import { Injectable, inject, signal } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { firstValueFrom } from 'rxjs';

import { AddCartRequest, AddCartResponse } from '../models/product.model';
import { environment } from '../../../environments/environment';

const API_BASE_URL = environment.apiBaseUrl;
const CART_COUNT_STORAGE_KEY = environment.cartCountStorageKey;

// Add cart implementation (just for visualization, not used in the app)
@Injectable({ providedIn: 'root' })
export class CartService {
  private readonly http = inject(HttpClient);

  //total items on cart
  readonly count = signal<number>(this.readPersistedCount());

  async addToCart(request: AddCartRequest): Promise<number> {
    const response = await firstValueFrom(
      this.http.post<AddCartResponse>(`${API_BASE_URL}/cart`, request)
    );

    //Note: can return always 1 because server has not SameSite=None. This will be taken as a third cookie, and the browser can ignore it.
    this.setCount(response.count);
    return response.count;
  }

  // reloads counter from localstorage
  private readPersistedCount(): number {
    const raw = localStorage.getItem(CART_COUNT_STORAGE_KEY);
    const parsed = raw ? Number(raw) : 0;
    return Number.isFinite(parsed) ? parsed : 0;
  }

  private setCount(count: number): void {
    this.count.set(count);
    localStorage.setItem(CART_COUNT_STORAGE_KEY, String(count));
  }
}