Merge pull request #58 from mjrousos/Issue54-PreserveCart

Merge anonymous carts upon login

apigateway/routes/cart.js

@@ -13,18 +13,29 @@ router.get('/', function stickerRouteCart(req, res) {
 
 router.use(bodyParser.json());
 
-// TODO this enables carts for unauthenticated users, passing the uuid
-// generated by the client to the session service as the user's id.
-// Moving the user's unauthenticated cart to one stored with their
-// permanent id upon login is unimplemented.
 router.use((req, res, next) => {
-    // the client passes the uuid in the query string for GET
-    // requests, in body JSON for PUT
+    var sessionId = req.query.token || req.body.token;
     if (!req.user) {
-        req.user = { id: req.query.token || req.body.token };
+        // If the user is unauthenticated, use
+        // the session uuid generated by the client as a
+        // temporary 'user id'
+        req.user = { id: sessionId };
+        next();
+    } else {
+        // If the user is authenticated, pass the client's
+        // session uuid so that any items that were added
+        // to the cart prior to the user authenticating can
+        // be merged into the user's cart.
+        request.put(`${CART_URL}/transfer/${sessionId}`, {
+            headers: { stickerUserId: req.user.id },
+            json: true
+        }, (error, response) => {
+            if (error) {
+                console.error(error);
+            }
+            next();
+        });
     }
-
-    next();
 });
 
 router.get('/api/items', function getCart(req, res) {

sessionService/data/index.js

@@ -8,6 +8,7 @@ module.exports = {
     addToCartAsync: cart.addToCartAsync,
     clearCartAsync: cart.clearCartAsync,
     getCartAsync: cart.getCartAsync,
+    mergeCartsAsync: cart.mergeCartsAsync,
     removeFromCartAsync: cart.removeFromCartAsync,
     addItemToHistoryAsync: history.addItemToHistoryAsync,
     getHistoryAsync: history.getHistoryAsync,

sessionService/data/sources/cart.js

@@ -31,6 +31,19 @@ exports.addToCartAsync = (userId, itemId) => {
     });
 }
 
+exports.mergeCartsAsync = (destUserId, userIds) => {
+    return new Promise((resolve, reject) => {
+        var args = [cartKey(destUserId)].concat(userIds.map(userId => cartKey(userId)));
+        redisClient.sunionstore(args, (error, result) => {
+            if (error) {
+                reject(error);
+            } else {
+                resolve();
+            }
+        });
+    });
+}
+
 exports.removeFromCartAsync = (userId, itemId) => {
     return new Promise((resolve, reject) => {
         redisClient.srem([cartKey(userId), itemId], (error, result) => {

sessionService/routes/cart.js

@@ -75,4 +75,28 @@ router.put('/:item_id', async (req, res) => {
     }
 });
 
+// Transfers one user's cart items to another user's cart
+// (useful for when a user begins a session with a temporary
+// un-auth'd user ID and then later logs in)
+router.put('/transfer/:oldUserId', async (req, res) => {
+    try {
+        // If the old user has cart items, transfer them to 
+        // the current user's cart.
+        if ((await dataAccess.getCartAsync(req.params.oldUserId)).length > 0) {
+            // Merge the two carts
+            await dataAccess.mergeCartsAsync(req.userId, [req.userId, req.params.oldUserId]);
+
+            // Once the carts are merged, it doesn't make sense to leave the partial
+            // cart for the original anonymous user.
+            await dataAccess.clearCartAsync(req.params.oldUserId);
+        }
+
+        // Return the user's current cart items (after merging, if necessary)
+        await sendItems(req.userId, res);
+    } catch (error) {
+        console.error(error);
+        res.sendStatus(500);
+    }
+});
+
 module.exports = router;