records.facade.ts

@Injectable()
export class RecordsFacade {

  private records$: Observable<Record[]>;

  constructor(private recordApi: RecordApi) {
    this.records$ = this.recordApi
        .getRecords()
        .pipe(shareReplay(1)); // armazena os dados em cache
  }

  getRecords() {
    return this.records$;
  }

  // projeta os dados cacheados para o componente
  getRecordsFromPeriod(period?: Period): Observable<Record[]> {
    return this.records$
      .pipe(map(records => records.filter(record => record.inPeriod(period))));
  }

  searchRecords(search: string): Observable<Record[]> {
    return this.recordApi.searchRecords(search);
  }
}