hokusai/flake.nix

{
  description = "bulkgen - Bulk-Generate Images with Generative AI";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";

    pyproject-nix = {
      url = "github:pyproject-nix/pyproject.nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    uv2nix = {
      url = "github:pyproject-nix/uv2nix";
      inputs.pyproject-nix.follows = "pyproject-nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    pyproject-build-systems = {
      url = "github:pyproject-nix/build-system-pkgs";
      inputs.pyproject-nix.follows = "pyproject-nix";
      inputs.uv2nix.follows = "uv2nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    {
      nixpkgs,
      pyproject-nix,
      uv2nix,
      pyproject-build-systems,
      ...
    }:
    let
      inherit (nixpkgs) lib;
      forAllSystems = lib.genAttrs lib.systems.flakeExposed;

      workspace = uv2nix.lib.workspace.loadWorkspace { workspaceRoot = ./.; };

      overlay = workspace.mkPyprojectOverlay {
        sourcePreference = "wheel";
      };

      editableOverlay = workspace.mkEditablePyprojectOverlay {
        root = "$REPO_ROOT";
      };

      pythonSets = forAllSystems (
        system:
        let
          pkgs = nixpkgs.legacyPackages.${system};
          inherit (pkgs) stdenv;

          baseSet = pkgs.callPackage pyproject-nix.build.packages {
            python = pkgs.python313;
          };

          pyprojectOverrides = _final: prev: {
            bulkgen = prev.bulkgen.overrideAttrs (old: {
              passthru = old.passthru // {
                tests = (old.passthru.tests or { }) // {
                  pytest = stdenv.mkDerivation {
                    name = "${_final.bulkgen.name}-pytest";
                    inherit (_final.bulkgen) src;
                    nativeBuildInputs = [
                      (_final.mkVirtualEnv "bulkgen-pytest-env" {
                        bulkgen = [ "dev" ];
                      })
                    ];
                    dontConfigure = true;
                    buildPhase = ''
                      runHook preBuild
                      # Exit code 5 means no tests collected — allow it so the
                      # check succeeds on an empty test suite.
                      pytest || [ $? -eq 5 ]
                      runHook postBuild
                    '';
                    installPhase = ''
                      runHook preInstall
                      touch $out
                      runHook postInstall
                    '';
                  };
                };
              };
            });
          };

        in
        baseSet.overrideScope (
          lib.composeManyExtensions [
            pyproject-build-systems.overlays.default
            overlay
            pyprojectOverrides
          ]
        )
      );

    in
    {
      packages = forAllSystems (
        system:
        let
          pythonSet = pythonSets.${system};
          pkgs = nixpkgs.legacyPackages.${system};
          inherit (pkgs.callPackages pyproject-nix.build.util { }) mkApplication;
        in
        {
          default = mkApplication {
            venv = pythonSet.mkVirtualEnv "bulkgen-env" workspace.deps.default;
            package = pythonSet.bulkgen;
          };
        }
      );

      checks = forAllSystems (
        system:
        let
          pythonSet = pythonSets.${system};
        in
        {
          inherit (pythonSet.bulkgen.passthru.tests) pytest;
        }
      );

      devShells = forAllSystems (
        system:
        let
          pkgs = nixpkgs.legacyPackages.${system};
          pythonSet = pythonSets.${system}.overrideScope editableOverlay;
          virtualenv = pythonSet.mkVirtualEnv "bulkgen-dev-env" workspace.deps.all;
        in
        {
          default = pkgs.mkShell {
            packages = [
              virtualenv
              pkgs.uv
            ];
            env = {
              UV_NO_SYNC = "1";
              UV_PYTHON = pythonSet.python.interpreter;
              UV_PYTHON_DOWNLOADS = "never";
            };
            shellHook = ''
              unset PYTHONPATH
              export REPO_ROOT=$(git rev-parse --show-toplevel)
            '';
          };
        }
      );
    };
}