Stream OpenAI response though NextJS API route

chat.ts

import { NextApiRequest, NextApiResponse } from 'next'
import { Readable } from 'node:stream'

export default async function handler(req: NextApiRequest, res: NextApiResponse) {
  const { authorization } = req.headers

  if (!authorization || authorization !== process.env.AUTHORIZATION_HEADER) {
    return res.status(401).json({ error: 'Unauthorized' })
  }
  const openAIUrl = process.env.OPENAI_URL as string
  const headers = new Headers()
  headers.set('Content-Type', 'application/json')
  headers.set('Authorization', `Bearer ${process.env.OPENAI_API_KEY as string}`)

  const body = JSON.stringify({
    model: 'gpt-3.5-turbo',
    max_tokens: 1024,
    temperature: 0.8,
    top_p: 1.0,
    frequency_penalty: 0,
    presence_penalty: 0,
    stream: true,
    messages: [
      { role: "user", content: req.body.input }
    ],
  })
  const response = await fetch(
    openAIUrl,
    {
    method: 'POST',
    headers,
    body,
    })
  Readable.fromWeb(response.body as any).pipe(res)
}