module SignedForm
  module ActionView
    module FormHelper
      def signed_form_for(record, options = {}, &block)
        options[:builder] ||= SignedForm::FormBuilder

        form_for(record, options) do |f|
          output = capture(f, &block)
          f.form_signature_tag + output
        end
      end
    end
  end
end

ActionView::Base.send :include, SignedForm::ActionView::FormHelper