import { app, shell, BrowserWindow, nativeTheme, dialog, Menu } from 'electron'
import { join, resolve } from 'path'
import { electronApp, optimizer, is } from '@electron-toolkit/utils'
import { IpcChannels } from '@shared/ipc'
import { PAGE_BACKGROUND } from '@shared/theme'
import {
  registerIpcHandlers,
  resolveBackgroundMode,
  applyNativeTheme,
  getSystemThemeInfo
} from './ipc'
import { runStartupYtdlpAutoUpdate } from './ytdlp'
import { hasActiveDownloads } from './download'
import { getSettings, applyLaunchAtStartup, migrateSecretsAtRest } from './settings'
import { ensureMediaDirs } from './paths'
import { setupPortableData } from './portable'
import { migrateLegacyCookies } from './cookies'
import { attachEditContextMenu } from './contextMenu'
import { flushAllStores } from './jsonStore'
import { extractIncomingUrl, registerSendToShortcut, focusWindow } from './deeplink'
import { isSyncLaunch } from './schedule'
import { createTray, markQuitting, isQuitting } from './tray'
import { logger } from './logger'
import { initialWindowState, saveWindowState } from './windowState'

// Only one instance ever runs. A second launch — e.g. the OS invoking us again
// for an aerofetch:// link or a "Send to AeroFetch" file — hands its argv to
// this instance via 'second-instance' below, instead of opening a duplicate window.
const isPrimaryInstance = app.requestSingleInstanceLock()
if (!isPrimaryInstance) app.quit()

// Redirect user data next to the exe when possible (portable, no-admin). Must run
// before the app is ready and before any user path is read — including the
// settings read for the hardware-acceleration gate just below.
setupPortableData()

// Software compositing (GPU acceleration off) is the DEFAULT, now behind an
// opt-in setting (W15). On this dev machine's old GeForce GT 625 — and plausibly
// on the old / locked-down public PCs this app targets — Chromium's GPU
// compositor renders blank: under hardware acceleration the WHOLE window paints
// white (popup overlays alone were blank earlier). Updating the NVIDIA driver to
// the last Fermi release did not fix it. Software compositing renders correctly
// and costs no meaningful performance for this lightweight UI, so it stays the
// safe default; users on modern GPUs can flip Settings → Appearance →
// "Hardware acceleration" (applies on next launch — this must run before the
// app is ready). The window backgroundColor is theme-matched (see createWindow).
if (!getSettings().useHardwareAcceleration) {
  app.disableHardwareAcceleration()
}
// Native window-occlusion tracking stays off in BOTH modes — it's a separate
// documented Windows blank/flicker cause, independent of GPU compositing.
app.commandLine.appendSwitch('disable-features', 'CalculateNativeWinOcclusion')

// Register aerofetch:// so a browser/another app can hand AeroFetch a link
// (?url=<encoded>) the way Android's share sheet hands Seal one. The NSIS
// installer also declares this scheme (electron-builder.yml's `protocols`)
// so it's registered even before first launch; this call additionally covers
// the portable build and dev, which have no installer step to do it for us.
const devScript = process.argv[1]
if (is.dev && devScript) {
  app.setAsDefaultProtocolClient('aerofetch', process.execPath, [resolve(devScript)])
} else {
  app.setAsDefaultProtocolClient('aerofetch')
}

let mainWindow: BrowserWindow | null = null

// Tell the user (once per run) that closing the window left AeroFetch running so
// an in-progress download could finish — shown only when they haven't already
// opted into tray mode, so a window that "won't close" doesn't read as a bug.
// L143: an in-window, tray-INDEPENDENT way to quit at the moment the window "won't
// close" because a download is running — without it the only exit is the tray menu
// (and Task Manager if the tray ever failed to create). Guarded so hammering the X
// can't stack dialogs. Only used when the user did NOT opt into tray mode; a
// deliberate minimize-to-tray close stays a silent hide.
let quitPromptOpen = false
function promptQuitWhileDownloading(win: BrowserWindow): void {
  if (quitPromptOpen) return
  quitPromptOpen = true
  dialog
    .showMessageBox(win, {
      type: 'question',
      buttons: ['Keep downloading', 'Quit anyway'],
      defaultId: 0,
      cancelId: 0,
      title: 'Download in progress',
      message: 'A download is still in progress.',
      detail:
        'AeroFetch will keep downloading in the background — reopen it from the tray icon. Quit anyway to stop the download and exit now.'
    })
    .then(({ response }) => {
      quitPromptOpen = false
      if (response === 1) {
        markQuitting() // lets the close handler through + runs the before-quit teardown
        app.quit()
      } else {
        win.hide() // keep downloading in the background
      }
    })
    .catch(() => {
      quitPromptOpen = false
      win.hide()
    })
}

// Web permissions a download manager never needs. They're denied for the app
// window as defence-in-depth (audit T6): even if the renderer were compromised
// (e.g. XSS via remote video metadata) it can't open the camera/mic, read
// location, or reach USB/HID/serial/Bluetooth devices — none of which the IPC
// surface grants either. Clipboard (paste/copy) and everything else is left to
// the default so the app's own features keep working.
const DENIED_PERMISSIONS = new Set([
  'media', // camera + microphone
  'geolocation',
  'midi',
  'midiSysex',
  'hid',
  'serial',
  'usb',
  'bluetooth',
  'speaker-selection',
  'idle-detection'
])

function createWindow(): void {
  // Reopen where the user left off (size / position / maximized), falling back to the
  // default size when there's no usable saved state — first run, or the saved monitor
  // is no longer connected (W2 / UX19).
  const ws = initialWindowState()
  const win = new BrowserWindow({
    title: 'AeroFetch',
    width: ws.width,
    height: ws.height,
    x: ws.x,
    y: ws.y,
    // Below this the 212px sidebar + content layout breaks; pin a sensible
    // floor so the window can't be dragged down to unusable widths (W1).
    minWidth: 640,
    minHeight: 480,
    show: false,
    backgroundColor: PAGE_BACKGROUND[resolveBackgroundMode(getSettings().theme)],
    autoHideMenuBar: true,
    webPreferences: {
      preload: join(__dirname, '../preload/index.cjs'),
      sandbox: true,
      contextIsolation: true,
      nodeIntegration: false
    }
  })
  mainWindow = win

  if (ws.maximized) win.maximize()

  // Persist size/position/maximized so the next launch restores them (W2). Debounced
  // so a drag-resize writes once when it settles; also saved on close (which may only
  // hide to tray) to capture the final state.
  let saveTimer: ReturnType<typeof setTimeout> | null = null
  const scheduleSave = (): void => {
    if (saveTimer) clearTimeout(saveTimer)
    saveTimer = setTimeout(() => saveWindowState(win), 500)
  }
  win.on('resize', scheduleSave)
  win.on('move', scheduleSave)

  // Standard Cut/Copy/Paste/Select All right-click menu on editable fields (W4).
  attachEditContextMenu(win.webContents)

  win.on('ready-to-show', () => {
    // A scheduled `--sync` launch starts unobtrusively (shown but not focused) so
    // the daily background sync doesn't steal focus; a normal launch shows + focuses.
    if (isSyncLaunch(process.argv)) win.showInactive()
    else win.show()
  })

  // Closing the window hides to the tray (instead of quitting) when either the
  // user opted into background mode, OR a download is in flight — quitting would
  // kill the spawned yt-dlp processes and lose the download. A real quit (tray
  // menu / before-quit) sets isQuitting() so this lets the close through.
  win.on('close', (e) => {
    // Capture the final bounds even when the close only hides to tray (W2).
    saveWindowState(win)
    if (isQuitting()) return
    const downloadsRunning = hasActiveDownloads()
    if (getSettings().minimizeToTray || downloadsRunning) {
      e.preventDefault()
      // A download (not tray mode) is the only thing holding the app open: offer a
      // tray-independent "Quit anyway" instead of silently hiding — otherwise a
      // window that won't close looks like a bug, with no in-window way out (L143).
      // A tray-mode close is the user's explicit choice, so that stays a silent hide.
      if (downloadsRunning && !getSettings().minimizeToTray) {
        promptQuitWhileDownloading(win)
      } else {
        win.hide()
      }
    }
  })

  win.on('closed', () => {
    if (mainWindow === win) mainWindow = null
  })

  // The OS may have launched us with an aerofetch:// link or a "Send to" .url
  // file on the command line — hand it to DownloadBar's link-suggestion banner
  // once the page (and its IPC listener) is actually ready to receive it.
  const incomingUrl = extractIncomingUrl(process.argv)
  if (incomingUrl) {
    win.webContents.once('did-finish-load', () => {
      win.webContents.send(IpcChannels.externalUrl, incomingUrl)
    })
  }

  // Open external links in the OS browser, never in-app — and only http(s), so a
  // file:// or custom-protocol URL can't be used to launch a local handler.
  win.webContents.setWindowOpenHandler((details) => {
    try {
      const { protocol } = new URL(details.url)
      if (protocol === 'http:' || protocol === 'https:') shell.openExternal(details.url)
    } catch {
      /* unparseable URL — ignore */
    }
    return { action: 'deny' }
  })

  // The app shell is local and self-contained — never let the renderer navigate
  // away from it (defence in depth; HMR uses websockets, not navigation).
  win.webContents.on('will-navigate', (e) => e.preventDefault())

  // Deny the sensitive hardware/location web permissions the app never uses, so
  // a compromised renderer can't escalate to capabilities the IPC surface
  // doesn't grant. Both the async request and the sync check are covered. (audit T6)
  const ses = win.webContents.session
  ses.setPermissionRequestHandler((_wc, permission, callback) =>
    callback(!DENIED_PERMISSIONS.has(permission))
  )
  ses.setPermissionCheckHandler((_wc, permission) => !DENIED_PERMISSIONS.has(permission))

  if (is.dev && process.env['ELECTRON_RENDERER_URL']) {
    win.loadURL(process.env['ELECTRON_RENDERER_URL'])
  } else {
    win.loadFile(join(__dirname, '../renderer/index.html'))
  }
}

// Push OS theme/contrast changes to every window, and keep the native
// background in sync for windows currently following 'system'.
function registerSystemThemeBridge(): void {
  nativeTheme.on('updated', () => {
    const info = getSystemThemeInfo()
    const bg = PAGE_BACKGROUND[resolveBackgroundMode(getSettings().theme)]
    for (const win of BrowserWindow.getAllWindows()) {
      win.webContents.send(IpcChannels.systemThemeUpdate, info)
      if (getSettings().theme === 'system') win.setBackgroundColor(bg)
    }
  })
}

if (isPrimaryInstance) {
  // A second launch arrives here as argv, not a real new process — extract any
  // link it carried and hand it to the window we already have.
  app.on('second-instance', (_e, argv) => {
    if (!mainWindow) return
    focusWindow(mainWindow)
    const incomingUrl = extractIncomingUrl(argv)
    if (incomingUrl) mainWindow.webContents.send(IpcChannels.externalUrl, incomingUrl)
  })

  app.whenReady().then(() => {
    electronApp.setAppUserModelId('com.aerofetch.app')

    // M31: suppress the default Electron menu (which exposes DevTools/Reload via
    // Alt) in production builds. In dev the menu is kept so DevTools are accessible.
    if (!is.dev) Menu.setApplicationMenu(null)

    // Create the default Documents\Video and Documents\Audio destinations so they
    // exist from first launch (downloads are routed into them by kind).
    ensureMediaDirs()

    // Encrypt any credential still stored as legacy plaintext (from before at-rest
    // encryption), once safeStorage is available post-ready.
    migrateSecretsAtRest()
    // Same for a pre-encryption plaintext cookies.txt — encrypt it and delete the
    // plaintext so a logged-in session no longer sits in the open (H7).
    migrateLegacyCookies()

    // Sync the Windows "run at sign-in" entry with the persisted setting, so it
    // reflects the user's choice even if they changed it on another install.
    applyLaunchAtStartup(getSettings().launchAtStartup)

    app.on('browser-window-created', (_, window) => {
      optimizer.watchWindowShortcuts(window)
    })

    registerIpcHandlers(() => mainWindow)
    registerSystemThemeBridge()
    registerSendToShortcut()
    // Apply the persisted theme to the OS title bar before the window opens (W3).
    applyNativeTheme(getSettings().theme)
    createWindow()
    createTray(() => mainWindow)

    // Taskbar right-click jump list: a quick "Open AeroFetch" task. Launching the
    // exe again is caught by the single-instance lock, which focuses this window.
    app.setUserTasks([
      {
        program: process.execPath,
        arguments: '',
        title: 'Open AeroFetch',
        description: 'Open the AeroFetch window',
        iconPath: process.execPath,
        iconIndex: 0
      }
    ])

    // Keep yt-dlp current on its own: seed the managed copy, then (throttled to
    // once a day) self-update it to the chosen channel so a stale binary can't
    // silently cause YouTube 403s. Best-effort and off the critical path — it
    // never blocks startup, and status is pushed to the window if it's listening.
    runStartupYtdlpAutoUpdate((status) => {
      if (mainWindow && !mainWindow.isDestroyed()) {
        mainWindow.webContents.send(IpcChannels.ytdlpAutoUpdateStatus, status)
      }
    }).catch((e) => logger.error('yt-dlp auto-update failed', e))
  })

  // Any real quit path (tray "Quit", OS shutdown, the updater's app.quit) must set
  // the quitting flag so the window's close handler exits instead of hiding to tray.
  // Also flush any debounced JSON-store writes synchronously so a quit mid-debounce
  // can't drop the last history/sources/template change (R3).
  app.on('before-quit', () => {
    markQuitting()
    flushAllStores()
  })

  // Windows-only app: closing the last window quits (the tray/in-flight-download
  // paths hide rather than close, so this only fires on a real exit). The former
  // macOS 'activate' handler and darwin guard were dead branches here (L147).
  app.on('window-all-closed', () => app.quit())
}