auth.js

const passport = require('koa-passport')
const bcrypt = require('bcrypt')
const {User} = require('../models')

/**
 * Serialize user
 * 
 * @param object        User info
 */
passport.serializeUser((user, done) => {
  done(null, user.id)
})

/**
 * Deserialize user from session
 * 
 * @param integer        User id
 * @returns
 */
passport.deserializeUser(async (id, done) => {
  try {
    const user = await User.findById(id)
    done(null, user)
  } catch(err) {
    done(err)
  }
})

/**
 * Localstrategy of Passport.js 
 * 
 * @param string        Username
 * @param string        password
 * @returns
 */
const LocalStrategy = require('passport-local').Strategy
  passport.use(new LocalStrategy(async (username, password, done) => {
    const user = await User.findOne({
      where: {
        email: username
      }
    })
    if (user) {
      bcrypt.compare(password, user.password, (error, response) => {
        if (response) {
          done(null, user)
        } else {
          done(null, false)
        }
      })
    } else {
      done(null, false)
    }
  }
))

/**
 * google strategy of Passport.js 
 * 
 * @param
 * @returns
 */
const GoogleStrategy = require('passport-google-auth').Strategy
passport.use(new GoogleStrategy({
    clientId: 'your-google-oauth-client-id',
    clientSecret: 'your-google-oauth-client-secret',
    callbackURL: 'http://localhost:' + (process.env.PORT || 3000) + '/users/auth/google/callback'
  },
  async (token, tokenSecret, profile, done) => {
    // Retrieve user from database, if exists
    const user = await User.findOne({
      where: {
        email: profile.emails[0].value
      }
    })
    if (user) {
      done(null, user)
    } else {
      // If user not exist, create it
      const newUser = {
        firstName: profile.name.givenName,
        lastName: profile.name.familyName,
        password: 'password-is-from-google',
        email: profile.emails[0].value
      }
      const createdUser = await User.create(newUser)
      if (createdUser) {
        done(null, createdUser)
      } else {
        done(null, false)
      }
    }
  }
))

/**
 * Facebook strategy of Passport.js 
 * 
 * @param
 * @returns
 */
const FacebookStrategy = require('passport-facebook').Strategy
passport.use(new FacebookStrategy({
    clientID: 'facebook-app-id',
    clientSecret: 'facebook-app-secret',
    callbackURL: 'http://localhost:' + (process.env.PORT || 3000) + '/users/auth/facebook/callback',
    profileFields: ['id', 'displayName', 'name', 'photos', 'email']
  },
  async (token, tokenSecret, profile, done) => {
     // Retrieve user from database, if exists
     const user = await User.findOne({
      where: {
        email: profile.emails[0].value
      }
    })
    if (user) {
      done(null, user)
    } else {
      // If user not exist, create it
      const newUser = {
        firstName: profile.name.givenName,
        lastName: profile.name.familyName,
        password: 'password-is-from-google',
        email: profile.emails[0].value
      }
      const createdUser = await User.create(newUser)
      if (createdUser) {
        done(null, createdUser)
      } else {
        done(null, false)
      }
    }
  }
))

/**
 * Twitter strategy of Passport.js 
 * 
 * @param
 * @returns
 */
const TwitterStrategy = require('passport-twitter').Strategy
passport.use(new TwitterStrategy({
    consumerKey: 'twitter-client-id',
    consumerSecret: 'twitter-client-secret',
    callbackURL: 'http://localhost:' + (process.env.PORT || 3000) + '/users/auth/twitter/callback',
    includeEmail: true
  },
  async (token, tokenSecret, profile, done) => {
    // Retrieve user from database, if exists
    const user = await User.findOne({
      where: {
        email: profile.emails[0].value
      }
    })
    if (user) {
      done(null, user)
    } else {
      // If user not exist, create it
      const newUser = {
        firstName: profile.username,
        lastName: profile.username,
        password: 'password-is-from-twitter',
        email: profile.emails[0].value
      }
      const createdUser = await User.create(newUser)
      if (createdUser) {
        done(null, createdUser)
      } else {
        done(null, false)
      }
    }
    console.log(profile)
  }
))