import { createReducer } from '@reduxjs/toolkit';
import { CartItem, MerchantCartGroup } from '@interfaces/cart';
import { addToCartThunk, getCartThunk, updateCartItemThunk } from './thunk';

// ─── State ───────────────────────────────────────────────────────────────────

export interface CartState {
  id: string | null;
  customerId: string | null;
  items: CartItem[];
  groupedByMerchant: MerchantCartGroup[];
  subtotal: number;
  totalItems: number;
  isLoading: boolean;
  error: string | null;
}

const initialState: CartState = {
  id: null,
  customerId: null,
  items: [],
  groupedByMerchant: [],
  subtotal: 0,
  totalItems: 0,
  isLoading: false,
  error: null,
};

// ─── Selector ────────────────────────────────────────────────────────────────

export const selectCartTotal = (state: { cart: CartState }) => {
  const subtotal = state.cart.subtotal || 0;
  const deliveryFee = 40; // Flat fee for now
  const platformFee = 10; // Flat fee for now
  const discount = 0; // Removing discount logic for now as requested
  return {
    subtotal,
    deliveryFee,
    platformFee,
    discount,
    total: Math.max(0, subtotal + deliveryFee + platformFee - discount),
    itemCount: state.cart.totalItems || 0,
  };
};

// ─── Reducer ─────────────────────────────────────────────────────────────────

const cartReducer = createReducer(initialState, builder => {
  builder
    // getCartThunk
    .addCase(getCartThunk.pending, state => {
      state.isLoading = true;
      state.error = null;
    })
    .addCase(getCartThunk.fulfilled, (state, action) => {
      state.isLoading = false;
      const cart = action.payload;
      state.id = cart.id;
      state.customerId = cart.customerId;
      state.items = cart.items || [];
      state.groupedByMerchant = cart.groupedByMerchant || [];
      state.subtotal = cart.subtotal || 0;
      state.totalItems = cart.totalItems || 0;
    })
    .addCase(getCartThunk.rejected, (state, action) => {
      state.isLoading = false;
      state.error = (action.payload as string) || 'Failed to get cart';
    })

    // addToCartThunk
    .addCase(addToCartThunk.pending, state => {
      state.isLoading = true;
      state.error = null;
    })
    .addCase(addToCartThunk.fulfilled, (state, action) => {
      state.isLoading = false;
      const cart = action.payload;
      state.id = cart.id;
      state.customerId = cart.customerId;
      state.items = cart.items || [];
      state.groupedByMerchant = cart.groupedByMerchant || [];
      state.subtotal = cart.subtotal || 0;
      state.totalItems = cart.totalItems || 0;
    })
    .addCase(addToCartThunk.rejected, (state, action) => {
      state.isLoading = false;
      state.error = (action.payload as string) || 'Failed to add to cart';
    })

    // updateCartItemThunk
    .addCase(updateCartItemThunk.pending, state => {
      state.isLoading = true;
      state.error = null;
    })
    .addCase(updateCartItemThunk.fulfilled, (state, action) => {
      state.isLoading = false;
      const cart = action.payload;
      state.id = cart.id;
      state.customerId = cart.customerId;
      state.items = cart.items || [];
      state.groupedByMerchant = cart.groupedByMerchant || [];
      state.subtotal = cart.subtotal || 0;
      state.totalItems = cart.totalItems || 0;
    })
    .addCase(updateCartItemThunk.rejected, (state, action) => {
      state.isLoading = false;
      state.error = (action.payload as string) || 'Failed to update cart item';
    });
});

export default cartReducer;