import { AngularFireModule } from '@angular/fire';
import { AngularFireAuthModule } from '@angular/fire/auth';
import { AngularFirestoreModule } from '@angular/fire/firestore';

@NgModule({
  imports: [
    BrowserModule.withServerTransition({ appId: 'serverApp' }),

    // Firebase
    AngularFireModule.initializeApp(environment.firebase),
    AngularFirestoreModule,
    AngularFireAuthModule,

    // App
    AppRoutingModule
  ],
  declarations: [
    AppComponent
  ],
  bootstrap: [AppComponent]
})

export class AppModule {}

import { Injectable } from '@angular/core';
import { CanActivate, CanActivateChild, CanLoad } from '@angular/router';
import * as firebase from 'firebase/app';

@Injectable({
  providedIn: 'root'
})

export class AuthGuard implements CanActivate, CanActivateChild, CanLoad {

  /** @ignore */
  constructor() {}

  canLoad(): boolean {
    return this.performCheck();
  }

  canActivate(): boolean {
    return this.performCheck();
  }

  canActivateChild(): boolean {
    return this.performCheck();
  }

  private performCheck() {
    return !!firebase.auth().currentUser;
  }
}

export const Routes = [
  {
    path: '',
    pathMatch: 'full',
    redirectTo: 'hello'
  },
  {
    path: 'hello',
    component: HelloComponent,
    canActivate: [AuthGuard]
  }
];

import { Injectable } from '@angular/core';
import { CanActivate, CanActivateChild, CanLoad } from '@angular/router';
import { AngularFireAuth } from '@angular/fire/auth'; // instead of firebase
import { Observable } from 'rxjs';
import { take, map } from 'rxjs/operators'

@Injectable({
  providedIn: 'root'
})

export class AuthGuard implements CanActivate, CanActivateChild, CanLoad {

  /** @ignore */
  constructor(private auth: AngularFireAuth) {}

  canLoad(): Observable<boolean> {
    return this.performCheck();
  }

  canActivate(): Observable<boolean> {
    return this.performCheck();
  }

  canActivateChild(): Observable<boolean> {
    return this.performCheck();
  }

  private performCheck(): Observable<boolean> {
    return this.auth.user.pipe(map((user) => {
      if (user) {
        // user is logged in
        return true;
      }
      // user is not logged in
      return false;
    }),
    take(1));
  }
}