{ config, lib, pkgs, ... }:

{
  options = {
    gnu = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = ''
        When enabled, GNU software is chosen by default whenever a there is
        a choice between GNU and non-GNU software (e.g., GNU lsh
        vs. OpenSSH).
      '';
    };
  };

  config = lib.mkIf config.gnu {

    environment.systemPackages = with pkgs;
      # TODO: Adjust `requiredPackages' from `system-path.nix'.
      # TODO: Add Inetutils once it has the new `ifconfig'.
      [ parted
        #fdisk  # XXX: GNU fdisk currently fails to build and it's redundant
                # with the `parted' command.
        nano zile
        texinfo # for the stand-alone Info reader
      ]
      ++ lib.optional (!stdenv.isAarch32) grub2;


    # GNU GRUB, where available.
    boot.loader.grub.enable = !pkgs.stdenv.isAarch32;
    boot.loader.grub.version = 2;

    # GNU lsh.
    services.openssh.enable = false;
    services.lshd.enable = true;
    programs.ssh.startAgent = false;
    services.xserver.startGnuPGAgent = true;

    # TODO: GNU dico.
    # TODO: GNU Inetutils' inetd.
    # TODO: GNU Pies.
  };
}