defmodule OpencadcVospaceClient do
  @moduledoc """
  VOSpace client to upload a stream of data.  Useful for transferring from one location to a VOSpace.
  """

  @doc """
  Upload a file to a VOSpace

  `sourceStream`:       The source of data to PUT to VOSpace.

  `destinationURI`:    VOS URI to put to.

  `cookieCredential`:   Cookie value for auth.
  """
  def upload(sourceStream, destinationURI, cookieCredential) do
    OpencadcRegistryClient.lookupServiceURL("ivo://cadc.nrc.ca/vospace", "ivo://ivoa.net/std/VOSpace/v2.0#nodes", "vs:ParamHTTP") <> URI.parse(destinationURI).path
    |> HTTPoison.put!(
      toXML(destinationURI),
      [{"Content-Type", "text/xml"}, {"Cookie", "CADC_SSO=\"" <> cookieCredential <> "\""}],
      [{:follow_redirect, true}]
    )
    |> write(sourceStream, destinationURI, cookieCredential)
  end

  defp write(%HTTPoison.Response{status_code: 200}, sourceStream, destinationURI, cookieCredential) do
    transferServiceURL = OpencadcRegistryClient.lookupServiceURL("ivo://cadc.nrc.ca/vospace", "ivo://ivoa.net/std/VOSpace/v2.0#transfers", "vs:ParamHTTP")
    OpencadcRegistryClient.lookupServiceURL("ivo://cadc.nrc.ca/vospace", "ivo://ivoa.net/std/VOSpace#sync-2.1", "vs:ParamHTTP")
    |> HTTPoison.post!(
      toXML(destinationURI, transferServiceURL),
      [{"Content-Type", "text/xml"}, {"Cookie", "CADC_SSO=\"" <> cookieCredential <> "\""}]
    )
    |> transfer(sourceStream, destinationURI, cookieCredential)
  end

  defp write(%HTTPoison.Response{status_code: 401}, _, destinationURI, _) do
    raise ArgumentError, message: "Write permission denied on " <> destinationURI
  end

  defp write(%HTTPoison.Response{status_code: 404}, _, destinationURI, _) do
    raise ArgumentError, message: "No such target " <> destinationURI
  end  

  defp transfer(%HTTPoison.Response{status_code: 303} = response, sourceStream, _, cookieCredential) do
    response.headers
    |> get_header("Location")
    |> HTTPoison.get!(
      [{"Cookie", "CADC_SSO=\"" <> cookieCredential <> "\""}]
    ) 
    |> upload_to(sourceStream, cookieCredential)
  end

  defp transfer(response, _, destinationURI, _) do
    raise ArgumentError, message: "Unable to transfer to " <> destinationURI <> "\n" <> response.body
  end

  defp upload_to(%HTTPoison.Response{status_code: 303} = response, sourceStream, cookieCredential) do
    response.headers
    |> get_header("Location")
    |> HTTPoison.get!(
      [{"Cookie", "CADC_SSO=\"" <> cookieCredential <> "\""}]
    )
    |> upload_to(sourceStream, cookieCredential)
  end

  defp upload_to(%HTTPoison.Response{status_code: 200} = response, sourceStream, cookieCredential) do
    Parser.all(Parser.from_string(response.body), "//vos:transfer/vos:protocol[@uri=\"ivo://ivoa.net/vospace/core#httpput\"]/vos:endpoint")
    |> extractTransferEndpointURL
    |> HTTPoison.put!({:stream, sourceStream}, [{"Cookie", "CADC_SSO=\"" <> cookieCredential <> "\""}])
  end

  defp upload_to(response, _, _) do
    raise ArgumentError, message: response.body
  end

  defp extractTransferEndpointURL([]) do
    raise ArgumentError, message: "No service endpoints found to transfer to."
  end

  defp extractTransferEndpointURL(endpoints) do
    endpoints |> Enum.at(0) |> Parser.text
  end  

  defp toXML(destinationURI) do
    "<vos:node uri=\"" <> destinationURI <> "\" busy=\"false\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:type=\"vos:DataNode\" xmlns:vos=\"http://www.ivoa.net/xml/VOSpace/v2.1\"><vos:properties/></vos:node>"
  end

  defp toXML(destinationURI, transferURL) do
    "<vos:transfer xmlns:vos=\"http://www.ivoa.net/xml/VOSpace/v2.1\"><vos:target>" <> destinationURI <> "</vos:target><vos:direction>pushToVoSpace</vos:direction><vos:view uri=\"ivo://ivoa.net/vospace/core#defaultview\"/><vos:protocol uri=\"ivo://ivoa.net/vospace/core#httpput\"><vos:endpoint>" <> transferURL <> "</vos:endpoint></vos:protocol><vos:keepBytes>true</vos:keepBytes></vos:transfer>"
  end

  defp get_header(headers, key) do
    headers
    |> Enum.filter(fn({k, _}) -> k == key end)
    |> hd
    |> elem(1)
  end
end