Backport of EE changes in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6195

Refactor AutocompleteSources#label:

1. The return value was inconsistent, sometimes returning a hash and sometimes returning an ActiveModel.
2. It was inconsistent with respect to other methods in the class since they all return ActiveModels.

2 files changed, 20 insertions, 16 deletions

diff --git a/app/controllers/projects/autocomplete_sources_controller.rb b/app/controllers/projects/autocomplete_sources_controller.rb
index 992c8ea6992..07627ffb69f 100644
--- a/app/controllers/projects/autocomplete_sources_controller.rb
+++ b/app/controllers/projects/autocomplete_sources_controller.rb
@@ -14,7 +14,7 @@ class Projects::AutocompleteSourcesController < Projects::ApplicationController
   end
 
   def labels
-    render json: @autocomplete_service.labels(target)
+    render json: @autocomplete_service.labels_as_hash(target)
   end
 
   def milestones
diff --git a/app/services/projects/autocomplete_service.rb b/app/services/projects/autocomplete_service.rb
index aa60661f7f2..9d0eaaf3152 100644
--- a/app/services/projects/autocomplete_service.rb
+++ b/app/services/projects/autocomplete_service.rb
@@ -20,24 +20,28 @@ module Projects
       MergeRequestsFinder.new(current_user, project_id: project.id, state: 'opened').execute.select([:iid, :title])
     end
 
-    def labels(target = nil)
-      labels = LabelsFinder.new(current_user, project_id: project.id, include_ancestor_groups: true)
-        .execute.select([:color, :title])
-
-      return labels unless target&.respond_to?(:labels)
-
-      issuable_label_titles = target.labels.pluck(:title)
-
-      if issuable_label_titles
-        labels = labels.as_json(only: [:title, :color])
-
-        issuable_label_titles.each do |issuable_label_title|
-          found_label = labels.find { |label| label['title'] == issuable_label_title }
-          found_label[:set] = true if found_label
+    def labels_as_hash(target = nil)
+      available_labels = LabelsFinder.new(
+        current_user,
+        project_id: project.id,
+        include_ancestor_groups: true
+      ).execute
+
+      label_hashes = available_labels.as_json(only: [:title, :color])
+
+      if target&.respond_to?(:labels)
+        already_set_labels = available_labels & target.labels
+        if already_set_labels.present?
+          titles = already_set_labels.map(&:title)
+          label_hashes.each do |hash|
+            if titles.include?(hash['title'])
+              hash[:set] = true
+            end
+          end
         end
       end
 
-      labels
+      label_hashes
     end
 
     def commands(noteable, type)