Extract checking if event is replacement to event_schedule model

app/models/event_schedule.rb

@@ -28,4 +28,8 @@ class EventSchedule < ActiveRecord::Base
   def intersecting_events
     room.event_schedules.where(start_time: start_time, schedule: schedule).where.not(id: id)
   end
+
+  def replacement?
+    event.state == 'confirmed' && (!intersecting_events.canceled.empty? || !intersecting_events.withdrawn.empty?)
+  end
 end