Replaces Route Handlers with Server Actions (#1050)

components/cart/edit-item-quantity-button.tsx

@@ -1,11 +1,12 @@
 import { useRouter } from 'next/navigation';
-import { startTransition, useState } from 'react';
+import { useTransition } from 'react';
 
 import clsx from 'clsx';
+import { removeItem, updateItemQuantity } from 'components/cart/actions';
 import MinusIcon from 'components/icons/minus';
 import PlusIcon from 'components/icons/plus';
+import LoadingDots from 'components/loading-dots';
 import type { CartItem } from 'lib/shopify/types';
-import LoadingDots from '../loading-dots';
 
 export default function EditItemQuantityButton({
   item,
@@ -15,47 +16,40 @@ export default function EditItemQuantityButton({
   type: 'plus' | 'minus';
 }) {
   const router = useRouter();
-  const [editing, setEditing] = useState(false);
+  const [isPending, startTransition] = useTransition();
 
-  async function handleEdit() {
-    setEditing(true);
-
-    const response = await fetch(`/api/cart`, {
-      method: type === 'minus' && item.quantity - 1 === 0 ? 'DELETE' : 'PUT',
-      body: JSON.stringify({
-        lineId: item.id,
-        variantId: item.merchandise.id,
-        quantity: type === 'plus' ? item.quantity + 1 : item.quantity - 1
-      })
-    });
-
-    const data = await response.json();
-
-    if (data.error) {
-      alert(data.error);
-      return;
-    }
-
-    setEditing(false);
-
-    startTransition(() => {
-      router.refresh();
-    });
-  }
   return (
     <button
       aria-label={type === 'plus' ? 'Increase item quantity' : 'Reduce item quantity'}
-      onClick={handleEdit}
-      disabled={editing}
+      onClick={() => {
+        startTransition(async () => {
+          const error =
+            type === 'minus' && item.quantity - 1 === 0
+              ? await removeItem(item.id)
+              : await updateItemQuantity({
+                  lineId: item.id,
+                  variantId: item.merchandise.id,
+                  quantity: type === 'plus' ? item.quantity + 1 : item.quantity - 1
+                });
+
+          if (error) {
+            alert(error);
+            return;
+          }
+
+          router.refresh();
+        });
+      }}
+      disabled={isPending}
       className={clsx(
         'ease flex min-w-[36px] max-w-[36px] items-center justify-center border px-2 transition-all duration-200 hover:border-gray-800 hover:bg-gray-100 dark:border-gray-700 dark:hover:border-gray-600 dark:hover:bg-gray-900',
         {
-          'cursor-not-allowed': editing,
+          'cursor-not-allowed': isPending,
           'ml-auto': type === 'minus'
         }
       )}
     >
-      {editing ? (
+      {isPending ? (
         <LoadingDots className="bg-black dark:bg-white" />
       ) : type === 'plus' ? (
         <PlusIcon className="h-4 w-4" />