{
  description = "Pre-built CPU-only OpenCV packages for Python.  ";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
        pythonPackages = pkgs.python312Packages;
        ultralytics-thop = pkgs.python3Packages.buildPythonPackage rec {
          version = "2.0.9";
          pname = "ultralytics-htop";
          pyproject = true;
          src = pkgs.fetchFromGitHub {
            owner = "ultralytics";
            repo = "thop";
            rev = "d304cebcc81f65a7b0d4304290f2abb100407ec0";
            hash = "sha256-FzjxEk6yiG+IWwQEzsHcEAB4iVQT1QsyoGlG4I9lSwU=";
            fetchSubmodules = true;
          };

          propagatedBuildInputs = [ pythonPackages.numpy pythonPackages.torch ];

          nativeBuildInputs =
            [ pythonPackages.setuptools pythonPackages.setuptools-scm ];

          meta = with pkgs.lib; {
            description = ''
              THOP offers an intuitive API to profile PyTorch models
              by calculating the number of MACs and parameters. This
              functionality is crucial for assessing the computational
              efficiency and memory footprint of deep learning models.
            '';
            homepage = "https://github.com/ultralytics/thop";
            license = pkgs.lib.licenses.mit;
            maintainers = with maintainers; [ ];
          };
        };

        ultralytics = pkgs.python3Packages.buildPythonPackage rec {
          # pname = "opencv-python";
          # version = "4.10.0.84";

          version = "8.3.13";
          pname = "ultralytics";
          pyproject = true;
          src = pkgs.fetchFromGitHub {
            owner = "ultralytics";
            repo = "ultralytics";
            rev = "15e6133534d82ec6845308f1e258d77c1b9bab36";
            hash = "sha256-Wq2pCD0l0AbdQ2IPfEfxPffSxgv/5qFadB4BHAExEbU=";
            fetchSubmodules = true;
          };

          propagatedBuildInputs = [
            pythonPackages.requests
            pythonPackages.pyyaml
            pythonPackages.torch
            pythonPackages.tqdm
            pythonPackages.psutil
            pythonPackages.torchvision
            pythonPackages.pandas
            pythonPackages.matplotlib
            pythonPackages.seaborn
            ultralytics-thop

          ];

          nativeBuildInputs = [
            pythonPackages.setuptools
            pythonPackages.setuptools-scm
            pythonPackages.pip
            # pythonPackages.scikit-build
            # pythonPackages.numpy_2
            # pythonPackages.cmake
          ];

          nativeCheckInputs =
            [ pythonPackages.more-itertools pythonPackages.pytestCheckHook ];

          # disabledTests = [
          #   # creates a file, checks when it was last accessed/modified
          #   # AssertionError: assert 1650036414.0 == 1650036414.960688
          #   # "test_utime"
          # ];

          # pythonImportsCheck = [ "cv2" ];

          meta = with pkgs.lib; {
            description = "Object-oriented file system path manipulation";
            homepage = "https://github.com/jaraco/path";
            changelog =
              "https://github.com/jaraco/path/blob/v${version}/NEWS.rst";
            license = pkgs.lib.licenses.mit;
            maintainers = with maintainers; [ ];
          };
        };

        env = pkgs.python312.withPackages (ps: [ ultralytics ]);

      in {
        packages = {
          default = pkgs.python312Packages.path;
          env = env;
        };
        devShells.default = pkgs.mkShell { buildInputs = [ env ]; };
      });
}