import { Directive, ElementRef, EventEmitter, Output, AfterViewInit, OnDestroy, NgZone } from '@angular/core';

@Directive({
  selector: '[appLazyLoad]',
  standalone: true
})
export class LazyLoadDirective implements AfterViewInit, OnDestroy {
  @Output() lazyLoad = new EventEmitter<void>();

  private observer!: IntersectionObserver;

  constructor(private element: ElementRef, private ngZone: NgZone) {}

  ngAfterViewInit(): void {
    // Run the intersection observer outside Angular's zone
    this.ngZone.runOutsideAngular(() => {
      this.observer = new IntersectionObserver(entries => {
        entries.forEach(entry => {
          if (entry.isIntersecting) {
            // Re-enter Angular's zone to trigger the lazy load event
            this.ngZone.run(() => {
              this.lazyLoad.emit();
              this.observer.disconnect(); // Disconnect after loading
            });
          }
        });
      });

      this.observer.observe(this.element.nativeElement);
    });
  }

  ngOnDestroy(): void {
    if (this.observer) {
      this.observer.disconnect();
    }
  }
}