project-templates/cad/default.nix

{
  flake-parts-lib,
  inputs,
  ...
}: {
  flake = {
    templates = {
      cad = {
        path = ./template;
        description = "A python flake with a build132d/cadquery parametric cad setup";
      };
    };

    flakeModules.cad = {
      imports = [
        inputs.treefmt-nix.flakeModule
      ];

      options.perSystem = flake-parts-lib.mkPerSystemOption ({
        lib,
        config,
        pkgs,
        system,
        ...
      }: let
        cfg = config.krantz.cad;

        cq = inputs.cadquery.packages.${system};

        pyEnv = cq.python3.withPackages (p:
          with p; [
            cadquery
            build123d
          ]);

        outputExt = [
          "step"
          "stl"
          "3mf"
        ];
      in {
        options.krantz.cad = {
          enable = lib.mkEnableOption "executing a python build123d/cadquery file to generate 3d files";

          builder = lib.mkOption {
            description = "The path to python cad script that generates the 3d file(s).";
            type = lib.types.path;
            example = lib.literalExpression "./build3d.py";
          };

          outputName = lib.mkOption {
            description = ''
              The derivation's name that will also be used to rename the following default outputs.

              ${
                # output.${ext} where ext is from the outputExt list
                lib.concatStringsSep "\n" (lib.map (ext: "* output.${ext}") outputExt)
              }

              If left empty no files will be renamed.
            '';
            type = lib.types.str;
            default = "";
            example = "box_for_stuf";
          };

          devShell = {
            enable = lib.mkEnableOption "a build123d/cadquery development environment" // {default = true;};

            name = lib.mkOption {
              description = "The name of the attribute in devShells to configure";
              type = lib.types.str;
              default = "default";
              example = "cad";
            };

            extraAttrs = lib.mkOption {
              description = "Extra attributes to merge into the devshell. See https://nixos.org/manual/nixpkgs/stable/#sec-pkgs-mkShell";
              type = lib.types.attrs;
              default = {};
              example = {
                shellHook = ''
                  export DEBUG=1
                '';
              };
            };
          };

          package = {
            enable = lib.mkEnableOption "a package output for the 3d file" // {default = true;};

            name = lib.mkOption {
              description = "The name of the attribute in packages to configure";
              type = lib.types.str;
              default = "default";
              example = "3dfiles";
            };
          };

          formatter = {
            enable = lib.mkEnableOption "treefmt for formatting multiple types of files" // {default = true;};

            nix = lib.mkEnableOption "formatting for nix files" // {default = true;};
          };
        };

        config = lib.mkIf cfg.enable {
          # Dev Shell that lets you enter an environment with all the necessary utilites
          # Available through 'nix develop'
          # Also can be activated automatically if direnv is installed on the system with 'direnv allow'
          devShells = lib.mkIf cfg.devShell.enable {
            ${cfg.devShell.name} =
              pkgs.mkShell {
                packages = [
                  pyEnv
                ];

                shellHook = ''
                  export PYTHONPATH="${pyEnv}/${pyEnv.sitePackages}:$PYTHONPATH"
                '';
              }
              // cfg.devShell.extraAttrs;
          };

          # Your custom packages
          # Accessible through 'nix build', 'nix shell', 'nix run', etc
          packages = lib.mkIf cfg.package.enable {
            ${cfg.package.name} =
              pkgs.runCommand cfg.outputName {}
              /*
              bash
              */
              ''
                mkdir $out
                cd $out

                ${pyEnv}/bin/python ${cfg.builder}

                ${
                  if cfg.outputName != ""
                  then
                    /*
                    bash
                    */
                    ''
                      for ext in ${lib.concatStringsSep " " outputExt}; do
                        if [[ -f output.$ext ]]; then
                          mv output.$ext ${cfg.outputName}.$ext
                        fi
                      done
                    ''
                  else ""
                }
              '';
          };

          # Formatter for nix files, available through 'nix fmt'
          treefmt.programs = lib.mkIf cfg.formatter.enable {
            alejandra.enable = lib.mkIf cfg.formatter.nix true;
          };
        };
      });
    };
  };
}