defimpl CWMP.Protocol.Generate, for: CWMP.Protocol.Messages.Upload do
  import XmlBuilder

  def generate(req) do
    Enum.map([:filetype, :url], fn(f) ->
      case Map.fetch(req, f) do
        {:ok,x} -> if x == nil do
          raise "key #{f} can not be nil"
        end
        {:error} -> raise "key #{f} must be set"
      end
    end)
    if not hd(to_charlist(req.filetype)) in [49,50,51,52,88] do
      raise "Invalid filetype"
    end
    element("cwmp:Upload", [
      element(:CommandKey,req.commandkey),
      element(:FileType,req.filetype),
      element(:URL,req.url),
      element(:Username,req.username),
      element(:Password,req.password),
      element(:DelaySeconds,req.delay_seconds)]
    )
  end
end