{ nixpkgs, flake-utils, ... }: flake-utils.lib.eachDefaultSystem (system:
let
  pkgs = nixpkgs.legacyPackages.${system};
  lib = pkgs.lib;

  machineOpts = { config, ... }: {
    options = {
      arch = lib.mkOption {
        default = null;
        type = with lib.types; nullOr str;
        description = ''
          CPU architecture of this machine.
        '';
      };

      isRaspberryPi = lib.mkOption {
        default = false;
        type = lib.types.bool;
      };

      nixosModule = lib.mkOption {
        default = { ... }: { };
        type = lib.types.anything;
        description = ''
          Customized configuration for this machine in the form of a NixOS module.
        '';
      };

      kubernetesNodeLabels = lib.mkOption {
        default = null;
        type = with lib.types; nullOr attrs;
        description = ''
          Any labels to add to the Kubernetes node.
        '';
      };
    };
  };

  allOpts = {
    options = {
      machines = lib.mkOption {
        type = with lib.types; attrsOf (submodule machineOpts);
      };
    };
  };
in
{
  machines = (lib.modules.evalModules {
    modules = [
      allOpts
      ./warwick.nix
      ./atlas.nix
      ./jefke.nix
      ./lewis.nix
      # ./talos.nix
      # ./pikvm.nix
    ];
  }).config.machines;
})