1 files changed, 50 insertions, 0 deletions
diff --git a/app/services/resource_events/change_milestone_service.rb b/app/services/resource_events/change_milestone_service.rb
new file mode 100644
index 00000000000..bad7d002c65
--- /dev/null
+++ b/app/services/resource_events/change_milestone_service.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module ResourceEvents
+  class ChangeMilestoneService
+    attr_reader :resource, :user, :event_created_at, :resource_args
+
+    def initialize(resource:, user:, created_at: Time.now)
+      @resource = resource
+      @user = user
+      @event_created_at = created_at
+
+      @resource_args = {
+        user_id: user.id,
+        created_at: event_created_at
+      }
+    end
+
+    def execute
+      args = build_resource_args
+
+      action = if milestone.nil?
+                 :remove
+               else
+                 :add
+               end
+
+      record = args.merge(milestone_id: milestone&.id, action: ResourceMilestoneEvent.actions[action])
+
+      create_event(record)
+    end
+
+    private
+
+    def milestone
+      resource&.milestone
+    end
+
+    def create_event(record)
+      ResourceMilestoneEvent.create(record)
+
+      resource.expire_note_etag_cache
+    end
+
+    def build_resource_args
+      key = resource.class.name.underscore.foreign_key
+
+      resource_args.merge(key => resource.id, state: ResourceMilestoneEvent.states[resource.state])
+    end
+  end
+end