Simplify rotation params handling

ee/app/graphql/mutations/incident_management/oncall_rotation/base.rb

@@ -38,22 +38,28 @@ module Mutations
         end
 
         def parsed_params(schedule, participants, args)
-          rotation_length = args.dig(:rotation_length, :length)
-          rotation_length_unit = args.dig(:rotation_length, :unit)
-          starts_at = parse_datetime(schedule, args[:starts_at])
-          ends_at = parse_datetime(schedule, args[:ends_at]) if args[:ends_at]
+          params = args.slice(:name)
 
-          active_period_start, active_period_end = active_period_times(args)
+          params[:participants] = find_participants(participants)
+          params[:starts_at] = parse_datetime(schedule, args[:starts_at]) if args[:starts_at]
+          params[:ends_at] = parse_datetime(schedule, args[:ends_at]) if args[:ends_at]
 
-          {
-            length: rotation_length,
-            length_unit: rotation_length_unit,
-            starts_at: starts_at,
-            ends_at: ends_at,
-            participants: find_participants(participants),
+          if args[:rotation_length]
+            params.merge!(
+              length: args.dig(:rotation_length, :length),
+              length_unit: args.dig(:rotation_length, :unit)
+            )
+          end
+
+          if args[:active_period].present?
+            active_period_start, active_period_end = active_period_times(args)
+            params.merge!(
               active_period_start: active_period_start,
               active_period_end: active_period_end
-          }
+            )
+          end
+
+          params
         end
 
         def parse_datetime(schedule, timestamp)

ee/app/graphql/mutations/incident_management/oncall_rotation/create.rb

@@ -57,7 +57,7 @@ module Mutations
             schedule,
             project,
             current_user,
-            create_service_params(schedule, participants, args)
+            parsed_params(schedule, participants, args)
           ).execute
 
           response(result)
@@ -65,12 +65,6 @@ module Mutations
         rescue ActiveRecord::RecordInvalid => e
           raise Gitlab::Graphql::Errors::ArgumentError, e.message
         end
-
-        private
-
-        def create_service_params(schedule, participants, args)
-          args.slice(:name).merge(parsed_params(schedule, participants, args))
-        end
       end
     end
   end

ee/app/graphql/mutations/incident_management/oncall_rotation/update.rb

@@ -43,7 +43,7 @@ module Mutations
           result = ::IncidentManagement::OncallRotations::EditService.new(
             rotation,
             current_user,
-            edit_service_params(rotation.schedule, args[:participants], args)
+            parsed_params(rotation.schedule, args[:participants], args)
           ).execute
 
           response(result)
@@ -51,24 +51,6 @@ module Mutations
 
         private
 
-        def edit_service_params(schedule, participants, args)
-          parsed_service_params = parsed_params(schedule, participants, args)
-
-          args_to_update = parsed_service_params.slice(*args.keys)
-
-          if args[:rotation_length]
-            args_to_update[:length] = parsed_service_params[:length]
-            args_to_update[:length_unit] = parsed_service_params[:length_unit]
-          end
-
-          if args[:active_period]
-            args_to_update[:active_period_start] = parsed_service_params[:active_period_start]
-            args_to_update[:active_period_end] = parsed_service_params[:active_period_end]
-          end
-
-          args.slice(:name).merge(args_to_update)
-        end
-
         def find_object(id:)
           GitlabSchema.object_from_id(id, expected_type: ::IncidentManagement::OncallRotation)
         end