OAuth with Angular and Firebase Tutorial

UPDATE Oct 10th, 2017: Fully updated tutorial for AngularFire v5 and Firestore https://youtu.be/e8GA1UOj8mE Angular OAuth with Firebase Tutorial https://angularfirebase.com/lessons/angular-firebase-authentication-tutorial-oauth/ In this episode, were going to build a user authentication system with Angular 4 and Firebase. Authentication is required in almost every Angular application, including this basic todo list app. The app currently has no authentication at all, but we want user to be able to log in with their Google, Facebook, Twitter, or Github account. At this point, it is assumed you have the AngularFire2 package installed and bootstrapped into your app. If not, go to the docs or checkout this video. STEP 1 - Generate Files We are going to keep this feature super simple. The Auth Service will handle interaction with the Firebase API. The User Login Component will handle the login and logout buttons. The User Profile Component will show details about the User. STEP 2 - Activate Providers in Firebase Head over to your firebase project and enable the providers you want. For non-google providers, you will need to get your own developer account and API keys. STEP 3 - Build the Service The way you handle authentication with Firebase is by subscribing to the AngularFire-Auth observable which returns a Firebase-Auth-State object. Now that we have the AuthState object, we can take advantage of TypeScript accessors to get attributes. In this case, I'm interested in the User ID. Here's the beauty of firebase - you can implement 4 social auth providers with very little code. I start by creating a reusable private function that takes the provider as an argument named `Social-Sign-In`. When a user attempts to sign in two things can happen - success or failure. If it's a success, the `then` code will execute, if its's an error the `catch` code will execute. You may be wondering what the `updateUserData` function is about. It's optional, but y