class Libtorch < Formula
  include Language::Python::Virtualenv

  desc "Tensors and dynamic neural networks"
  homepage "https://pytorch.org/"
  url "https://github.com/pytorch/pytorch.git",
      tag:      "v1.7.1",
      revision: "57bffc3a8e4fee0cce31e1ff1f662ccf7b16db57"
  license "BSD-3-Clause"
  revision 1

  livecheck do
    url :stable
    strategy :github_latest
  end

  bottle do
    sha256 cellar: :any, big_sur:  "b0688c3e965b190612de4ebc1b3b8e37b5b334e0c250ede0f69257e6bd4be7df"
    sha256 cellar: :any, catalina: "4fc2881e79a5ddd302c9239c577480086b7988d052000d784fd30c8666024a30"
    sha256 cellar: :any, mojave:   "c11f64cab20420978c90c49259c7bce8da7e03f0bba6f6d51d3041b3788697da"
  end

  depends_on "cmake" => :build
  depends_on "python@3.9" => :build
  depends_on "eigen"
  depends_on "libomp"
  depends_on "libyaml"
  depends_on "protobuf"
  depends_on "pybind11"

  resource "PyYAML" do
    url "https://files.pythonhosted.org/packages/64/c2/b80047c7ac2478f9501676c988a5411ed5572f35d1beff9cae07d321512c/PyYAML-5.3.1.tar.gz"
    sha256 "b8eac752c5e14d3eca0e6dd9199cd627518cb5ec06add0de9d32baeee6fe645d"
  end

  resource "typing" do
    url "https://files.pythonhosted.org/packages/05/d9/6eebe19d46bd05360c9a9aae822e67a80f9242aabbfc58b641b957546607/typing-3.7.4.3.tar.gz"
    sha256 "1187fb9c82fd670d10aa07bbb6cfcfe4bdda42d6fab8d5134f04e8c4d0b71cc9"
  end

  def install
    venv = virtualenv_create(libexec, Formula["python@3.9"].opt_bin/"python3")
    venv.pip_install resources

    args = %W[
      -DBUILD_CUSTOM_PROTOBUF=OFF
      -DBUILD_PYTHON=OFF
      -DPYTHON_EXECUTABLE=#{libexec}/bin/python
      -Dpybind11_PREFER_third_party=OFF
      -DUSE_CUDA=OFF
      -DUSE_METAL=OFF
      -DUSE_MKLDNN=OFF
      -DUSE_NNPACK=OFF
      -DUSE_SYSTEM_EIGEN_INSTALL=ON
    ]

    mkdir "build" do
      system "cmake", "..", *std_cmake_args, *args
      system "make"
      system "make", "install"
    end
  end

  test do
    (testpath/"test.cpp").write <<~EOS
      #include <torch/torch.h>
      #include <iostream>

      int main() {
        torch::Tensor tensor = torch::rand({2, 3});
        std::cout << tensor << std::endl;
      }
    EOS
    system ENV.cxx, "-std=c++14", "-L#{lib}", "-ltorch", "-ltorch_cpu", "-lc10",
      "-I#{include}/torch/csrc/api/include", "test.cpp", "-o", "test"
    system "./test"
  end
end