import { Injectable, inject } from '@angular/core';
import { MatSnackBar } from '@angular/material/snack-bar';
import { BehaviorSubject, Observable } from 'rxjs';
import { CategoryRestService } from '../../core/rest-services/category/category.rest-service';
import { Category } from '../../core/rest-services/category/model/category';

export interface DisplayableCategory {
  id: string;
  name: string;
  subCategories: DisplayableSubCategory[];
  isOpenned: boolean;
}

export interface DisplayableSubCategory {
  id: string;
  name: string;
}

@Injectable({
  providedIn: 'root'
})
export class SideMenuService {
  private categoryRestService = inject(CategoryRestService);
  private snackBar = inject(MatSnackBar);
  private categoriesSubject = new BehaviorSubject<DisplayableCategory[]>([]);
  private isLoadingSubject = new BehaviorSubject<boolean>(false);
  private isLoadedSubject = new BehaviorSubject<boolean>(false);

  private mapToDisplayableCategory(category: Category): DisplayableCategory {
    return {
      id: category.id,
      name: category.name,
      subCategories: category.subCategories.map(subCategory => this.mapToDisplayableSubCategory(subCategory)),
      isOpenned: false
    };
  }

  private mapToDisplayableSubCategory(subCategory: Category): DisplayableSubCategory {
    return {
      id: subCategory.id,
      name: subCategory.name
    }
  }

  private get categories(): DisplayableCategory[] {
    return this.categoriesSubject.value;
  }

  private save(categories: DisplayableCategory[]): void {
    this.categoriesSubject.next(categories);
  }

  get categories$(): Observable<DisplayableCategory[]> {
    return this.categoriesSubject.asObservable();
  }
  
  get isLoading$(): Observable<boolean> {
    return this.isLoadingSubject.asObservable();
  }

  loadCategories(): void {
    this.isLoadingSubject.next(true);
    this.isLoadedSubject.next(false);

    this.categoryRestService.getCategories()
      .then(categories => {
        const displayableCategories = categories
          .filter(category => category.subCategories?.length)
          .map(category => this.mapToDisplayableCategory(category));
        this.categoriesSubject.next(displayableCategories);
      })
      .catch(error => {
        const errorMessage = $localize`An error occured while loading categories.`;
        console.error(errorMessage, error);
        this.snackBar.open(errorMessage, $localize`Close`, { duration: 5000 });
      })
      .finally(() => {
        this.isLoadingSubject.next(false);
        this.isLoadedSubject.next(true);
      });
  }

  setOpenned(category: DisplayableCategory): void {
    const categories = this.categories;
    const matchingCategory = categories.find(categoryTemp => categoryTemp.id === category.id);
    if (matchingCategory) {
      const actualOpennedCategory = categories.find(category => category.isOpenned);
      if (actualOpennedCategory && actualOpennedCategory.id === matchingCategory.id) {
        matchingCategory.isOpenned = false;
      } else {
        categories.forEach(categoryTemp => categoryTemp.isOpenned = false);
        matchingCategory.isOpenned = true;
      }
      this.save(categories);
    }
  }
}