backend

//server

const { ApolloServer } = require("apollo-server");

const typeDefs = require("./typeDefs");
const resolvers = require("./resolvers");
const { findOrCreateUser } = require("./controllers/userController");
const mongoose = require("mongoose");
require("dotenv").config();

mongoose
  .connect(process.env.MONGO_URI, { useNewUrlParser: true })
  .then(() => console.log("DB connected!"))
  .catch(err => console.error(err));

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: async ({ req }) => {
    let authToken = null;
    let currentUser = null;
    try {
      authToken = req.headers.authorization;
      if (authToken) {
        currentUser = await findOrCreateUser(authToken);
      }
    } catch (err) {
      console.warn(`Unable to authenticate using auth token: ${authToken}`);
    }
    return { authToken, currentUser };
  }
});

server.listen().then(({ url }) => {
  console.log(`Server listening on ${url}`);
});


//userController.js

const User = require("../models/User");
const { AuthenticationError } = require("apollo-server");
const { OAuth2Client } = require("google-auth-library");
const client = new OAuth2Client(process.env.OAUTH_CLIENT_ID);

exports.findOrCreateUser = async token => {
  if (!token) {
    throw new AuthenticationError("No auth token provided");
  }
  const googleUser = await verifyAuthToken(token);
  const user = await checkIfUserExists(googleUser.email);
  return user ? user : saveUser(googleUser);
};

const checkIfUserExists = async email => await User.findOne({ email }).exec();

const saveUser = googleUser => {
  const { email, name, picture } = googleUser;
  const user = { email, name, picture };
  return new User(user).save();
};

const verifyAuthToken = async token => {
  try {
    const ticket = await client.verifyIdToken({
      idToken: token,
      audience: process.env.OAUTH_CLIENT_ID
    });
    return ticket.getPayload();
  } catch (err) {
    console.error("Error verifying auth token", err);
  }
};