Go to next step is enabled after user finishes step challenge

server/boot/challenge.js

@@ -41,6 +41,14 @@ const challengeView = {
   7: 'coursewares/showStep'
 };
 
+function isChallengeCompleted(user, challengeId) {
+  if (!user) {
+    return false;
+  }
+  return user.completedChallenges.some(challenge =>
+    challenge.id === challengeId );
+}
+
 function numberWithCommas(x) {
   return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
 }
@@ -293,6 +301,9 @@ module.exports = function(app) {
           tail: challenge.tail,
           tests: challenge.tests,
 
+          // identifies if a challenge is completed
+          isCompleted: isChallengeCompleted(req.user, challenge.id),
+
           // video challenges
           video: challenge.challengeSeed[0],
 

server/views/coursewares/showStep.jade

@@ -18,9 +18,9 @@ block content
                                 .btn.btn-warning.col-sm-5.col-xs-12.challenge-step-btn-prev(id='#{index - 1}') Go to my previous step
                             .challenge-step-counter.large-p.col-sm-2.col-xs-12.text-center (#{index + 1} / #{description.length})
                             if index + 1 === description.length
-                                .btn.btn-primary.col-sm-5.col-xs-12.challenge-step-btn-finish(id='last' class=step[3] ? 'disabled' : '') Finish challenge
+                                .btn.btn-primary.col-sm-5.col-xs-12.challenge-step-btn-finish(id='last' class=step[3] && !isCompleted ? 'disabled' : '') Finish challenge
                             else
-                                .btn.btn-primary.col-sm-5.col-xs-12.challenge-step-btn-next(id='#{index}' class=step[3] ? 'disabled' : '') Go to my next step
+                                .btn.btn-primary.col-sm-5.col-xs-12.challenge-step-btn-next(id='#{index}' class=step[3] && !isCompleted ? 'disabled' : '') Go to my next step
                         .clearfix
     #challenge-step-modal.modal(tabindex='-1')
         .modal-dialog.animated.fadeIn.fast-animation