transporter.js

const nodemailer = require("nodemailer");
const { google } = require("googleapis");
const OAuth2 = google.auth.OAuth2;

require("dotenv").config();

const createTransporter = async () => {
  const oauth2Client = new OAuth2(
    process.env.CLIENT_ID,
    process.env.CLIENT_SECRET,
    process.env.REDIRECT_URI
  );

  oauth2Client.setCredentials({
    refresh_token: process.env.REFRESH_TOKEN,
  });

  const accessToken = await new Promise((resolve, reject) => {
    oauth2Client.getAccessToken((err, token) => {
      if (err) {
        reject("Failed to create access token :(");
      }
      resolve(token);
    });
  });

  const transporter = nodemailer.createTransport({
    service: "Gmail",
    auth: {
      type: "OAuth2",
      user: process.env.EMAIL,
      accessToken,
      clientId: process.env.CLIENT_ID,
      clientSecret: process.env.CLIENT_SECRET,
      refreshToken: process.env.REFRESH_TOKEN,
    },
    from: process.env.EMAIL,
  }
  );

  return transporter;
};

module.exports = createTransporter;