First.

Author: jamesdaniels

src/auth/auth.module.ts

@@ -1,24 +1,9 @@
-import { NgModule, NgZone } from '@angular/core';
-import { FirebaseApp, AngularFireModule } from 'angularfire2';
+import { NgModule } from '@angular/core';
 import { AngularFireAuth } from './auth';
 import '@firebase/auth';
-
-export function _getAngularFireAuth(app: FirebaseApp) {
-  return new AngularFireAuth(app);
-}
-
-export const AngularFireAuthProvider = {
-  provide: AngularFireAuth,
-  useFactory: _getAngularFireAuth,
-  deps: [ FirebaseApp ]
-};
-
-export const AUTH_PROVIDERS = [
-  AngularFireAuthProvider,
-];
+import { FirebaseApp } from '@firebase/app-types'
 
 @NgModule({
-  imports: [ AngularFireModule ],
-  providers: [ AUTH_PROVIDERS ]
+  providers: [ AngularFireAuth ]
 })
 export class AngularFireAuthModule { }

src/auth/auth.spec.ts

@@ -8,7 +8,7 @@ import { TestBed, inject } from '@angular/core/testing';
 import { _do } from 'rxjs/operator/do';
 import { take } from 'rxjs/operator/take';
 import { skip } from 'rxjs/operator/skip';
-import { FirebaseApp, FirebaseAppConfig, AngularFireModule } from 'angularfire2';
+import { FirebaseAppConfig, AngularFireModule } from 'angularfire2';
 import { AngularFireAuth, AngularFireAuthModule } from 'angularfire2/auth';
 import { COMMON_CONFIG } from './test-config';
 
@@ -51,7 +51,7 @@ describe('AngularFireAuth', () => {
   });
 
   afterEach(done => {
-    app.delete().then(done, done.fail);
+    afAuth.auth.app.delete().then(done, done.fail);
   });
 
   describe('Zones', () => {

src/auth/auth.ts

@@ -1,8 +1,11 @@
 import { FirebaseAuth, User } from '@firebase/auth-types';
-import { Injectable, NgZone } from '@angular/core';
+import { FirebaseOptions } from '@firebase/app-types';
+import { Injectable, NgZone, Inject, Optional } from '@angular/core';
 import { Observable } from 'rxjs/Observable';
 import { observeOn } from 'rxjs/operator/observeOn';
-import { FirebaseApp, ZoneScheduler } from 'angularfire2';
+import { ZoneScheduler } from 'angularfire2';
+
+import { FirebaseAppConfig, FirebaseAppName, firebaseAppFactory } from 'angularfire2';
 
 import 'rxjs/add/operator/switchMap';
 import 'rxjs/add/observable/of';
@@ -26,8 +29,12 @@ export class AngularFireAuth {
    */
   public readonly idToken: Observable<string|null>;
 
-  constructor(public app: FirebaseApp) {
-    this.auth = app.auth();
+  constructor(
+    @Inject(FirebaseAppConfig) config:FirebaseOptions,
+    @Optional() @Inject(FirebaseAppName) name:string
+  ) {
+    const app = firebaseAppFactory(config, name);
+    this.auth = app.auth!();
 
     const authState$ = new Observable(subscriber => {
       const unsubscribe = this.auth.onAuthStateChanged(subscriber);

src/core/angularfire2.ts

@@ -1,35 +1,55 @@
-import { FirebaseAppConfigToken, FirebaseApp, _firebaseAppFactory } from './firebase.app.module';
 import { Injectable, InjectionToken, NgModule } from '@angular/core';
 import { Subscription } from 'rxjs/Subscription';
 import { Scheduler } from 'rxjs/Scheduler';
 import { queue } from 'rxjs/scheduler/queue';
 
-export interface FirebaseAppConfig {
-  apiKey?: string;
-  authDomain?: string;
-  databaseURL?: string;
-  storageBucket?: string;
-  messagingSenderId?: string;
-  projectId?: string;
+import firebase from '@firebase/app';
+import { FirebaseApp as FBApp, FirebaseOptions } from '@firebase/app-types';
+import { FirebaseAuth } from '@firebase/auth-types';
+import { FirebaseDatabase } from '@firebase/database-types';
+import { FirebaseMessaging } from '@firebase/messaging-types';
+import { FirebaseStorage } from '@firebase/storage-types';
+import { FirebaseFirestore } from '@firebase/firestore-types';
+
+export function firebaseAppFactory(config: FirebaseOptions, name?: string): FBApp {
+  const appName = name || '[DEFAULT]';
+  const existingApp = firebase.apps.filter(app => app.name == appName)[0];
+  return existingApp || firebase.initializeApp(config, appName);
 }
 
-const FirebaseAppName = new InjectionToken<string>('FirebaseAppName');
+export class FirebaseApp implements FBApp {
+  constructor() {
+    console.warn('FirebaseApp will be depreciated in favor @firebase/auth-types/FirebaseApp');
+  }
+  name: string;
+  options: {};
+  auth: () => FirebaseAuth;
+  database: () => FirebaseDatabase;
+  messaging: () => FirebaseMessaging;
+  storage: () => FirebaseStorage;
+  delete: () => Promise<any>;
+  firestore: () => FirebaseFirestore;
+}
+
+export const FirebaseAppName = new InjectionToken<string>('angularfire2.appName');
+export const FirebaseAppConfig = new InjectionToken<FirebaseOptions>('angularfire2.config');
 
 export const FirebaseAppProvider = {
   provide: FirebaseApp,
-  useFactory: _firebaseAppFactory,
-  deps: [ FirebaseAppConfigToken, FirebaseAppName ]
+  useFactory: firebaseAppFactory,
+  deps: [ FirebaseAppConfig, FirebaseAppName ]
 };
 
 @NgModule({
   providers: [ FirebaseAppProvider ],
 })
 export class AngularFireModule {
-  static initializeApp(config: FirebaseAppConfig, appName?: string) {
+  static initializeApp(config: FirebaseOptions, appName?: string) {
+    console.warn('initializeApp will be depreciated in favor of the angularfire2/FirebaseAppConfig provider');
     return {
       ngModule: AngularFireModule,
       providers: [
-        { provide: FirebaseAppConfigToken, useValue: config },
+        { provide: FirebaseAppConfig, useValue: config },
         { provide: FirebaseAppName, useValue: appName }
       ]
     }
@@ -49,5 +69,3 @@ export class ZoneScheduler {
     return <Subscription>this.zone.run(() => queue.schedule.apply(queue, args));
   }
 }
-
-export { FirebaseApp, FirebaseAppName, FirebaseAppConfigToken };

src/core/firebase.app.module.ts

@@ -1,5 +1,6 @@
 import { NgModule } from '@angular/core';
-import { AngularFireModule, FirebaseApp } from 'angularfire2';
+import { AngularFireModule } from 'angularfire2';
+import { FirebaseApp } from '@firebase/app-types';
 import { AngularFireDatabase } from './database';
 import '@firebase/database';
 

src/database-deprecated/database.module.ts

@@ -1,6 +1,6 @@
 import { FirebaseDatabase } from '@firebase/database-types';
 import { Inject, Injectable } from '@angular/core';
-import { FirebaseAppConfigToken, FirebaseAppConfig, FirebaseApp } from 'angularfire2';
+import { FirebaseApp } from '@firebase/app-types';
 import { FirebaseListFactory } from './firebase_list_factory';
 import { FirebaseListObservable } from './firebase_list_observable';
 import { FirebaseListFactoryOpts, FirebaseObjectFactoryOpts, PathReference } from './interfaces';
@@ -17,7 +17,7 @@ export class AngularFireDatabase {
   database: FirebaseDatabase;
 
   constructor(public app: FirebaseApp) {
-    this.database = app.database();
+    this.database = app.database!();
   }
 
   list(pathOrRef: PathReference, opts?:FirebaseListFactoryOpts):FirebaseListObservable<any[]> {

src/database-deprecated/database.ts

@@ -3,7 +3,7 @@ import { Subscription } from 'rxjs/Subscription';
 import { Scheduler } from 'rxjs/Scheduler';
 import { queue } from 'rxjs/scheduler/queue';
 import { AFUnwrappedDataSnapshot, PathReference, DatabaseReference } from './interfaces';
-import { FirebaseApp } from 'angularfire2';
+import { FirebaseApp } from '@firebase/app-types';
 
 const REGEX_ABSOLUTE_URL = /^[a-z]+:\/\/.*/;
 
@@ -118,7 +118,7 @@ export function getRef(app: FirebaseApp, pathRef: PathReference): DatabaseRefere
 
   const path = pathRef as string;
   if(isAbsoluteUrl(<string>pathRef)) {
-    return app.database().refFromURL(path);
+    return app.database!().refFromURL(path);
   }
-  return app.database().ref(path);
+  return app.database!().ref(path);
 }

src/database-deprecated/utils.ts

@@ -1,24 +1,8 @@
 import { NgModule } from '@angular/core';
-import { AngularFireModule, FirebaseApp } from 'angularfire2';
-import { AngularFireDatabase } from './database';
+import { AngularFireDatabase, RealtimeDatabaseURL } from './database';
 import '@firebase/database';
 
-export function _getAngularFireDatabase(app: FirebaseApp) {
-  return new AngularFireDatabase(app);
-}
-
-export const AngularFireDatabaseProvider = {
-  provide: AngularFireDatabase,
-  useFactory: _getAngularFireDatabase,
-  deps: [ FirebaseApp ]
-};
-
-export const DATABASE_PROVIDERS = [
-  AngularFireDatabaseProvider,
-];
-
 @NgModule({
-  imports: [ AngularFireModule ],
-  providers: [ DATABASE_PROVIDERS ]
+  providers: [ AngularFireDatabase ]
 })
 export class AngularFireDatabaseModule { }

src/database/database.module.ts

@@ -1,21 +1,30 @@
-import { Injectable } from '@angular/core';
+import { Injectable, Inject, Optional } from '@angular/core';
 import { FirebaseDatabase } from '@firebase/database-types';
-import { FirebaseApp } from 'angularfire2';
 import { PathReference, DatabaseQuery, DatabaseReference, DatabaseSnapshot, ChildEvent, ListenEvent, QueryFn, AngularFireList, AngularFireObject } from './interfaces';
 import { getRef } from './utils';
+import { InjectionToken } from '@angular/core';
+import { FirebaseApp, FirebaseOptions } from '@firebase/app-types';
 import { createListReference } from './list/create-reference';
 import { createObjectReference } from './object/create-reference';
+import { FirebaseAppConfig, FirebaseAppName, firebaseAppFactory } from 'angularfire2';
+
+export const RealtimeDatabaseURL = new InjectionToken<string>('angularfire2.realtimeDatabaseURL');
 
 @Injectable()
 export class AngularFireDatabase {
-  database: FirebaseDatabase;
+  public readonly database: FirebaseDatabase;
 
-  constructor(public app: FirebaseApp) {
-    this.database = app.database();
+  constructor(
+    @Inject(FirebaseAppConfig) config:FirebaseOptions,
+    @Optional() @Inject(FirebaseAppName) name:string,
+    @Optional() @Inject(RealtimeDatabaseURL) databaseURL:string
+  ) {
+    const app = firebaseAppFactory(config, name);
+    this.database = app.database!(databaseURL);
   }
 
   list<T>(pathOrRef: PathReference, queryFn?: QueryFn): AngularFireList<T> {
-    const ref = getRef(this.app, pathOrRef);
+    const ref = getRef(this.database, pathOrRef);
     let query: DatabaseQuery = ref;
     if(queryFn) {
       query = queryFn(ref);
@@ -24,7 +33,7 @@ export class AngularFireDatabase {
   }
 
   object<T>(pathOrRef: PathReference): AngularFireObject<T>  {
-    const ref = getRef(this.app, pathOrRef);
+    const ref = getRef(this.database, pathOrRef);
     return createObjectReference<T>(ref);
   }
 

src/database/database.ts

@@ -2,7 +2,7 @@ import { Subscription } from 'rxjs/Subscription';
 import { Scheduler } from 'rxjs/Scheduler';
 import { queue } from 'rxjs/scheduler/queue';
 import { PathReference, DatabaseReference, FirebaseOperation, FirebaseOperationCases } from './interfaces';
-import { FirebaseApp } from 'angularfire2';
+import { FirebaseDatabase } from '@firebase/database-types';
 
 export function isString(value: any): boolean {
   return typeof value === 'string';
@@ -26,10 +26,10 @@ export function isFirebaseRef(value: any): boolean {
  * @param app - Firebase App
  * @param path - Database path, relative or absolute
  */
-export function getRef(app: FirebaseApp, pathRef: PathReference): DatabaseReference {
+export function getRef(database: FirebaseDatabase, pathRef: PathReference): DatabaseReference {
   // if a db ref was passed in, just return it
   return isFirebaseRef(pathRef) ? pathRef as DatabaseReference
-    : app.database().ref(pathRef as string);
+    : database.ref(pathRef as string);
 }
 
 export function checkOperationCases(item: FirebaseOperation, cases: FirebaseOperationCases) : Promise<void> {

src/database/utils.ts

@@ -6,7 +6,7 @@ import 'rxjs/add/operator/map';
 import 'rxjs/add/operator/filter';
 
 import { Injectable } from '@angular/core';
-import { FirebaseApp } from 'angularfire2';
+import { FirebaseApp } from '@firebase/app-types';
 
 import { QueryFn, AssociatedReference, DocumentChangeAction } from '../interfaces';
 import { docChanges, sortedChanges } from './changes';

src/firestore/collection/collection.ts

@@ -6,12 +6,11 @@ import { fromDocRef } from '../observable/fromRef';
 import 'rxjs/add/operator/map';
 
 import { Injectable } from '@angular/core';
-import { FirebaseApp } from 'angularfire2';
+import { FirebaseApp } from '@firebase/app-types';
 
 import { associateQuery } from '../firestore';
 import { AngularFirestoreCollection } from '../collection/collection';
 
-
 /**
  * AngularFirestoreDocument service
  *

src/firestore/document/document.ts

@@ -1,16 +1,9 @@
 import { InjectionToken, ModuleWithProviders, NgModule } from '@angular/core';
-import { FirebaseApp, AngularFireModule } from 'angularfire2';
-import { AngularFirestore } from './firestore';
-import { from } from 'rxjs/observable/from';
+import { AngularFirestore, EnablePersistenceToken } from './firestore';
 import '@firebase/firestore';
 
-import { EnablePersistenceToken } from './enable-persistance-token';
-
 @NgModule({
-  imports: [ AngularFireModule ],
-  providers: [
-    AngularFirestore,
-  ]
+  providers: [ AngularFirestore ]
 })
 export class AngularFirestoreModule {
   /**