server.js

const express = require('express');
const { spawn, exec } = require('child_process');
const fs = require('fs');
const path = require('path');
const https = require('https');
const crypto = require('node:crypto');
const QRCode = require('qrcode');
const { normalizePairingRequest, runAdbPair } = require('./lib/adb-pair');
const { QR_PAIRING_TIMEOUT_MS, createQrPairingCredentials, findQrPairingEndpoint } = require('./lib/adb-qr');

const app = express();
const PORT = 3000;

app.use(express.json());
// Serve the dashboard with caching disabled. This is a local control panel, so
// always delivering fresh HTML/CSS/JS prevents the browser from showing a stale
// UI (e.g. phantom download prompts or recording badges) after code changes.
app.use(express.static(path.join(__dirname, 'public'), {
  etag: false,
  lastModified: false,
  setHeaders: (res) => {
    res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
    res.setHeader('Pragma', 'no-cache');
    res.setHeader('Expires', '0');
  }
}));

// Global state variables
let scrcpyProcess = null;
let downloadProgress = { active: false, progress: 0, downloaded: 0, total: 0 };
let eventClients = [];
let logBuffer = [];
let qrPairingSession = null;
const deviceNameCachePath = path.join(__dirname, 'device-name-cache.json');
let deviceNameCache = { byAdbId: {}, byHardwareId: {}, byHost: {} };
const autoDiscoveryState = {
  lastScanAt: null,
  devices: [],
  scanning: false,
  lastError: null,
  lastHint: '',
  lastConnectAttemptAt: {},
  announcedPairingHosts: {},
  announcedConnectedEndpoints: {}
};

// Helper function to broadcast events to SSE clients
function broadcastEvent(type, data) {
  eventClients.forEach(client => {
    client.write(`event: ${type}\ndata: ${JSON.stringify(data)}\n\n`);
  });
}

// Helper function to log messages and broadcast them
function logMessage(message) {
  const timestamp = new Date().toLocaleTimeString();
  const formattedMessage = `[${timestamp}] ${message}`;
  console.log(formattedMessage);
  logBuffer.push(formattedMessage);
  // Limit buffer to 1000 lines
  if (logBuffer.length > 1000) logBuffer.shift();
  broadcastEvent('log', { message: formattedMessage });
}

function loadDeviceNameCache() {
  try {
    if (!fs.existsSync(deviceNameCachePath)) return;
    const raw = fs.readFileSync(deviceNameCachePath, 'utf8');
    const parsed = JSON.parse(raw);
    deviceNameCache = {
      byAdbId: parsed?.byAdbId || {},
      byHardwareId: parsed?.byHardwareId || {},
      byHost: parsed?.byHost || {}
    };
  } catch (e) {
    logMessage(`Device name cache load warning: ${e.message}`);
    deviceNameCache = { byAdbId: {}, byHardwareId: {}, byHost: {} };
  }
}

function saveDeviceNameCache() {
  try {
    fs.writeFileSync(deviceNameCachePath, JSON.stringify(deviceNameCache, null, 2), 'utf8');
  } catch (e) {
    logMessage(`Device name cache save warning: ${e.message}`);
  }
}

function normalizeHardwareId(value) {
  const cleaned = String(value || '').trim();
  const invalid = new Set([ '', 'unknown', 'null', 'n/a', 'undefined' ]);
  return invalid.has(cleaned.toLowerCase()) ? '' : cleaned;
}

function toTitleCase(value) {
  return String(value || '')
    .trim()
    .split(/\s+/)
    .map((part) => part.charAt(0).toUpperCase() + part.slice(1).toLowerCase())
    .join(' ');
}

function buildDeviceDisplayName(manufacturer, model) {
  const cleanManufacturer = String(manufacturer || '').trim();
  const cleanModel = String(model || '').trim();
  if (cleanManufacturer && cleanModel) {
    const mfrLower = cleanManufacturer.toLowerCase();
    const modelLower = cleanModel.toLowerCase();
    if (modelLower.startsWith(mfrLower)) return cleanModel;
    return `${toTitleCase(cleanManufacturer)} ${cleanModel}`;
  }
  return cleanModel || cleanManufacturer || '';
}

function extractHostFromAdbId(adbId) {
  const match = String(adbId || '').match(/^(\d+\.\d+\.\d+\.\d+):\d+$/);
  return match ? match[ 1 ] : '';
}

// Get the path to Scrcpy binaries
function getPaths() {
  const scrcpyDir = path.join(__dirname, 'scrcpy-win64');
  const adbPath = path.join(scrcpyDir, 'adb.exe');
  const scrcpyPath = path.join(scrcpyDir, 'scrcpy.exe');
  return {
    dir: scrcpyDir,
    adb: adbPath,
    scrcpy: scrcpyPath,
    exists: fs.existsSync(scrcpyDir) && fs.existsSync(adbPath) && fs.existsSync(scrcpyPath)
  };
}

async function resolveDeviceNameInfo(adbId) {
  const paths = getPaths();
  if (!paths.exists || !adbId) return null;

  const escapedId = String(adbId).replace(/"/g, '\\"');
  const modelResult = await runShellCommand(`"${paths.adb}" -s "${escapedId}" shell getprop ro.product.model`, { timeout: 4000 });
  const manufacturerResult = await runShellCommand(`"${paths.adb}" -s "${escapedId}" shell getprop ro.product.manufacturer`, { timeout: 4000 });
  const serialResult = await runShellCommand(`"${paths.adb}" -s "${escapedId}" shell getprop ro.serialno`, { timeout: 4000 });

  const model = String(modelResult.stdout || '').trim();
  const manufacturer = String(manufacturerResult.stdout || '').trim();
  const hardwareId = normalizeHardwareId(serialResult.stdout);
  const name = buildDeviceDisplayName(manufacturer, model);

  if (!name) return null;
  return { name, hardwareId };
}

async function enrichDeviceWithName(device) {
  const knownByAdb = deviceNameCache.byAdbId[ device.id ];
  if (knownByAdb?.name) {
    const hostFromId = extractHostFromAdbId(device.id);
    if (hostFromId) {
      deviceNameCache.byHost[ hostFromId ] = { name: knownByAdb.name };
      saveDeviceNameCache();
    }
    return { ...device, name: knownByAdb.name };
  }

  // Resolve only for active devices to avoid noisy lookups on offline endpoints.
  if (device.status !== 'device') {
    return { ...device, name: null };
  }

  const resolved = await resolveDeviceNameInfo(device.id);
  if (!resolved?.name) {
    return { ...device, name: null };
  }

  if (resolved.hardwareId && deviceNameCache.byHardwareId[ resolved.hardwareId ]?.name) {
    const cached = deviceNameCache.byHardwareId[ resolved.hardwareId ].name;
    deviceNameCache.byAdbId[ device.id ] = { name: cached, hardwareId: resolved.hardwareId };
    const hostFromId = extractHostFromAdbId(device.id);
    if (hostFromId) {
      deviceNameCache.byHost[ hostFromId ] = { name: cached };
    }
    saveDeviceNameCache();
    return { ...device, name: cached };
  }

  deviceNameCache.byAdbId[ device.id ] = { name: resolved.name, hardwareId: resolved.hardwareId || '' };
  if (resolved.hardwareId) {
    deviceNameCache.byHardwareId[ resolved.hardwareId ] = { name: resolved.name };
  }
  const hostFromId = extractHostFromAdbId(device.id);
  if (hostFromId) {
    deviceNameCache.byHost[ hostFromId ] = { name: resolved.name };
  }
  saveDeviceNameCache();

  return { ...device, name: resolved.name };
}

// Parse device list from adb devices command output
function parseDevices(stdout) {
  const lines = stdout.split('\n');
  const devices = [];
  for (let i = 1; i < lines.length; i++) {
    const line = lines[ i ].trim();
    if (line && !line.startsWith('*')) {
      const parts = line.split(/\s+/);
      if (parts.length >= 2) {
        const adbId = parts[ 0 ];
        // Hide mDNS TLS pseudo-devices from UI.
        // They are aliases, not the real connectable endpoint for mirroring.
        if (adbId.includes('._adb-tls-connect._tcp')) {
          continue;
        }
        devices.push({
          id: adbId,
          status: parts[ 1 ]
        });
      }
    }
  }
  return devices;
}

loadDeviceNameCache();

function parseMdnsServicesOutput(output) {
  const lines = String(output || '').split('\n').map((line) => line.trim()).filter(Boolean);
  const byHost = {};

  for (const line of lines) {
    const endpointMatch = line.match(/(\d+\.\d+\.\d+\.\d+):(\d+)/);
    if (!endpointMatch) continue;

    const host = endpointMatch[ 1 ];
    const port = endpointMatch[ 2 ];
    const endpoint = `${host}:${port}`;
    const lower = line.toLowerCase();

    if (!byHost[ host ]) {
      byHost[ host ] = {
        host,
        connectEndpoint: null,
        pairingEndpoint: null
      };
    }

    if (lower.includes('_adb-tls-connect._tcp')) {
      byHost[ host ].connectEndpoint = endpoint;
    } else if (lower.includes('_adb-tls-pairing._tcp')) {
      byHost[ host ].pairingEndpoint = endpoint;
    }
  }

  return Object.values(byHost);
}

async function refreshAutoDiscovery() {
  if (autoDiscoveryState.scanning) {
    return;
  }
  autoDiscoveryState.scanning = true;

  try {
    const paths = getPaths();
    if (!paths.exists) {
      autoDiscoveryState.lastScanAt = new Date().toISOString();
      autoDiscoveryState.devices = [];
      autoDiscoveryState.lastHint = 'Scrcpy/ADB binaries are missing.';
      return;
    }

    await runShellCommand(`"${paths.adb}" start-server`, { timeout: 8000 });
    const mdnsResult = await runShellCommand(`"${paths.adb}" mdns services`, { timeout: 12000 });
    if (mdnsResult.err) {
      autoDiscoveryState.lastScanAt = new Date().toISOString();
      autoDiscoveryState.lastError = (mdnsResult.stderr || mdnsResult.err.message || 'mDNS discovery failed').trim();
      autoDiscoveryState.lastHint = 'Make sure phone and PC are on same Wi-Fi and Wireless Debugging screen is open.';
      return;
    }

    const mdnsHosts = parseMdnsServicesOutput(`${mdnsResult.stdout}\n${mdnsResult.stderr}`);
    const devicesResult = await runShellCommand(`"${paths.adb}" devices`, { timeout: 8000 });
    const connected = parseDevices(devicesResult.stdout || '').filter((d) => d.status === 'device');
    const connectedSet = new Set(connected.map((d) => d.id));

    const discoveryEntries = [];
    const now = Date.now();

    for (const hostEntry of mdnsHosts) {
      const host = hostEntry.host;
      const connectEndpoint = hostEntry.connectEndpoint;
      const pairingEndpoint = hostEntry.pairingEndpoint;
      const cachedName = deviceNameCache.byHost[ host ]?.name || null;
      const displayName = cachedName || 'Unknown Android device';

      let status = 'needs_pairing';
      let detail = 'Pairing is required for first-time devices.';

      if (connectEndpoint) {
        let isConnected = connectedSet.has(connectEndpoint);
        let authRequired = false;
        if (!isConnected) {
          const lastAttempt = autoDiscoveryState.lastConnectAttemptAt[ connectEndpoint ] || 0;
          if (now - lastAttempt > 15000) {
            autoDiscoveryState.lastConnectAttemptAt[ connectEndpoint ] = now;
            const connectResult = await runShellCommand(`"${paths.adb}" connect ${connectEndpoint}`, { timeout: 8000 });
            const connectOutput = `${connectResult.stdout}\n${connectResult.stderr}`.toLowerCase();
            if (connectOutput.includes('connected to') || connectOutput.includes('already connected')) {
              isConnected = true;
              connectedSet.add(connectEndpoint);
              if (!autoDiscoveryState.announcedConnectedEndpoints[ connectEndpoint ]) {
                autoDiscoveryState.announcedConnectedEndpoints[ connectEndpoint ] = true;
                logMessage(`Auto-discovery connected to ${connectEndpoint}.`);
              }
            } else if (
              connectOutput.includes('failed to authenticate') ||
              connectOutput.includes('authentication') ||
              connectOutput.includes('pair')
            ) {
              authRequired = true;
            }
          }
        }

        if (isConnected) {
          status = 'paired_connected';
          detail = 'Already paired and ready to mirror.';
        } else if (authRequired) {
          status = 'waiting_pairing_endpoint';
          detail = 'Pairing required. If scan still shows no pairing endpoint, enter IP/Port from the phone manually.';
        } else {
          status = 'discovered_not_connected';
          detail = 'Discovered but not connected yet. Will keep retrying auto-connect.';
        }
      } else if (pairingEndpoint) {
        detail = 'Pairing required: use this pairing endpoint from your phone screen.';
        if (!autoDiscoveryState.announcedPairingHosts[ host ]) {
          autoDiscoveryState.announcedPairingHosts[ host ] = true;
          logMessage(`Discovered new device at ${host}. Pairing is required before auto-connect.`);
        }
      } else {
        status = 'waiting_pairing_endpoint';
        detail = 'Device discovered, but pairing endpoint is hidden. Use IP/Port shown on phone if scan does not update.';
      }

      discoveryEntries.push({
        host,
        name: displayName,
        connectEndpoint: connectEndpoint || null,
        pairingEndpoint: pairingEndpoint || null,
        status,
        detail
      });
    }

    discoveryEntries.sort((a, b) => {
      const rank = (entry) => (entry.status === 'paired_connected' ? 0 : entry.status === 'discovered_not_connected' ? 1 : 2);
      return rank(a) - rank(b);
    });

    autoDiscoveryState.lastScanAt = new Date().toISOString();
    autoDiscoveryState.devices = discoveryEntries;
    autoDiscoveryState.lastError = null;
    autoDiscoveryState.lastHint = discoveryEntries.length
      ? 'Auto-discovery is active.'
      : 'No devices found yet. Open Wireless Debugging on your phone, then tap Scan.';
  } finally {
    autoDiscoveryState.scanning = false;
  }
}

// Execute adb command
function runAdbCommand(args) {
  return new Promise((resolve, reject) => {
    const paths = getPaths();
    if (!paths.exists) {
      return reject(new Error('Scrcpy / ADB binaries not found. Ensure the scrcpy-win64/ folder is present.'));
    }
    const adbCmd = `"${paths.adb}" ${args}`;
    logMessage(`Running: adb ${args}`);
    exec(adbCmd, (err, stdout, stderr) => {
      if (err) {
        logMessage(`ADB Error: ${stderr || err.message}`);
        reject(new Error(stderr || err.message));
      } else {
        logMessage(`ADB Output: ${stdout.trim()}`);
        resolve(stdout);
      }
    });
  });
}

// Execute shell command and always resolve with output details.
function runShellCommand(command, options = {}) {
  return new Promise((resolve) => {
    exec(command, options, (err, stdout, stderr) => {
      resolve({
        err,
        stdout: stdout || '',
        stderr: stderr || ''
      });
    });
  });
}

function getPublicQrPairingSession(session = qrPairingSession, includeQrData = false) {
  if (!session) return null;
  return {
    id: session.id,
    status: session.status,
    ...(includeQrData ? { qrDataUrl: session.qrDataUrl } : {}),
    message: session.message,
    startedAt: session.startedAt,
    expiresAt: session.expiresAt,
    endpoint: session.endpoint || null
  };
}

async function runQrPairingSession(session) {
  const paths = getPaths();
  while (!session.cancelled && Date.now() < session.expiresAt) {
    const mdns = await runShellCommand(`"${paths.adb}" mdns services`, { timeout: 6000 });
    if (session.cancelled) return;

    const endpoint = findQrPairingEndpoint(`${mdns.stdout}\n${mdns.stderr}`, session.serviceName);
    if (endpoint) {
      session.status = 'pairing';
      session.endpoint = endpoint;
      session.message = `Phone found at ${endpoint}. Completing secure pairing...`;
      logMessage(`QR pairing phone discovered at ${endpoint}.`);
      try {
        const result = await runAdbPair({
          adbPath: paths.adb,
          cwd: paths.dir,
          endpoint,
          code: session.password,
          timeoutMs: 30000,
          onOutput: ({ stream, text }) => {
            const cleanText = text.trim();
            if (cleanText) logMessage(`adb QR pair${stream === 'stderr' ? ' error' : ''}: ${cleanText}`);
          }
        });
        if (session.cancelled) return;
        session.status = 'paired';
        session.message = result.message || `Successfully paired to ${endpoint}`;
        logMessage(`QR pairing completed for ${endpoint}.`);
        refreshAutoDiscovery();
      } catch (error) {
        if (session.cancelled) return;
        session.status = 'failed';
        session.message = error.message || 'QR pairing failed.';
        logMessage(`QR pairing failed for ${endpoint}: ${session.message}`);
      }
      return;
    }

    await new Promise((resolve) => setTimeout(resolve, 1000));
  }

  if (!session.cancelled) {
    session.status = 'expired';
    session.message = 'QR pairing expired. Generate a new code and try again. If the phone is on another router, mDNS may not cross between the two networks.';
    logMessage('QR pairing expired before the phone was discovered.');
  }
}

function isScrcpyRunning() {
  return new Promise((resolve) => {
    exec('tasklist /FI "IMAGENAME eq scrcpy.exe" /NH', (err, stdout) => {
      if (err) return resolve(false);
      resolve((stdout || '').includes('scrcpy.exe'));
    });
  });
}

// Politely ask every running scrcpy instance to close its main window. This is
// equivalent to the user clicking the window's X button, which lets scrcpy run
// its clean shutdown path and finalize any in-progress MP4 recording (writing
// the moov trailer) so the file remains playable.
function closeScrcpyWindowsGracefully() {
  const psCommand =
    "Get-Process scrcpy -ErrorAction SilentlyContinue | ForEach-Object { $_.CloseMainWindow() | Out-Null }";
  return runShellCommand(`powershell -NoProfile -ExecutionPolicy Bypass -Command "${psCommand}"`);
}

// Poll until scrcpy.exe is no longer running or the timeout elapses.
async function waitForScrcpyExit(timeoutMs) {
  const start = Date.now();
  while (Date.now() - start < timeoutMs) {
    if (!(await isScrcpyRunning())) {
      return true;
    }
    await new Promise((resolve) => setTimeout(resolve, 400));
  }
  return !(await isScrcpyRunning());
}

async function stopScrcpyProcessGracefully({ allowForceFallback = true, isRecording = false } = {}) {
  if (!(await isScrcpyRunning())) {
    return { mode: 'none', output: 'No running scrcpy.exe process found.' };
  }

  // 1) Request a clean window close (finalizes recordings). Also send a plain
  //    taskkill (no /F) as a secondary graceful signal for console-only cases.
  await closeScrcpyWindowsGracefully();
  await runShellCommand('taskkill /IM scrcpy.exe');

  // 2) Allow time to flush/finalize. Recordings need noticeably longer to write
  //    the MP4 trailer, so give them a generous window before considering force.
  const gracePeriodMs = isRecording ? 12000 : 4000;
  if (await waitForScrcpyExit(gracePeriodMs)) {
    return { mode: 'graceful', output: 'scrcpy.exe closed cleanly.' };
  }

  if (!allowForceFallback) {
    return { mode: 'error', output: 'scrcpy.exe did not exit within the grace period.' };
  }

  // 3) Last resort. A forced kill can corrupt an in-progress recording, so this
  //    only runs when the clean close failed to terminate scrcpy in time.
  const forced = await runShellCommand('taskkill /IM scrcpy.exe /T /F');
  if (await waitForScrcpyExit(3000) || !forced.err) {
    return { mode: 'force', output: 'scrcpy.exe force-terminated.' };
  }

  return { mode: 'error', output: (forced.stderr || (forced.err && forced.err.message) || 'Failed to force terminate scrcpy.exe').trim() };
}

// SERVER EVENTS (SSE) Endpoint
app.get('/api/events', (req, res) => {
  res.writeHead(200, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    'Connection': 'keep-alive'
  });

  res.write('\n');
  eventClients.push(res);

  // Send current log history to newly connected client
  res.write(`event: log-history\ndata: ${JSON.stringify({ logs: logBuffer })}\n\n`);

  req.on('close', () => {
    eventClients = eventClients.filter(client => client !== res);
  });
});

// STATUS API
app.get('/api/status', async (req, res) => {
  const paths = getPaths();
  let adbDevices = [];
  let adbRunning = false;

  // Reconcile tracked mirroring/recording state with reality. If we believe a
  // scrcpy session is active but the process is actually gone (window closed,
  // crashed, or finished), clear the stale state so the UI does not show a
  // phantom "mirroring"/"recording" badge on a device that is not being shared.
  // A short grace window avoids false negatives right after launch, since
  // scrcpy.exe can take a moment to appear in the task list.
  if (scrcpyProcess && Date.now() - (scrcpyProcess.startedAt || 0) > 8000) {
    const stillRunning = await isScrcpyRunning();
    if (!stillRunning) {
      const staleDeviceId = scrcpyProcess.deviceId || null;
      if (scrcpyProcess._pollInterval) {
        clearInterval(scrcpyProcess._pollInterval);
      }
      scrcpyProcess = null;
      logMessage('Detected scrcpy is no longer running; cleared stale mirroring state.');
      broadcastEvent('mirroring-ended', { code: 0, deviceId: staleDeviceId });
    }
  }

  if (paths.exists) {
    try {
      // Test adb connectivity
      const stdout = await new Promise((resolve) => {
        exec(`"${paths.adb}" devices`, (err, stdout) => {
          resolve(stdout || '');
        });
      });
      adbDevices = parseDevices(stdout);
      adbDevices = await Promise.all(adbDevices.map((device) => enrichDeviceWithName(device)));
      adbRunning = true;
    } catch (e) {
      adbRunning = false;
    }
  }

  res.json({
    scrcpyInstalled: paths.exists,
    mirroringActive: scrcpyProcess !== null,
    mirroredDeviceId: scrcpyProcess?.deviceId || null,
    recordingActive: !!scrcpyProcess?.recordingEnabled,
    autoDiscovery: {
      lastScanAt: autoDiscoveryState.lastScanAt,
      devices: autoDiscoveryState.devices,
      needsPairingCount: autoDiscoveryState.devices.filter((d) => d.status === 'needs_pairing').length,
      scanning: autoDiscoveryState.scanning,
      lastError: autoDiscoveryState.lastError,
      lastHint: autoDiscoveryState.lastHint
    },
    adbRunning,
    devices: adbDevices,
    downloadState: downloadProgress
  });
});

// DOWNLOAD & EXTRACT SCRCPY
app.post('/api/download', (req, res) => {
  const paths = getPaths();
  if (paths.exists) {
    return res.status(400).json({ error: 'Scrcpy is already downloaded and installed.' });
  }
  if (downloadProgress.active) {
    return res.status(400).json({ error: 'Download is already in progress.' });
  }

  downloadProgress = { active: true, progress: 0, downloaded: 0, total: 0 };
  broadcastEvent('status-change', { downloadState: downloadProgress });

  const zipUrl = 'https://github.com/Genymobile/scrcpy/releases/download/v4.1/scrcpy-win64-v4.1.zip';
  const zipPath = path.join(__dirname, 'scrcpy.zip');

  logMessage(`Starting download of Scrcpy v4.1 from ${zipUrl}...`);

  const file = fs.createWriteStream(zipPath);

  // Follow redirects if necessary
  const downloadFile = (url) => {
    https.get(url, (response) => {
      // Handle redirects
      if (response.statusCode === 302 || response.statusCode === 301) {
        downloadFile(response.headers.location);
        return;
      }

      if (response.statusCode !== 200) {
        logMessage(`Download failed: HTTP Status ${response.statusCode}`);
        downloadProgress.active = false;
        broadcastEvent('status-change', { downloadState: downloadProgress });
        return res.status(500).json({ error: `Download failed: HTTP ${response.statusCode}` });
      }

      const totalLength = parseInt(response.headers[ 'content-length' ], 10);
      downloadProgress.total = totalLength;

      let downloadedLength = 0;

      response.on('data', (chunk) => {
        downloadedLength += chunk.length;
        const pct = totalLength ? Math.round((downloadedLength / totalLength) * 100) : 0;
        downloadProgress.progress = pct;
        downloadProgress.downloaded = downloadedLength;

        broadcastEvent('download-progress', downloadProgress);
      });

      response.pipe(file);

      file.on('finish', () => {
        file.close();
        logMessage('Download completed. Extracting archive...');

        downloadProgress.progress = 100;
        broadcastEvent('download-progress', downloadProgress);

        // Extract archive using PowerShell
        const psCommand = `powershell -Command "Expand-Archive -Path '${zipPath}' -DestinationPath '${__dirname}' -Force"`;
        exec(psCommand, (err, stdout, stderr) => {
          // Cleanup ZIP file
          fs.unlink(zipPath, () => { });

          if (err) {
            logMessage(`Extraction failed: ${stderr || err.message}`);
            downloadProgress.active = false;
            broadcastEvent('status-change', { downloadState: downloadProgress });
            return;
          }

          logMessage('Extraction completed. Organizing files...');

          // Locate the extracted folder and rename to scrcpy-win64
          try {
            const files = fs.readdirSync(__dirname);
            const extractedDir = files.find(f => f.startsWith('scrcpy-win64-') && fs.statSync(path.join(__dirname, f)).isDirectory());

            if (extractedDir) {
              const targetPath = path.join(__dirname, 'scrcpy-win64');
              if (fs.existsSync(targetPath)) {
                fs.rmSync(targetPath, { recursive: true, force: true });
              }
              fs.renameSync(path.join(__dirname, extractedDir), targetPath);
              logMessage('Scrcpy successfully set up and ready to use.');
            } else {
              logMessage('Extraction succeeded, but could not find the folder structure. Please verify manually.');
            }
          } catch (renameErr) {
            logMessage(`Error organizing directory: ${renameErr.message}`);
          }

          downloadProgress.active = false;
          broadcastEvent('status-change', { downloadState: downloadProgress });
          broadcastEvent('installed', { success: true });
        });
      });
    }).on('error', (err) => {
      fs.unlink(zipPath, () => { });
      logMessage(`Network Error: ${err.message}`);
      downloadProgress.active = false;
      broadcastEvent('status-change', { downloadState: downloadProgress });
    });
  };

  downloadFile(zipUrl);
  res.json({ message: 'Download started in background' });
});

// KILL ADB SERVER
app.post('/api/kill-server', async (req, res) => {
  try {
    await runAdbCommand('kill-server');
    res.json({ success: true, message: 'ADB server killed successfully' });
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

// ADB QR PAIR (Wireless Debugging Android 11+)
app.post('/api/pair/qr/start', async (req, res) => {
  const paths = getPaths();
  if (!paths.exists) {
    return res.status(400).json({ success: false, error: 'Scrcpy or ADB is missing. Please install it first.' });
  }

  if (qrPairingSession && ['waiting', 'pairing'].includes(qrPairingSession.status)) {
    qrPairingSession.cancelled = true;
  }

  const credentials = createQrPairingCredentials();
  let qrDataUrl;
  try {
    qrDataUrl = await QRCode.toDataURL(credentials.payload, { width: 320, margin: 2, errorCorrectionLevel: 'M' });
  } catch (error) {
    logMessage(`Could not generate pairing QR code: ${error.message}`);
    return res.status(500).json({ success: false, error: 'Could not generate the pairing QR code.' });
  }

  const now = Date.now();
  const session = {
    id: crypto.randomUUID(),
    ...credentials,
    qrDataUrl,
    status: 'waiting',
    message: 'Waiting for the phone to scan the QR code...',
    startedAt: new Date(now).toISOString(),
    expiresAt: now + QR_PAIRING_TIMEOUT_MS,
    endpoint: null,
    cancelled: false
  };
  qrPairingSession = session;
  logMessage('Started a new QR pairing session.');
  runQrPairingSession(session).catch((error) => {
    if (session.cancelled) return;
    session.status = 'failed';
    session.message = error.message || 'QR pairing failed unexpectedly.';
    logMessage(`QR pairing error: ${session.message}`);
  });
  return res.json({ success: true, session: getPublicQrPairingSession(session, true) });
});

app.get('/api/pair/qr/status', (req, res) => {
  if (!qrPairingSession || req.query.id !== qrPairingSession.id) {
    return res.status(404).json({ success: false, error: 'QR pairing session not found.' });
  }
  return res.json({ success: true, session: getPublicQrPairingSession() });
});

app.post('/api/pair/qr/cancel', (req, res) => {
  if (qrPairingSession && (!req.body?.id || req.body.id === qrPairingSession.id)) {
    qrPairingSession.cancelled = true;
    qrPairingSession.status = 'cancelled';
    qrPairingSession.message = 'QR pairing cancelled.';
  }
  return res.json({ success: true });
});

// ADB PAIRING CODE (Wireless Debugging Android 11+)
app.post('/api/pair', async (req, res) => {
  let pairing;
  try {
    pairing = normalizePairingRequest(req.body);
  } catch (error) {
    return res.status(400).json({ success: false, error: error.message });
  }

  const paths = getPaths();
  if (!paths.exists) {
    return res.status(400).json({ success: false, error: 'Scrcpy or ADB is missing. Please install it first.' });
  }

  logMessage(`Attempting to pair with ${pairing.endpoint}...`);

  try {
    const result = await runAdbPair({
      adbPath: paths.adb,
      cwd: paths.dir,
      endpoint: pairing.endpoint,
      code: pairing.code,
      onOutput: ({ stream, text }) => {
        const cleanText = text.trim();
        if (cleanText) {
          logMessage(`adb pair${stream === 'stderr' ? ' error' : ''}: ${cleanText}`);
        }
      }
    });

    logMessage(`Successfully paired to ${pairing.endpoint}!`);
    return res.json({ success: true, message: result.message });
  } catch (error) {
    logMessage(`Pairing failed for ${pairing.endpoint}: ${error.message}`);
    return res.status(500).json({
      success: false,
      error: error.message || 'Pairing failed. Check the IP, port, and fresh pairing code.'
    });
  }
});

// ADB CONNECT
app.post('/api/connect', async (req, res) => {
  const { ip, port } = req.body;
  if (!ip || !port) {
    return res.status(400).json({ error: 'IP and Port are required.' });
  }

  try {
    const stdout = await runAdbCommand(`connect ${ip}:${port}`);
    if (stdout.includes('connected to') || stdout.includes('already connected')) {
      res.json({ success: true, message: stdout.trim() });
    } else {
      res.status(500).json({ success: false, error: stdout.trim() });
    }
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

// ADB DISCONNECT
app.post('/api/disconnect', async (req, res) => {
  try {
    const stdout = await runAdbCommand('disconnect');
    res.json({ success: true, message: stdout.trim() });
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

// ADB TCPIP 5555 (Enable wireless mode via USB)
app.post('/api/tcpip', async (req, res) => {
  try {
    const stdout = await runAdbCommand('tcpip 5555');
    res.json({ success: true, message: stdout.trim() });
  } catch (e) {
    res.status(500).json({ success: false, error: e.message });
  }
});

// MANUAL AUTO-DISCOVERY SCAN
app.post('/api/discovery/scan', async (req, res) => {
  await refreshAutoDiscovery();
  res.json({
    success: true,
    message: 'Discovery scan completed.',
    autoDiscovery: {
      lastScanAt: autoDiscoveryState.lastScanAt,
      devices: autoDiscoveryState.devices,
      needsPairingCount: autoDiscoveryState.devices.filter((d) => d.status === 'needs_pairing').length,
      scanning: autoDiscoveryState.scanning,
      lastError: autoDiscoveryState.lastError,
      lastHint: autoDiscoveryState.lastHint
    }
  });
});

// START SCRCPY MIRRORING
app.post('/api/start-scrcpy', async (req, res) => {
  const settings = req.body || {};
  const paths = getPaths();
  const isIpPortTarget = (value) => /^\d+\.\d+\.\d+\.\d+:\d+$/.test(String(value || ''));

  if (!paths.exists) {
    return res.status(400).json({ error: 'Scrcpy not found. Please install first.' });
  }

  if (scrcpyProcess) {
    return res.json({ success: true, message: 'Mirroring is already active.' });
  }

  let target = settings.serial;

  // Scrcpy often crashes if targeted directly at the mDNS TLS device name instead of its IP port.
  // Auto-resolve to the IP:port target if the user accidentally selected the TLS one.
  if (target && target.includes('._adb-tls-connect._tcp')) {
    try {
      const devicesOut = await runAdbCommand('devices');
      const lines = devicesOut.split('\n');
      for (const line of lines) {
        const match = line.match(/^(\d+\.\d+\.\d+\.\d+:\d+)\s+device/);
        if (match) {
          target = match[ 1 ];
          logMessage(`Auto-resolved TLS target to ${target}`);
          break;
        }
      }
    } catch (e) {
      logMessage(`Failed to resolve TLS target: ${e.message}`);
    }
  }

  // If TCP/IP preference is enabled and current target is not a concrete IP:port device,
  // try to auto-pick the first active TCP/IP target.
  if (settings.selectTcpIp && !isIpPortTarget(target)) {
    try {
      const devicesOut = await runAdbCommand('devices');
      const lines = devicesOut.split('\n');
      for (const line of lines) {
        const match = line.match(/^(\d+\.\d+\.\d+\.\d+:\d+)\s+device/);
        if (match) {
          target = match[ 1 ];
          logMessage(`TCP/IP preference selected target ${target}`);
          break;
        }
      }
    } catch (e) {
      logMessage(`Failed to apply TCP/IP preference: ${e.message}`);
    }
  }

  // Let scrcpy choose the best renderer automatically.
  // For some Windows setups, forcing OpenGL can result in a non-visible viewer window.
  const args = [];

  // Device Selection
  if (target) {
    args.push('-s');
    args.push(target);
  } else if (settings.selectTcpIp) {
    args.push('-e');
  } else if (settings.selectUsb) {
    args.push('-d');
  }

  // Visuals & Resolution
  if (settings.maxSize) {
    args.push('--max-size');
    args.push(String(settings.maxSize));
  }
  if (settings.bitRate) {
    args.push('--video-bit-rate');
    args.push(`${String(settings.bitRate)}M`);
  }
  if (settings.fps) {
    args.push('--max-fps');
    args.push(String(settings.fps));
  }

  // Control Preferences
  if (settings.stayAwake) args.push('--stay-awake');
  if (settings.alwaysOnTop) args.push('--always-on-top');
  if (settings.noAudio) args.push('--no-audio');
  if (settings.turnScreenOff) args.push('--turn-screen-off');
  if (settings.showTouches) args.push('--show-touches');

  let recordingFile = null;
  if (settings.record) {
    // Save recording in a local recordings directory
    const recDir = path.join(__dirname, 'recordings');
    if (!fs.existsSync(recDir)) {
      fs.mkdirSync(recDir);
    }
    const filename = `recording_${Date.now()}.mp4`;
    recordingFile = path.join(recDir, filename);
    args.push('--record');
    args.push(recordingFile);
    logMessage(`Recording enabled. File will be saved to: recordings/${filename}`);
  }

  logMessage(`Launching Scrcpy with arguments: ${args.join(' ')}`);

  // Clean up previous scrcpy instance before launching a new one.
  const preLaunchStop = await stopScrcpyProcessGracefully({ allowForceFallback: true });
  if (preLaunchStop.mode === 'force') {
    logMessage('Pre-launch cleanup required force termination of previous scrcpy process.');
  } else if (preLaunchStop.mode === 'error') {
    logMessage(`Pre-launch cleanup warning: ${preLaunchStop.output}`);
  }

  // Explorer hands the batch file to the interactive Windows desktop. Keep a
  // startup log and verify that scrcpy actually remains alive before reporting
  // success; an Explorer access error previously looked like a successful
  // launch and was only corrected by the process poll several seconds later.
  const launchLogPath = path.join(paths.dir, '_flect_scrcpy.log');
  try {
    if (fs.existsSync(launchLogPath)) fs.unlinkSync(launchLogPath);
  } catch (error) {
    logMessage(`Could not clear previous scrcpy startup log: ${error.message}`);
  }

  const batContent = [
    '@echo off',
    `cd /d "${paths.dir}"`,
    `scrcpy.exe ${args.join(' ')} > "${launchLogPath}" 2>&1`,
    ''
  ].join('\r\n');

  const batPath = path.join(paths.dir, '_flect_launch.bat');
  fs.writeFileSync(batPath, batContent);

  // Launch via explorer.exe to force execution in the interactive user desktop.
  let explorerError = '';
  await new Promise((resolve) => {
    exec(`explorer.exe "${batPath}"`, { cwd: paths.dir }, (err, stdout, stderr) => {
      if (err) {
        explorerError = String(stderr || err.message || '').trim();
      } else {
        logMessage('Scrcpy process launched via the interactive Windows desktop.');
      }
      resolve();
    });
  });

  // ARM64 Windows may take a little longer while translating the x64 client.
  await new Promise((resolve) => setTimeout(resolve, 3000));
  const launchVerified = await isScrcpyRunning();
  if (!launchVerified) {
    let scrcpyLog = '';
    try {
      scrcpyLog = fs.existsSync(launchLogPath) ? fs.readFileSync(launchLogPath, 'utf8').trim() : '';
    } catch (error) {
      logMessage(`Could not read scrcpy startup log: ${error.message}`);
    }

    const failureDetail = scrcpyLog || explorerError || 'scrcpy exited before creating the mirror window.';
    const launchError = explorerError.toLowerCase().includes('access is denied')
      ? 'Windows blocked the desktop launcher. Close Flect and start it with run.bat, then try again.'
      : failureDetail;
    logMessage(`Scrcpy failed to start: ${failureDetail}`);
    return res.status(500).json({ success: false, error: launchError });
  }

  if (explorerError) {
    logMessage('Scrcpy startup verified by process state (Explorer returned before confirming the launch).');
  }

  // Track active mirroring state and device so UI can show the actual mirrored target.
  scrcpyProcess = { active: true, deviceId: target || null, recordingEnabled: !!settings.record, recordingFile, startedAt: Date.now() };

  // Poll for scrcpy.exe process to detect when user closes the mirroring window
  setTimeout(() => {
    const pollInterval = setInterval(() => {
      exec('tasklist /FI "IMAGENAME eq scrcpy.exe" /NH', (err, stdout) => {
        if (err || !stdout.includes('scrcpy.exe')) {
          clearInterval(pollInterval);
          if (scrcpyProcess) {
            const exitedDeviceId = scrcpyProcess.deviceId || null;
            logMessage('Scrcpy process has exited.');
            scrcpyProcess = null;
            broadcastEvent('mirroring-ended', { code: 0, deviceId: exitedDeviceId });
          }
        }
      });
    }, 3000);

    if (scrcpyProcess) {
      scrcpyProcess._pollInterval = pollInterval;
    }
  }, 5000);

  broadcastEvent('mirroring-started', { deviceId: target || null, recordingEnabled: !!settings.record });
  res.json({ success: true, message: 'Mirroring launched successfully' });
});

// STOP SCRCPY MIRRORING
app.post('/api/stop-scrcpy', async (req, res) => {
  logMessage('Stop requested: attempting to terminate any running scrcpy process...');
  const mirroredDeviceId = scrcpyProcess?.deviceId || null;
  const wasRecording = !!scrcpyProcess?.recordingEnabled;
  const recordingFile = scrcpyProcess?.recordingFile || null;

  // Clear the polling interval if we have a tracked process.
  if (scrcpyProcess && scrcpyProcess._pollInterval) {
    clearInterval(scrcpyProcess._pollInterval);
  }

  // Close cleanly first so an in-progress recording can finalize its MP4 trailer.
  const stopResult = await stopScrcpyProcessGracefully({ allowForceFallback: true, isRecording: wasRecording });

  // Clear tracked state after stop attempt so UI does not remain stuck in active mode.
  scrcpyProcess = null;
  broadcastEvent('mirroring-ended', { code: 0, deviceId: mirroredDeviceId });

  if (stopResult.mode === 'error') {
    logMessage(`Stop result: ${stopResult.output}`);
    return res.json({ success: false, message: `Failed to stop mirroring cleanly: ${stopResult.output}` });
  }

  if (stopResult.mode === 'force' && wasRecording) {
    logMessage('Stop used force termination while recording; resulting file may be incomplete.');
    return res.json({ success: true, message: 'Mirroring stopped, but the recording was force-closed and may be incomplete.' });
  }

  logMessage(`Stop result: ${stopResult.output}`);

  if (wasRecording && recordingFile) {
    // Confirm the finalized recording exists and has real content.
    try {
      const stats = fs.existsSync(recordingFile) ? fs.statSync(recordingFile) : null;
      const relativePath = path.relative(__dirname, recordingFile);
      if (stats && stats.size > 0) {
        logMessage(`Recording finalized: ${relativePath} (${(stats.size / 1024 / 1024).toFixed(1)} MB).`);
        return res.json({ success: true, message: `Recording saved and finalized: ${relativePath}` });
      }
      logMessage(`Recording stopped but file looks empty: ${relativePath}`);
    } catch (e) {
      logMessage(`Could not verify recording file: ${e.message}`);
    }
  }

  return res.json({ success: true, message: 'Mirroring stopped successfully.' });
});

// DEVICE SCREEN PREVIEW (still screenshot, not live)
app.get('/api/preview', (req, res) => {
  const paths = getPaths();
  if (!paths.exists) {
    return res.status(400).json({ error: 'Scrcpy / ADB binaries not found.' });
  }

  const serial = (req.query.serial || '').trim();
  if (!serial) {
    return res.status(400).json({ error: 'A device serial is required.' });
  }

  // `exec-out` streams raw bytes, avoiding the newline translation that
  // corrupts PNG output when using `adb shell screencap -p` on Windows.
  const child = spawn(paths.adb, ['-s', serial, 'exec-out', 'screencap', '-p']);
  const chunks = [];
  let errOutput = '';

  child.stdout.on('data', (d) => chunks.push(d));
  child.stderr.on('data', (d) => { errOutput += d.toString(); });

  child.on('error', (e) => {
    if (!res.headersSent) {
      res.status(500).json({ error: e.message || 'Failed to run screencap.' });
    }
  });

  child.on('close', (code) => {
    const buf = Buffer.concat(chunks);
    if (code !== 0 || buf.length === 0) {
      if (!res.headersSent) {
        res.status(500).json({ error: errOutput.trim() || `screencap failed (exit code ${code}).` });
      }
      return;
    }

    // Auto-save every capture to the screenshots/ folder.
    try {
      const shotsDir = path.join(__dirname, 'screenshots');
      if (!fs.existsSync(shotsDir)) { fs.mkdirSync(shotsDir); }
      const safeSerial = serial.replace(/[^a-zA-Z0-9]+/g, '-');
      const filename = `screenshot_${safeSerial}_${Date.now()}.png`;
      fs.writeFileSync(path.join(shotsDir, filename), buf);
      logMessage(`Saved screen preview to: screenshots/${filename}`);
    } catch (e) {
      logMessage(`Warning: failed to save screen preview: ${e.message}`);
    }

    res.setHeader('Content-Type', 'image/png');
    res.setHeader('Cache-Control', 'no-store');
    res.end(buf);
  });
});

// LIVE SETTING: TURN SCREEN OFF / WAKE SCREEN DURING ACTIVE MIRRORING
app.post('/api/live/turn-screen', async (req, res) => {
  const { enabled } = req.body || {};
  if (typeof enabled !== 'boolean') {
    return res.status(400).json({ success: false, error: 'enabled boolean is required.' });
  }

  const targetDevice = scrcpyProcess?.deviceId;
  if (!scrcpyProcess || !targetDevice) {
    return res.status(400).json({ success: false, error: 'No active mirrored device found.' });
  }

  try {
    // KEYCODE_SLEEP (223) and KEYCODE_WAKEUP (224) provide deterministic power state changes.
    const keyCode = enabled ? 223 : 224;
    await runAdbCommand(`-s ${targetDevice} shell input keyevent ${keyCode}`);

    if (enabled) {
      logMessage(`Live setting applied: turned physical screen off for ${targetDevice}.`);
      return res.json({ success: true, message: 'Phone screen turned off (live).' });
    }

    logMessage(`Live setting applied: wake command sent to ${targetDevice}.`);
    return res.json({ success: true, message: 'Wake command sent to phone screen (live).' });
  } catch (e) {
    logMessage(`Live screen power update failed: ${e.message}`);
    return res.status(500).json({ success: false, error: e.message || 'Failed to apply live screen power setting.' });
  }
});

// Start the server and auto-open the browser
app.listen(PORT, () => {
  console.log(`Server is running at http://localhost:${PORT}`);
  refreshAutoDiscovery();
  setInterval(refreshAutoDiscovery, 7000);

  // Auto-open browser in Windows
  const openUrl = `http://localhost:${PORT}`;
  exec(`start ${openUrl}`, (err) => {
    if (err) {
      console.error('Failed to automatically open browser:', err);
    }
  });
});