From 632726fe0273ad507138ae9c30a8a890659e8a0f Mon Sep 17 00:00:00 2001
From: Tyler Renelle <tylerrenelle@gmail.com>
Date: Wed, 24 Sep 2014 19:35:00 -0600
Subject: [PATCH] perf(challenges): WIP

---
 src/controllers/challenges.js | 57 +++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/src/controllers/challenges.js b/src/controllers/challenges.js
index 9d2fb5992c..9d5869a7be 100644
--- a/src/controllers/challenges.js
+++ b/src/controllers/challenges.js
@@ -105,23 +105,48 @@ api.csv = function(req, res, next) {
 }
 
 api.getMember = function(req, res, next) {
-  var cid = req.params.cid, uid = req.params.uid;
-  User.findById(uid)
-    .select('profile.name habits dailys todos rewards')
-    .exec(function(err, member){
-      if(err) return next(err);
+  var cid = req.params.cid;
+  var uid = req.params.uid;
+
+  // See http://stackoverflow.com/a/18546277/362790
+  // However, this doesn't work. If not all $match conditions are met (eg, if a challenge doesn't have any one of habit/daily/todo/reward
+  // then the $match fails and that user object is removed from the results. See http://stackoverflow.com/questions/23636175/filter-subdocument-array-while-still-returning-parent-data-if-empty
+//  User.aggregate()
+//  .match({_id: uid})
+//  .unwind('habits').match({'habits.challenge.id': cid})
+//  .unwind('dailys').match({'dailys.challenge.id': cid})
+//  .unwind('todos').match({'todos.challenge.id': cid})
+//  .unwind('rewards').match({'rewards.challenge.id': cid})
+//  .group({_id:'$_id', 'profile.name':'$profile.name', habits:{$push: '$habits'}, dailys:{$push:'$dailys'}, todos:{$push:'$todos'}, rewards:{$push:'$rewards'}})
+//  .exec(function(err, member){
+//    if (err) return next(err);
+//    if (!member) return res.json(404, {err: 'Member '+uid+' for challenge '+cid+' not found'});
+//    res.json(member[0]);
+//  });
+
+  //http://stackoverflow.com/questions/24027213/how-to-match-multiple-array-elements-without-using-unwind
+  var proj = {'profile.name':'$profile.name'};
+  _.each(['habits','dailys','todos','rewards'], function(type){
+    proj[type] = {
+      $setDifference: [{
+        $map: {
+          input: '$'+type,
+          as: "el",
+          in: {
+            $cond: [{$eq: ["$$el.challenge.id", cid]}, '$$el', false]
+          }
+        }
+      }, [false]]
+    }
+  });
+  User.aggregate()
+  .match({_id: uid})
+  .project(proj)
+  .exec(function(err, member){
+    if (err) return next(err);
       if (!member) return res.json(404, {err: 'Member '+uid+' for challenge '+cid+' not found'});
-
-      // Prune un-related tasks. See http://goo.gl/9fnwei
-      // See http://stackoverflow.com/a/18546277/362790 for fix
-      _.each(['habits','dailys','todos', 'rewards'], function(type){
-        member[type] = _.filter(member[type], function(task){
-          return task.challenge && task.challenge.id && task.challenge.id == cid;
-        });
-      });
-
-      res.json(member);
-    })
+    res.json(member[0]);
+  });
 }
 
 // CREATE