My application controller

application_controller.rb

class ApplicationController < ActionController::Base
  protect_from_forgery
  helper_method :current_user_session, :current_user
  before_filter :ensure_domain
  before_filter :production_down

  APP_DOMAIN = 'davidbeveridge.net'

  protected

  def ensure_domain
    if Rails.env.production?
      if request.env['HTTP_HOST'] != APP_DOMAIN
        # HTTP 301 is a "permanent" redirect
        redirect_to "http://#{APP_DOMAIN}", :status => 301
      end
    end
  end

  def current_user
    @current_user = current_user_session.record if (current_user_session and current_user_session.record)
  end

  def require_user!
    (login_page and return) unless current_user
  end

  def require_admin!
    (login_page and return) unless is_admin?
  end

  def require_no_user!
    return
    (confirm_logout_page and return) if current_user
  end


  def is_admin?
    current_user and current_user.admin?
  end

  def store_location
    session[:return_to] = request.request_uri
  end

  def redirect_back_or_default(default=nil)
    redirect_to(session[:return_to] || default || root_url)
    session[:return_to] = nil
  end

  def login_page
    store_location
    redirect_to(login_url) and return
  end

  def logout_page
    store_location
    redirect_to(confirm_logout_url) and return
  end

  # Temp page
  def production_down
    if Rails.env.production?
      render(:nothing => true, :layout => 'comingsoon') and return
    end
  end

  # 404
  # def method_missing(methodname, *args)
  #   @methodname = methodname
  #   @args = args
  #   render 'shared/404', :status => 404
  # end

  # 403
  def forbidden_403
    render "shared/403", :status => 403
  end

  def not_found_404
    render "shared/404", :status => 404
  end

  private
  def current_user_session
    return @user_session if defined?(@user_session)
    @user_session = UserSession.find
  end

  def render(opts=nil, extra_opts={},&block)
    extra_opts.merge({:layout => false}) if request.xhr?
    super(opts, extra_opts, &block)
  end


end