src/pages/api/llm.js

import { Configuration, OpenAIApi } from "openai";
import { GoogleCustomSearch } from "openai-function-calling-tools";

export default function handler(req, res) {
  if (req.method !== 'GET') {
    res.status(405).send({ error: 'Method Not Allowed', method: req.method });
    return;
  }

  const QUESTION = req.query.question;

  if (!QUESTION) {
    res.status(400).send({ error: 'Question is missing in request' });
    return;
  }

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

  const messages = [
    {
      role: "user",
      content: QUESTION,
    },
  ];

  const { googleCustomSearch, googleCustomSearchSchema } = new GoogleCustomSearch({
    apiKey: process.env.API_KEY,
    googleCSEId: process.env.CONTEXT_KEY,
  });

  const functions = {
    googleCustomSearch,
  };

  const getCompletion = async (messages) => {
    const response = await openai.createChatCompletion({
      model: "gpt-3.5-turbo-0613",
      messages,
      functions: [googleCustomSearchSchema],
      temperature: 0,
    });

    return response;
  };

  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');

  const processCompletions = async () => {
    let response;

    while (true) {
      response = await getCompletion(messages);
      console.log(response);

      if (response.data.choices[0].finish_reason === "stop") {
        res.write(`data: ${JSON.stringify({ result: response.data.choices[0].message.content })}\n\n`);
        break;
      } else if (response.data.choices[0].finish_reason === "function_call") {
        const fnName = response.data.choices[0].message.function_call.name;
        const args = response.data.choices[0].message.function_call.arguments;

        const fn = functions[fnName];
        const result = await fn(...Object.values(JSON.parse(args)));

        messages.push({
          role: "assistant",
          content: "",
          function_call: {
            name: fnName,
            arguments: args,
          },
        });

        messages.push({
          role: "function",
          name: fnName,
          content: JSON.stringify({ result: result }),
        });
      }
    }
  };

  processCompletions().catch(err => {
    console.error(err);
    res.status(500).send({ error: 'Internal Server Error' });
  });
}