app.module.ts

import {StoreModule, MetaReducer, META_REDUCERS} from '@ngrx/store';
import {ROOT_STORAGE_KEYS, LOCAL_STORAGE_KEY} from './app.tokens';
import {LocalStorageService} from './shared/local-storage.service';
import {storageMetaReducer} from './storage.metareducer';

// factory meta-reducer configuration function
export function getMetaReducers(saveKeys: string[],
                                 localStorageKey: string,
                                 storageService: LocalStorageService
                                ): MetaReducer<any>[] {
  return [storageMetaReducer(saveKeys, localStorageKey, storageService)];
}
@NgModule({
  imports  : [
    StoreModule.forRoot(reducers)
  ],
  providers: [
    {provide: ROOT_STORAGE_KEYS, useValue: ['layout.theme']},
    {provide: ROOT_LOCAL_STORAGE_KEY, useValue: '__app_storage__'},
    {
      provide   : META_REDUCERS,
      deps      : [ROOT_STORAGE_KEYS, ROOT_LOCAL_STORAGE_KEY, LocalStorageService],
      useFactory: getMetaReducers
    },
  ]
})
export class AppModule {
}