Extract token param to a middleware

lib/cartodb/middleware/prepare-context.js

@@ -36,38 +36,52 @@ module.exports = function prepareContextMiddleware (authApi, pgConnection) {
 
             next();
         },
-        function prepareContext (req, res, next) {
+        function parseTokenParam (req, res, next) {
+            if (!req.params.token) {
+                return next();
+            }
+
             var user = req.context.user;
 
-            if ( req.params.token ) {
             // Token might match the following patterns:
             // - {user}@{tpl_id}@{token}:{cache_buster}
             var tksplit = req.params.token.split(':');
+
             req.params.token = tksplit[0];
+
             if ( tksplit.length > 1 ) {
                 req.params.cache_buster= tksplit[1];
             }
+
             tksplit = req.params.token.split('@');
+
             if ( tksplit.length > 1 ) {
                 req.params.signer = tksplit.shift();
+
                 if ( ! req.params.signer ) {
                     req.params.signer = user;
-                    }
+                } else if ( req.params.signer !== user ) {
-                    else if ( req.params.signer !== user ) {
                     var err = new Error(
-                                'Cannot use map signature of user "' + req.params.signer + '" on db of user "' + user + '"'
+                        `Cannot use map signature of user "${req.params.signer}" on db of user "${user}"`
                     );
                     err.http_status = 403;
                     req.profiler.done('req2params');
-                        next(err);
+
-                        return;
+                    return next(err);
                 }
-                    if ( tksplit.length > 1 ) {
+
-                        /*var template_hash = */tksplit.shift(); // unused
+                // skip template hash
+                if (tksplit.length > 1) {
+                    tksplit.shift();
                 }
+
                 req.params.token = tksplit.shift();
             }
-            }
+
+            next();
+        },
+        function prepareContext (req, res, next) {
+            var user = req.context.user;
 
             // bring all query values onto req.params object
             _.extend(req.params, req.query);