# frozen_string_literal: true

module ChronoModel
  module Patches
    module Relation
      include ChronoModel::Patches::AsOfTimeHolder

      def preload_associations(records) # :nodoc:
        preload = preload_values
        preload += includes_values unless eager_loading?
        scope = StrictLoadingScope if strict_loading_value

        preload.each do |associations|
          ActiveRecord::Associations::Preloader.new(
            records: records, associations: associations, scope: scope, model: model, as_of_time: as_of_time
          ).call
        end
      end

      def empty_scope?
        return super unless @_as_of_time

        @values == klass.unscoped.as_of(as_of_time).values
      end

      def load
        return super unless @_as_of_time && !loaded?

        super.each { |record| record.as_of_time!(@_as_of_time) }
      end

      def merge(*)
        return super unless @_as_of_time

        super.as_of_time!(@_as_of_time)
      end

      def build_arel(*)
        return super unless @_as_of_time

        super.tap do |arel|
          arel.join_sources.each do |join|
            chrono_join_history(join)
          end
        end
      end

      # Replaces a join with the current data with another that
      # loads records As-Of time against the history data.
      #
      def chrono_join_history(join)
        # This case happens with nested includes, where the below
        # code has already replaced the join.left with a JoinNode.
        #
        return if join.left.respond_to?(:as_of_time)

        model =
          if join.left.respond_to?(:table_name)
            ChronoModel.history_models[join.left.table_name]
          else
            ChronoModel.history_models[join.left]
          end

        return unless model

        join.left = ChronoModel::Patches::JoinNode.new(
          join.left, model.history, @_as_of_time
        )
      end

      # Build a preloader at the +as_of_time+ of this relation.
      # Pass the current model to define Relation
      #
      def build_preloader
        ActiveRecord::Associations::Preloader.new(
          model: model, as_of_time: as_of_time
        )
      end

      def find_nth(*)
        return super unless try(:history?)

        with_hid_pkey { super }
      end

      def last(*)
        return super unless try(:history?)

        with_hid_pkey { super }
      end

      private

      def ordered_relation
        return super unless try(:history?)

        with_hid_pkey { super }
      end
    end
  end
end