import { app, shell, BrowserWindow, ipcMain, dialog, clipboard, nativeTheme } from 'electron'
import { join, resolve } from 'path'
import { electronApp, optimizer, is } from '@electron-toolkit/utils'
import {
  IpcChannels,
  type StartDownloadOptions,
  type Settings,
  type HistoryEntry,
  type CommandTemplate,
  type YtdlpUpdateChannel,
  type SystemThemeInfo
} from '@shared/ipc'
import { getYtdlpVersion, updateYtdlp } from './ytdlp'
import { probeMedia } from './probe'
import { startDownload, cancelDownload, previewCommand } from './download'
import { getSettings, setSettings } from './settings'
import { listHistory, addHistory, removeHistory, removeManyHistory, clearHistory } from './history'
import { listTemplates, saveTemplate, removeTemplate } from './templates'
import { setupPortableData } from './portable'
import { safeOpenPath, safeShowInFolder } from './reveal'
import { openCookieLoginWindow, getCookiesStatus, clearCookies } from './cookies'
import { listErrorLog, addErrorLog, clearErrorLog } from './errorlog'
import { exportBackup, importBackup } from './backup'
import { extractIncomingUrl, registerSendToShortcut, focusWindow } from './deeplink'

// 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()

// Force software compositing (GPU acceleration off). 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 is the safe default for
// this app's target hardware. The only downside is a minor overlay-repaint flicker that
// appears on the most broken GPUs. The window backgroundColor is theme-matched (see
// createWindow); native window-occlusion tracking is disabled (a separate documented
// Windows blank/flicker cause). Must run before the app is ready.
app.disableHardwareAcceleration()
app.commandLine.appendSwitch('disable-features', 'CalculateNativeWinOcclusion')

// 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.
setupPortableData()

// 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.
if (is.dev && process.argv.length >= 2) {
  app.setAsDefaultProtocolClient('aerofetch', process.execPath, [resolve(process.argv[1])])
} else {
  app.setAsDefaultProtocolClient('aerofetch')
}

let mainWindow: BrowserWindow | null = null

// Page background per theme — keep in sync with `pageBackground` in
// src/renderer/src/theme.ts. Set as the window's NATIVE background so the
// one-frame compositor repaint (when a tooltip/dropdown overlay first paints on
// Windows) shows the app's current color instead of a mismatched white flash.
const THEME_BACKGROUND = { light: '#f6f1ef', dark: '#161618' } as const

// 'system' isn't a real background — resolve it against the OS's current
// preference (nativeTheme.themeSource defaults to 'system', so this tracks it
// without AeroFetch ever touching themeSource itself).
function resolveBackgroundMode(theme: Settings['theme']): 'light' | 'dark' {
  return theme === 'system' ? (nativeTheme.shouldUseDarkColors ? 'dark' : 'light') : theme
}

function getSystemThemeInfo(): SystemThemeInfo {
  return {
    shouldUseDarkColors: nativeTheme.shouldUseDarkColors,
    shouldUseHighContrastColors: nativeTheme.shouldUseHighContrastColors
  }
}

function createWindow(): void {
  const win = new BrowserWindow({
    width: 920,
    height: 700,
    show: false,
    backgroundColor: THEME_BACKGROUND[resolveBackgroundMode(getSettings().theme)],
    autoHideMenuBar: true,
    webPreferences: {
      preload: join(__dirname, '../preload/index.cjs'),
      sandbox: true,
      contextIsolation: true,
      nodeIntegration: false
    }
  })
  mainWindow = win

  win.on('ready-to-show', () => {
    win.show()
  })

  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())

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

function registerIpcHandlers(): void {
  ipcMain.handle(IpcChannels.ytdlpVersion, () => getYtdlpVersion())

  ipcMain.handle(IpcChannels.probe, (_e, url: string) => probeMedia(url))

  ipcMain.handle(IpcChannels.downloadStart, (e, opts: StartDownloadOptions) => {
    const result = startDownload(e.sender, opts)
    // Pre-spawn failures (missing yt-dlp.exe, bad URL, duplicate id) never reach
    // download.ts's own close/error handlers, so log them here instead.
    if (!result.ok) {
      addErrorLog({
        id: opts.id,
        url: opts.url,
        kind: opts.kind,
        error: result.error ?? 'Unknown error',
        occurredAt: Date.now()
      })
    }
    return result
  })
  ipcMain.handle(IpcChannels.downloadCancel, (_e, id: string) => cancelDownload(id))

  ipcMain.handle(IpcChannels.defaultFolder, () => app.getPath('downloads'))

  ipcMain.handle(IpcChannels.chooseFolder, async (e) => {
    const win = BrowserWindow.fromWebContents(e.sender) ?? undefined
    const res = await dialog.showOpenDialog(win!, {
      properties: ['openDirectory', 'createDirectory']
    })
    return res.canceled || !res.filePaths[0] ? null : res.filePaths[0]
  })

  ipcMain.handle(IpcChannels.openPath, (_e, p: string) => safeOpenPath(p))
  ipcMain.handle(IpcChannels.showInFolder, (_e, p: string) => safeShowInFolder(p))

  ipcMain.handle(IpcChannels.clipboardRead, () => clipboard.readText())

  ipcMain.handle(IpcChannels.settingsGet, () => getSettings())
  ipcMain.handle(IpcChannels.settingsSet, (e, partial: Partial<Settings>) => {
    const result = setSettings(partial)
    // Keep the window's native background in sync with the theme so a compositor
    // repaint never flashes a mismatched color behind an overlay. Use the
    // validated result, not the raw partial (which may hold a bogus value).
    if (partial.theme) {
      BrowserWindow.fromWebContents(e.sender)?.setBackgroundColor(
        THEME_BACKGROUND[resolveBackgroundMode(result.theme)]
      )
    }
    return result
  })

  ipcMain.handle(IpcChannels.systemThemeGet, () => getSystemThemeInfo())

  ipcMain.handle(IpcChannels.openHighContrastSettings, () =>
    shell.openExternal('ms-settings:easeofaccess-highcontrast')
  )

  ipcMain.handle(IpcChannels.historyList, () => listHistory())
  ipcMain.handle(IpcChannels.historyAdd, (_e, entry: HistoryEntry) => addHistory(entry))
  ipcMain.handle(IpcChannels.historyRemove, (_e, id: string) => removeHistory(id))
  ipcMain.handle(IpcChannels.historyRemoveMany, (_e, ids: string[]) => removeManyHistory(ids))
  ipcMain.handle(IpcChannels.historyClear, () => clearHistory())

  ipcMain.handle(IpcChannels.cookiesLogin, (_e, url: string) => openCookieLoginWindow(url))
  ipcMain.handle(IpcChannels.cookiesStatus, () => getCookiesStatus())
  ipcMain.handle(IpcChannels.cookiesClear, () => clearCookies())

  ipcMain.handle(IpcChannels.templatesList, () => listTemplates())
  ipcMain.handle(IpcChannels.templatesSave, (_e, template: CommandTemplate) => saveTemplate(template))
  ipcMain.handle(IpcChannels.templatesRemove, (_e, id: string) => removeTemplate(id))

  ipcMain.handle(IpcChannels.commandPreview, (_e, opts: StartDownloadOptions) =>
    previewCommand(opts)
  )

  ipcMain.handle(IpcChannels.ytdlpUpdate, (_e, channel: YtdlpUpdateChannel) => updateYtdlp(channel))

  ipcMain.handle(IpcChannels.errorLogList, () => listErrorLog())
  ipcMain.handle(IpcChannels.errorLogClear, () => clearErrorLog())

  ipcMain.handle(IpcChannels.backupExport, (e) =>
    exportBackup(BrowserWindow.fromWebContents(e.sender) ?? undefined)
  )
  ipcMain.handle(IpcChannels.backupImport, async (e) => {
    const win = BrowserWindow.fromWebContents(e.sender) ?? undefined
    const result = await importBackup(win)
    // A restored backup may have changed the theme; keep the native window
    // background in sync the same way settingsSet does.
    if (result.ok) {
      win?.setBackgroundColor(THEME_BACKGROUND[resolveBackgroundMode(getSettings().theme)])
    }
    return result
  })
}

// 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 = THEME_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')

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

    registerIpcHandlers()
    registerSystemThemeBridge()
    registerSendToShortcut()
    createWindow()

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

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