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.

lib/shopify/queries/cart.ts

@@ -0,0 +1,10 @@
+import cartFragment from '../fragments/cart';
+
+export const getCartQuery = /* GraphQL */ `
+  query getCart($cartId: ID!) {
+    cart(id: $cartId) {
+      ...cart
+    }
+  }
+  ${cartFragment}
+`;

lib/shopify/queries/collection.ts

@@ -0,0 +1,51 @@
+import productFragment from '../fragments/product';
+import seoFragment from '../fragments/seo';
+
+const collectionFragment = /* GraphQL */ `
+  fragment collection on Collection {
+    handle
+    title
+    description
+    seo {
+      ...seo
+    }
+  }
+  ${seoFragment}
+`;
+
+export const getCollectionQuery = /* GraphQL */ `
+  query getCollection($handle: String!) {
+    collection(handle: $handle) {
+      ...collection
+    }
+  }
+  ${collectionFragment}
+`;
+
+export const getCollectionsQuery = /* GraphQL */ `
+  query getCollections {
+    collections(first: 100, sortKey: TITLE) {
+      edges {
+        node {
+          ...collection
+        }
+      }
+    }
+  }
+  ${collectionFragment}
+`;
+
+export const getCollectionProductsQuery = /* GraphQL */ `
+  query getCollectionProducts($handle: String!, $first: Int = 100) {
+    collection(handle: $handle) {
+      products(first: $first) {
+        edges {
+          node {
+            ...product
+          }
+        }
+      }
+    }
+  }
+  ${productFragment}
+`;

lib/shopify/queries/menu.ts

@@ -0,0 +1,10 @@
+export const getMenuQuery = /* GraphQL */ `
+  query getMenu($handle: String!) {
+    menu(handle: $handle) {
+      items {
+        title
+        url
+      }
+    }
+  }
+`;

lib/shopify/queries/page.ts

@@ -0,0 +1,21 @@
+import seoFragment from '../fragments/seo';
+
+export const getPageQuery = /* GraphQL */ `
+  query getPage($handle: String!) {
+    pageByHandle(handle: $handle) {
+      id
+      ... on Page {
+        title
+        handle
+        body
+        bodySummary
+        seo {
+          ...seo
+        }
+        createdAt
+        updatedAt
+      }
+    }
+  }
+  ${seoFragment}
+`;

lib/shopify/queries/product.ts

@@ -0,0 +1,32 @@
+import productFragment from '../fragments/product';
+
+export const getProductQuery = /* GraphQL */ `
+  query getProduct($handle: String!) {
+    product(handle: $handle) {
+      ...product
+    }
+  }
+  ${productFragment}
+`;
+
+export const getProductsQuery = /* GraphQL */ `
+  query getProducts($sortKey: ProductSortKeys, $reverse: Boolean, $query: String) {
+    products(sortKey: $sortKey, reverse: $reverse, query: $query, first: 100) {
+      edges {
+        node {
+          ...product
+        }
+      }
+    }
+  }
+  ${productFragment}
+`;
+
+export const getProductRecommendationsQuery = /* GraphQL */ `
+  query getProductRecommendations($productId: ID!) {
+    productRecommendations(productId: $productId) {
+      ...product
+    }
+  }
+  ${productFragment}
+`;