@NgModule()
export class AnalyticsModule {
  private static readonly EVENTS_MAP_TOKEN = new InjectionToken<EventsMap[]>(
    'eventsMap'
  );
  static readonly EVENTS_MAP: EventsMap = {};

  constructor(
    @Inject(AnalyticsModule.EVENTS_MAP_TOKEN) eventsMaps: EventsMap[][]
  ) {
    eventsMaps.forEach(events => {
      Object.assign(AnalyticsModule.EVENTS_MAP, ...events);
    });
  }

  static forEventsMap(eventsMap: () => EventsMap): ModuleWithProviders {
    return {
      ngModule: AnalyticsModule,
      providers: [{
        provide: AnalyticsModule.EVENTS_MAP_TOKEN,
        multi: true,
        useFactory: eventsMap
      }]
    };
  }
}