module RailsConnector

  class ObjDataFromDatabase < ObjData

    def initialize(data, revision)
      @rtc_ref = data["rtc_ref"]
      @values = data["values"]
      @ext_ref = data["ext_ref"]
      @revision = revision
    end

    def value_and_type_of(attribute_name)
      if internal_attribute?(attribute_name)
        attribute_type = type_of_internal(attribute_name)

        attribute_value = read_value(attribute_name)
        if attribute_name == '_text_links'
          attribute_value = attribute_value && attribute_value.values
        elsif attribute_name == '_path'
          attribute_value = PathConversion.path_from_list(attribute_value)
        end
      else
        attribute_type = current_attribute_type(attribute_name)
        if legacy_attribute_type(attribute_name) == attribute_type
          attribute_value = read_value(attribute_name)
        else
          attribute_value = default_attribute_value(attribute_type)
        end
      end

      [attribute_value, attribute_type]
    end

    def has_custom_attribute?(name)
      obj_class_attributes.include?(name)
    end

    def all_custom_attributes
      obj_class_attributes
    end

    private

    attr_reader :values, :rtc_ref, :revision

    def current_attribute_type(name)
      revision.attributes[name]["type"]
    end

    def obj_class_attributes
      @obj_class_attributes ||=
        begin
          name = values["_obj_class"]
          if data = revision.obj_classes[name]
            Set.new(data["attributes"]) || Set.new
          else
            raise "Could not find ObjClass with name #{name} in Revision #{revision.id}!"
          end
        end
    end

    def read_value(attribute_name)
      return values[attribute_name] if values.key?(attribute_name)
      if @ext_ref && (attribute_name == "_text_links" || attribute_name[0] != ?_)
        extend_values_with_dict_storage_values
      end
      values[attribute_name]
    end

    def extend_values_with_dict_storage_values
      return unless @ext_ref

      # may raise Kvom::Storage::NotFound
      ext_values = DictStorage.get(@ext_ref)
      values.reverse_merge!(ext_values)
      @ext_ref = nil
    end

    SPECIAL_INTERNAL_ATTRIBUTES = Set.new(%w[title body blob])

    def internal_attribute?(attribute_name)
      ?_ == attribute_name[0] || SPECIAL_INTERNAL_ATTRIBUTES.include?(attribute_name)
    end

    def legacy_attribute_type(name)
      if attr_def = legacy_attributes[name]
        attr_def["type"]
      end
    end

    def legacy_attributes
      @attributes ||=
        begin
          rtc = DictStorage.get(rtc_ref)
          if rtc['obj_classes'] && rtc['attributes'] && oc = rtc['obj_classes'][values['_obj_class']]
            rtc['attributes'].inject({}) do |attrs, (name, value)|
              attrs[name] = value if oc['attributes'] && oc['attributes'].include?(name)
              attrs
            end
          else
            {}
          end
        end
    end

  end

end