import { useState, useCallback } from 'react';

export const __trackCalls: { name: string; props: any }[] = [];
export const __zipStore: string[] = [];
export const analytics = {
  track: (name: string, props: any) => __trackCalls.push({ name, props }),
};

export interface CartItem { id: string; price: number; quantity: number }

export interface UseCartReturn {
  items: CartItem[];
  addItem: (item: CartItem) => void;
  getItemById: (id: string) => CartItem | undefined;
  calculateShipping: (zipCode: string) => number;
}

// TODO:
//   - getItemById 와 calculateShipping 을 순수하게 만들어라
//   - 트래킹/저장은 trackItemLookup / persistShippingZip 같은 별도 함수로 분리
//   - hook return 객체에 추가 export 또는 모듈 레벨로 export
export function useCart(initial: CartItem[] = []): UseCartReturn {
  const [items, setItems] = useState<CartItem[]>(initial);

  const addItem = useCallback((item: CartItem) => {
    setItems((prev) => [...prev, item]);
  }, []);

  const getItemById = useCallback(
    (id: string): CartItem | undefined => {
      const item = items.find((i) => i.id === id);
      analytics.track('cart_item_lookup', { id, found: !!item });
      return item;
    },
    [items]
  );

  const calculateShipping = useCallback(
    (zipCode: string): number => {
      __zipStore.push(zipCode);
      analytics.track('shipping_calculated', { zipCode });
      const base = 5.99;
      const distance = zipCode.startsWith('9') ? 1.5 : 1;
      const surcharge = items.length > 5 ? 2.99 : 0;
      return base * distance + surcharge;
    },
    [items]
  );

  return { items, addItem, getItemById, calculateShipping };
}