class HTTP::Features::AutoDeflate

def deflate(headers, body)
  return body unless body
  return body unless body.is_a?(String)
  # We need to delete Content-Length header. It will be set automatically
  # by HTTP::Request::Writer
  headers.delete(Headers::CONTENT_LENGTH)
  headers[Headers::CONTENT_ENCODING] = method
  case method
  when "gzip" then
    StringIO.open do |out|
      Zlib::GzipWriter.wrap(out) do |gz|
        gz.write body
        gz.finish
        out.tap(&:rewind).read
      end
    end
  when "deflate" then
    Zlib::Deflate.deflate(body)
  else
    raise ArgumentError, "Unsupported deflate method: #{method}"
  end
end