app/api/chat/route.ts

import { OpenAIStream, StreamingTextResponse } from 'ai';
import OpenAI from 'openai';

import { auth } from '@/auth';
import {
  ChatCompletionMessageParam,
  ChatCompletionContentPart,
} from 'openai/resources';
import { MessageUI } from '@/lib/types';

export const runtime = 'edge';

export const POST = async (req: Request) => {
  const json = await req.json();
  const { messages } = json as {
    messages: MessageUI[];
    id: string;
    url: string;
  };

  const session = await auth();
  if (!session?.user?.email) {
    return new Response('Unauthorized', {
      status: 401,
    });
  }

  const formattedMessage: ChatCompletionMessageParam[] = messages.map(
    message => {
      const contentWithImage: ChatCompletionContentPart[] = [
        {
          type: 'text',
          text: message.content as string,
        },
      ];
      return {
        role: 'user',
        content: contentWithImage,
      };
    },
  );
  const openai = new OpenAI({
    apiKey: process.env.OPENAI_API_KEY,
  });
  const res = await openai.chat.completions.create({
    model: 'gpt-4-vision-preview',
    messages: formattedMessage,
    temperature: 0.3,
    stream: true,
    max_tokens: 300,
  });

  const stream = OpenAIStream(res);

  return new StreamingTextResponse(stream);
};