Load discussion and posts with one request

Speeds things up a heap.
Also fix a whole bunch of bugs with the post stream.

ember/app/routes/discussion.js

@@ -1,13 +1,22 @@
 import Ember from 'ember';
 
-export default Ember.Route.extend({
+import PostStream from '../models/post-stream';
 
+export default Ember.Route.extend({
 	queryParams: {
 		start: {replace: true}
 	},
 
 	model: function(params) {
-		return this.store.find('discussion', params.id);
+		// Each time we view a discussion we want to reload its posts from
+		// scratch so that we have the most up-to-date data. Also, if we were
+		// to leave them in the store, the stream would try and render them
+		// which has the potential to be slow.
+		this.store.unloadAll('post');
+		return this.store.findQueryOne('discussion', params.id, {
+			include: 'posts',
+			near: params.start
+		});
 	},
 
 	resetController: function(controller) {
@@ -19,18 +28,42 @@ export default Ember.Route.extend({
 		controller.set('stream', null);
 	},
 
-	setupController: function(controller, model) {
-		controller.setup(model);
+	setupController: function(controller, discussion) {
+		controller.set('model', discussion);
 
-		// Tell the discussions controller that the discussions list should be
-		// displayed as a pane, hidden on the side of the screen. Also set the
-		// application back button's target as the discussions controller.
-		this.controllerFor('index').set('paned', true);
-		this.controllerFor('application').set('backButtonTarget', this.controllerFor('index'));
+        // Set up the post stream object. It needs to know about the discussion
+        // it's representing the posts for, and we also need to inject the Ember
+        // Data store.
+        var stream = PostStream.create({
+        	discussion: discussion,
+        	store: this.store
+        });
+        controller.set('stream', stream);
+
+        // Next, we need to make sure we have a list of the discussion's post
+        // IDs. If we don't already have this information, we'll need to
+        // reload the discussion model.
+        var promise = discussion.get('posts') ? Ember.RSVP.resolve(discussion) : this.model({
+        	id: discussion.get('id'),
+        	start: controller.get('start')
+        });
+
+        // When we know we have the post IDs, we can set up the post stream with
+        // them. Then we will tell the view that we have finished loading so that
+        // it can scroll down to the appropriate post.
+        promise.then(function(discussion) {
+            stream.setup(discussion.get('postIds'));
+            controller.store.push('discussion', {id: discussion.get('id'), posts: ''});
+            if (controller.get('model') === discussion) {
+	            controller.set('loaded', true);
+	            Ember.run.scheduleOnce('afterRender', function() {
+	            	controller.trigger('loaded');
+	            });
+	        }
+        });
 	},
 
 	actions: {
-
 		queryParamsDidChange: function(params) {
 			// If the ?start param has changed, we want to tell the view to
 			// tell the streamContent component to jump to this start point.
@@ -39,26 +72,25 @@ export default Ember.Route.extend({
 			// queryParamsDidChange is fired before the controller is reset.
 			// Thus, controller.loaded would still be true and the
 			// startWasChanged event would be triggered inappropriately.
-			var controller = this.get('controller'),
-			    oldStart = parseInt(this.get('controller.start'));
+			var newStart = parseInt(params.start) || 1;
+			var controller = this.controllerFor('discussion');
+			var oldStart = parseInt(controller.get('start'));
 			Ember.run.next(function() {
-				if (! params.start || ! controller || ! controller.get('loaded') || parseInt(params.start) === oldStart) {
-					return;
+				if (controller.get('loaded') && newStart !== oldStart) {
+					controller.trigger('startWasChanged', newStart);
 				}
-				controller.trigger('startWasChanged', params.start);
 			});
 		},
 
-		willTransition: function() {
+		didTransition: function() {
 			// When we transition into a new discussion, we want to hide the
 			// discussions list pane. This means that when the user selects a
 			// different discussion within the pane, the pane will slide away.
-			this.controllerFor('index').set('paneShowing', false);
+			// We also minimize the composer.
+			this.controllerFor('index')
+				.set('paned', true)
+				.set('paneShowing', false);
+			this.controllerFor('composer').send('minimize');
 		},
-
-	    didTransition: function() {
-	    	this.controllerFor('composer').send('minimize');
-	    }
-
 	}
 });