module HtmlBlankable
  extend ActiveSupport::Concern

  class_methods do
    def clears_blank_html(*attributes)
      before_validation do
        attributes.each do |attribute|
          value = public_send(attribute)
          public_send("#{attribute}=", "") if HtmlBlankable.blank_html?(value)
        end
      end
    end
  end

  def self.blank_html?(html)
    html.to_s.gsub(/<[^>]*>/, " ").gsub("&nbsp;", " ").gsub(/\s+/, " ").strip.blank?
  end
end