ama-team / ruby-entity-mapper

require_relative '../../mixin/reflection'

require_relative '../../mixin/errors'

module AMA

  module Entity

    class Mapper

      module Handler

        module Entity

          # Default denormalization processor

          class Denormalizer

            include Mixin::Reflection

            include Mixin::Errors

            INSTANCE = new

            # @param [Hash] source

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

            # @param [AMA::Entity::Mapper::Context] context

            def denormalize(source, type, context = nil)

              validate_source!(source, type, context)

              entity = type.factory.create(type, source, context)

              type.attributes.values.each do |attribute|

                next if attribute.virtual

                candidate_names(attribute).each do |name|

                  next unless source.key?(name)

                  value = source[name]

                  break set_object_attribute(entity, attribute.name, value)

                end

              end

              entity

            end

            private

            # @param [AMA::Entity::Mapper::Type::Attribute] attribute

            # @return [Array<Symbol, String>]

            # @param [Hash] source

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

            # @param [AMA::Entity::Mapper::Context] context

            def validate_source!(source, type, context)

              return if source.is_a?(Hash)

              message = "Expected Hash, #{source.class} provided " \

                "(while denormalizing #{type})"

              mapping_error(message, context: context)

            end

            class << self

              include Mixin::Reflection

              # @param [Denormalizer] implementation

              # @return [Denormalizer]

                handler = handler_factory(implementation, INSTANCE)

                depiction = "Safety wrapper for #{implementation}"

                wrapper = method_object(:denormalize, to_s: depiction, &handler)

                wrapper.singleton_class.instance_eval do

                  include Mixin::Errors

                end

                wrapper

              end

              private

              # @param [Denormalizer] implementation

              # @param [Denormalizer] fallback

              # @return [Denormalizer]

              def handler_factory(implementation, fallback)

                lambda do |source, type, ctx|

                  begin

                    implementation.denormalize(source, type, ctx) do |s, t, c|

                      fallback.denormalize(s, t, c)

                    end

                  rescue StandardError => e

                    raise_if_internal(e)

                    message = 'Unexpected error from denormalizer ' \

                      "#{implementation}"

                    signature = '(source, type, context)'

                    options = { parent: e, context: ctx, signature: signature }

                    compliance_error(message, **options)

                  end

                end

              end

            end

          end

        end

      end

    end

  end

end