Added update item hook

lib/bigcommerce/cart/use-update-item.tsx

@@ -0,0 +1,40 @@
+import type { Fetcher } from '@lib/commerce'
+import { default as useCartUpdateItem } from '@lib/commerce/cart/use-update-item'
+import type { Item } from '../api/cart'
+import { Cart, useCart } from '.'
+
+export type { Item }
+
+export type UpdateItemInput = {
+  itemId: string
+  item: Item
+}
+
+function fetcher(fetch: Fetcher<Cart>, { itemId, item }: UpdateItemInput) {
+  if (
+    item.quantity &&
+    (!Number.isInteger(item.quantity) || item.quantity! < 1)
+  ) {
+    throw new Error(
+      'The item quantity has to be a valid integer greater than 0'
+    )
+  }
+
+  return fetch({
+    url: '/api/bigcommerce/cart',
+    method: 'PUT',
+    body: { itemId, item },
+  })
+}
+
+export default function useUpdateItem() {
+  const { mutate } = useCart()
+  const fn = useCartUpdateItem<Cart, UpdateItemInput>(fetcher)
+  const updateItem: typeof fn = async (input) => {
+    const data = await fn(input)
+    mutate(data)
+    return data
+  }
+
+  return updateItem
+}

lib/commerce/cart/use-update-item.tsx

@@ -0,0 +1,11 @@
+import { Fetcher, useCommerce } from '..'
+
+export default function useUpdateItem<T, Input>(
+  fetcher: (fetch: Fetcher<T>, input: Input) => T | Promise<T>
+) {
+  const { fetcher: fetch } = useCommerce()
+
+  return async function updateItem(input: Input) {
+    return fetcher(fetch, input)
+  }
+}