{ lib, ... }:
{
  nix.settings = {
    experimental-features = [ "nix-command" "flakes" ];
    auto-optimise-store = true;
    substituters = [
      "https://cache.nixos.org"
      "https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store"
      "https://mirror.sjtu.edu.cn/nix-channels/store"
    ];
    trusted-public-keys = [
      "cache.nixos.org-1:6NCHdD59X431o0gWypbtr1HEhF2M7wP6+jJj6Jm23UM="
    ];
  };

  nix.gc = {
    automatic = true;
    dates = "weekly";
    options = "--delete-older-than 14d";
  };

  nixpkgs.config.allowUnfree = true;

  time.timeZone = lib.mkDefault "Asia/Shanghai";
  i18n.defaultLocale = lib.mkDefault "zh_CN.UTF-8";

  # 允许 wheel 组免密 sudo
  security.sudo.wheelNeedsPassword = false;

}