module SimpleForm::Components::Readonly

def readonly
  if readonly_attribute? && !has_readonly?
    input_html_options[:readonly] ||= true
    input_html_classes << :readonly
  end
  nil
end

def readonly_attribute?
  object.class.respond_to?(:readonly_attributes) &&
    object.persisted? &&
    object.class.readonly_attributes.include?(attribute_name)
end