passport.js

const configuration = require("./server/config/constants.js");

const dotenv = require("dotenv");
dotenv.config();

const mongoose = require("mongoose");
const Student = mongoose.model("student");
const Login = mongoose.model("login");
const passport = require("passport");
const GoogleStrategy = require("passport-google-oauth20");

const GOOGLE_CLIENT_ID = process.env.GOOGLE_CLIENT_ID;
const GOOGLE_CLIENT_SECRET = process.env.GOOGLE_CLIENT_SECRET;

passport.serializeUser((user, done) => {
  done(null, user.id);
});

passport.deserializeUser((id, done) => {
  Student.findById(id).then(user => {
    done(null, user);
  });
});

passport.use(
  new GoogleStrategy(
    {
      clientID: GOOGLE_CLIENT_ID,
      clientSecret: GOOGLE_CLIENT_SECRET,
      callbackURL: configuration.urls.googleAuthCallback
    },
    (accessToken, refreshToken, profile, done) => {
      Student.findOne({ email: profile.emails[0].value }).then(existingUser => {
        if (existingUser) {
          new Login({
            userId: existingUser._id
          }).save();
          done(null, existingUser);
        } else {
          new Student({
            googleId: profile.id,
            name: profile.displayName,
            email: profile.emails[0].value,
            submittedForm: false,
            branch: [],
            year: 0
          })
            .save()
            .then(user => {
              new Login({
                userId: user._id
              }).save();
              done(null, user);
            });
        }
      });
    }
  )
);