Main.js

import '../modules/index.js';
import { Meteor } from 'meteor/meteor';
const {google} = require('googleapis');
const fs = require('fs');

Meteor.startup( function (){

    Meteor.methods({
        //credits: https://morioh.com/p/1313d7785668/node-js-using-google-sheets-api-with-oauth-2
        //credits: http://www.gethugames.in/2012/04/authentication-and-authorization-for-google-apis-in-javascript-popup-window-tutorial.html
        //authenticate the app to get access to user's google drive sheets
         'googleAuth'(){
            const path = process.env.PWD + '/credentials.json';
            const credentials = JSON.parse(fs.readFileSync(path, 'utf-8'));  
            const {
              client_secret: clientSecret,
              client_id: clientId,
              redirect_uris: redirectUris,
            } = credentials.web;

            const oauth2Client = new google.auth.OAuth2(
            
                clientId, clientSecret, redirectUris[0],
            
            );

            // generate a url that asks permissions for Blogger and Google Calendar scopes
            const scopes = [
            'https://www.googleapis.com/auth/spreadsheets'
            ];

            const url = oauth2Client.generateAuthUrl({
            // 'online' (default) or 'offline' (gets refresh_token)
            access_type: 'offline',

            // If you only need one scope you can pass it as a string
            scope: scopes
            });

            try {
                return url
            } catch(exception){
                
            }

            return url;

         }
  
    })

})