Initialise Authentication via Rails Engine

engine.rb

require 'initialise_authentication'

module Refinery
  module AuthenticateIdentities
    class Engine < Rails::Engine
      extend Refinery::Engine
      isolate_namespace Refinery::AuthenticateIdentities

      engine_name :refinery_authenticate_identities

      before_inclusion do
        Refinery::Plugin.register do |plugin|
          plugin.name = "authenticate_identities"
          plugin.url = proc { Refinery::Core::Engine.routes.url_helpers.authenticate_identities_admin_authenticate_identities_path }
          plugin.pathname = root
          plugin.activity = {
            :class_name => :'refinery/authenticate_identities/authenticate_identity',
            :title => 'name'
          }
          plugin.hide_from_menu = true
        end
      end

      config.before_initialize do
        # NOTE Secure frontend access with Omniauth Identity strategy
        ::Authentication.secure_frontend
      end

      config.after_initialize do
        Refinery.register_extension(Refinery::AuthenticateIdentities)
      end

      config.to_prepare do
        Decorators.register! Engine.root
      end
    end
  end
end

initialise_authentication.rb

puts ">> Initialising Authentication: Omniauth Identity"

module Authentication
  def self.secure_frontend
    ActionController::Base.class_eval do
      class << self
        def you_shall_not_pass!
          include ::Authentication::ApplicationController
        end
      end
    end
  end

  module ApplicationController

    def self.included _klass
      _klass.class_eval do
        include InstanceMethods

        _klass.send(:before_filter, :set_current_user)

        helper_method :set_current_user, :current_user, :user_signed_in?
        private :set_current_user, :current_user, :user_signed_in?
      end
    end

    module InstanceMethods
      def set_current_user
        current_user
      end

      def current_user
        @current_user ||= User.find(session[:user_id]) if session[:user_id]
      end

      def user_signed_in?
        @current_user.present?
      end
    end

  end
end