import { create } from 'zustand';
import { persist } from 'zustand/middleware';

export interface CartItem {
  id: string; // Unikalne ID, połączenie slug + wybrane opcje
  slug: string;
  name: string;
  brand: string;
  image: string;
  power?: number;
  label?: string; // Np. "2.5 kW" z wariantu
  price: number; // Podstawowa cena za 1 szt. bez montażu
  priceWithInstall: number; // Cena za 1 szt. z montażem
  withInstall: boolean;
  quantity: number;
}

interface CartState {
  items: CartItem[];
  addItem: (item: Omit<CartItem, 'id' | 'quantity'>) => void;
  removeItem: (id: string) => void;
  updateQuantity: (id: string, quantity: number) => void;
  toggleInstall: (id: string) => void;
  clearCart: () => void;
  getTotals: () => { subtotal: number; vat: number; total: number };
}

export const useCartStore = create<CartState>()(
  persist(
    (set, get) => ({
      items: [],

      addItem: (newItem) => {
        set((state) => {
          const id = `${newItem.slug}-${newItem.label || 'base'}-${newItem.withInstall}`;
          const existingItem = state.items.find((item) => item.id === id);

          if (existingItem) {
            return {
              items: state.items.map((item) =>
                item.id === id ? { ...item, quantity: item.quantity + 1 } : item
              ),
            };
          }

          return { items: [...state.items, { ...newItem, id, quantity: 1 }] };
        });
      },

      removeItem: (id) => {
        set((state) => ({
          items: state.items.filter((item) => item.id !== id),
        }));
      },

      updateQuantity: (id, quantity) => {
        if (quantity < 1) return;
        set((state) => ({
          items: state.items.map((item) =>
            item.id === id ? { ...item, quantity } : item
          ),
        }));
      },

      toggleInstall: (id) => {
        set((state) => {
          const itemToUpdate = state.items.find(item => item.id === id);
          if (!itemToUpdate) return state;

          const newWithInstall = !itemToUpdate.withInstall;
          const newId = `${itemToUpdate.slug}-${itemToUpdate.label || 'base'}-${newWithInstall}`;

          const targetExists = state.items.find(item => item.id === newId);

          if (targetExists) {
             return {
               items: state.items
                .map(item => item.id === newId ? { ...item, quantity: item.quantity + itemToUpdate.quantity } : item)
                .filter(item => item.id !== id)
             }
          }

          return {
            items: state.items.map((item) =>
              item.id === id ? { ...item, withInstall: newWithInstall, id: newId } : item
            ),
          };
        });
      },

      clearCart: () => set({ items: [] }),

      getTotals: () => {
        const { items } = get();
        let subtotal = 0;
        let vat = 0;
        
        items.forEach((item) => {
          const itemPrice = item.withInstall ? item.priceWithInstall : item.price;
          const itemTotalGross = itemPrice * item.quantity;
          const vatRate = item.withInstall ? 0.08 : 0.23;
          const itemTotalNet = itemTotalGross / (1 + vatRate);
          const itemVat = itemTotalGross - itemTotalNet;

          subtotal += itemTotalNet;
          vat += itemVat;
        });

        return {
          subtotal,
          vat,
          total: subtotal + vat
        };
      },
    }),
    {
      name: 'air-project-cart',
    }
  )
);