fullstack-starter/apps/desktop/src/main/index.ts

import { spawn } from 'node:child_process'
import { createServer } from 'node:net'
import { join } from 'node:path'
import { app, BrowserWindow, shell } from 'electron'
import killProcessTree from 'tree-kill'

const DEV_SERVER_URL = 'http://localhost:3000'

let mainWindow: BrowserWindow | null = null
let serverProcess: ReturnType<typeof spawn> | null = null
let isQuitting = false

const getAvailablePort = (): Promise<number> =>
  new Promise((resolve, reject) => {
    const server = createServer()
    server.listen(0, () => {
      const addr = server.address()
      if (!addr || typeof addr === 'string') {
        server.close()
        reject(new Error('Failed to resolve port'))
        return
      }
      server.close(() => resolve(addr.port))
    })
    server.on('error', reject)
  })

const isServerReady = async (url: string): Promise<boolean> => {
  try {
    const response = await fetch(url, { method: 'HEAD' })
    return response.ok
  } catch {
    return false
  }
}

const waitForServer = async (
  url: string,
  timeoutMs = 15_000,
): Promise<boolean> => {
  const start = Date.now()
  while (Date.now() - start < timeoutMs && !isQuitting) {
    if (await isServerReady(url)) return true
    await new Promise<void>((resolve) => setTimeout(resolve, 200))
  }
  return false
}

const stopServerProcess = () => {
  if (!serverProcess) {
    return
  }

  const runningServer = serverProcess
  serverProcess = null

  if (!runningServer.pid || runningServer.exitCode !== null) {
    return
  }

  killProcessTree(runningServer.pid, (error?: Error) => {
    if (error) {
      console.error('Failed to stop server process:', error)
    }
  })
}

const spawnServer = (port: number): string => {
  const binaryName = process.platform === 'win32' ? 'server.exe' : 'server'
  const binaryPath = join(process.resourcesPath, binaryName)

  serverProcess = spawn(binaryPath, [], {
    env: {
      ...process.env,
      PORT: String(port),
      HOST: '127.0.0.1',
    },
    stdio: 'ignore',
  })
  serverProcess.unref()

  serverProcess.on('error', (err) => {
    console.error('Failed to start server:', err)
  })

  serverProcess.on('exit', () => {
    serverProcess = null
  })

  return `http://127.0.0.1:${port}`
}

const getServerUrl = async (): Promise<string | null> => {
  if (!app.isPackaged) {
    return DEV_SERVER_URL
  }

  const port = await getAvailablePort()

  if (isQuitting) {
    return null
  }

  return spawnServer(port)
}

const createWindow = async () => {
  mainWindow = new BrowserWindow({
    width: 1200,
    height: 800,
    show: false,
    webPreferences: {
      preload: join(__dirname, '../preload/index.mjs'),
      sandbox: true,
    },
  })

  mainWindow.webContents.setWindowOpenHandler(({ url }) => {
    shell.openExternal(url)
    return { action: 'deny' }
  })

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

  if (process.env.ELECTRON_RENDERER_URL) {
    mainWindow.loadURL(process.env.ELECTRON_RENDERER_URL)
  } else {
    mainWindow.loadFile(join(__dirname, '../renderer/index.html'))
  }
  mainWindow.show()

  const serverUrl = await getServerUrl()
  if (!serverUrl || isQuitting || !mainWindow || mainWindow.isDestroyed()) {
    stopServerProcess()
    return
  }

  console.log(`Waiting for server at ${serverUrl}...`)
  const ready = await waitForServer(serverUrl)
  if (isQuitting || !mainWindow || mainWindow.isDestroyed()) {
    stopServerProcess()
    return
  }

  if (!ready) {
    console.error(
      app.isPackaged
        ? 'Server binary did not start in time.'
        : 'Dev server not responding. Run `bun dev` in apps/server first.',
    )
    app.quit()
    return
  }

  console.log(`Loading ${serverUrl}`)
  if (!mainWindow || mainWindow.isDestroyed()) {
    return
  }
  mainWindow.loadURL(serverUrl)
}

app.whenReady().then(createWindow)

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

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

app.on('before-quit', () => {
  isQuitting = true
  stopServerProcess()
})