module RailsConnector
  module Authenticable
    def self.included(mod)
      %w(logged_in? admin? current_user).each do |method_name|
        unless instance_method_defined?(mod, method_name)
          mod.class_eval do
            private
            define_method(method_name, InstanceMethods.method(method_name).to_proc)
          end
        end

        mod.send(:helper_method, method_name)
      end
    end

    module InstanceMethods
      def self.logged_in?; false; end
      def self.admin?; false; end
      def self.current_user; nil; end
    end

    private

    def self.instance_method_defined?(mod, method_name)
      (
        mod.instance_methods + mod.protected_instance_methods + mod.private_instance_methods
      ).map(&:to_s).include?(method_name)
    end
  end
end