```ruby
if defined?(Spree::CheckoutController)
  Spree::CheckoutController.class_eval do
    before_filter :check_authorization
    before_filter :check_registration, :except => [:registration, :update_registration]

    helper 'spree/users'

    def registration
      @user = Spree::User.new
    end

    def update_registration
      fire_event("spree.user.signup", :order => current_order)
      # hack - temporarily change the state to something other than cart so we can validate the order email address
      current_order.state = 'address'
      if current_order.update_attributes(params[:order])
        redirect_to checkout_path
      else
        @user = Spree::User.new
        render 'registration'
      end
    end

    private

      def skip_state_validation?
        %w(registration update_registration).include?(params[:action])
      end

      def check_authorization
        authorize!(:edit, current_order, session[:access_token])
      end

      # Introduces a registration step whenever the +registration_step+ preference is true.
      def check_registration
        return unless Spree::Auth::Config[:registration_step]
        return if spree_current_user or current_order.email
        store_location
        redirect_to spree.checkout_registration_path
      end

      # Overrides the equivalent method defined in Spree::Core.  This variation of the method will ensure that users
      # are redirected to the tokenized order url unless authenticated as a registered user.
      def completion_route
        return order_path(@order) if spree_current_user
        spree.token_order_path(@order, @order.token)
      end
  end
end
```

Address state is required (and shouldn't be)
user
```ruby
if defined?(Spree::CheckoutController)
  Spree::CheckoutController.class_eval do
    before_filter :check_authorization
    before_filter :check_registration, :except => [:registration, :update_registration]

    helper 'spree/users'

    def registration
      @user = Spree::User.new
    end

    def update_registration
      fire_event("spree.user.signup", :order => current_order)
      # hack - temporarily change the state to something other than cart so we can validate the order email address
      current_order.state = current_order.checkout_steps.first
      if current_order.update_attributes(params[:order])
        redirect_to checkout_path
      else
        @user = Spree::User.new
        render 'registration'
      end
    end

    private

      def skip_state_validation?
        %w(registration update_registration).include?(params[:action])
      end

      def check_authorization
        authorize!(:edit, current_order, session[:access_token])
      end

      # Introduces a registration step whenever the +registration_step+ preference is true.
      def check_registration
        return unless Spree::Auth::Config[:registration_step]
        return if spree_current_user or current_order.email
        store_location
        redirect_to spree.checkout_registration_path
      end

      # Overrides the equivalent method defined in Spree::Core.  This variation of the method will ensure that users
      # are redirected to the tokenized order url unless authenticated as a registered user.
      def completion_route
        return order_path(@order) if spree_current_user
        spree.token_order_path(@order, @order.token)
      end
  end
end
```
assistant