2 files changed, 88 insertions, 0 deletions
diff --git a/lib/gitlab/import_export/project/sample/date_calculator.rb b/lib/gitlab/import_export/project/sample/date_calculator.rb
new file mode 100644
index 00000000000..2d989d21166
--- /dev/null
+++ b/lib/gitlab/import_export/project/sample/date_calculator.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module ImportExport
+    module Project
+      module Sample
+        class DateCalculator
+          include Gitlab::Utils::StrongMemoize
+
+          def initialize(dates)
+            @dates = dates.dup
+            @dates.flatten!
+            @dates.compact!
+            @dates.sort!
+            @dates.map! { |date| date.to_time.to_f }
+          end
+
+          def closest_date_to_average
+            strong_memoize(:closest_date_to_average) do
+              next if @dates.empty?
+
+              average_date = (@dates.first + @dates.last) / 2.0
+              closest_date = @dates.min_by { |date| (date - average_date).abs }
+              Time.zone.at(closest_date)
+            end
+          end
+
+          def calculate_by_closest_date_to_average(date)
+            return date unless closest_date_to_average && closest_date_to_average < Time.current
+
+            date + (Time.current - closest_date_to_average).seconds
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/import_export/project/sample/sample_data_relation_tree_restorer.rb b/lib/gitlab/import_export/project/sample/sample_data_relation_tree_restorer.rb
new file mode 100644
index 00000000000..b0c3940b5f9
--- /dev/null
+++ b/lib/gitlab/import_export/project/sample/sample_data_relation_tree_restorer.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module ImportExport
+    module Project
+      module Sample
+        class SampleDataRelationTreeRestorer < RelationTreeRestorer
+          DATE_MODELS = %i[issues milestones].freeze
+
+          def initialize(*args)
+            super
+
+            date_calculator
+          end
+
+          private
+
+          def build_relation(relation_key, relation_definition, data_hash)
+            # Override due date attributes in data hash for Sample Data templates
+            # Dates are moved by taking the closest one to average and moving that (and rest around it) to the date of import
+            # TODO: To move this logic to RelationFactory (see: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41699#note_430465333)
+            override_date_attributes!(relation_key, data_hash)
+            super
+          end
+
+          def override_date_attributes!(relation_key, data_hash)
+            return unless DATE_MODELS.include?(relation_key.to_sym)
+
+            data_hash['start_date'] = date_calculator.calculate_by_closest_date_to_average(data_hash['start_date'].to_time) unless data_hash['start_date'].nil?
+            data_hash['due_date'] = date_calculator.calculate_by_closest_date_to_average(data_hash['due_date'].to_time) unless data_hash['due_date'].nil?
+          end
+
+          # TODO: Move clear logic into main comsume_relation method (see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41699#note_430465330)
+          def dates
+            unless relation_reader.legacy?
+              DATE_MODELS.map do |tag|
+                relation_reader.consume_relation(@importable_path, tag).map { |model| model.first['due_date'] }.tap do
+                  relation_reader.clear_consumed_relations
+                end
+              end
+            end
+          end
+
+          def date_calculator
+            @date_calculator ||= Gitlab::ImportExport::Project::Sample::DateCalculator.new(dates)
+          end
+        end
+      end
+    end
+  end
+end