1 files changed, 81 insertions, 0 deletions
diff --git a/app/services/issuable/common_system_notes_service.rb b/app/services/issuable/common_system_notes_service.rb
new file mode 100644
index 00000000000..92eaa5d5115
--- /dev/null
+++ b/app/services/issuable/common_system_notes_service.rb
@@ -0,0 +1,81 @@
+module Issuable
+  class CommonSystemNotesService < ::BaseService
+    attr_reader :issuable
+
+    def execute(issuable, old_labels)
+      @issuable = issuable
+
+      if issuable.previous_changes.include?('title')
+        create_title_change_note(issuable.previous_changes['title'].first)
+      end
+
+      handle_description_change_note
+
+      handle_time_tracking_note if issuable.is_a?(TimeTrackable)
+      create_labels_note(old_labels) if issuable.labels != old_labels
+      create_discussion_lock_note if issuable.previous_changes.include?('discussion_locked')
+      create_milestone_note if issuable.previous_changes.include?('milestone_id')
+    end
+
+    private
+
+    def handle_time_tracking_note
+      if issuable.previous_changes.include?('time_estimate')
+        create_time_estimate_note
+      end
+
+      if issuable.time_spent?
+        create_time_spent_note
+      end
+    end
+
+    def handle_description_change_note
+      if issuable.previous_changes.include?('description')
+        if issuable.tasks? && issuable.updated_tasks.any?
+          create_task_status_note
+        else
+          # TODO: Show this note if non-task content was modified.
+          # https://gitlab.com/gitlab-org/gitlab-ce/issues/33577
+          create_description_change_note
+        end
+      end
+    end
+
+    def create_labels_note(old_labels)
+      added_labels = issuable.labels - old_labels
+      removed_labels = old_labels - issuable.labels
+
+      SystemNoteService.change_label(issuable, issuable.project, current_user, added_labels, removed_labels)
+    end
+
+    def create_title_change_note(old_title)
+      SystemNoteService.change_title(issuable, issuable.project, current_user, old_title)
+    end
+
+    def create_description_change_note
+      SystemNoteService.change_description(issuable, issuable.project, current_user)
+    end
+
+    def create_task_status_note
+      issuable.updated_tasks.each do |task|
+        SystemNoteService.change_task_status(issuable, issuable.project, current_user, task)
+      end
+    end
+
+    def create_time_estimate_note
+      SystemNoteService.change_time_estimate(issuable, issuable.project, current_user)
+    end
+
+    def create_time_spent_note
+      SystemNoteService.change_time_spent(issuable, issuable.project, issuable.time_spent_user)
+    end
+
+    def create_milestone_note
+      SystemNoteService.change_milestone(issuable, issuable.project, current_user, issuable.milestone)
+    end
+
+    def create_discussion_lock_note
+      SystemNoteService.discussion_lock(issuable, current_user)
+    end
+  end
+end