import {AuthProviders, FirebaseAuthState, FirebaseAuth} from "angularfire2";import {Injectable} from "@angular/core";@Injectable()export class AuthService {  private authState: FirebaseAuthState = null;  constructor(public auth$: FirebaseAuth) {    auth$.subscribe((state: FirebaseAuthState) => {      this.authState = state;    });  }  get authenticated(): boolean {    return this.authState !== null;  }  get id(): string {    return this.authenticated ? this.authState.uid : ‘‘;  }  signIn(provider: number): firebase.Promise<FirebaseAuthState> {    return this.auth$.login({provider})      .catch(error => console.log(‘ERROR @ AuthService#signIn() :‘, error));  }  signInWithGithub(): firebase.Promise<FirebaseAuthState> {    return this.signIn(AuthProviders.Github)  }  signInWithGoogle(): firebase.Promise<FirebaseAuthState> {    return this.signIn(AuthProviders.Google);  }  signInWithTwitter(): firebase.Promise<FirebaseAuthState> {    return this.signIn(AuthProviders.Twitter);  }  signOut(): void {    this.auth$.logout();  }}

<section class="signup">  <button md-button (click)="signInWithGoogle()">Google</button>  <button md-button (click)="signInWithTwitter()">Twitter</button>  <button md-button (click)="signInWithGithub()">Github</button></section>

import {Component, OnInit} from ‘@angular/core‘;import {AuthService} from "../shared";import {Router} from "@angular/router";@Component({  selector: ‘app-signup‘,  templateUrl: ‘./signup.component.html‘,  styleUrls: [‘./signup.component.css‘]})export class SignupComponent implements OnInit {  constructor(private auth: AuthService, private router: Router) {  }  ngOnInit() {  }  signInWithGithub(){    this.auth.signInWithGithub()      .then(this.postSignIn.bind(this))  }  signInWithTwitter(){    this.auth.signInWithTwitter()      .then(this.postSignIn.bind(this))  }  signInWithGoogle(){    this.auth.signInWithGoogle()      .then(this.postSignIn.bind(this))  }  postSignIn() {    console.log("Auth id: ", this.auth.id);    this.router.navigate([‘/home‘]);  }}