commerce/framework/shopify/cart/use-add-item.tsx

import { useCallback } from 'react'
import type { MutationHook } from '@commerce/utils/types'
import { CommerceError } from '@commerce/utils/errors'
import useAddItem, { UseAddItem } from '@commerce/cart/use-add-item'
import type { AddItemHook } from '../types/cart'
import useCart from './use-cart'
import {
  getCartId,
  normalizeCart,
  throwUserErrors,
  cartLineItemAddMutation,
  cartCreate,
} from '../utils'
import { CartLinesAddMutation, CartLinesAddMutationVariables } from '../schema'

export default useAddItem as UseAddItem<typeof handler>

export const handler: MutationHook<AddItemHook> = {
  fetchOptions: {
    query: cartLineItemAddMutation,
  },
  async fetcher({ input: item, options, fetch }) {
    if (
      item.quantity &&
      (!Number.isInteger(item.quantity) || item.quantity! < 1)
    ) {
      throw new CommerceError({
        message: 'The item quantity has to be a valid integer greater than 0',
      })
    }

    let cartId = getCartId()

    if (!cartId) {
      const { id } = await cartCreate(fetch)
      cartId = id
    }

    const { cartLinesAdd } = await fetch<
      CartLinesAddMutation,
      CartLinesAddMutationVariables
    >({
      ...options,
      variables: {
        cartId,
        lineItems: [
          {
            variantId: item.variantId,
            quantity: item.quantity ?? 1,
          },
        ],
      },
    })

    throwUserErrors(cartLinesAdd?.userErrors)

    return normalizeCart(cartLinesAdd?.cart)
  },
  useHook:
    ({ fetch }) =>
    () => {
      const { mutate } = useCart()

      return useCallback(
        async function addItem(input) {
          const data = await fetch({ input })
          await mutate(data, false)
          return data
        },
        [fetch, mutate]
      )
    },
}