import {inject, Injectable, Signal, signal} from '@angular/core';
import {MatSnackBar} from '@angular/material/snack-bar';
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 {
  readonly #categoryRestService = inject(CategoryRestService);
  readonly #snackBar = inject(MatSnackBar);
  #categories = signal<DisplayableCategory[]>([]);
  #isLoading = signal(false);
  isLoaded = signal(false);

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

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

  get categories(): Signal<DisplayableCategory[]> {
    return this.#categories.asReadonly();
  }

  get isLoading(): Signal<boolean> {
    return this.#isLoading.asReadonly();
  }

  loadCategories(): void {
    this.#isLoading.set(true);
    this.isLoaded.set(false);

    this.#categoryRestService.getCategories()
      .then(categories => {
        const displayableCategories = categories
          .filter(category => category.subCategories?.length)
          .map(category => this.#mapToDisplayableCategory(category));
        this.#categories.set(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.#isLoading.set(false);
        this.isLoaded.set(true);
      });
  }

  setOpened(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.#categories.set(categories);
    }
  }
}