Configuration builder with meta programming

public_api.rb

module Api
  class PublicApi
    PANEL_KEYS = [
      :priority,
      :template_type,
      :title,
      link: [
        :id,
        :title,
        :url,
        image: [
          :width,
          :height,
          :url
        ]
      ]
    ]

    KEYS = [
      :id,
      :title,
      :url,
      left_panel: PANEL_KEYS,
      right_panel: PANEL_KEYS
    ]

    attr_reader :params

    def initialize
      @params = {}
    end

    def self.build(&block)
      instance = new
      Configuration.new(instance.params, KEYS).configure(&block)
      instance
    end

    class Configuration
      def initialize(params, keys)
        @params = params
        keys.each do |key|
          if key.is_a?(Hash)
            key.each do |k, v|
              define_container_setter(k, v)
            end
          else
            define_value_setter(key)
          end
        end
      end

      def configure(&block)
        instance_exec(&block)
        @params
      end

      private

      def define_container_setter(name, keys)
        define_singleton_method(name) do |&block|
          @params[name] = {}
          Configuration.new(@params[name], keys).configure(&block)
        end
      end

      def define_value_setter(name)
        define_singleton_method(name) do |value|
          @params[name] = value
        end
      end
    end
  end
end

api = Api::PublicApi.build do
  id '999'
  title 'サンプルタイトル'
  url '//www.example.com/'
  left_panel do
    priority 'normal'
    template_type 'template'
    title 'サンプルタイトル'
    link do
      id 'left-sample1'
      title 'left-title-sample1'
      url '//www.example.com/'
      image do
        width 200
        height 300
        url 'imageurl'
      end
    end
  end
  right_panel do
    priority 'normal'
    template_type 'template'
    title 'サンプルタイトル'
    link do
      id 'right-sample1'
      title 'right-title-sample1'
      url '//www.example.com/'
      image do
        width 200
        height 300
        url 'imageurl'
      end
    end
  end
end

puts api.params.inspect