class WWW::Mechanize::Chain::AuthHeaders

def gen_auth_header(uri, request, auth_header, is_IIS = false)
  @@nonce_count += 1
  auth_header =~ /^(\w+) (.*)/
  params = {}
  $2.gsub(/(\w+)=("[^"]*"|[^,]*)/) {
    params[$1] = $2.gsub(/^"/, '').gsub(/"$/, '')
  }
  a_1 = "#{@user}:#{params['realm']}:#{@password}"
  a_2 = "#{request.method}:#{uri.path}"
  request_digest = ''
  request_digest << Digest::MD5.hexdigest(a_1)
  request_digest << ':' << params['nonce']
  request_digest << ':' << ('%08x' % @@nonce_count)
  request_digest << ':' << CNONCE
  request_digest << ':' << params['qop']
  request_digest << ':' << Digest::MD5.hexdigest(a_2)
  header = ''
  header << "Digest username=\"#{@user}\", "
  if is_IIS then
    header << "qop=\"#{params['qop']}\", "
  else
    header << "qop=#{params['qop']}, "
  end
  header << "uri=\"#{uri.path}\", "
  header << %w{ algorithm opaque nonce realm }.map { |field|
    next unless params[field]
    "#{field}=\"#{params[field]}\""
  }.compact.join(', ')
  header << "nc=#{'%08x' % @@nonce_count}, "
  header << "cnonce=\"#{CNONCE}\", "
  header << "response=\"#{Digest::MD5.hexdigest(request_digest)}\""
  return header
end

def handle(ctx, params)
  uri     = params[:uri]
  request = params[:request]
  if( @auth_hash[uri.host] )
    case @auth_hash[uri.host]
    when :basic
      request.basic_auth(@user, @password)
    when :iis_digest
        digest_response = self.gen_auth_header(uri,request, @digest, true)
        request['Authorization'] = digest_response
    when :digest
      if @digest
        digest_response = self.gen_auth_header(uri,request, @digest)
        request['Authorization'] = digest_response
      end
    end
  end
  super
end

def initialize(auth_hash, user, password, digest)
  @auth_hash = auth_hash
  @user      = user
  @password  = password
  @digest    = digest
end