{ lib, stdenv, python3}:

let

  default = {
    python3 = let
      env = (python3.withPackages (ps: with ps; [ ipykernel ]));
    in {
      displayName = "Python 3";
      argv = [
        "${env.interpreter}"
        "-m"
        "ipykernel_launcher"
        "-f"
        "{connection_file}"
      ];
      language = "python";
      logo32 = "${env.sitePackages}/ipykernel/resources/logo-32x32.png";
      logo64 = "${env.sitePackages}/ipykernel/resources/logo-64x64.png";
    };
  };

in
{
  inherit default;

  # Definitions is an attribute set.

  create = { definitions ?  default }: with lib; stdenv.mkDerivation rec {

    name = "jupyter-kernels";

    src = "/dev/null";

    unpackCmd = "mkdir jupyter_kernels";

    installPhase =  ''
      mkdir kernels

      ${concatStringsSep "\n" (mapAttrsToList (kernelName: kernel:
        let
          config = builtins.toJSON {
            display_name = if (kernel.displayName != "")
              then kernel.displayName
              else kernelName;
            argv = kernel.argv;
            language = kernel.language;
          };
          logo32 =
            if (kernel.logo32 != null)
            then "ln -s ${kernel.logo32} 'kernels/${kernelName}/logo-32x32.png';"
            else "";
          logo64 =
            if (kernel.logo64 != null)
            then "ln -s ${kernel.logo64} 'kernels/${kernelName}/logo-64x64.png';"
            else "";
        in ''
          mkdir 'kernels/${kernelName}';
          echo '${config}' > 'kernels/${kernelName}/kernel.json';
          ${logo32}
          ${logo64}
        '') definitions)}

      mkdir $out
      cp -r kernels $out
    '';

    meta = {
      description = "Wrapper to create jupyter notebook kernel definitions";
      homepage = http://jupyter.org/;
      maintainers = with maintainers; [ aborsu ];
    };
  };
}