import { FormControl } from '@angular/forms';
import { concat, of, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

type Nullable<T> = T | null;

/**
 * @see AbstractControl.status
 */
export enum RxFormControlStatus {
  VALID = 'VALID',
  INVALID = 'INVALID',
  PENDING = 'PENDING',
  DISABLED = 'DISABLED',
}

export class RxFormControl<T = Nullable<string>> {
  constructor(public _formControl: FormControl) {}

  /**
   * Shortcut.
   * @see AbstractControl.valueChanges
   */
  public changes$: Observable<Nullable<T>> = this._formControl.valueChanges;

  /**
   * The value of the control.
   */
  public value$: Observable<Nullable<T>> = concat(of(this._formControl.value), this.changes$);

  /**
   * The validation status of the control.
   */
  public status$: Observable<RxFormControlStatus> = concat(of(this._formControl.status), this._formControl.statusChanges);

  /**
   * Is the control status invalid.
   */
  public invalid$: Observable<boolean> = this.status$.pipe(map(status => status === RxFormControlStatus.INVALID));

  /**
   * Shortcut.
   * @see FormControl.setValue
   */
  public setValue(value: Nullable<T>, options?: {
    onlySelf?: boolean;
    emitEvent?: boolean;
    emitModelToViewChange?: boolean;
    emitViewToModelChange?: boolean;
  }) {
    return this._formControl.setValue(value, options);
  }
}