Added add to cart method

lib/bigcommerce/api/cart.ts

@@ -15,6 +15,7 @@ const cartApi: BigcommerceApiHandler = async (req, res, config) => {
   const { cookies } = req
   const cartId = cookies[config.cartCookie]
 
+  try {
     // Return current cart info
     if (req.method === 'GET') {
       let result: { data?: Cart } = {}
@@ -34,16 +35,53 @@ const cartApi: BigcommerceApiHandler = async (req, res, config) => {
 
       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 ONE_DAY = 60 * 60 * 24
+      const options = {
-const MAX_AGE = ONE_DAY * 30
+        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)
 
-function getCartCookie(name: string, cartId?: string) {
+      // Create or update the cart cookie
-  const options: CookieSerializeOptions = cartId
+      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 }] })
+  }
+}
+
+function getCartCookie(name: string, cartId?: string, maxAge?: number) {
+  const options: CookieSerializeOptions =
+    cartId && maxAge
       ? {
-        maxAge: MAX_AGE,
+          maxAge,
-        expires: new Date(Date.now() + MAX_AGE * 1000),
+          expires: new Date(Date.now() + maxAge * 1000),
           httpOnly: true,
           secure: process.env.NODE_ENV === 'production',
           path: '/',
@@ -54,4 +92,10 @@ function getCartCookie(name: string, cartId?: string) {
   return serialize(name, cartId || '', options)
 }
 
+const parseProduct = (product: any) => ({
+  quantity: product.quantity,
+  product_id: product.productId,
+  variant_id: product.variantId,
+})
+
 export default createApiHandler(cartApi)

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,

lib/bigcommerce/api/utils/errors.ts

@@ -1,16 +1,5 @@
 // Used for GraphQL errors
-export class BigcommerceError extends Error {
+export class BigcommerceGraphQLError extends Error {}
-  status?: number
-
-  constructor(msg: string, res?: Response) {
-    super(msg)
-    this.name = 'BigcommerceError'
-
-    if (res) {
-      this.status = res.status
-    }
-  }
-}
 
 export class BigcommerceApiError extends Error {
   status: number

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>