Stream-Fehler' });
    });
    nodeStream.pipe(res);
  } catch (err) {
    console.error(`webcam/snapshot/${req.params.id} error:`, err);
    if (!res.headersSent) res.status(502).json({ error: 'WebCam-Fehler', details: String(err) });
  }
});

async function findLatestSnapshotFile() {
  const files = await fsPromises.readdir(snapshotsDir);
  const entries = await Promise.all(
    files
      .filter((name) => name.endsWith('.csv'))
      .map(async (name) => ({
        name,
        mtime: (await fsPromises.stat(path.join(snapshotsDir, name))).mtime.valueOf()
      }))
  );
  if (entries.length === 0) return null;
  entries.sort((a, b) => b.mtime - a.mtime);
  return entries[0].name;
}

app.get('/api/latest-snapshot', async (req, res) => {
  try {
    if (WEBCAM_URL) {
      const url = new URL('/api/latest-snapshot', WEBCAM_URL).toString();
      const fetchRes = await fetch(url);
      const contentType = fetchRes.headers.get('content-type') || '';

      if (!fetchRes.ok) {
        const text = await fetchRes.text();
        return res.status(fetchRes.status).type('text/plain').send(text);
      }

      if (contentType.includes('application/json')) {
        const body = await fetchRes.json();
        return res.json(body);
      }

      const text = await fetchRes.text();
      return res.json({ filename: 'latest.csv', mtime: new Date().toISOString(), content: text });
    }

    const latestFile = await findLatestSnapshotFile();
    if (!latestFile) {
      return res.status(404).json({ error: 'Keine Snapshot-CSV-Datei gefunden' });
    }

    const baseName = path.basename(latestFile, path.extname(latestFile));
    const csvPath = path.join(snapshotsDir, latestFile);
    const jsonPath = path.join(snapshotsDir, `${baseName}.json`);
    const imagePath = path.join(snapshotsDir, `${baseName}_annotated.jpg`);
    const imagePath2 = path.join(snapshotsDir, `${baseName}_annotated2.jpg`);

    const content = await fsPromises.readFile(csvPath, 'utf8');
    const result = { filename: latestFile, mtime: (await fsPromises.stat(csvPath)).mtime.toISOString(), content };

    try {
      result.jsonFile = { filename: `${baseName}.json`, content: await fsPromises.readFile(jsonPath, 'utf8') };
    } catch {}

    try {
      const jpg = await fsPromises.readFile(imagePath);
      result.imageFile = {
        filename: path.basename(imagePath),
        mimeType: 'image/jpeg',
        contentBase64: jpg.toString('base64')
      };
    } catch {}

    try {
      const jpg2 = await fsPromises.readFile(imagePath2);
      result.image2 = {
        filename: path.basename(imagePath2),
        mimeType: 'image/jpeg',
        contentBase64: jpg2.toString('base64')
      };
    } catch {}

    return res.json(result);
  } catch (err) {
    console.error('latest-snapshot error:', err);
    return res.status(500).json({ error: 'Fehler beim Laden des Snapshots', details: String(err) });
  }
});

app.post('/api/estimate', async (req, res) => {
  if (!BODYTRACKER_URL) {
    return res.status(501).json({ error: 'BODYTRACKER_URL ist nicht konfiguriert' });
  }

  try {
    const { imageFile, image2, robotIntrinsics } = req.body;
    const formData = new FormData();

    if (imageFile?.contentBase64) {
      const buffer = Buffer.from(imageFile.contentBase64, 'base64');
      formData.append('images', new Blob([buffer], { type: imageFile.mimeType || 'image/jpeg' }), imageFile.filename || 'snapshot.jpg');
    }

    if (image2?.contentBase64) {
      const buffer2 = Buffer.from(image2.contentBase64, 'base64');
      formData.append('images', new Blob([buffer2], { type: image2.mimeType || 'image/jpeg' }), image2.filename || 'snapshot2.jpg');
    }

    if (robotIntrinsics) {
      formData.append('intrinsics', new Blob([JSON.stringify(robotIntrinsics)], { type: 'application/json' }), 'intrinsics.json');
    }

    const estimateUrl = new URL('/v1/estimate', BODYTRACKER_URL).toString();
    const fetchRes = await fetch(estimateUrl, { method: 'POST', body: formData });

    if (!fetchRes.ok) {
      const message = await fetchRes.text();
      return res.status(fetchRes.status).json({ error: 'BodyTracker-Fehler', details: message });
    }

    const body = await fetchRes.json();
    return res.json(body);
  } catch (err) {
    console.error('estimate error:', err);
    return res.status(500).json({ error: 'Fehler beim Aufruf des BodyTracker', details: String(err) });
  }
});

// ── Kalibrierung ─────────────────────────────────────────────────────────────

const calibDataDir = path.join(__dirname, '..', 'data', 'calibration');

/** Timestamp-String im Format YYYYMMDD_HHmmss */
function makeTimestamp() {
  const now = new Date();
  const p = (n, l = 2) => String(n).padStart(l, '0');
  return `${now.getFullYear()}${p(now.getMonth() + 1)}${p(now.getDate())}_${p(now.getHours())}${p(now.getMinutes())}${p(now.getSeconds())}`;
}

/** Neueste Kalibrierungs-Session (Verzeichnisname) oder null */
async function findLatestCalibSession() {
  try {
    await fsPromises.access(calibDataDir);
    const entries = await fsPromises.readdir(calibDataDir, { withFileTypes: true });
    const dirs = entries.filter(e => e.isDirectory()).map(e => e.name).sort().reverse();
    return dirs[0] ?? null;
  } catch {
    return null;
  }
}

/** Liest meta.json einer Session */
async function readCalibMeta(sessionName) {
  try {
    const raw = await fsPromises.readFile(path.join(calibDataDir, sessionName, 'meta.json'), 'utf8');
    return JSON.parse(raw);
  } catch {
    return null;
  }
}

/** Schreibt meta.json einer Session */
async function writeCalibMeta(sessionName, meta) {
  await fsPromises.writeFile(
    path.join(calibDataDir, sessionName, 'meta.json'),
    JSON.stringify(meta, null, 2),
    'utf8'
  );
}

/**
 * Holt Snapshots aller verfügbaren Kameras und speichert sie im Session-Verzeichnis.
 * Dateiname: {cameraId}_{setNr}.jpg  (setNr = 001, 002, …)
 */
async function capturePhotos(sessionName) {
  if (!WEBCAM_URL) throw new Error('WEBCAM_URL ist nicht konfiguriert – keine Kameras erreichbar');

  const wc = new WebcamClient(WEBCAM_URL);
  const data = await wc.getCameras();
  const cameraIds = (data.cameras ?? []).map(c => c.id);
  if (cameraIds.length === 0) throw new Error('Keine Kameras vom WebCam-Service gemeldet');

  // Nächste Set-Nummer bestimmen (höchste vorhandene + 1)
  const sessionDir = path.join(calibDataDir, sessionName);
  const existing = await fsPromises.readdir(sessionDir);
  const maxSet = existing.reduce((max, f) => {
    const m = f.match(/_(\d+)\.jpg$/);
    return m ? Math.max(max, parseInt(m[1], 10)) : max;
  }, 0);
  const setNr = String(maxSet + 1).padStart(3, '0');

  const savedFiles = [];
  for (const camId of cameraIds) {
    const response = await new WebcamClient(WEBCAM_URL).getSnapshot(camId, true);
    const buffer = Buffer.from(await response.arrayBuffer());
    const filename = `${camId}_${setNr}.jpg`;
    await fsPromises.writeFile(path.join(sessionDir, filename), buffer);
    savedFiles.push(filename);
  }

  return { cameraIds, savedFiles, setNr: parseInt(setNr, 10) };
}

/** GET /api/calibration/current — aktuelle Session-Info */
app.get('/api/calibration/current', async (req, res) => {
  try {
    const session = await findLatestCalibSession();
    if (!session) return res.json({ session: null, meta: null });
    const meta = await readCalibMeta(session);
    return res.json({ session, meta });
  } catch (err) {
    return res.status(500).json({ error: String(err) });
  }
});

/** POST /api/calibration/new — neue Session anlegen + erste Fotos */
app.post('/api/calibration/new', async (req, res) => {
  try {
    const ts = makeTimestamp();
    const sessionDir = path.join(calibDataDir, ts);
    await fsPromises.mkdir(sessionDir, { recursive: true });

    const meta = { timestamp: ts, createdAt: new Date().toISOString(), cameras: [], imageSets: 0, imageCount: 0 };
    await writeCalibMeta(ts, meta);

    try {
      const capture = await capturePhotos(ts);
      meta.cameras    = capture.cameraIds;
      meta.imageSets  = capture.setNr;
      meta.imageCount = capture.setNr * capture.cameraIds.length;
      await writeCalibMeta(ts, meta);
      return res.json({ session: ts, meta, savedFiles: capture.savedFiles });
    } catch (captureErr) {
      // Session angelegt, aber Fotos nicht verfügbar → trotzdem OK zurück
      return res.json({ session: ts, meta, warning: String(captureErr) });
    }
  } catch (err) {
    return res.status(500).json({ error: String(err) });
  }
});

/** POST /api/calibration/foto — weitere Fotos für aktuelle Session */
app.post('/api/calibration/foto', async (req, res) => {
  try {
    const session = await findLatestCalibSession();
    if (!session) {
      return res.status(400).json({ error: 'Keine Session vorhanden. Bitte zuerst "Neue Kalibrierung anlegen".' });
    }

    const capture = await capturePhotos(session);

    const meta = await readCalibMeta(session) ?? {
      timestamp: session, createdAt: new Date().toISOString(),
      cameras: [], imageSets: 0, imageCount: 0
    };
    meta.cameras    = capture.cameraIds;
    meta.imageSets  = capture.setNr;
    meta.imageCount = capture.setNr * capture.cameraIds.length;
    await writeCalibMeta(session, meta);

    return res.json({ session, meta, savedFiles: capture.savedFiles });
  } catch (err) {
    return res.status(500).json({ error: String(err) });
  }
});

/**
 * POST /api/calibration/compute
 * Führt scripts/callibriate.py für eine Kamera aus.
 * Body: { camera: "cam0" }
 * Antwortet als Server-Sent Events (SSE): jede Zeile stdout/stderr als
 *   data: {"type":"log","text":"..."}
 * Abschluss:
 *   data: {"type":"done","exitCode":0}
 */
const PYTHON_BIN     = process.env.PYTHON_BIN     || 'python3';
const calibScriptPath = path.join(__dirname, '..', 'scripts', 'callibriate.py');

app.post('/api/calibration/compute', async (req, res) => {
  const { camera } = req.body ?? {};
  if (!camera) return res.status(400).json({ error: '"camera" parameter fehlt' });

  const session = await findLatestCalibSession();
  if (!session) return res.status(400).json({ error: 'Keine Kalibrierungs-Session vorhanden' });

  const sessionDir = path.join(calibDataDir, session);

  // SSE-Header
  res.setHeader('Content-Type',  'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection',    'keep-alive');
  res.flushHeaders();

  const send = (obj) => res.write(`data: ${JSON.stringify(obj)}\n\n`);

  send({ type: 'log', text: `▶ Session:    ${session}` });
  send({ type: 'log', text: `▶ Kamera:     ${camera}` });
  send({ type: 'log', text: `▶ Script:     ${calibScriptPath}` });
  send({ type: 'log', text: '' });

  const proc = spawn(PYTHON_BIN, [
    calibScriptPath,
    '--camera',     camera,
    '--input-dir',  sessionDir,
    '--output-dir', sessionDir,
  ]);

  // stdout zeilenweise weiterleiten
  let stdoutBuf = '';
  proc.stdout.on('data', (chunk) => {
    stdoutBuf += chunk.toString();
    const lines = stdoutBuf.split('\n');
    stdoutBuf = lines.pop();                    // letztes (unvollständiges) Fragment behalten
    for (const line of lines) send({ type: 'log', text: line });
  });

  // stderr als Warnung weiterleiten
  let stderrBuf = '';
  proc.stderr.on('data', (chunk) => {
    stderrBuf += chunk.toString();
    const lines = stderrBuf.split('\n');
    stderrBuf = lines.pop();
    for (const line of lines) send({ type: 'log', text: `[stderr] ${line}` });
  });

  proc.on('error', (err) => {
    send({ type: 'log',  text: `Fehler beim Starten: ${err.message}` });
    send({ type: 'done', exitCode: -1 });
    res.end();
  });

  proc.on('close', (code) => {
    if (stdoutBuf) send({ type: 'log', text: stdoutBuf });   // Rest ausgeben
    if (stderrBuf) send({ type: 'log', text: `[stderr] ${stderrBuf}` });
    send({ type: 'done', exitCode: code });
    res.end();
  });
});

async function checkServiceReachability(name, url) {
  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 5000);
    const res = await fetch(url, { signal: controller.signal });
    clearTimeout(timeout);

    if (!res.ok) {
      console.warn(`${name} ist nicht vollständig erreichbar (${res.status}) unter ${url}`);
      return false;
    }

    console.log(`${name} erreichbar unter ${url}`);
    return true;
  } catch (err) {
    console.warn(`${name} konnte nicht erreicht werden unter ${url}:`, err.message || err);
    return false;
  }
}

async function createHttpsServer() {
  try {
    await fsPromises.access(HTTPS_KEY_PATH);
    await fsPromises.access(HTTPS_CERT_PATH);

    const key = fs.readFileSync(HTTPS_KEY_PATH);
    const cert = fs.readFileSync(HTTPS_CERT_PATH);
    const httpsOptions = { key, cert, passphrase: HTTPS_PASSPHRASE };

    console.log(`HTTPS-Zertifikate geladen: ${HTTPS_KEY_PATH}, ${HTTPS_CERT_PATH}`);
    return https.createServer(httpsOptions, app);
  } catch (err) {
    console.warn('HTTPS-Zertifikate konnten nicht geladen werden:', err.message || err);
    console.warn('Fallback auf HTTP. External proxy muss HTTPS terminieren.');
    return null;
  }
}

async function startServer() {
  if (WEBCAM_URL) {
    await checkServiceReachability('WEBCAM_URL', new URL('/health', WEBCAM_URL).toString());
  }

  if (BODYTRACKER_URL) {
    await checkServiceReachability('BODYTRACKER_URL', new URL('/v1/health', BODYTRACKER_URL).toString());
  }

  const server = await createHttpsServer();
  const isHttps = Boolean(server);
  const listenServer = server || app;

  listenServer.listen(PORT, () => {
    console.log(`appRobotHoming backend listening on port ${PORT} (${isHttps ? 'HTTPS' : 'HTTP'})`);
    console.log(`WEBCAM_URL=${WEBCAM_URL || '<lokal>'}`);
    console.log(`BODYTRACKER_URL=${BODYTRACKER_URL || '<nicht konfiguriert>'}`);
  });
}

startServer().catch((err) => {
  console.error('Fehler beim Starten des Servers:', err);
  console.log('Starte trotzdem den Server weiter...');
  app.listen(PORT, () => {
    console.log(`appRobotHoming backend listening on port ${PORT} (HTTP)`);
    console.log(`WEBCAM_URL=${WEBCAM_URL || '<lokal>'}`);
    console.log(`BODYTRACKER_URL=${BODYTRACKER_URL || '<nicht konfiguriert>'}`);
  });
});