commerce/packages/reactioncommerce/cart/use-cart.tsx

import { useMemo } from 'react'
import { SWRHook } from '@commerce/utils/types'
import useCart, { UseCart, FetchCartInput } from '@commerce/cart/use-cart'
import type { Cart } from '../types'

export default useCart as UseCart<typeof handler>

export const handler: SWRHook<
  Cart | null,
  {},
  FetchCartInput,
  { isEmpty?: boolean }
> = {
  fetchOptions: {
    method: 'GET',
    url: '/api/cart',
  },
  async fetcher({ input: { cartId }, options, fetch }) {
    console.log('cart API fetcher', options)
    const data = await fetch(options)
    return data
  },
  useHook:
    ({ useData }) =>
    (input) => {
      const response = useData({
        swrOptions: { revalidateOnFocus: false, ...input?.swrOptions },
      })

      return useMemo(
        () =>
          Object.create(response, {
            isEmpty: {
              get() {
                return (response.data?.lineItems?.length ?? 0) <= 0
              },
              enumerable: true,
            },
          }),
        [response]
      )
    },
}