import { TalyPageDataService } from '@allianz/taly-core';
import { DestroyRef, Injectable, TemplateRef, inject } from '@angular/core';
import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
import { BehaviorSubject } from 'rxjs';
import { skip } from 'rxjs/operators';

@Injectable({ providedIn: 'root' })
export class TalyFrameSmallPrintService {
  private registeredTemplates = new Map<TemplateRef<unknown>, number>();
  private templatesListSubject = new BehaviorSubject<TemplateRef<unknown>[]>([]);

  templateList$ = this.templatesListSubject.asObservable();

  private destroyRef = inject(DestroyRef);

  constructor(private talyPageDataService: TalyPageDataService) {
    this.init();
  }

  init() {
    this.talyPageDataService.pageData$
      .pipe(
        skip(1), // skip the first as we subscribe to a behavior subject
        takeUntilDestroyed(this.destroyRef)
      )
      .subscribe(() => this.pageChanged());
  }

  registerTemplate(template: TemplateRef<unknown>, index = 0) {
    this.registeredTemplates.set(template, index);
    this.update();
  }

  removeTemplate(template: TemplateRef<unknown>) {
    this.registeredTemplates.delete(template);
    this.update();
  }

  private pageChanged() {
    this.registeredTemplates.clear();
    this.update();
  }

  private update() {
    const sortedTemplates: TemplateRef<unknown>[] = Array.from(this.registeredTemplates.entries())
      .sort((a, b) => a[1] - b[1])
      .map((entry) => entry[0]);

    this.templatesListSubject.next(sortedTemplates);
  }
}