inputs:
{
  options.nixos.packages.firefox = let inherit (inputs.lib) mkOption types; in mkOption
  {
    type = types.nullOr (types.submodule {});
    default = if inputs.config.nixos.system.gui.enable then {} else null;
  };
  config = let inherit (inputs.config.nixos.packages) firefox; in inputs.lib.mkIf (firefox != null)
  {
    # still enable global firefox, to install language packs
    programs.firefox =
    {
      enable = true;
      languagePacks = [ "zh-CN" "en-US" ];
      nativeMessagingHosts.packages = with inputs.pkgs; [ uget-integrator ];
    };
  };
}