import { app, BrowserWindow, dialog, Menu, screen, session, shell, utilityProcess } from 'electron'
import type { UtilityProcess, MenuItemConstructorOptions } from 'electron'
import { appendFileSync, mkdirSync, readFileSync, statSync, truncateSync, writeFileSync } from 'node:fs'
import { createServer as createTcpServer } from 'node:net'
import { join } from 'node:path'
import { desktopEnvironment, desktopStateHome, isDesktopPermissionAllowed, isExternalUrl, isInternalUrl, storedPort } from './runtime'
import { desktopStrings } from './strings'
import type { ViteDevServer } from 'vite'

const development = !app.isPackaged && process.argv.includes('--dev')
let backend: UtilityProcess | undefined
let devServer: ViteDevServer | undefined
let window: BrowserWindow | undefined
let stateHome = ''
let origin = ''
let quitting = false
let shutdownComplete = false
let startupComplete = false
let backendExited = false

// Tests and parallel development can use an entirely separate Chromium profile.
if (process.env.HERMES_ELECTRON_USER_DATA) app.setPath('userData', process.env.HERMES_ELECTRON_USER_DATA)
app.setName('Hermes Desktop')

function readState(): Record<string, any> {
  try {
    const state = JSON.parse(readFileSync(join(app.getPath('userData'), 'desktop.json'), 'utf8'))
    return state && typeof state === 'object' && !Array.isArray(state) ? state : {}
  } catch { return {} }
}

function saveState(value: Record<string, unknown>) {
  mkdirSync(app.getPath('userData'), { recursive: true })
  writeFileSync(join(app.getPath('userData'), 'desktop.json'), JSON.stringify({ ...readState(), ...value }), { mode: 0o600 })
}

function openExternal(url: string) {
  if (isExternalUrl(url)) void shell.openExternal(url).catch(console.error)
}

function createWindow() {
  if (quitting) return
  const saved = readState()
  const bounds = saved.bounds
  const validBounds = bounds && ['width', 'height', 'x', 'y'].every(key => Number.isFinite(bounds[key]))
  const visible = validBounds && screen.getAllDisplays().some(({ workArea }) =>
    bounds.x < workArea.x + workArea.width && bounds.x + bounds.width > workArea.x &&
    bounds.y < workArea.y + workArea.height && bounds.y + bounds.height > workArea.y)
  window = new BrowserWindow({
    width: 1440, height: 960, minWidth: 960, minHeight: 640,
    ...(visible ? bounds : {}),
    title: 'Hermes Desktop', backgroundColor: '#101014', show: false,
    webPreferences: {
      preload: join(__dirname, 'preload.js'),
      nodeIntegration: false, contextIsolation: true, sandbox: true,
      webviewTag: false, navigateOnDragDrop: false,
    },
  })
  const current = window
  if (saved.maximized) current.maximize()
  current.once('ready-to-show', () => current.show())
  current.on('page-title-updated', event => event.preventDefault())
  current.on('close', () => saveState({ bounds: current.getNormalBounds(), maximized: current.isMaximized() }))
  current.on('closed', () => { if (window === current) window = undefined })
  current.webContents.setWindowOpenHandler(({ url }) => { openExternal(url); return { action: 'deny' } })
  current.webContents.on('will-navigate', (event, url) => {
    if (!isInternalUrl(url, origin)) { event.preventDefault(); openExternal(url) }
  })
  current.webContents.on('will-attach-webview', event => event.preventDefault())
  current.webContents.on('will-redirect', (event, url) => {
    if (!isInternalUrl(url, origin)) event.preventDefault()
  })
  void current.loadURL(origin).catch(error => { if (!quitting) void fail(error) })
}

async function fail(error: unknown) {
  if (quitting) return
  const text = desktopStrings(app.getLocale())
  console.error(error)
  const result = await dialog.showMessageBox({
    type: 'error', title: text.failed, message: error instanceof Error ? error.message : String(error),
    detail: `${text.logHint} ${join(stateHome, 'logs')}`,
    buttons: [text.quit, text.logs], defaultId: 0, cancelId: 0,
  })
  if (result.response === 1) await shell.openPath(join(stateHome, 'logs'))
  app.quit()
}

async function startBackend(): Promise<string> {
  // Windows has no Unix-domain bridge socket; reserve a free private TCP endpoint.
  let bridgeEndpoint = process.env.HERMES_AGENT_BRIDGE_ENDPOINT
  if (process.platform === 'win32' && !bridgeEndpoint) {
    bridgeEndpoint = await new Promise<string>((resolve, reject) => {
      const probe = createTcpServer()
      probe.once('error', reject)
      probe.listen(0, '127.0.0.1', () => {
        const address = probe.address() as { port: number }
        probe.close(error => error ? reject(error) : resolve(`tcp://127.0.0.1:${address.port}`))
      })
    })
  }
  return new Promise((resolve, reject) => {
    const root = app.getAppPath()
    const env = desktopEnvironment(root, stateHome, storedPort(readState().port))
    if (development) env.CORS_ORIGINS = `http://127.0.0.1:${process.env.HERMES_WEB_UI_FRONTEND_PORT || '8649'}`
    // The MCP Python subprocess launches the app executable in Node mode.
    env.HERMES_AGENT_NODE = process.execPath
    if (bridgeEndpoint) env.HERMES_AGENT_BRIDGE_ENDPOINT = bridgeEndpoint
    backend = utilityProcess.fork(join(root, 'dist/electron/backend.js'), [], {
      cwd: stateHome, env, stdio: 'pipe', serviceName: 'Hermes local service',
    })
    mkdirSync(join(stateHome, 'logs'), { recursive: true })
    const output = (data: Buffer) => {
      const file = join(stateHome, 'logs/desktop.log')
      try {
        try { if (statSync(file).size > 3 * 1024 * 1024) truncateSync(file, 0) } catch { /* First output creates the file. */ }
        appendFileSync(file, data)
      } catch (error) { console.error('Unable to write desktop log', error) }
      process.stdout.write(data)
    }
    backend.stdout?.on('data', output)
    backend.stderr?.on('data', output)
    const timeout = setTimeout(() => reject(new Error('Local service startup timed out (90s)')), 90_000)
    backend.on('message', message => {
      if (message?.type !== 'hermes:ready') return
      const url = new URL(message.url)
      if (url.hostname !== '127.0.0.1' || url.protocol !== 'http:') return
      clearTimeout(timeout)
      saveState({ port: Number(url.port) })
      resolve(url.origin)
    })
    backend.on('exit', code => {
      backendExited = true
      clearTimeout(timeout)
      reject(new Error(`Local service exited during startup (${code})`))
      if (startupComplete && !quitting) void fail(new Error(desktopStrings(app.getLocale()).stopped))
    })
  })
}

async function stopBackend() {
  const child = backend
  if (!child || backendExited) return
  await new Promise<void>(resolve => {
    const timeout = setTimeout(() => { child.kill(); resolve() }, 18_000)
    child.once('exit', () => { clearTimeout(timeout); resolve() })
    child.postMessage({ type: 'hermes:shutdown' })
  })
}

function installMenu() {
  const text = desktopStrings(app.getLocale())
  const items: MenuItemConstructorOptions[] = [
    ...(process.platform === 'darwin' ? [{ role: 'appMenu' as const }] : []),
    { role: 'fileMenu' }, { role: 'editMenu' }, { role: 'viewMenu' }, { role: 'windowMenu' },
    { role: 'help', submenu: [
      { label: text.about, click: () => app.showAboutPanel() },
      { label: text.logs, click: () => { void shell.openPath(join(stateHome, 'logs')) } },
      { label: text.state, click: () => { void shell.openPath(stateHome) } },
    ] },
  ]
  Menu.setApplicationMenu(Menu.buildFromTemplate(items))
  app.setAboutPanelOptions({ applicationName: 'Hermes Desktop', applicationVersion: app.getVersion() })
}

const singleInstance = app.requestSingleInstanceLock()
if (!singleInstance) app.quit()
else {
  app.on('second-instance', () => {
    if (!window && startupComplete) createWindow()
    if (window?.isMinimized()) window.restore()
    window?.show()
    window?.focus()
  })
  app.on('activate', () => { if (!window && startupComplete) createWindow() })
  app.on('window-all-closed', () => { if (process.platform !== 'darwin') app.quit() })
  app.on('before-quit', event => {
    if (shutdownComplete) return
    event.preventDefault()
    if (quitting) return
    quitting = true
    // Close renderer WebSockets first so terminal shells are disposed before HTTP shutdown.
    for (const current of BrowserWindow.getAllWindows()) {
      saveState({ bounds: current.getNormalBounds(), maximized: current.isMaximized() })
      current.destroy()
    }
    void (async () => {
      try { await devServer?.close(); await stopBackend() }
      finally { shutdownComplete = true; app.quit() }
    })()
  })
  app.whenReady().then(async () => {
    stateHome = desktopStateHome(app.getPath('userData'))
    mkdirSync(stateHome, { recursive: true })
    installMenu()
    const backendOrigin = await startBackend()
    if (quitting) return
    origin = backendOrigin
    if (development) {
      process.env.HERMES_WEB_UI_BACKEND_PORT = new URL(backendOrigin).port
      const { createServer } = await import('vite')
      devServer = await createServer({ configFile: join(app.getAppPath(), 'vite.config.ts'), server: { host: '127.0.0.1' } })
      await devServer.listen()
      origin = devServer.resolvedUrls!.local[0]!.replace(/\/$/, '')
    }
    const ses = session.defaultSession
    ses.setPermissionCheckHandler((_contents, permission, requestingOrigin, details) =>
      isDesktopPermissionAllowed(permission, requestingOrigin, origin, details.mediaType ? [details.mediaType] : []))
    ses.setPermissionRequestHandler((contents, permission, callback, details) =>
      callback(isDesktopPermissionAllowed(permission, contents.getURL(), origin, 'mediaTypes' in details ? details.mediaTypes : [])))
    // Electron's native Save dialog handles all browser download links.
    ses.on('will-download', (_event, item) => item.setSaveDialogOptions({ defaultPath: join(app.getPath('downloads'), item.getFilename()) }))
    startupComplete = true
    createWindow()
  }).catch(fail)
}