Update rotation active period after schedule changes

ee/app/services/incident_management/oncall_schedules/update_service.rb

@@ -8,6 +8,8 @@ module IncidentManagement
       # @param params [Hash]
       def initialize(oncall_schedule, user, params)
         @oncall_schedule = oncall_schedule
+        @original_schedule_timezone = oncall_schedule&.timezone
+        @oncall_rotations = oncall_schedule&.rotations
         @user = user
         @params = params
         @project = oncall_schedule.project
@@ -18,6 +20,7 @@ module IncidentManagement
         return error_no_permissions unless allowed?
 
         if oncall_schedule.update(params)
+          update_rotation_active_periods
           success(oncall_schedule)
         else
           error(oncall_schedule.errors.full_messages.to_sentence)
@@ -26,7 +29,23 @@ module IncidentManagement
 
       private
 
-      attr_reader :oncall_schedule, :user, :params, :project
+      attr_reader :oncall_schedule, :original_schedule_timezone, :oncall_rotations, :user, :params, :project
+
+      def update_rotation_active_periods
+        oncall_schedule.rotations.select(&:has_shift_active_period?).each do |rotation|
+          rotation.update!(
+            active_period_start: new_rotation_active_period(rotation.active_period_start).strftime('%H:%M'),
+            active_period_end: new_rotation_active_period(rotation.active_period_end).strftime('%H:%M')
+          )
+        end
+
+        # TODO do we need to handle run update rotation job?
+        # Should the above be moved to update rotation job?
+      end
+
+      def new_rotation_active_period(time_string)
+        time_string.in_time_zone(original_schedule_timezone).in_time_zone(oncall_schedule.timezone)
+      end
 
       def error_no_permissions
         error(_('You have insufficient permissions to update an on-call schedule for this project'))

ee/spec/services/incident_management/oncall_schedules/update_service_spec.rb

@@ -68,6 +68,28 @@ RSpec.describe IncidentManagement::OncallSchedules::UpdateService do
         expect(oncall_schedule.description).to eq(params[:description])
         expect(oncall_schedule.timezone).to eq(params[:timezone])
       end
+
+      context 'schedule has a rotation' do
+        # Setting fixed timezone for rotation active period updates
+        around do |example|
+          freeze_time do
+            travel_to Time.utc(2021, 03, 22)
+
+            example.run
+          end
+        end
+
+        let_it_be_with_reload(:oncall_rotation) { create(:incident_management_oncall_rotation, :with_active_period, schedule: oncall_schedule) }
+
+        it 'updates the rotation active periods with new timezone' do
+          expect { execute }.to change { time_from_time_column(oncall_rotation.reload.active_period_start) }.from('08:00').to('03:00')
+           .and change { time_from_time_column(oncall_rotation.active_period_end) }.from('17:00').to('12:00')
+        end
+      end
+
+      def time_from_time_column(attribute)
+        attribute.strftime('%H:%M')
+      end
     end
   end
 end