jfredett/exegesis

module Exegesis
  module Registerable
    def self.included(base)
      base.instance_eval do
        extend  ClassMethods
        include InstanceMethods
      end
    end

    module ClassMethods
      def create(*args)
        retrieve(*args) || build(*args)
      end

      def retrieve(*args)
        path = build_path(*args.take(2))
        registry[path] if registry.has_key?(path)
      end

      def build(*args)
        new(*args).tap do |instance|
          registry.register! instance
        end
      end

      def registry
        @flyweight ||= Flyweight.new do |dir|
          if dir.respond_to? :path
            dir.path
          else
            dir
          end
        end
      end

      def clear_registry!
        registry.clear!
      end

      def build_path(*args)
        parent, name = *args
        return parent if name.nil?
        File.join(parent.path, name)
      end
    end

    module InstanceMethods
      def path
        build_path(parent, name)
      end

      private

      def build_path(parent, child)
        self.class.build_path(parent, child)
      end
    end
  end
end