Angular App Initializer

app.module.ts

import { NgModule, APP_INITIALIZER } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouteReuseStrategy } from '@angular/router';
import { HttpClientModule } from '@angular/common/http';

import { IonicModule, IonicRouteStrategy } from '@ionic/angular';
import { SplashScreen } from '@ionic-native/splash-screen/ngx';
import { StatusBar } from '@ionic-native/status-bar/ngx';
import { IonicStorageModule } from '@ionic/storage'

import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';

import { UserService } from './providers/user.service';
import { SocketService } from './providers/socket.service';
import { HttpService } from './providers/http.service';
import { ImageModalComponent } from './components/image-modal/image-modal.component';
import { PinchZoomModule } from 'ngx-pinch-zoom';
import { OneSignalService } from './providers/onsignal.service';
import { InAppBrowser } from '@ionic-native/in-app-browser/ngx';
import { Device } from '@ionic-native/device/ngx';
import { OneSignal } from '@ionic-native/onesignal/ngx';
import { OneSignalNativeService } from './providers/onsignal-native.service';
import { Media } from '@ionic-native/media/ngx';
import { File } from '@ionic-native/file/ngx';
import { TabsPage } from './pages/tabs/tabs.page';
import { TabsService } from './pages/tabs/tabs.service';

import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

export function userServiceFactory(userService: UserService): Function {
  return () => userService.authenticate();
}

@NgModule({
  declarations: [AppComponent, ImageModalComponent, TabsPage],
  entryComponents: [ImageModalComponent],
  imports: [
    BrowserModule,
    IonicModule.forRoot(),
    IonicStorageModule.forRoot(),
    AppRoutingModule,
    HttpClientModule,
    PinchZoomModule,
  ],
  providers: [
    StatusBar,
    SplashScreen,
    HttpService,
    UserService,
    SocketService,
    OneSignalService,
    OneSignalNativeService,
    InAppBrowser,
    Device,
    OneSignal,
    Media,
    TabsService,
    BrowserAnimationsModule,
    File,
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy },
    {
      provide: APP_INITIALIZER,
      useFactory: userServiceFactory,
      deps: [UserService],
      multi: true
    }
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

http.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse, HttpHeaders } from '@angular/common/http';
import { environment } from '../../environments/environment';
import { catchError, retry } from 'rxjs/operators';
import { throwError } from 'rxjs';

@Injectable()
export class HttpService {
  DOMAIN = environment.domain;
  headers;

  constructor(private http: HttpClient) { }

  /**
   * Login with provided info and return token
   * @param mobile 
   * @param password 
   */
  login(mobile, password) {
    return this.http.post<LoginInterface>(`${this.DOMAIN}/auth/local`, { mobile, password });
  }

  /**
   * Authenticate User token
   * @param token 
   */
  authenticate(token) {
    this.headers = new HttpHeaders({
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`
    })
    return this.http.get<UserInterface>(`${this.DOMAIN}/api/users/me`, { headers: this.headers });
  }
}

user.service.ts

import { Injectable, Injector } from '@angular/core';
import { Storage } from '@ionic/storage';
import { Router } from '@angular/router';
import { HttpService, UserInterface } from './http.service';
import { OneSignalService } from './onsignal.service';
import { environment } from '../../environments/environment';
import { OneSignalNativeService } from './onsignal-native.service';
import { Device } from '@ionic-native/device/ngx';

@Injectable()
export class UserService {
  private _token: string;
  private _userInfo: UserInterface;
  TOKEN = 'token';

  constructor(
    public storage: Storage,
    private http: HttpService,
    private injector: Injector,
    private oneSignal: OneSignalService,
    private oneSignalNative: OneSignalNativeService,
    private device: Device
  ) { }

  public get router(): Router {
    return this.injector.get(Router);
  }

  async authenticate(): Promise<any> {
    let token = await this.storage.get(this.TOKEN);
    if (!token) return Promise.resolve();

    return this.http.authenticate(token).toPromise()
      .then(res => {
        this._token = token;
        this._userInfo = res;
        if (environment.production) this.device.cordova ? this.oneSignalNative.init() : this.oneSignal.init();
      }).catch(err => {
        return Promise.resolve();
      });
  }
}