From 38f2e345d935f0095415babb7506fa5a5afe24ed Mon Sep 17 00:00:00 2001
From: Mo Bitar <me@bitar.io>
Date: Wed, 27 Dec 2017 11:09:49 -0600
Subject: [PATCH] Updated SingletonManager

---
 .../javascripts/app/services/authManager.js   |  2 +-
 .../app/services/componentManager.js          |  1 -
 .../app/services/singletonManager.js          | 42 +++++++++++++++----
 3 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/app/assets/javascripts/app/services/authManager.js b/app/assets/javascripts/app/services/authManager.js
index ef29e12f9..4e7f1936f 100644
--- a/app/assets/javascripts/app/services/authManager.js
+++ b/app/assets/javascripts/app/services/authManager.js
@@ -296,7 +296,7 @@ angular.module('app.frontend')
       let prefsContentType = "SN|UserPreferences";
 
       singletonManager.registerSingleton({content_type: prefsContentType}, (resolvedSingleton) => {
-        console.log("AuthManager received resolved", resolvedSingleton);
+        console.log("AuthManager received resolved UserPreferences", resolvedSingleton);
         this.userPreferences = resolvedSingleton;
       }, () => {
         // Safe to create. Create and return object.
diff --git a/app/assets/javascripts/app/services/componentManager.js b/app/assets/javascripts/app/services/componentManager.js
index 46b71f3c6..8fc753043 100644
--- a/app/assets/javascripts/app/services/componentManager.js
+++ b/app/assets/javascripts/app/services/componentManager.js
@@ -48,7 +48,6 @@ class ComponentManager {
         recursion caused by the component being modified and saved after it is updated.
       */
       if(syncedComponents.length > 0 && source != ModelManager.MappingSourceRemoteSaved) {
-        console.log("Web, Syncing Components", syncedComponents, "source", source);
         // Ensure any component in our data is installed by the system
         this.desktopManager.syncComponentsInstallation(syncedComponents);
       }
diff --git a/app/assets/javascripts/app/services/singletonManager.js b/app/assets/javascripts/app/services/singletonManager.js
index 07e892c82..3f6d260e7 100644
--- a/app/assets/javascripts/app/services/singletonManager.js
+++ b/app/assets/javascripts/app/services/singletonManager.js
@@ -1,7 +1,11 @@
 /*
   The SingletonManager allows controllers to register an item as a singleton, which means only one instance of that model
   should exist, both on the server and on the client. When the SingletonManager detects multiple items matching the singleton predicate,
-  the oldest ones will be deleted, leaving the newest ones
+  the oldest ones will be deleted, leaving the newest ones.
+
+  We will treat the model most recently arrived from the server as the most recent one. The reason for this is, if you're offline,
+  a singleton can be created, as in the case of UserPreferneces. Then when you sign in, you'll retrieve your actual user preferences.
+  In that case, even though the offline singleton has a more recent updated_at, the server retreived value is the one we care more about.
 */
 
 class SingletonManager {
@@ -16,13 +20,14 @@ class SingletonManager {
     })
 
     $rootScope.$on("sync:completed", (event, data) => {
-      console.log("Sync completed", data);
       this.resolveSingletons(data.retrievedItems || []);
     })
 
+    // Testing code to make sure only 1 exists
     setTimeout(function () {
-      var userPrefsTotal = modelManager.itemsForContentType("SN|UserPreferences");
-      console.log("All extant prefs", userPrefsTotal);
+      var userPrefs = modelManager.itemsForContentType("SN|UserPreferences");
+      console.assert(userPrefs.length == 1);
+      console.log("All extant prefs", userPrefs);
     }, 1000);
   }
 
@@ -44,25 +49,46 @@ class SingletonManager {
       var predicate = singletonHandler.predicate;
       var singletonItems = this.filterItemsWithPredicate(retrievedItems, predicate);
       if(singletonItems.length > 0) {
-        // Check local inventory and make sure only 1 similar item exists. If more than 1, delete oldest
+        /*
+          Check local inventory and make sure only 1 similar item exists. If more than 1, delete oldest
+          Note that this local inventory will also contain whatever is in retrievedItems.
+          However, as stated in the header comment, retrievedItems take precendence over existing items,
+          even if they have a lower updated_at value
+        */
         var allExtantItemsMatchingPredicate = this.filterItemsWithPredicate(this.modelManager.allItems, predicate);
 
+        /*
+          If there are more than 1 matches, delete everything not in `singletonItems`,
+          then delete all but the latest in `singletonItems`
+        */
         if(allExtantItemsMatchingPredicate.length >= 2) {
-          // Purge old ones
-          var sorted = allExtantItemsMatchingPredicate.sort((a, b) => {
+          var toDelete = [];
+          for(var extantItem of allExtantItemsMatchingPredicate) {
+            if(!singletonItems.includes(extantItem)) {
+              // Delete it
+              toDelete.push(extantItem);
+            }
+          }
+
+          // Sort incoming singleton items by most recently updated first, then delete all the rest
+          var sorted = singletonItems.sort((a, b) => {
             return a.updated_at < b.updated_at;
           })
 
-          var toDelete = sorted.slice(1, sorted.length);
+          // Delete everything but the first one
+          toDelete = toDelete.concat(sorted.slice(1, sorted.length));
+
           for(var d of toDelete) {
             this.modelManager.setItemToBeDeleted(d);
           }
 
           this.$rootScope.sync();
+
           // Send remaining item to callback
           var singleton = sorted[0];
           singletonHandler.singleton = singleton;
           singletonHandler.resolutionCallback(singleton);
+
         } else if(allExtantItemsMatchingPredicate.length == 1) {
           if(!singletonHandler.singleton) {
             // Not yet notified interested parties of object