class AWS::Core::Resource::AttributeProvider

def attributes_from_response resource, response
  if response_object = resource.send(finder_method, response)
    attributes_from_response_object(response_object)
  else
    nil
  end
end

def attributes_from_response_object resp_obj
  @provides.inject({}) do |attributes,(attr_name,options)|
    attr = @klass.attributes[attr_name]
    methods = [options[:from] || attr.from].flatten
    v = resp_obj
    methods.each do |method|
      v = v.key?(method) ? v[method] : v[method.to_s]
      break if v.nil?
    end
    v = v[:value] if v and options[:value_wrapped]
    v = attr.translate_output_value(v)
    attributes.merge(attr_name => v)
  end
end

def find &block
  @klass.send(:define_method, finder_method, &block)
end

def finder_method
  "_find_in_#{request_types.join('_or_')}_response_#{@id}"
end

def initialize klass, request_types
  @klass = klass
  @id = klass.attribute_providers.length
  @request_types = request_types
  @provides = {}
end

def provides *attr_names
  options = attr_names.last.is_a?(Hash) ? attr_names.pop : {}
  attr_names.each do |attr_name|
    attr = @klass.attributes[attr_name]
    attr.request_types.push(*request_types)
    @provides[attr_name] = options
  end
end