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

import { createServer } from 'node:net'
import { dirname, join } from 'node:path'
import { BrowserWindow, PATHS } from 'electrobun/bun'

const DEV_SERVER_URL = 'http://localhost:3000'
const SERVER_READY_TIMEOUT_MS = 5_000
const MAX_SPAWN_RETRIES = 3

const isDev = (): boolean => {
  const env = process.env.ELECTROBUN_BUILD_ENV
  return !env || env === 'dev'
}

const getServerEntryPath = (): string => {
  return join(PATHS.VIEWS_FOLDER, '..', 'server-output', 'server', 'index.mjs')
}

const getFreePort = (): Promise<number> => {
  return new Promise((resolve, reject) => {
    const srv = createServer()
    srv.unref()
    srv.once('error', reject)
    srv.listen({ port: 0, host: '127.0.0.1', exclusive: true }, () => {
      const addr = srv.address()
      if (addr && typeof addr === 'object') {
        const port = addr.port
        srv.close((err) => (err ? reject(err) : resolve(port)))
      } else {
        srv.close(() => reject(new Error('Unexpected address() result')))
      }
    })
  })
}

const waitForServer = async (
  url: string,
  timeoutMs = SERVER_READY_TIMEOUT_MS,
): Promise<boolean> => {
  const start = Date.now()
  while (Date.now() - start < timeoutMs) {
    try {
      const response = await fetch(url, { method: 'HEAD' })
      if (response.ok) return true
    } catch (_) {
      // Server not up yet, retry after sleep
    }
    await Bun.sleep(100)
  }
  return false
}

const spawnServer = async (): Promise<{
  process: ReturnType<typeof Bun.spawn>
  url: string
}> => {
  const serverEntryPath = getServerEntryPath()
  const serverDir = dirname(serverEntryPath)

  for (let attempt = 1; attempt <= MAX_SPAWN_RETRIES; attempt++) {
    const port = await getFreePort()
    const url = `http://127.0.0.1:${port}`

    const serverProc = Bun.spawn([process.execPath, serverEntryPath], {
      cwd: serverDir,
      env: {
        ...process.env,
        PORT: String(port),
        HOST: '127.0.0.1',
      },
      stdio: ['ignore', 'inherit', 'inherit'],
    })

    const ready = await Promise.race([
      waitForServer(url),
      serverProc.exited.then((code) => {
        throw new Error(`Server exited with code ${code} before becoming ready`)
      }),
    ])

    if (ready) {
      return { process: serverProc, url }
    }

    serverProc.kill()
    await serverProc.exited
    console.warn(
      `Server failed to become ready on port ${port} (attempt ${attempt}/${MAX_SPAWN_RETRIES})`,
    )
  }

  throw new Error(`Server failed to start after ${MAX_SPAWN_RETRIES} attempts`)
}

const main = async () => {
  console.log('Starting Furtherverse Desktop...')

  let serverUrl: string
  let serverProcess: ReturnType<typeof Bun.spawn> | null = null

  if (isDev()) {
    console.log('Dev mode: waiting for external server at', DEV_SERVER_URL)
    const ready = await waitForServer(DEV_SERVER_URL)
    if (!ready) {
      console.error(
        'Dev server not responding. Make sure to run: bun dev in apps/server',
      )
      process.exit(1)
    }
    console.log('Dev server ready!')
    serverUrl = DEV_SERVER_URL
  } else {
    console.log('Production mode: starting embedded server...')
    try {
      const server = await spawnServer()
      serverProcess = server.process
      serverUrl = server.url
      console.log('Server ready at', serverUrl)
    } catch (err) {
      console.error('Failed to start embedded server:', err)
      process.exit(1)
    }
  }

  new BrowserWindow({
    title: 'Furtherverse',
    url: serverUrl,
    frame: {
      x: 100,
      y: 100,
      width: 1200,
      height: 800,
    },
    renderer: 'cef',
  })

  if (serverProcess) {
    const cleanup = () => {
      if (serverProcess) {
        serverProcess.kill()
        serverProcess = null
      }
    }

    process.on('exit', cleanup)
    process.on('SIGTERM', () => {
      cleanup()
      process.exit(0)
    })
    process.on('SIGINT', () => {
      cleanup()
      process.exit(0)
    })

    serverProcess.exited.then((code) => {
      if (serverProcess) {
        console.error(`Server exited unexpectedly with code ${code}`)
        process.exit(1)
      }
    })
  }
}

main().catch((error) => {
  console.error('Failed to start:', error)
  process.exit(1)
})