# Discourse SSO Rails::Engine gem to perform cookie-based SSO login in [Discourse](http://www.discourse.org/). It expects your main app to set a cookie readable by Discourse with a Discourse `user_id` as the value (encrypting the value is a very good idea). See: http://meta.discourse.org/t/give-me-those-authentication-hooks-d/3943

discourse_sso.rb

module DiscourseSso

  module ControllerExtensions

    def self.included(klass)
      klass.append_before_filter :ensure_sso_login
    end

    private

      def ensure_sso_login
        if cookies[:discourse_sso_cookie].present?
          cookie_user_id = cookies[:discourse_sso_cookie] # makes sense to have this value encrypted in the cookie

          unless current_user && current_user.id == cookie_user_id
            begin
              user = User.find cookie_user_id
              log_on_user(user)
              redirect_to url_for # we need to "reload" the page, so the user sees that he's logged in
            rescue => exception
              notify_airbrake(exception)
            end
          end

        else
          reset_session
          cookies[:_t] = nil
        end
      end
  end

  class Engine < Rails::Engine
    engine_name 'discourse_sso'

    initializer "discourse_sso.rails_initialization" do |app|
      app.config.after_initialize do
        ActiveSupport.on_load(:action_controller) do
          include DiscourseSso::ControllerExtensions
        end
      end
    end
  end

end