require 'gpgme'
require 'net/http'
require 'yaml'

class String
  def to_html
    self.gsub("\n", "<br />") 
  end

  def strip_html
    ret = self.gsub(/<br \/>/, "\n").gsub(/<\/?[^>]*>/, "")
    ret = ret.gsub(/^- /, "")
  end
end

class PgpFilter < MouseHole::App
  name        "PGP Filter"
  namespace   "http://rhnh.net/"
  description "Verifies PGP signatures found in the page"
  version     "0.1"

  def redirect host, port, path
    if "mail.google.com".eql?(host) && 
        path =~ /^\/pgpirate\/(.*)/
      host = "localhost"
      port = 3704
      path = "/pgpirate/#$1"
    end
    [host, port, path]
  end
              
  url("http://mail.google.com/mail/h/*", :ugly_rewrite)
  
  StartPgpSignedMessage = "-----BEGIN PGP SIGNED MESSAGE-----"
  EndPgpSignedMessage   = "-----END PGP SIGNATURE-----"
  StartPgpMessage       = "-----BEGIN PGP MESSAGE-----"
  EndPgpMessage         = "-----END PGP MESSAGE-----"
  
  def ugly_rewrite page
    cont = true
    buffer = page.document
    page.document = ""
    id = 1
    while cont
      message = buffer.match(/<div class=msg>(.*?)<\/div>/m)

      if message
        pre = message.pre_match
        text = message[1].strip_html

        append = nil
        function_hash.each_pair do |key, value|
          if text =~ key
            append = value.call(pre, text, id)
            break
          end
        end
        page.document += (append ? append : pre + message[0])

        buffer = message.post_match
      else
        page.document += buffer
        cont = false
      end
      id += 1
    end
  end

  def function_hash
   signed_regex    = /#{StartPgpSignedMessage}.*?#{EndPgpSignedMessage}/m
   encrypted_regex = /#{StartPgpMessage}.*?#{EndPgpMessage}/m
   return { signed_regex    => method(:ajax_replace_signed_message).to_proc,
            encrypted_regex => method(:ajax_replace_encrypted_message).to_proc}
  end

  def ajax_replace_signed_message buffer, text, id
    plain = text.match(/\n\n(.*)\n-----BEGIN PGP SIGNATURE-----/m)[1]
    sig = text.match(/-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----/m)[0]
    
    mab = Markaby::Builder.new
    js = <<-EOS
      var ajax = new Ajax.Updater('pgpmsg#{id}', '/pgpirate/verify',
                                  { method: 'post', 
                                    parameters:Form.serialize($('pgpform#{id}')), 
                                    evalScripts:true });
    EOS
    mab.div.msg(:id => "pgpmsg#{id}") do
      form(:id => "pgpform#{id}", :style => 'display: none') do
        textarea plain, :name => 'message'
        textarea sig,   :name => 'signature'
        
        input :value => id, :name => 'id'
      end
      script :src => "http://localhost:3704/pgpirate/static/js/prototype-1.4.0.js",
             :language => "Javascript",
             :type     => "text/javascript" if id == 1
      script js, :language => "Javascript", :type     => "text/javascript"
  end
  
    buffer.gsub!(/(Show original<\/a>)/, "\\1 | <span id='pgpstatus#{id}'>PGP Signature verification in progress...</span>")
    return buffer + mab.to_s
  end

  def ajax_replace_encrypted_message buffer, text, id
    js = <<-EOS
      var ajax = new Ajax.Updater('pgpmsg#{id}', '/pgpirate/decrypt',
                                  { method: 'post', 
                                    parameters:Form.serialize($('pgpform#{id}')), 
                                    evalScripts:true });
    EOS
    mab = Markaby::Builder.new
    mab.div.msg(:id => "pgpmsg#{id}") do
      form(:id => "pgpform#{id}", :style => 'display: none') do
        textarea text, :name => 'cipher'
        
        input :value => id, :name => 'id'
      end
      script :src => "http://localhost:3704/pgpirate/static/js/prototype-1.4.0.js",
             :language => "Javascript",
             :type     => "text/javascript" if id == 1
      script js, :language => "Javascript", :type     => "text/javascript"
    end

    buffer.gsub!(/(Show original<\/a>)/, "\\1 | <span id='pgpstatus#{id}'>PGP decryption in progress...</span>")
    return buffer + mab.to_s
  end
end