// ./app/api/chat/route.js
import OpenAI from 'openai';
import { OpenAIStream, StreamingTextResponse } from 'ai';

const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});

export const runtime = 'edge';

export async function POST(req) {
  const { messages } = await req.json();
  const response = await openai.chat.completions.create({
    model: 'gpt-4',
    stream: true,
    messages,
  });
  const stream = OpenAIStream(response);
  return new StreamingTextResponse(stream);
}

// ./app/page.js
'use client';

import { useChat } from 'ai/react';

export default function Chat() {
  const { messages, input, handleInputChange, handleSubmit } = useChat();

  return (
    <div>
      {messages.map(m => (
        <div key={m.id}>
          {m.role}: {m.content}
        </div>
      ))}

      <form onSubmit={handleSubmit}>
        <input
          value={input}
          placeholder="Say something..."
          onChange={handleInputChange}
        />
      </form>
    </div>
  );
}