module Concerns
  module Dupable
    def duplicate
      # copy self with attributes only, includes belongs_to associations
      duplicate = self.dup

      # copy all has_many associations...
      # reject through target associations, we only want to duplicate the association models

      self.class.reflect_on_all_associations(:has_many).select { |a| a.through_reflection.nil? }.each do |assoc|
        duplicate.send(:"#{assoc.name}=", self.send(assoc.name.to_sym).map { |item|
          item = item.respond_to?(:duplicate) ? item.duplicate : item.dup

          # delete foreign_key
          item.send(:"#{assoc.foreign_key}=", nil)

          # populate inverse assoc if present
          if assoc.inverse_of.present?
            item.send(:"#{assoc.inverse_of.name}=", duplicate)
          end

          item
        })
      end

      # copy all has_many through target by copying collection_ids... only needed to populate throught association targets and pass some children presence validations
      # rails is too dumb to inspect association models and deduce through association targets
      #
      self.class.reflect_on_all_associations(:has_many).select { |a| a.through_reflection.present? }.each do |assoc|
        duplicate.send(:"#{assoc.name.to_s.singularize}_ids=", self.send(:"#{assoc.name.to_s.singularize.to_sym}_ids"))
      end

      # copy all has_one associations
      self.class.reflect_on_all_associations(:has_one).each do |assoc|
        item = self.send(assoc.name.to_sym)
        duplicate.send(:"#{assoc.name}=", item.respond_to?(:duplicate) ? item.duplicate : item.dup) if !item.nil?
      end

      duplicate
    end
  end
end