ama-team / ruby-entity-mapper

        class Attribute

          include Mixin::Errors

          include Mixin::Reflection

          include Mixin::HandlerSupport

          # @!attribute

          #   @return [AMA::Entity::Mapper::Type]

          attr_accessor :owner

          # @!attribute

          #   @return [Symbol]

          attr_accessor :name

          # @!attribute types List of possible types attribute may take

          #   @return [Array<AMA::Entity::Mapper::Type>]

          attr_accessor :types

          # If attribute is declared as virtual, it is omitted from all

          # automatic actions, such enumeration, normalization and

          # denormalization. Main motivation behind virtual attributes was

          # collections problem: collection can't be represented as hash of

          # attributes, however, virtual attribute may describe collection

          # content.

          #

          # @!attribute virtual

          #   @return [TrueClass, FalseClass]

          attr_accessor :virtual

          # If set to true, this attribute will be omitted during normalization

          # and won't be present in resulting structure.

          #

          # @!attribute sensitive

          #   @return [TrueClass, FalseClass]

          attr_accessor :sensitive

          # Default value that is set on automatic object creation.

          #

          # @!attribute default

          #   @return [Object]

          attr_accessor :default

          # Whether or not this attribute may be represented by null.

          #

          # @!attribute nullable

          #   @return [TrueClass, FalseClass]

          attr_accessor :nullable

          # List of values this attribute acceptable to take. Part of automatic

          # validation.

          #

          # @!attribute values

          #   @return [Array<Object>]

          attr_accessor :values

          # @!attribute aliases

          #   @return [Array<Symbol>]

          attr_accessor :aliases

          handler_namespace Handler::Attribute

          # Custom attribute validator

          #

          # @!attribute validator

          #   @return [API::AttributeValidator]

          handler :validator, :validate

          def self.defaults

            {

              virtual: false,

              sensitive: false,

              default: nil,

              nullable: false,

              values: [],

              validator: nil,

              aliases: []

            }

          end

          # @param [Mapper::Type] owner

          # @param [Symbol] name

          # @param [Array<Mapper::Type>] types

          # @param [Hash<Symbol, Object] options

          def initialize(owner, name, *types, **options)

            @owner = validate_owner!(owner)

            @name = validate_name!(name)

            @types = validate_types!(types)

            self.class.defaults.each do |key, value|

              value = options.fetch(key, value)

              unless value.nil?

                set_object_attribute(self, key, options.fetch(key, value))

              end

            end

          end

          def violations(value, context)

            validator.validate(value, self, context)

          end

          def valid?(value, context)

            violations(value, context).empty?

          end

          def valid!(value, context)

            violations = self.violations(value, context)

            return if violations.empty?

            repr = violations.join(', ')

            message = "Attribute #{self} has failed validation: #{repr}"

            validation_error(message, context: context)

          end

          def resolved?

            types.all?(&:resolved?)

          end

          def resolved!(context = nil)

            types.each { |type| type.resolved!(context) }

          end

          # @param [AMA::Entity::Mapper::Type] parameter

          # @param [AMA::Entity::Mapper::Type] substitution

          # @return [AMA::Entity::Mapper::Type::Attribute]

          def resolve_parameter(parameter, substitution)

            clone.tap do |clone|

              clone.types = types.each_with_object([]) do |type, carrier|

                if type == parameter

                  buffer = substitution

                  buffer = [buffer] unless buffer.is_a?(Enumerable)

                  next carrier.push(*buffer)

                end

                carrier.push(type.resolve_parameter(parameter, substitution))

              end

            end

          end

          def hash

            @owner.hash ^ @name.hash

          end

          def eql?(other)

            return false unless other.is_a?(self.class)

            @owner == other.owner && @name == other.name

          end

          def ==(other)

            eql?(other)

          end

          def to_def

            types = @types ? @types.map(&:to_def).join(', ') : 'none'

            message = "#{owner.type}.#{name}"

            message += ':virtual' if virtual

            "#{message}<#{types}>"

          end

          def to_s

            message = "Attribute #{owner.type}.#{name}"

            message = "#{message} (virtual)" if virtual

            types = @types ? @types.map(&:to_def).join(', ') : 'none'

            "#{message} <#{types}>"

          end

          private

          def validate_owner!(owner)

            return owner if owner.is_a?(Type)

            message = 'Provided owner has to be a Type instance,' \

              " #{owner.class} received"

            compliance_error(message)

          end

          def validate_name!(name)

            return name if name.is_a?(Symbol)

            message = "Provided name has to be Symbol, #{name.class} received"

            compliance_error(message)

          end

          def validate_types!(types)

            compliance_error("No types provided for #{self}") if types.empty?

            types.each do |type|

              next if type.is_a?(Type) || type.is_a?(Parameter)

              message = 'Provided type has to be a Type instance, ' \

                "#{type.class} received"

              compliance_error(message)

            end

          end

        end