Avoid redundant view reloads on startup and simplify group focus change handling

 * Remove the logic from app-controller.coffee to focus the Public group
   on logout. This is no longer needed as the 'groups' service automatically
   updates the focused group if the previously focused group is removed.

 * Only emit the SESSION_CHANGED event on updates to the session state,
   not the initial app load, since initialization of the view is deferred
   until the session has already been loaded.

   Since the SESSION_CHANGED handler currently reloads the whole view,
   this avoids reloading the view twice on startup.

   Refactoring handling of SESSION_CHANGED to only update the relevant
   app state is left for a future refactoring.

T-105

h/static/scripts/app-controller.coffee

@@ -42,8 +42,8 @@ module.exports = class AppController
 
     # Reload the view when the focused group changes or the
     # list of groups that the user is a member of changes
-    groupChangeEvents = [events.SESSION_CHANGED, events.GROUP_FOCUSED];
-    groupChangeEvents.forEach((eventName) ->
+    reloadEvents = [events.SESSION_CHANGED, events.GROUP_FOCUSED];
+    reloadEvents.forEach((eventName) ->
       $scope.$on(eventName, (event) ->
         $route.reload()
       )
@@ -51,14 +51,7 @@ module.exports = class AppController
 
     identity.watch({
       onlogin: (identity) -> $scope.auth.user = auth.userid(identity)
-      onlogout: ->
-        $scope.auth.user = null
-
-        # Currently all groups are private so when the user logs out they can
-        # no longer see the annotations from any group they may have had
-        # focused. Focus the public group instead, so that they see any public
-        # annotations in the sidebar.
-        groups.focus('__world__')
+      onlogout: -> $scope.auth.user = null
       onready: -> $scope.auth.user ?= null
     })
 
@@ -84,10 +77,6 @@ module.exports = class AppController
       else
         $scope.accountDialog.visible = false
 
-      # Reload the view if this is not the initial load.
-      if oldVal isnt undefined
-        $route.reload()
-
     $scope.login = ->
       $scope.accountDialog.visible = true
       identity.request({

h/static/scripts/events.js

@@ -4,6 +4,10 @@
  */
 
 module.exports = {
+  /** Broadcast when the currently selected group changes */
   GROUP_FOCUSED: 'groupFocused',
+  /** Broadcast when the session state is updated.
+   * This event is NOT broadcast after the initial session load.
+   */
   SESSION_CHANGED: 'sessionChanged',
 };

h/static/scripts/session.js

@@ -115,6 +115,8 @@ function session($document, $http, $resource, $rootScope, flash) {
    *              when new state has been pushed to it by the server.
    */
   resource.update = function (model) {
+    var isInitialLoad = !resource.state.csrf;
+
     // Copy the model data (including the CSRF token) into `resource.state`.
     angular.copy(model, resource.state);
 
@@ -122,7 +124,9 @@ function session($document, $http, $resource, $rootScope, flash) {
     lastLoad = {$promise: Promise.resolve(model), $resolved: true};
     lastLoadTime = Date.now();
 
-    $rootScope.$broadcast(events.SESSION_CHANGED);
+    if (!isInitialLoad) {
+      $rootScope.$broadcast(events.SESSION_CHANGED);
+    }
 
     // Return the model
     return model;

h/static/scripts/streamer.js

@@ -73,7 +73,7 @@ function connect($websocket, annotationMapper, groups, session) {
 
   // Listen for updates
   socket.onMessage(function (event) {
-    message = JSON.parse(event.data)
+    message = JSON.parse(event.data);
     if (!message) {
       return;
     }

h/static/scripts/test/app-controller-test.coffee

@@ -124,12 +124,6 @@ describe 'AppController', ->
     onlogout()
     assert.strictEqual($scope.auth.user, null)
 
-  it 'focuses the default group in logout', ->
-    createController()
-    {onlogout} = fakeIdentity.watch.args[0][0]
-    onlogout()
-    assert.calledWith(fakeGroups.focus, '__world__')
-
   it 'does not show login form for logged in users', ->
     createController()
     assert.isFalse($scope.accountDialog.visible)

h/static/scripts/test/session-test.js

@@ -160,11 +160,23 @@ describe('h:session', function () {
   describe('#update()', function () {
     it('broadcasts an event when the session is updated', function () {
       var sessionChangeCallback = sinon.stub();
+
+      // the initial load should not trigger a SESSION_CHANGED event
       $rootScope.$on(events.SESSION_CHANGED, sessionChangeCallback);
       session.update({
         groups: [{
           id: 'groupid'
-        }]
+        }],
+        csrf: 'dummytoken',
+      });
+
+      // subsequent loads should trigger a SESSION_CHANGED event
+      assert.isFalse(sessionChangeCallback.called);
+      session.update({
+        groups: [{
+          id: 'groupid2'
+        }],
+        csrf: 'dummytoken'
       });
       assert.calledOnce(sessionChangeCallback);
     });