{
  inputs,
  lib,
  config,
  ...
}:
let
  configurationLimit = config.mod.gc.configurationLimit;
in
{
  imports = [ inputs.nix-gc-env.nixosModules.default ];

  options = {
    mod.gc = {
      configurationLimit = lib.mkOption {
        type = lib.types.int;
        default = 10;
        description = "number of configuration generations to keep";
      };
    };
  };

  config = {
    nix.gc = {
      automatic = true;
      dates = "weekly";

      # `delete_generations` added by nix-gc-env
      delete_generations = "+${builtins.toString configurationLimit}";
    };

    boot = {
      loader = {
        grub = {
          enable = true;
          device = "/dev/sda";

          inherit configurationLimit;
        };
      };
    };
  };
}