import {Directive, Input} from '@angular/core';
import { AbstractControl, NG_VALIDATORS, ValidationErrors, Validator, ValidatorFn } from '@angular/forms';


export function rangeRequired( enabled:boolean): ValidatorFn {
  return (control: AbstractControl): ValidationErrors | null => {
    const yearFrom = control.get('yearFrom');
    const yearTo = control.get('yearTo');
    return ((yearFrom && yearTo && enabled && (yearFrom.value == "" || yearTo.value == "")) ? { 'rangeRequired': true } : null);
  };
}


@Directive({
  selector: '[rangeRequired]',
  providers: [{ provide: NG_VALIDATORS, useExisting: RangeYearsRequiredDirective, multi: true }]
})
export class RangeYearsRequiredDirective implements Validator {
  @Input('rangeRequired') enabled:boolean = false;
  validate(control: AbstractControl): ValidationErrors {
    return rangeRequired(this.enabled)(control)
  }
}