import { HttpClient, HttpErrorResponse } from "@angular/common/http";
import { effect, inject, Injectable } from "@angular/core";
import { API_URL } from "../tokens/api-url-tokens";
import { CartItemRequest, CartModel } from "../models/cart.model";
import { AuthService } from "@core/services/auth-service";
import { BehaviorSubject, tap } from "rxjs";

@Injectable({
  providedIn: "root",
})
export class CartService {
  private authService = inject(AuthService);
  // dependencies
  private http = inject(HttpClient);
  private apiUrl = inject(API_URL);

  private _cartItems = new BehaviorSubject<CartModel>({} as CartModel);

  cartItems$ = this._cartItems.asObservable();

  constructor() {
    effect(() => {
      if (this.authService.isAuthenticated()) {
        this.fetchCart();
      } else {
        this._cartItems.next({} as CartModel);
      }
    });
  }

  fetchCart() {
    return this.http.get<CartModel>(this.apiUrl + "/cart").subscribe({
      next: (data) => this._cartItems.next(data),
      error: (error: HttpErrorResponse) => {
        if (error.status === 401) {
          this.authService.purgeAuth();
        }
        // show an error in toast
      },
    });
  }

  addToCart(data: CartItemRequest) {
    return this.http
      .post<CartModel>(this.apiUrl + "/cart", data)
      .pipe(tap((updatedCart: CartModel) => this._cartItems.next(updatedCart)));
  }

  updateCart(data: CartItemRequest) {
    return this.http
      .patch<CartModel>(this.apiUrl + "/cart", data)
      .pipe(tap((updatedCart: CartModel) => this._cartItems.next(updatedCart)));
  }

  removeFromCart(productId: number) {
    return this.http
      .delete<CartModel>(this.apiUrl + "/cart", { body: { productId: productId } })
      .pipe(tap((updatedCart: CartModel) => this._cartItems.next(updatedCart)));
  }
}