[AngularFire] Firebase OAuth Login With Custom Firestore User Data

import { NgModule } from '@angular/core';
import { AuthService } from './auth.service';
import { AngularFireAuthModule } from 'angularfire2/auth';
import { AngularFirestoreModule } from 'angularfire2/firestore';
@NgModule({
  imports: [
    AngularFireAuthModule,
    AngularFirestoreModule
  ],
  providers: [AuthService]
})
export class CoreModule { }

AuthService:

import { Injectable } from '@angular/core';
import { Router } from '@angular/router';
import * as firebase from 'firebase/app';
import { AngularFireAuth } from 'angularfire2/auth';
import { AngularFirestore, AngularFirestoreDocument } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/switchMap'
interface User {
  uid: string;
  email: string;
  photoURL?: string;
  displayName?: string;
  favoriteColor?: string;
}
@Injectable()
export class AuthService {
  user: Observable<User>;
  constructor(private afAuth: AngularFireAuth,
              private afs: AngularFirestore,
              private router: Router) {
      //// Get auth data, then get firestore user document || null
      this.user = this.afAuth.authState
        .switchMap(user => {
          if (user) {
            return this.afs.doc<User>(`users/${user.uid}`).valueChanges()
          } else {
            return Observable.of(null)
          }
        })
  }
  googleLogin() {
    const provider = new firebase.auth.GoogleAuthProvider()
    return this.oAuthLogin(provider);
  }
  private oAuthLogin(provider) {
    return this.afAuth.auth.signInWithPopup(provider)
      .then((credential) => {
        this.updateUserData(credential.user)
      })
  }
  private updateUserData(user) {
    // Sets user data to firestore on login
    const userRef: AngularFirestoreDocument<any> = this.afs.doc(`users/${user.uid}`);
    const data: User = {
      uid: user.uid,
      email: user.email,
      displayName: user.displayName,
      photoURL: user.photoURL
    }
    return userRef.set(data)
  }
  signOut() {
    this.afAuth.auth.signOut().then(() => {
        this.router.navigate(['/']);
    });
  }
}

Guard:

import { Injectable } from '@angular/core';
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, Router } from '@angular/router';
import { AuthService} from './auth.service'
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/do';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/take';
@Injectable()
export class AuthGuard implements CanActivate {
  constructor(private auth: AuthService, private router: Router) {}
  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): Observable<boolean> | boolean {
      return this.auth.user
           .take(1)
           .map(user => !!user)
           .do(loggedIn => {
             if (!loggedIn) {
               console.log('access denied')
               this.router.navigate(['/login']);
             }
         })
  }
}