From ca959f6491ac63d62f9c725d4690972eb021d926 Mon Sep 17 00:00:00 2001
From: Luis Alvarez <luis@vercel.com>
Date: Sat, 3 Oct 2020 20:49:09 -0500
Subject: [PATCH] Added add to cart method

---
 lib/bigcommerce/api/cart.ts         | 100 ++++++++++++++++++++--------
 lib/bigcommerce/api/index.ts        |   2 +
 lib/bigcommerce/api/utils/errors.ts |  13 +---
 lib/commerce/api/index.ts           |   1 +
 4 files changed, 76 insertions(+), 40 deletions(-)

diff --git a/lib/bigcommerce/api/cart.ts b/lib/bigcommerce/api/cart.ts
index ebf5c50b1..e21d3c436 100644
--- a/lib/bigcommerce/api/cart.ts
+++ b/lib/bigcommerce/api/cart.ts
@@ -15,43 +15,87 @@ const cartApi: BigcommerceApiHandler = async (req, res, config) => {
   const { cookies } = req
   const cartId = cookies[config.cartCookie]
 
-  // Return current cart info
-  if (req.method === 'GET') {
-    let result: { data?: Cart } = {}
+  try {
+    // Return current cart info
+    if (req.method === 'GET') {
+      let result: { data?: Cart } = {}
 
-    try {
-      result = await config.storeApiFetch(
-        `/v3/carts/${cartId}?include=redirect_urls`
-      )
-    } catch (error) {
-      if (error instanceof BigcommerceApiError && error.status === 404) {
-        // Remove the cookie if it exists but the cart wasn't found
-        res.setHeader('Set-Cookie', getCartCookie(name))
-      } else {
-        throw error
+      try {
+        result = await config.storeApiFetch(
+          `/v3/carts/${cartId}?include=redirect_urls`
+        )
+      } catch (error) {
+        if (error instanceof BigcommerceApiError && error.status === 404) {
+          // Remove the cookie if it exists but the cart wasn't found
+          res.setHeader('Set-Cookie', getCartCookie(name))
+        } else {
+          throw error
+        }
       }
+
+      return res.status(200).json({ cart: result.data ?? null })
     }
 
-    return res.status(200).json({ cart: result.data ?? null })
+    // Create or add a product to the cart
+    if (req.method === 'POST') {
+      const { product } = req.body
+
+      if (!product) {
+        return res.status(400).json({
+          errors: [{ message: 'Missing product' }],
+        })
+      }
+
+      const options = {
+        method: 'POST',
+        body: JSON.stringify({
+          line_items: [parseProduct(product)],
+        }),
+      }
+      const { data } = cartId
+        ? await config.storeApiFetch(`/v3/carts/${cartId}/items`, options)
+        : await config.storeApiFetch('/v3/carts', options)
+
+      // Create or update the cart cookie
+      res.setHeader(
+        'Set-Cookie',
+        getCartCookie(name, data.id, config.cartCookieMaxAge)
+      )
+
+      // There's no need to send any additional data here, the UI can use this response to display a
+      // "success" for the operation and revalidate the GET request for this same endpoint right after.
+      return res.status(200).json({ done: true })
+    }
+  } catch (error) {
+    const message =
+      error instanceof BigcommerceApiError
+        ? 'An unexpected error ocurred with the Bigcommerce API'
+        : 'An unexpected error ocurred'
+
+    res.status(500).json({ errors: [{ message }] })
   }
 }
 
-const ONE_DAY = 60 * 60 * 24
-const MAX_AGE = ONE_DAY * 30
-
-function getCartCookie(name: string, cartId?: string) {
-  const options: CookieSerializeOptions = cartId
-    ? {
-        maxAge: MAX_AGE,
-        expires: new Date(Date.now() + MAX_AGE * 1000),
-        httpOnly: true,
-        secure: process.env.NODE_ENV === 'production',
-        path: '/',
-        sameSite: 'lax',
-      }
-    : { maxAge: -1, path: '/' } // Removes the cookie
+function getCartCookie(name: string, cartId?: string, maxAge?: number) {
+  const options: CookieSerializeOptions =
+    cartId && maxAge
+      ? {
+          maxAge,
+          expires: new Date(Date.now() + maxAge * 1000),
+          httpOnly: true,
+          secure: process.env.NODE_ENV === 'production',
+          path: '/',
+          sameSite: 'lax',
+        }
+      : { maxAge: -1, path: '/' } // Removes the cookie
 
   return serialize(name, cartId || '', options)
 }
 
+const parseProduct = (product: any) => ({
+  quantity: product.quantity,
+  product_id: product.productId,
+  variant_id: product.variantId,
+})
+
 export default createApiHandler(cartApi)
diff --git a/lib/bigcommerce/api/index.ts b/lib/bigcommerce/api/index.ts
index 752ef038d..69e26f523 100644
--- a/lib/bigcommerce/api/index.ts
+++ b/lib/bigcommerce/api/index.ts
@@ -103,10 +103,12 @@ export class Config {
   }
 }
 
+const ONE_DAY = 60 * 60 * 24
 const config = new Config({
   commerceUrl: API_URL,
   apiToken: API_TOKEN,
   cartCookie: process.env.BIGCOMMERCE_CART_COOKIE ?? 'bc_cartId',
+  cartCookieMaxAge: ONE_DAY * 30,
   fetch: fetchGraphqlApi,
   // REST API only
   storeApiUrl: STORE_API_URL,
diff --git a/lib/bigcommerce/api/utils/errors.ts b/lib/bigcommerce/api/utils/errors.ts
index 70f97953e..1cdd72214 100644
--- a/lib/bigcommerce/api/utils/errors.ts
+++ b/lib/bigcommerce/api/utils/errors.ts
@@ -1,16 +1,5 @@
 // Used for GraphQL errors
-export class BigcommerceError extends Error {
-  status?: number
-
-  constructor(msg: string, res?: Response) {
-    super(msg)
-    this.name = 'BigcommerceError'
-
-    if (res) {
-      this.status = res.status
-    }
-  }
-}
+export class BigcommerceGraphQLError extends Error {}
 
 export class BigcommerceApiError extends Error {
   status: number
diff --git a/lib/commerce/api/index.ts b/lib/commerce/api/index.ts
index dcf95498f..6c4bf0544 100644
--- a/lib/commerce/api/index.ts
+++ b/lib/commerce/api/index.ts
@@ -2,6 +2,7 @@ export interface CommerceAPIConfig {
   commerceUrl: string
   apiToken: string
   cartCookie: string
+  cartCookieMaxAge: number
   fetch<Q, V = any>(
     query: string,
     queryData?: CommerceAPIFetchOptions<V>