gui/apps/sandbox/scripts/find-port.ts

import { createServer } from 'node:net'

async function isPortAvailable(port: number): Promise<boolean> {
  return new Promise((resolve) => {
    const server = createServer()
    server.once('error', () => resolve(false))
    server.once('listening', () => {
      server.close()
      resolve(true)
    })
    server.listen(port, '127.0.0.1')
  })
}

export async function findAvailablePort(
  startPort = 8085,
  maxAttempts = 100
): Promise<number> {
  for (let i = 0; i < maxAttempts; i++) {
    const port = startPort + i
    if (await isPortAvailable(port)) {
      return port
    }
  }
  throw new Error(
    `No available port found after ${maxAttempts} attempts starting from ${startPort}`
  )
}

// when run directly, print port
if (import.meta.url === `file://${process.argv[1]}`) {
  findAvailablePort().then((port) => {
    console.log(port)
  })
}