Next.js Commerce refresh. (#966)

We're making some updates to Next.js Commerce. Everything prior to this commit marks what we're calling [`v1`](https://github.com/vercel/commerce/releases/tag/v1) as a point in time to be able to reference and still use going into the future. The current architecture of Commerce is a multi-vendor, interoperable solution, including:

- [Shopify](https://shopify.vercel.store/)
- [Swell](https://swell.vercel.store/)
- [BigCommerce](https://bigcommerce.vercel.store/)
- [Vendure](https://vendure.vercel.store/)
- [Saleor](https://saleor.vercel.store/)
- [Ordercloud](https://ordercloud.vercel.store/)
- [Spree](https://spree.vercel.store/)
- [Kibo Commerce](https://kibocommerce.vercel.store/)
- [Commerce.js](https://commercejs.vercel.store/)
- [SalesForce Cloud Commerce](https://salesforce-cloud-commerce.vercel.store/)

All features can be toggled on or off, and it's easy to change between commerce providers. To support this, we needed to create a ["commerce metaframework"](d1d9e8c434/packages/commerce/new-provider.md) where providers could confirm to an API spec to add support for Next.js Commerce. While this worked and was successful for `v1`, we have different design goals and ambitions for `v2`.

**What You Need To Know**

- `v1` will not be updated moving forward. If you need to reference `v1`, you will still be able to clone and deploy the version tagged at this release.
- `v2` will be shifting to be a single provider vs. provider agnostic. Other providers are welcome to fork this repository and swap out the underlying `lib/` implementation that connects to the selected commerce provider (Shopify). This architecture was chosen to reduce the surface area of the codebase, remove the intermediate metaframework layer for provider-interoperability, and enable usage with the latest Next.js and React features.
- We will be sharing more about `v2` in the future as we continue to iterate before the marked release.

components/cart/button.tsx

@@ -0,0 +1,64 @@
+'use client';
+
+import { useEffect, useRef, useState } from 'react';
+import { useCookies } from 'react-cookie';
+
+import CartIcon from 'components/icons/cart';
+import CartModal from './modal';
+
+import type { Cart } from 'lib/shopify/types';
+
+export default function CartButton({
+  cart,
+  cartIdUpdated
+}: {
+  cart: Cart;
+  cartIdUpdated: boolean;
+}) {
+  const [, setCookie] = useCookies(['cartId']);
+  const [cartIsOpen, setCartIsOpen] = useState(false);
+  const quantityRef = useRef(cart.totalQuantity);
+
+  // Temporary hack to update the `cartId` cookie when it changes since we cannot update it
+  // on the server-side (yet).
+  useEffect(() => {
+    if (cartIdUpdated) {
+      setCookie('cartId', cart.id, {
+        path: '/',
+        sameSite: 'strict',
+        secure: process.env.NODE_ENV === 'production'
+      });
+    }
+    return;
+  }, [setCookie, cartIdUpdated, cart.id]);
+
+  useEffect(() => {
+    // Open cart modal when when quantity changes.
+    if (cart.totalQuantity !== quantityRef.current) {
+      // But only if it's not already open (quantity also changes when editing items in cart).
+      if (!cartIsOpen) {
+        setCartIsOpen(true);
+      }
+
+      // Always update the quantity reference
+      quantityRef.current = cart.totalQuantity;
+    }
+  }, [cartIsOpen, cart.totalQuantity, quantityRef]);
+
+  return (
+    <>
+      <CartModal isOpen={cartIsOpen} onClose={() => setCartIsOpen(false)} cart={cart} />
+
+      <button
+        aria-label="Open cart"
+        onClick={() => {
+          setCartIsOpen(true);
+        }}
+        className="relative top-0 right-0"
+        data-testid="open-cart"
+      >
+        <CartIcon quantity={cart.totalQuantity} />
+      </button>
+    </>
+  );
+}

components/cart/delete-item-button.tsx

@@ -0,0 +1,50 @@
+import CloseIcon from 'components/icons/close';
+import LoadingDots from 'components/loading-dots';
+import { useRouter } from 'next/navigation';
+import { startTransition, useState } from 'react';
+
+import type { CartItem } from 'lib/shopify/types';
+
+export default function DeleteItemButton({ item }: { item: CartItem }) {
+  const router = useRouter();
+  const [removing, setRemoving] = useState(false);
+
+  async function handleRemove() {
+    setRemoving(true);
+
+    const response = await fetch(`/api/cart`, {
+      method: 'DELETE',
+      body: JSON.stringify({
+        lineId: item.id
+      })
+    });
+    const data = await response.json();
+
+    if (data.error) {
+      alert(data.error);
+      return;
+    }
+
+    setRemoving(false);
+
+    startTransition(() => {
+      router.refresh();
+    });
+  }
+  return (
+    <button
+      aria-label="Remove cart item"
+      onClick={handleRemove}
+      disabled={removing}
+      className={`${
+        removing ? 'cursor-not-allowed' : ''
+      } mr-2 flex h-8 w-8 items-center justify-center border border-black/40 bg-black/0 hover:bg-black/10 dark:border-white/40 dark:bg-white/0 dark:hover:bg-white/10`}
+    >
+      {removing ? (
+        <LoadingDots className="bg-white dark:bg-black" />
+      ) : (
+        <CloseIcon className="hover:text-accent-3 h-6" />
+      )}
+    </button>
+  );
+}

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

@@ -0,0 +1,62 @@
+import { useRouter } from 'next/navigation';
+import { startTransition, useState } from 'react';
+
+import MinusIcon from 'components/icons/minus';
+import PlusIcon from 'components/icons/plus';
+import type { CartItem } from 'lib/shopify/types';
+import LoadingDots from '../loading-dots';
+
+export default function EditItemQuantityButton({
+  item,
+  type
+}: {
+  item: CartItem;
+  type: 'plus' | 'minus';
+}) {
+  const router = useRouter();
+  const [editing, setEditing] = useState(false);
+
+  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}
+      className={`${editing ? 'cursor-not-allowed' : ''} ${
+        type === 'minus' ? 'ml-auto' : ''
+      } flex h-8 w-8 items-center justify-center border-l border-black/40 bg-black/0 hover:bg-black/10 dark:border-white/40 dark:bg-white/0 dark:hover:bg-white/10`}
+    >
+      {editing ? (
+        <LoadingDots className="bg-white dark:bg-black" />
+      ) : type === 'plus' ? (
+        <PlusIcon className="h-4" />
+      ) : (
+        <MinusIcon className="h-4" />
+      )}
+    </button>
+  );
+}

components/cart/index.tsx

@@ -0,0 +1,23 @@
+import { createCart, getCart } from 'lib/shopify';
+import { cookies } from 'next/headers';
+import CartButton from './button';
+
+export default async function Cart() {
+  const cartId = cookies().get('cartId')?.value;
+  let cartIdUpdated = false;
+  let cart;
+
+  if (cartId) {
+    cart = await getCart(cartId);
+  }
+
+  // If the `cartId` from the cookie is not set or the cart is empty
+  // (old carts becomes `null` when you checkout), then get a new `cartId`
+  //  and re-fetch the cart.
+  if (!cartId || !cart) {
+    cart = await createCart();
+    cartIdUpdated = true;
+  }
+
+  return <CartButton cart={cart} cartIdUpdated={cartIdUpdated} />;
+}

components/cart/modal.tsx

@@ -0,0 +1,174 @@
+import { Dialog } from '@headlessui/react';
+import { AnimatePresence, motion } from 'framer-motion';
+import Image from 'next/image';
+
+import CloseIcon from 'components/icons/close';
+import ShoppingBagIcon from 'components/icons/shopping-bag';
+import Price from 'components/price';
+import { DEFAULT_OPTION } from 'lib/constants';
+import type { Cart } from 'lib/shopify/types';
+import DeleteItemButton from './delete-item-button';
+import EditItemQuantityButton from './edit-item-quantity-button';
+
+export default function CartModal({
+  isOpen,
+  onClose,
+  cart
+}: {
+  isOpen: boolean;
+  onClose: () => void;
+  cart: Cart;
+}) {
+  return (
+    <AnimatePresence initial={false}>
+      {isOpen && (
+        <Dialog
+          as={motion.div}
+          initial="closed"
+          animate="open"
+          exit="closed"
+          key="dialog"
+          static
+          open={isOpen}
+          onClose={onClose}
+          className="relative z-50"
+        >
+          <motion.div
+            variants={{
+              open: { opacity: 1, backdropFilter: 'blur(0.5px)' },
+              closed: { opacity: 0, backdropFilter: 'blur(0px)' }
+            }}
+            className="fixed inset-0 bg-black/30"
+            aria-hidden="true"
+          />
+
+          <div className="fixed inset-0 flex justify-end" data-testid="cart">
+            <Dialog.Panel
+              as={motion.div}
+              variants={{
+                open: { translateX: 0 },
+                closed: { translateX: '100%' }
+              }}
+              transition={{ type: 'spring', bounce: 0, duration: 0.3 }}
+              className="flex w-full flex-col bg-white p-8 text-black dark:bg-black dark:text-white md:w-1/3 lg:w-[30%] lg:px-6"
+            >
+              <div className="flex items-center justify-between">
+                <p className="text-lg font-bold">My Cart</p>
+                <button
+                  aria-label="Close cart"
+                  onClick={onClose}
+                  className="text-black transition-colors hover:text-gray-500 dark:text-gray-100"
+                  data-testid="close-cart"
+                >
+                  <CloseIcon className="h-7" />
+                </button>
+              </div>
+
+              {cart.lines.length === 0 ? (
+                <div className="mt-20 flex w-full flex-col items-center justify-center overflow-hidden">
+                  <ShoppingBagIcon className="h-16" />
+                  <p className="mt-6 text-center text-2xl font-bold">Your cart is empty.</p>
+                </div>
+              ) : null}
+              {cart.lines.length !== 0 ? (
+                <div className="flex h-full flex-col justify-between overflow-hidden">
+                  <ul className="flex-grow overflow-auto p-6">
+                    {cart.lines.map((item, i) => {
+                      return (
+                        <li key={i} data-testid="cart-item">
+                          <div className="mb-2 flex w-full">
+                            <div className="relative h-20 w-20 flex-none">
+                              {item.merchandise.product.featuredImage.url && (
+                                <Image
+                                  alt={
+                                    item.merchandise.product.featuredImage.altText ||
+                                    item.merchandise.product.title
+                                  }
+                                  className="bg-white"
+                                  fill
+                                  src={item.merchandise.product.featuredImage.url}
+                                />
+                              )}
+                            </div>
+                            <div className="ml-4 flex w-full flex-col justify-between">
+                              <div className="flex w-full justify-between">
+                                <div>
+                                  <p
+                                    className="text-lg font-medium"
+                                    data-testid="cart-product-name"
+                                  >
+                                    {item.merchandise.product.title}
+                                  </p>
+                                  {item.merchandise.title !== DEFAULT_OPTION ? (
+                                    <p className="text-sm" data-testid="cart-product-variant">
+                                      {item.merchandise.title}
+                                    </p>
+                                  ) : null}
+                                </div>
+                                <Price
+                                  className="font-medium"
+                                  amount={item.cost.totalAmount.amount}
+                                  currencyCode={item.cost.totalAmount.currencyCode}
+                                />
+                              </div>
+                            </div>
+                          </div>
+                          <div className="mb-4 flex w-full">
+                            <DeleteItemButton item={item} />
+                            <div className="flex h-8 w-full border border-black/40 dark:border-white/40">
+                              <div className="flex h-full items-center px-2 ">{item.quantity}</div>
+                              <EditItemQuantityButton item={item} type="minus" />
+                              <EditItemQuantityButton item={item} type="plus" />
+                            </div>
+                          </div>
+                        </li>
+                      );
+                    })}
+                  </ul>
+                  <div className="border-t border-white/60 p-6">
+                    <div className="text-sm text-white">
+                      <div className="mb-2 flex items-center justify-between">
+                        <p>Subtotal</p>
+                        <Price
+                          className="text-right"
+                          amount={cart.cost.subtotalAmount.amount}
+                          currencyCode={cart.cost.subtotalAmount.currencyCode}
+                        />
+                      </div>
+                      <div className="mb-2 flex items-center justify-between">
+                        <p>Taxes</p>
+                        <Price
+                          className="text-right"
+                          amount={cart.cost.totalTaxAmount.amount}
+                          currencyCode={cart.cost.totalTaxAmount.currencyCode}
+                        />
+                      </div>
+                      <div className="mb-2 flex items-center justify-between border-b border-white/30 pb-2">
+                        <p>Shipping</p>
+                        <p className="text-right uppercase">calculated at checkout</p>
+                      </div>
+                      <div className="mb-2 flex items-center justify-between font-bold">
+                        <p>Total</p>
+                        <Price
+                          className="text-right"
+                          amount={cart.cost.totalAmount.amount}
+                          currencyCode={cart.cost.totalAmount.currencyCode}
+                        />
+                      </div>
+                    </div>
+                    <a
+                      href={cart.checkoutUrl}
+                      className="mt-6 flex w-full items-center justify-center bg-black p-3 text-sm font-medium uppercase text-white opacity-90 hover:opacity-100 dark:bg-white dark:text-black"
+                    >
+                      <span>Proceed to Checkout</span>
+                    </a>
+                  </div>
+                </div>
+              ) : null}
+            </Dialog.Panel>
+          </div>
+        </Dialog>
+      )}
+    </AnimatePresence>
+  );
+}