const path = require('path');
const fs = require('fs');
const os = require('os');
const express = require('express');
const ServiceManager = require('./service-manager');
const Patcher = require('./patcher');
const UpdateClient = require('./update-client');
const FileUpdater = require('./file-updater');

function getDefaultAppData() {
  if (process.platform === 'darwin') {
    return path.join(os.homedir(), 'Library', 'Application Support', 'vyla-home', 'vyla-home-files');
  }
  if (process.platform === 'linux') {
    return path.join(os.homedir(), '.local', 'share', 'vyla-home', 'vyla-home-files');
  }
  return path.join(os.homedir(), 'AppData', 'Roaming', 'vyla-home', 'vyla-home-files');
}

const APPDATA_DIR = (process.env.APPDATA_PATH && !process.env.APPDATA_PATH.includes('com.vyla.home'))
  ? process.env.APPDATA_PATH
  : getDefaultAppData();

const LOGS_DIR = path.join(APPDATA_DIR, 'logs');
try { fs.mkdirSync(LOGS_DIR, { recursive: true }); } catch (e) { }

const debugLogPath = path.join(LOGS_DIR, 'node-debug.log');

function debugLog(msg) {
  try { fs.appendFile(debugLogPath, `[NODE] ${msg}\n`, 'utf8', () => { }); } catch (e) { }
}

debugLog("--- Node.js Process Started ---");

let serviceManager;
let updateDecisionHandler = null;

debugLog(`AppData Dir: ${APPDATA_DIR}`);

function sendToTauri(event, data) {
  debugLog(`Emitting to Tauri: [${event}] -> ${JSON.stringify(data)}`);
  process.stdout.write(JSON.stringify({ event, data }) + '\n');
}

process.stdin.resume();
process.stdin.on('end', () => {
  debugLog('stdin closed - parent died. Self-terminating...');
  process.exit(0);
});
process.stdin.on('error', () => {
  process.exit(0);
});

process.on('uncaughtException', (err) => {
  debugLog(`CRITICAL UNCAUGHT EXCEPTION: ${err.stack || err.message}`);
  if (err.code === 'EPIPE' || err.code === 'EOF') {
    debugLog('Pipe to parent closed - parent process gone, exiting');
    process.exit(0);
  }
  try { sendToTauri('error', { message: err.message }); } catch (e) { }
});

process.on('unhandledRejection', (reason) => {
  const msg = reason && reason.stack ? reason.stack : String(reason);
  debugLog(`CRITICAL UNHANDLED REJECTION: ${msg}`);
  sendToTauri('error', { message: reason && reason.message ? reason.message : String(reason) });
});

function getEnvConfig() {
  try {
    const appPath = path.join(APPDATA_DIR, 'config/env.json');
    if (fs.existsSync(appPath)) return JSON.parse(fs.readFileSync(appPath, 'utf8'));
    return JSON.parse(fs.readFileSync(path.join(__dirname, 'config/env.json'), 'utf8'));
  } catch (e) { return {}; }
}

function getReplacementsConfig() {
  try {
    const appPath = path.join(APPDATA_DIR, 'config/replacements.json');
    if (fs.existsSync(appPath)) return JSON.parse(fs.readFileSync(appPath, 'utf8'));
    return JSON.parse(fs.readFileSync(path.join(__dirname, 'config/replacements.json'), 'utf8'));
  } catch (e) { return {}; }
}

const updateClient = new UpdateClient(APPDATA_DIR);
const fileUpdater = new FileUpdater(APPDATA_DIR, updateClient);
let lastFilePercent = -1;
fileUpdater.onProgress = (downloaded, total) => {
  const percent = total > 0 ? Math.round((downloaded / total) * 100) : 0;
  if (percent === lastFilePercent) return;
  lastFilePercent = percent;
  sendToTauri('download-progress', { downloaded, total, percent });
};

function withTimeout(promise, ms) {
  return Promise.race([promise, new Promise((resolve) => setTimeout(() => resolve(null), ms))]);
}

function portInUse(port) {
  return new Promise((resolve) => {
    const socket = new (require('net').Socket)();
    socket.setTimeout(500);
    socket.once('connect', () => {
      socket.destroy();
      resolve(true);
    });
    socket.once('error', () => resolve(false));
    socket.once('timeout', () => {
      socket.destroy();
      resolve(false);
    });
    socket.connect(port, '127.0.0.1');
  });
}


async function start() {
  debugLog("Inside start() function");
  sendToTauri('status', { message: 'Loading core configuration files...' });

  const patcher = new Patcher(APPDATA_DIR);
  serviceManager = new ServiceManager(APPDATA_DIR, getEnvConfig());

  const installBuild = async (release) => {
    const tempZipPath = path.join(APPDATA_DIR, 'download-temp.zip');
    if (fs.existsSync(tempZipPath)) {
      try { fs.unlinkSync(tempZipPath); } catch (e) { }
    }
    let attempts = 0;
    let downloadSuccess = false;

    while (attempts < 3 && !downloadSuccess) {
      attempts++;
      try {
        debugLog(`Attempting to download update (Attempt ${attempts})...`);
        sendToTauri('status', { message: `Connecting to download servers (Attempt ${attempts}/3)...` });

        let lastPercent = -1;
        await updateClient.downloadUpdate(release, tempZipPath, (downloaded, total) => {
          const percent = total > 0 ? Math.round((downloaded / total) * 100) : 0;
          if (percent !== lastPercent) {
            lastPercent = percent;
            sendToTauri('download-progress', { downloaded, total, percent });
          }
        });

        debugLog('Download complete. Verifying checksum...');
        sendToTauri('status', { message: 'Verifying SHA-256 integrity...' });
        if (!release.sha256) {
          throw new Error('Release has no SHA-256 in manifest.json; refusing unverified install.');
        }
        if (!patcher.verifyChecksum(tempZipPath, release.sha256)) {
          throw new Error('SHA-256 checksum verification failed.');
        }

        debugLog('Checksum verified. Extracting to staging...');
        sendToTauri('status', { message: 'Unpacking update archive...' });
        let lastEmit = 0;
        const stagingDir = await patcher.extractToStaging(tempZipPath, (file, done, total) => {
          const now = Date.now();
          if (done !== total && now - lastEmit < 40) return;
          lastEmit = now;
          sendToTauri('extract-progress', {
            file,
            done,
            total,
            percent: Math.round((done / total) * 100)
          });
        });

        sendToTauri('status', { message: 'Verifying file integrity...' });
        if (!patcher.verifyExtraction(stagingDir)) {
          fs.rmSync(stagingDir, { recursive: true, force: true });
          throw new Error('Extraction verification failed: critical startup files missing.');
        }

        sendToTauri('status', { message: 'Replacing old version...' });
        patcher.commitStaging(stagingDir);

        debugLog('Extraction complete. Applying patches...');
        sendToTauri('status', { message: 'Applying configuration patches...' });
        fileUpdater.snapshotBase();
        patcher.applyPatches(getReplacementsConfig());

        sendToTauri('status', { message: 'Migrating security credentials...' });
        patcher.bridgeCredentials(serviceManager.credentialManager);
        patcher.saveCurrentVersion(release.version, release.sha256);

        serviceManager.envConfig = getEnvConfig();

        if (fs.existsSync(tempZipPath)) {
          fs.unlinkSync(tempZipPath);
        }
        downloadSuccess = true;
        debugLog('Update installed successfully!');
      } catch (err) {
        debugLog(`Download/Install error on attempt ${attempts}: ${err.message}`);
        sendToTauri('status', { message: `Install error: ${err.message}. Retrying...` });
        if (fs.existsSync(tempZipPath)) {
          try { fs.unlinkSync(tempZipPath); } catch (e) { }
        }
        if (attempts >= 3) {
          throw new Error(`Failed to download and verify build after 3 attempts: ${err.message}`);
        }
        await new Promise(r => setTimeout(r, 2000));
      }
    }
  };

  try {
    sendToTauri('status', { message: 'Inspecting local workspace and installed files...' });
    const isFirstRun = !patcher.verifyExtraction();
    const localVersion = patcher.getCurrentVersion();
    const localSha = patcher.getCurrentSha();
    debugLog(`Is First Run: ${isFirstRun}, Local Version: ${localVersion}, Local SHA: ${localSha}`);

    sendToTauri('status', { message: 'Connecting to update servers...' });
    let release = null;
    try {
      debugLog("Fetching updates from updateClient...");
      release = await updateClient.checkForUpdates();
      debugLog(`Update check finished. Found: ${release ? release.version : 'None'}`);
    } catch (e) {
      debugLog(`Update check failed (offline?): ${e.message}`);
      sendToTauri('status', { message: `Update server check skipped (${e.message})` });
    }

    const normalizeVer = (v) => (v || '').toString().replace(/^v/, '').trim();
    const parseVer = (v) => normalizeVer(v).split(/[.\-+]/).map((n) => parseInt(n, 10) || 0);
    const isNewer = (remote, local) => {
      const a = parseVer(remote);
      const b = parseVer(local);
      for (let i = 0; i < Math.max(a.length, b.length); i++) {
        const x = a[i] || 0;
        const y = b[i] || 0;
        if (x !== y) return x > y;
      }
      return false;
    };

    if (release) {
      const versionNewer = isNewer(release.version, localVersion);
      const sameVerNewBuild = normalizeVer(release.version) === normalizeVer(localVersion) &&
        !!release.sha256 && !!localSha && release.sha256 !== localSha;
      const hasUpdate = versionNewer;

      if (isFirstRun) {
        debugLog("First run with no local payload. Installing remote build...");
        sendToTauri('status', { message: 'First run detected. Preparing initial installation...' });
        await installBuild(release);
      } else if (hasUpdate) {
        debugLog("Update available. Installing update...");
        sendToTauri('status', { message: `Updating to ${release.version}...` });
        await installBuild(release);
      } else {
        debugLog("Already on the latest version.");
        sendToTauri('status', { message: 'Up to date.' });
      }
    } else if (isFirstRun) {
      debugLog("No remote release found, but it's the first run. Looking for local update-payload.zip...");
      sendToTauri('status', { message: 'Looking for local payload archive...' });
      const localZip = path.join(__dirname, 'update-payload.zip');
      if (fs.existsSync(localZip)) {
        sendToTauri('status', { message: 'Extracting local baseline payload...' });
        patcher.purgeOldCode();
        patcher.extractZipPayload(localZip);
        fileUpdater.snapshotBase();
        patcher.applyPatches(getReplacementsConfig());
        patcher.bridgeCredentials(serviceManager.credentialManager);

        let ver = "1.0.0";
        try {
          const man = JSON.parse(fs.readFileSync(path.join(__dirname, 'manifest.json'), 'utf8'));
          ver = man.version || ver;
        } catch (e) { }

        patcher.saveCurrentVersion(ver);
        serviceManager.envConfig = getEnvConfig();
        debugLog("Local payload extracted successfully.");
      } else {
        debugLog("No local payload found!");
      }
    }

    sendToTauri('status', { message: 'Validating critical components...' });
    if (!patcher.verifyExtraction()) {
      throw new Error('Could not download the app files. Check your internet connection and relaunch.');
    }

    sendToTauri('status', { message: 'Checking UI files and SDK...' });
    const [filesCheck, sdkCheck] = await Promise.all([
      withTimeout(fileUpdater.checkFiles().catch((e) => {
        debugLog(`File check failed: ${e.message}`);
        return null;
      }), 180000),
      withTimeout(fileUpdater.checkSdk().catch((e) => {
        debugLog(`SDK check failed: ${e.message}`);
        return null;
      }), 12000)
    ]);

    if (filesCheck && filesCheck.changes.length > 0) {
      sendToTauri('status', { message: `Updating ${filesCheck.changes.length} file(s)...` });
      try {
        await fileUpdater.applyFiles(filesCheck.changes, filesCheck.seq, getReplacementsConfig(), (file, done, total) => {
          sendToTauri('extract-progress', { file, done, total, percent: Math.round((done / total) * 100) });
        });
        sendToTauri('status', { message: `Updated ${filesCheck.changes.length} file(s).` });
      } catch (e) {
        debugLog(`File update failed: ${e.message}`);
        sendToTauri('status', { message: `File update failed: ${e.message}` });
      }
    }

    if (sdkCheck && sdkCheck.outdated) {
      sendToTauri('status', { message: `Updating SDK (${sdkCheck.latest})...` });
      try {
        await fileUpdater.installSdk(sdkCheck);
        sendToTauri('status', { message: `SDK updated to ${sdkCheck.latest}.` });
      } catch (e) {
        debugLog(`SDK install failed: ${e.message}`);
        sendToTauri('status', { message: `SDK update failed: ${e.message}` });
      }
    }

    sendToTauri('status', { message: 'Loading encrypted credentials...' });
    serviceManager.credentialManager.loadCredentials();

    const busyPorts = [];
    for (const port of [3000, 4890]) {
      if (await portInUse(port)) busyPorts.push(port);
    }
    if (busyPorts.length > 0) {
      throw new Error(`Port ${busyPorts.join(' and ')} is already in use by another program. Close it or any other running Vyla Home, then relaunch.`);
    }

    sendToTauri('status', { message: 'Starting services (player, frontend)...' });
    await serviceManager.startServices([
      { name: 'player', relativeDir: 'player', startScript: 'server.js' },
      { name: 'frontend', relativeDir: 'frontend', startScript: 'server.js' }
    ]);
    debugLog("Backend services spawn requested.");

    sendToTauri('status', { message: 'Waiting for microservices to bind...' });
    try {
      await serviceManager.waitForPorts([3000, 4890], 60000);
    } catch (e) {
      throw new Error(`${e.message}. Check logs in ${LOGS_DIR}`);
    }
    debugLog("Ports 3000 and 4890 are ready.");

    sendToTauri('status', { message: 'All backend services running and healthy.' });
    debugLog("Sending READY to Tauri.");
    sendToTauri('ready', { url: 'http://127.0.0.1:4890' });

  } catch (error) {
    debugLog(`Fatal Start Error: ${error.message}`);
    sendToTauri('error', { message: error.message });
  }
}

process.on('exit', () => {
  if (serviceManager) {
    serviceManager.stopAll();
  }
});

process.on('SIGINT', () => {
  process.exit(0);
});
process.on('SIGTERM', () => {
  process.exit(0);
});

start();