FIX: Prevent duplicate flags after undoing on the server side too.

app/controllers/post_actions_controller.rb

@@ -7,7 +7,8 @@ class PostActionsController < ApplicationController
   before_filter :fetch_post_action_type_id_from_params
 
   def create
-    guardian.ensure_post_can_act!(@post, PostActionType.types[@post_action_type_id])
+    taken = PostAction.counts_for([@post], current_user)[@post.id]
+    guardian.ensure_post_can_act!(@post, PostActionType.types[@post_action_type_id], taken_actions: taken)
 
     args = {}
     args[:message] = params[:message] if params[:message].present?

spec/controllers/post_actions_controller_spec.rb

@@ -28,7 +28,7 @@ describe PostActionsController do
       end
 
       it "fails when the user doesn't have permission to perform that action" do
-        Guardian.any_instance.expects(:post_can_act?).with(@post, :like).returns(false)
+        Guardian.any_instance.expects(:post_can_act?).with(@post, :like, taken_actions: nil).returns(false)
         xhr :post, :create, id: @post.id, post_action_type_id: PostActionType.types[:like]
         response.should be_forbidden
       end
@@ -38,6 +38,12 @@ describe PostActionsController do
         xhr :post, :create, id: @post.id, post_action_type_id: PostActionType.types[:like]
       end
 
+      it "passes a list of taken actions through" do
+        PostAction.create(post_id: @post.id, user_id: @user.id, post_action_type_id: PostActionType.types[:inappropriate])
+        Guardian.any_instance.expects(:post_can_act?).with(@post, :off_topic, has_entry({:taken_actions => has_key(PostActionType.types[:inappropriate])}))
+        xhr :post, :create, id: @post.id, post_action_type_id: PostActionType.types[:off_topic]
+      end
+
       it 'passes the message through' do
         PostAction.expects(:act).once.with(@user, @post, PostActionType.types[:like], {message: 'action message goes here'})
         xhr :post, :create, id: @post.id, post_action_type_id: PostActionType.types[:like], message: 'action message goes here'