@Directive({
  selector: '[asyncControl]'
})
export class AsyncControlDirective implements AfterViewInit, OnDestroy {
  destroyed$: Subject<boolean> = new Subject();

  constructor(private changeDetector: ChangeDetectorRef, private formControl: NgControl) {
  }

  public ngAfterViewInit(): void {
    this.formControl.statusChanges
      .pipe(
        takeUntil(this.destroyed$)
      )
      .subscribe(
        _ => this.changeDetector.markForCheck()
      );
  }

  ngOnDestroy() {
    this.destroyed$.next(true);
  }
}