import {
  addOrderLine,
  calculateOrderItemCount,
  calculateOrderTotal,
  updateOrderLineQuantity,
} from '../shared/order-line';
import type { CartAction, CartState } from './entities';

/** Pure cart state machine — no React, no localStorage. */
export function cartReducer(state: CartState, action: CartAction): CartState {
  switch (action.type) {
    case 'ADD_ITEM':
      return { ...state, items: addOrderLine(state.items, action.payload) };

    case 'REMOVE_ITEM':
      return {
        ...state,
        items: state.items.filter((item) => item.id !== action.payload),
      };

    case 'UPDATE_QUANTITY':
      return {
        ...state,
        items: updateOrderLineQuantity(
          state.items,
          action.payload.id,
          action.payload.quantity
        ),
      };

    case 'CLEAR_CART':
      return { ...state, items: [] };

    case 'RESTORE_ITEMS':
      return { ...state, items: action.payload };

    case 'TOGGLE_CART':
      return { ...state, isOpen: !state.isOpen };

    case 'OPEN_CART':
      return { ...state, isOpen: true };

    case 'CLOSE_CART':
      return { ...state, isOpen: false };

    default:
      return state;
  }
}

export function getCartTotals(items: CartState['items']) {
  return {
    totalItems: calculateOrderItemCount(items),
    totalPrice: calculateOrderTotal(items),
  };
}