{
  # Snowfall Lib provides a customized `lib` instance with access to your flake's library
  # as well as the libraries available from your flake's inputs.
  lib,
  # An instance of `pkgs` with your overlays and packages applied is also available.
  pkgs,
  # You also have access to your flake's inputs.
  inputs,

  # Additional metadata is provided by Snowfall Lib.
  namespace, # The namespace used for your flake, defaulting to "internal" if not set.
  system, # The system architecture for this host (eg. `x86_64-linux`).
  target, # The Snowfall Lib target for this system (eg. `x86_64-iso`).
  format, # A normalized name for the system target (eg. `iso`).
  virtual, # A boolean to determine whether this system is a virtual target using nixos-generators.
  systems, # An attribute map of your defined hosts.

  # All other arguments come from the module system.
  config,
  ...
}:

let
  cfg = config.modules.x11;
in
{
  options.modules.x11 = {
    enable = lib.mkOption { default = false; };
  };

  config = lib.mkIf cfg.enable {
    services.xserver.windowManager.i3.enable = true;
    services.xserver.windowManager.i3.package = pkgs.i3-gaps;

    services.xserver.wacom.enable = true;

    # TODO: move into i3 module
    programs.xss-lock = {
      # responds to "loginctl lock-session" via dbus
      enable = true;
      lockerCommand = "${pkgs.i3lock}/bin/i3lock --ignore-empty-password --color=000000";
    };
    # services.xserver.xautolock = { # TODO: does not work
    #   enable = true;
    #   time = 1;
    # };

    # Configure keymap in X11
    services.xserver = {
      enable = true;
      displayManager.gdm.enable = true;
      xkb.layout = "de";
      xkb.variant = "";
    };
  };
}