default.nix

{
  lib,
  stdenv,
  cmake,
  libtorch-bin,
  linkFarm,
  symlinkJoin,

  cudaSupport,
  cudaPackages ? { },
}:
let
  inherit (cudaPackages) cudatoolkit cudnn;

  cudatoolkit_joined = symlinkJoin {
    name = "${cudatoolkit.name}-unsplit";
    paths = [
      cudatoolkit.out
      cudatoolkit.lib
    ];
  };

  # We do not have access to /run/opengl-driver/lib in the sandbox,
  # so use a stub instead.
  cudaStub = linkFarm "cuda-stub" [
    {
      name = "libcuda.so.1";
      path = "${cudatoolkit}/lib/stubs/libcuda.so";
    }
  ];

in
stdenv.mkDerivation {
  pname = "libtorch-test";
  version = libtorch-bin.version;

  src = lib.fileset.toSource {
    root = ./.;
    fileset = lib.fileset.unions [
      ./CMakeLists.txt
      ./test.cpp
    ];
  };

  nativeBuildInputs = [ cmake ];

  buildInputs = [ libtorch-bin ] ++ lib.optionals cudaSupport [ cudnn ];

  cmakeFlags = lib.optionals cudaSupport [ "-DCUDA_TOOLKIT_ROOT_DIR=${cudatoolkit_joined}" ];

  doCheck = true;

  installPhase = ''
    touch $out
  '';

  checkPhase =
    lib.optionalString cudaSupport ''
      LD_LIBRARY_PATH=${cudaStub}''${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH \
    ''
    + ''
      ./test
    '';
}