import {
  ChangeDetectorRef,
  Directive,
  Inject,
  Input,
  OnDestroy,
  OnInit,
  Optional,
  TemplateRef,
  ViewContainerRef,
} from '@angular/core';
import { Subscription } from 'rxjs';
import {
  distinctUntilChanged,
  tap,
} from 'rxjs/operators';
import { AuthorizationService } from './authorization.service';
import { RXAP_AUTHORIZATION_SCOPE } from './tokens';

@Directive({
  selector: '[rxapIfHasPermission]',
  standalone: true,
})
export class IfHasPermissionDirective implements OnInit, OnDestroy {

  @Input({ required: true, alias: 'rxapIfHasPermission' })
  public identifier!: string;

  @Input({ alias: 'rxapIfHasPermissionElse' })
  public else?: TemplateRef<any>;

  private _subscription?: Subscription;

  constructor(
    @Inject(AuthorizationService)
    private readonly authorization: AuthorizationService,
    @Inject(TemplateRef)
    private readonly template: TemplateRef<any>,
    @Inject(ViewContainerRef)
    private readonly viewContainerRef: ViewContainerRef,
    @Inject(ChangeDetectorRef)
    private readonly cdr: ChangeDetectorRef,
    @Optional()
    @Inject(RXAP_AUTHORIZATION_SCOPE)
    private readonly scope: string | null = null,
  ) {
  }

  public ngOnInit() {
    this._subscription = this.authorization
                             .hasPermission$(this.identifier, this.scope || null)
                             .pipe(
                               distinctUntilChanged(),
                               tap((hasPermission) => {
                                 this.viewContainerRef.clear();
                                 if (hasPermission) {
                                   this.viewContainerRef.createEmbeddedView(this.template);
                                 } else if (this.else) {
                                   this.viewContainerRef.createEmbeddedView(this.else);
                                 }
                                 this.cdr.markForCheck();
                               }),
                             )
                             .subscribe();
  }

  public ngOnDestroy() {
    this._subscription?.unsubscribe();
  }
}