const { app, BrowserWindow, ipcMain, protocol, shell } = require('electron');
const fs = require('node:fs/promises');
const path = require('node:path');
const https = require('node:https');
const {
  LATEST_RELEASE_API,
  evaluateUpdate,
  normalizeRelease,
} = require('../static/webavp-utils.js');

const APP_SCHEME = 'webavp';
const ROOT_DIR = path.resolve(__dirname, '..');
const TEMPLATE_DIR = path.join(ROOT_DIR, 'templates');
const STATIC_DIR = path.join(ROOT_DIR, 'static');
const APP_ICON = path.join(ROOT_DIR, 'build', 'icon.png');
const REQUEST_TIMEOUT_MS = 10000;
const MAX_RESPONSE_BYTES = 1024 * 1024;
const MAX_SERIAL_LENGTH = 128;
const MAX_CERT_HASH_LENGTH = 256;

if (process.env.WEBAVP_DISABLE_GPU === '1') {
  app.disableHardwareAcceleration();
}

protocol.registerSchemesAsPrivileged([
  {
    scheme: APP_SCHEME,
    privileges: {
      standard: true,
      secure: true,
      supportFetchAPI: true,
      corsEnabled: true,
      stream: true,
    },
  },
]);

function contentTypeFor(filePath) {
  const ext = path.extname(filePath).toLowerCase();
  switch (ext) {
    case '.html': return 'text/html; charset=utf-8';
    case '.js': return 'text/javascript; charset=utf-8';
    case '.css': return 'text/css; charset=utf-8';
    case '.json': return 'application/json; charset=utf-8';
    case '.svg': return 'image/svg+xml';
    case '.png': return 'image/png';
    case '.jpg':
    case '.jpeg': return 'image/jpeg';
    case '.webp': return 'image/webp';
    case '.mp4': return 'video/mp4';
    case '.webm': return 'video/webm';
    default: return 'application/octet-stream';
  }
}

function safeJoin(baseDir, requestPath) {
  const decoded = decodeURIComponent(requestPath);
  if (decoded.includes('\0')) throw new Error('Null byte blocked');
  const normalized = path.normalize(decoded).replace(/^([/\\])+/, '');
  const resolved = path.resolve(baseDir, normalized);
  const base = path.resolve(baseDir);
  if (resolved !== base && !resolved.startsWith(base + path.sep)) {
    throw new Error('Path traversal blocked');
  }
  return resolved;
}

function isAppUrl(rawUrl) {
  try {
    const url = new URL(rawUrl);
    return url.protocol === `${APP_SCHEME}:` && url.hostname === 'app';
  } catch {
    return false;
  }
}

function isSafeExternalUrl(rawUrl) {
  try {
    const url = new URL(rawUrl);
    return url.protocol === 'https:' || url.protocol === 'http:';
  } catch {
    return false;
  }
}

function isGitPejiReleaseAssetUrl(rawUrl) {
  try {
    const url = new URL(rawUrl);
    return url.origin === 'https://git.pejicorp.com'
      && url.pathname.startsWith('/peji/WebAVP/releases/download/')
      && !url.username
      && !url.password;
  } catch {
    return false;
  }
}

function isAuthorizedRenderer(event) {
  const senderUrl = event.senderFrame?.url || event.sender?.getURL?.() || '';
  return isAppUrl(senderUrl);
}

async function serveFile(filePath) {
  try {
    const data = await fs.readFile(filePath);
    return new Response(data, {
      headers: { 'content-type': contentTypeFor(filePath) },
    });
  } catch (err) {
    if (err && err.code === 'ENOENT') {
      return new Response('Not found', { status: 404 });
    }
    console.error('[WebAVP] app protocol error:', err);
    return new Response('Internal server error', { status: 500 });
  }
}

function registerAppProtocol() {
  protocol.handle(APP_SCHEME, async (request) => {
    const url = new URL(request.url);
    if (url.hostname !== 'app') {
      return new Response('Unknown host', { status: 404 });
    }

    if (url.pathname === '/' || url.pathname === '/index.html') {
      return serveFile(path.join(TEMPLATE_DIR, 'index.html'));
    }

    if (url.pathname.startsWith('/static/')) {
      try {
        const relativeStaticPath = url.pathname.slice('/static/'.length);
        return serveFile(safeJoin(STATIC_DIR, relativeStaticPath));
      } catch (err) {
        return new Response('Forbidden', { status: 403 });
      }
    }

    return new Response('Not found', { status: 404 });
  });
}

// Node's TLS proceeds when Alta requests an optional client certificate, unlike
// Chromium's net stack. It also gives update checks one bounded request path.
function httpsGetResponse(url, timeoutMs = REQUEST_TIMEOUT_MS) {
  return new Promise((resolve, reject) => {
    const req = https.get(url, {
      headers: {
        Accept: 'application/json, text/plain;q=0.9, */*;q=0.8',
        'User-Agent': `WebAVP/${app.getVersion()}`,
      },
    }, (res) => {
      const chunks = [];
      let total = 0;
      res.on('data', (chunk) => {
        total += chunk.length;
        if (total > MAX_RESPONSE_BYTES) {
          req.destroy(new Error('Response exceeded size limit'));
          return;
        }
        chunks.push(chunk);
      });
      res.on('end', () => resolve({
        status: res.statusCode || 0,
        body: Buffer.concat(chunks).toString('utf8'),
      }));
    });
    req.on('error', reject);
    req.setTimeout(timeoutMs, () => {
      req.destroy(new Error('Certificate verification request timed out'));
    });
  });
}

function interpretVerifyBody(body) {
  const text = String(body || '').trim();
  if (!text) return null;
  const lowered = text.toLowerCase();
  if (lowered === 'true' || lowered === 'false') return lowered === 'true';
  try {
    const data = JSON.parse(text);
    if (typeof data === 'boolean') return data;
    if (data && typeof data === 'object') {
      for (const field of ['verified', 'valid', 'isValid', 'success', 'result']) {
        if (typeof data[field] === 'boolean') return data[field];
      }
    }
  } catch {
    return null;
  }
  return null;
}

async function verifyCertificateOnline(event, { serial, certificateHash } = {}) {
  if (!isAuthorizedRenderer(event)) {
    return { verified: false, error: 'Unauthorized certificate verification request' };
  }
  const serialValue = typeof serial === 'string' ? serial.trim() : '';
  const hashValue = typeof certificateHash === 'string' ? certificateHash.trim() : '';
  if (!serialValue || !hashValue) {
    return { verified: false, error: 'Missing parameters' };
  }
  if (serialValue.length > MAX_SERIAL_LENGTH || hashValue.length > MAX_CERT_HASH_LENGTH) {
    return { verified: false, error: 'Invalid parameter length' };
  }

  const params = new URLSearchParams({
    serial: serialValue.toLowerCase(),
    certificateHash: hashValue,
  });
  const url = `https://aware.avasecurity.com/api/v1/public/verifyServerCertificate?${params.toString()}`;

  try {
    const response = await httpsGetResponse(url);
    if (response.status < 200 || response.status >= 300) {
      return { verified: false, error: `HTTP ${response.status}` };
    }
    if (interpretVerifyBody(response.body) === false) {
      return { verified: false, error: 'Certificate not recognized by Alta/Ava' };
    }
    return { verified: true };
  } catch (err) {
    return { verified: false, error: err.message || 'Certificate verification request failed' };
  }
}

async function checkForUpdates(event) {
  if (!isAuthorizedRenderer(event)) return { status: 'error', message: 'Unauthorized update request' };
  const currentVersion = app.getVersion();
  try {
    const response = await httpsGetResponse(LATEST_RELEASE_API);
    if (response.status === 404) return { status: 'error', message: 'No public GitPeji release is published yet.' };
    if (response.status < 200 || response.status >= 300) {
      return { status: 'error', message: `GitPeji release check failed (HTTP ${response.status}).` };
    }
    const release = normalizeRelease(JSON.parse(response.body));
    const update = evaluateUpdate(release, currentVersion, process.platform, process.arch);
    if (update.status === 'current') {
      return { status: 'current', currentVersion, releaseVersion: release.version, pageUrl: release.pageUrl };
    }
    if (update.status === 'unavailable-platform') {
      return {
        status: 'unavailable-platform',
        currentVersion,
        releaseVersion: release.version,
        pageUrl: release.pageUrl,
        message: `Version ${release.version} is available, but no ${process.platform}/${process.arch} installer was published.`,
      };
    }
    return {
      status: 'available',
      currentVersion,
      releaseVersion: release.version,
      pageUrl: release.pageUrl,
      asset: update.asset,
    };
  } catch (err) {
    return { status: 'error', message: err.message || 'GitPeji release check failed.' };
  }
}

async function downloadUpdate(event, { url } = {}) {
  if (!isAuthorizedRenderer(event) || !isGitPejiReleaseAssetUrl(url)) {
    return { opened: false, error: 'Invalid update download request' };
  }
  try {
    await shell.openExternal(url);
    return { opened: true };
  } catch (err) {
    return { opened: false, error: err.message || 'Could not open the update download' };
  }
}

function createWindow() {
  const win = new BrowserWindow({
    width: 1440,
    height: 960,
    minWidth: 1024,
    minHeight: 720,
    backgroundColor: '#121826',
    title: 'Alta Video Player',
    icon: APP_ICON,
    webPreferences: {
      preload: path.join(__dirname, 'preload.js'),
      contextIsolation: true,
      nodeIntegration: false,
      sandbox: true,
      webviewTag: false,
      navigateOnDragDrop: false,
    },
  });

  win.webContents.on('will-navigate', (event, url) => {
    if (!isAppUrl(url)) {
      event.preventDefault();
      console.warn('[WebAVP] Blocked navigation to:', url);
    }
  });

  win.webContents.setWindowOpenHandler(({ url }) => {
    if (isSafeExternalUrl(url)) {
      shell.openExternal(url).catch((err) => console.warn('[WebAVP] Failed to open external URL:', err.message || err));
    } else {
      console.warn('[WebAVP] Blocked external URL:', url);
    }
    return { action: 'deny' };
  });

  win.webContents.session.setPermissionRequestHandler((_webContents, _permission, callback) => callback(false));

  win.loadURL(`${APP_SCHEME}://app/index.html`);

  if (process.env.WEBAVP_SMOKE_QUIT_AFTER_MS) {
    const quitAfterMs = Number(process.env.WEBAVP_SMOKE_QUIT_AFTER_MS);
    win.webContents.once('did-finish-load', async () => {
      try {
        const result = await win.webContents.executeJavaScript(`(async () => ({
          title: document.title,
          hasJsZip: typeof window.JSZip === 'function',
          hasNativeBridge: !!window.webavpNative?.verifyCertificateOnline,
          hasUpdateBridge: !!window.webavpNative?.checkForUpdates,
          hasFourByFourLayout: !!document.querySelector('[data-layout="4x4"]'),
          bridgeResult: await window.webavpNative?.verifyCertificateOnline?.({ serial: '', certificateHash: '' })
        }))()`);
        if (result.title !== 'Alta Video Player' || !result.hasJsZip || !result.hasNativeBridge || !result.hasUpdateBridge || !result.hasFourByFourLayout || result.bridgeResult?.error !== 'Missing parameters') {
          console.error('[WebAVP] Electron smoke checks failed:', JSON.stringify(result));
          app.exit(1);
          return;
        }
        console.log('[WebAVP] Electron smoke loaded webavp://app/index.html with JSZip and native bridge');
        setTimeout(() => app.quit(), Number.isFinite(quitAfterMs) ? quitAfterMs : 250);
      } catch (err) {
        console.error('[WebAVP] Electron smoke failed:', err);
        app.exit(1);
      }
    });
    win.webContents.once('did-fail-load', (_event, errorCode, errorDescription, validatedURL) => {
      console.error(`[WebAVP] Electron smoke failed to load ${validatedURL}: ${errorCode} ${errorDescription}`);
      app.exit(1);
    });
  }

  return win;
}

app.whenReady().then(() => {
  registerAppProtocol();
  ipcMain.handle('certificate:verify-online', verifyCertificateOnline);
  ipcMain.handle('release:check-update', checkForUpdates);
  ipcMain.handle('release:download-update', downloadUpdate);
  createWindow();

  app.on('activate', () => {
    if (BrowserWindow.getAllWindows().length === 0) createWindow();
  });
});

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') app.quit();
});