fix(labels/folders): Temporarily disable changing nested messages

- It's slow, and causes performLocal to take much longer
- It's making changes we receive from the streaming API a few moments later
- We don't actually display nested folder data anywhere important

spec-nylas/tasks/change-mail-task-spec.coffee

@@ -103,11 +103,13 @@ describe "ChangeMailTask", ->
           expect(@task._applyChanges).toHaveBeenCalledWith(@task.threads)
           expect(DatabaseStore.persistModels).toHaveBeenCalledWith([@threadAChanged])
 
-    it "fetches messages on changed threads and appends them to the messages to update", ->
-      waitsForPromise =>
-        @task._performLocalThreads().then =>
-          expect(@task._applyChanges).toHaveBeenCalledWith(@task.threads)
-          expect(@task.messages).toEqual([@threadAMesage1, @threadAMesage2])
+    describe "when _processesNestedMessages is overridden to return true", ->
+      it "fetches messages on changed threads and appends them to the messages to update", ->
+        waitsForPromise =>
+          @task._processesNestedMessages = => true
+          @task._performLocalThreads().then =>
+            expect(@task._applyChanges).toHaveBeenCalledWith(@task.threads)
+            expect(@task.messages).toEqual([@threadAMesage1, @threadAMesage2])
 
   describe "_performLocalMessages", ->
     beforeEach ->

src/flux/tasks/change-folder-task.coffee

@@ -65,6 +65,9 @@ class ChangeFolderTask extends ChangeMailTask
       # The base class does the heavy lifting and calls _changesToModel
       return super
 
+  _processesNestedMessages: ->
+    false
+
   _changesToModel: (model) ->
     if model instanceof Thread
       {folders: [@folder]}

src/flux/tasks/change-labels-task.coffee

@@ -59,8 +59,9 @@ class ChangeLabelsTask extends ChangeMailTask
       # The base class does the heavy lifting and calls _changesToModel
       return super
 
-  # Returns a new set of {Label} objects that incoprates the existing,
-  # new, and removed labels.
+  _processesNestedMessages: ->
+    false
+
   _changesToModel: (model) ->
     labelsToRemoveIds = _.pluck(@labelsToRemove, 'id')
 

src/flux/tasks/change-mail-task.coffee

@@ -18,12 +18,7 @@ NamespaceStore = require '../stores/namespace-store'
 # ChangeMailTask stores the previous values of all models it changes into @_restoreValues
 # and handles undo/redo. When undoing, it restores previous values and calls
 # `_requestBodyForModel` to make undo API requests. It does not call `_changesToModel`.
-#
-# Generally, you cannot provide both messages and threads at the same time. However,
-# ChangeMailTask runs for provided `threads` first, so your subclass can populate
-# @messages with the messages of those threads to make adjustments to them.
-# API requests are only made for threads if threads are present.
-#
+##
 class ChangeMailTask extends Task
 
   constructor: ({@threads, thread, @messages, message} = {}) ->
@@ -48,6 +43,17 @@ class ChangeMailTask extends Task
   _requestBodyForModel: (model) ->
     throw new Error("You must override this method.")
 
+  # Generally, you cannot provide both messages and threads at the same time. However,
+  # ChangeMailTask runs for provided threads first and then messages. Override
+  # and return true, and you will receive `_changesToModel` for messages in
+  # changed threads, and any changes you make will be written to the database
+  # and undone during undo.
+  #
+  # Note that API requests are only made for threads if threads are present.
+  #
+  _processesNestedMessages: ->
+    false
+
   # Perform Local
 
   # Subclasses should override `performLocal` and call super once they've
@@ -72,8 +78,11 @@ class ChangeMailTask extends Task
     changedIds = _.pluck(changed, 'id')
 
     DatabaseStore.persistModels(changed).then =>
-      DatabaseStore.findAll(Message).where(Message.attributes.threadId.in(changedIds)).then (messages) =>
-        @messages = [].concat(messages, @messages)
+      if @_processesNestedMessages()
+        DatabaseStore.findAll(Message).where(Message.attributes.threadId.in(changedIds)).then (messages) =>
+          @messages = [].concat(messages, @messages)
+          Promise.resolve()
+      else
         Promise.resolve()
 
   _performLocalMessages: ->