src/pages/api/llm.js

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

export default async function handler(req, res) {
  if (req.method !== 'POST') {
    // Handle any other HTTP method
    res.status(405).send({ error: 'Method Not Allowed', method: req.method });
    return;
  }

  const QUESTION = req.body.question;

  if (!QUESTION) {
    res.status(400).send({ error: 'Question is missing in request body' });
    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.GOOGLE_API_KEY,
    googleCSEId: process.env.GOOGLE_CSE_ID,
  });

  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;
  };
  
  let response;

  while (true) {
    response = await getCompletion(messages);

    if (response.data.choices[0].finish_reason === "stop") {
      res.status(200).json({ result: response.data.choices[0].message.content });
      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 }),
      });
    }
  }
}