An email obfuscation filter for nanoc. It should find and hide all links in the form of: <a href="mailto:"></a>

obfuscate_mail.rb

module Nanoc3::Filters

  class ObfuscateMail < Nanoc3::Filter

    identifier :obfuscate_mail

    require 'digest/sha1'

    def run(content, params={})
        link_count=0
        content.split("\n").each do |line|
            line.gsub!(/<a href="mailto:[^>]+>[^<]+<\/a>/) { |match|
                link_count+=1
                hashed = Digest::SHA1.hexdigest(match+link_count.to_s)
                
                '<span id="'+hashed+'">'+
                simple_obfuscate(match)+
                '</span>'+
                '<script type="text/javascript">'+
                'document.getElementById("'+hashed+'").innerHTML='+js_de_rot13(match.tr("A-Ma-mN-Zn-z","N-Zn-zA-Ma-m"))+';'+
                '</script>'
            }
        end.join("\n")
    end
    
    def js_de_rot13(content)
        "'"+content+"'"+'.replace(/[a-zA-Z]/g,function(c){return String.fromCharCode((c<="Z"?90:122)>=(c=c.charCodeAt(0)+13)?c:c-26);})'
    end
    
    def simple_obfuscate(content)
        c = content.sub(/mailto:[^"]+/) { |m| m.gsub(/@/," AT ").gsub(/\./," DOT ") }
        c.sub(/>[^<]+</) { |m| m.gsub(/@/," AT ").gsub(/\./," DOT ") }
    end

  end

end