module Granite
  module Form
    module Model
      module Attributes
        class ReferenceOne < Base
          def write(value)
            pollute do
              previous = type_casted_value
              result = write_value value
              changed = (!value.nil? && type_casted_value.nil?) || type_casted_value != previous

              association.reset if changed
              result
            end
          end

          def read
            if association.target
              association.identify
            else
              type_casted_value
            end
          end

          def type_casted_value
            variable_cache(:value) do
              type_definition.ensure_type(read_before_type_cast)
            end
          end

          def read_before_type_cast
            @value_cache
          end

        private

          def association
            @association ||= owner.association(reflection.association)
          end
        end
      end
    end
  end
end