Avoid reloading whole view when focused group changes

When the focused group changes, instead of reloading the whole
view just unload the currently displayed annotations and then
reload the annotations for the newly selected group(s) and
any drafts of unsaved annotations.

The only immediately 'visible' effect of the change is
that switching groups now only results in a call to /search
rather than network requests to fetch session state and features.

In future this should make it easier to preserve state
for the area below the top bar when switching groups.

h/static/scripts/app-controller.coffee

@@ -48,7 +48,7 @@ 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
-    reloadEvents = [events.USER_CHANGED, events.GROUP_FOCUSED];
+    reloadEvents = [events.USER_CHANGED];
     reloadEvents.forEach((eventName) ->
       $scope.$on(eventName, (event, data) ->
         if !data || !data.initialLoad

h/static/scripts/app.coffee

@@ -19,15 +19,13 @@ resolve =
     'annotationMapper', 'drafts', 'threading'
     (annotationMapper,   drafts,   threading) ->
       # Unload all the annotations
-      idTable = threading.idTable
-      annotations = (message for id, {message} of idTable when message)
-      annotationMapper.unloadAnnotations(annotations)
+      annotationMapper.unloadAnnotations(threading.annotationList())
 
       # Reset the threading root
       threading.createIdTable([])
       threading.root = mail.messageContainer()
 
-      # Thread all the drafts
+      # Reload all unsaved annotations
       threading.thread(drafts.all())
 
       return threading

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

@@ -145,12 +145,6 @@ describe 'AppController', ->
     createController()
     assert.isFalse($scope.shareDialog.visible)
 
-  it 'reloads the view when the focused group changes', ->
-    createController()
-    fakeRoute.reload = sinon.spy()
-    $scope.$broadcast(events.GROUP_FOCUSED)
-    assert.calledOnce(fakeRoute.reload)
-
   it 'does not reload the view when the logged-in user changes on first load', ->
     createController()
     fakeRoute.reload = sinon.spy()

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

 {module, inject} = angular.mock
 
+events = require('../events')
+
 describe 'WidgetController', ->
   $scope = null
   fakeAnnotationMapper = null
   fakeAnnotationUI = null
   fakeAuth = null
   fakeCrossFrame = null
+  fakeDrafts = null
   fakeStore = null
   fakeStreamer = null
   fakeStreamFilter = null
   fakeThreading = null
   fakeGroups = null
+  lastSearchResult = null
   sandbox = null
   viewer = null
 
@@ -23,13 +27,22 @@ describe 'WidgetController', ->
   beforeEach module ($provide) ->
     sandbox = sinon.sandbox.create()
 
-    fakeAnnotationMapper = {loadAnnotations: sandbox.spy()}
+    fakeAnnotationMapper = {
+      loadAnnotations: sandbox.spy()
+      unloadAnnotations: sandbox.spy()
+    }
+
     fakeAnnotationUI = {
       tool: 'comment'
       clearSelectedAnnotations: sandbox.spy()
     }
     fakeAuth = {user: null}
     fakeCrossFrame = {frames: []}
+    fakeDrafts = {
+      all: sandbox.stub()
+    }
+
+    lastSearchResult = null
 
     fakeStore = {
       SearchResource:
@@ -39,7 +52,7 @@ describe 'WidgetController', ->
           result =
             total: 100
             rows: [offset..offset+limit-1]
-
+          lastSearchResult = result
           callback result
     }
 
@@ -56,7 +69,8 @@ describe 'WidgetController', ->
     }
 
     fakeThreading = {
-      root: {}
+      root: {},
+      thread: sandbox.stub()
     }
 
     fakeGroups = {
@@ -66,6 +80,7 @@ describe 'WidgetController', ->
     $provide.value 'annotationMapper', fakeAnnotationMapper
     $provide.value 'annotationUI', fakeAnnotationUI
     $provide.value 'crossframe', fakeCrossFrame
+    $provide.value 'drafts', fakeDrafts
     $provide.value 'store', fakeStore
     $provide.value 'streamer', fakeStreamer
     $provide.value 'streamFilter', fakeStreamFilter
@@ -92,3 +107,16 @@ describe 'WidgetController', ->
       assert.calledWith(loadSpy, [40..59])
       assert.calledWith(loadSpy, [60..79])
       assert.calledWith(loadSpy, [80..99])
+
+  describe 'when the focused group changes', ->
+    it 'should load annotations for the new group', ->
+      fakeThreading.annotationList = sandbox.stub().returns([{id: '1'}])
+      fakeCrossFrame.frames.push({uri: 'http://example.com'})
+      $scope.$broadcast(events.GROUP_FOCUSED)
+
+      assert.calledWith(fakeAnnotationMapper.unloadAnnotations,
+        [{id: '1'}])
+      $scope.$digest();
+      assert.calledWith(fakeAnnotationMapper.loadAnnotations,
+        lastSearchResult.rows)
+      assert.calledWith(fakeThreading.thread, fakeDrafts.all())

h/static/scripts/threading.coffee

@@ -61,6 +61,11 @@ module.exports = class Threading
     this.pruneEmpties(@root)
     @root
 
+  # Returns a flat list of every annotation that is currently loaded
+  # in the thread
+  annotationList: ->
+    (message for id, {message} of @idTable when message)
+
   pruneEmpties: (parent) ->
     for container in parent.children
       this.pruneEmpties(container)

h/static/scripts/widget-controller.coffee

 angular = require('angular')
 
+events = require('./events')
 
 module.exports = class WidgetController
   this.$inject = [
-    '$scope', 'annotationUI', 'crossframe', 'annotationMapper', 'groups',
+    '$scope', 'annotationUI', 'crossframe', 'annotationMapper', 'drafts', 'groups',
     'streamer', 'streamFilter', 'store', 'threading'
   ]
   constructor:   (
-     $scope,   annotationUI,   crossframe,   annotationMapper,   groups,
+     $scope,   annotationUI,   crossframe,   annotationMapper,  drafts,    groups,
      streamer,   streamFilter,   store,   threading
   ) ->
     $scope.isStream = true
@@ -17,6 +18,12 @@ module.exports = class WidgetController
     @chunkSize = 200
     loaded = []
 
+    _resetAnnotations = ->
+      # Unload all the annotations
+      annotationMapper.unloadAnnotations(threading.annotationList())
+      # Reload all the drafts
+      threading.thread(drafts.all())
+
     _loadAnnotationsFrom = (query, offset) =>
       queryCore =
         limit: @chunkSize
@@ -45,6 +52,11 @@ module.exports = class WidgetController
         streamFilter.resetFilter().addClause('/uri', 'one_of', loaded)
         streamer.send({filter: streamFilter.getFilter()})
 
+    $scope.$on events.GROUP_FOCUSED, ->
+      _resetAnnotations(annotationMapper, drafts, threading)
+      loaded = []
+      loadAnnotations crossframe.frames
+
     $scope.$watchCollection (-> crossframe.frames), loadAnnotations
 
     $scope.focus = (annotation) ->