{ pkgs, lib, ... }: {
  sound.enable = true;
  networking.networkmanager.enable = true;
  time.timeZone = "Asia/Shanghai";
  security.sudo.wheelNeedsPassword = false;

  environment.variables.VDPAU_DRIVER = "va_gl";
  hardware = {
    opengl = {
      enable = true;
      extraPackages = with pkgs; [
        mesa.drivers
        libvdpau-va-gl
        vaapiVdpau

        (
          if (lib.versionOlder (lib.versions.majorMinor lib.version) "23.11") then
            vaapiIntel
          else
            intel-vaapi-driver
        )
      ];
    };
  };

  # Select internationalisation properties.
  i18n = {
    defaultLocale = "zh_CN.UTF-8";
    extraLocaleSettings = {
      LC_ADDRESS = "zh_CN.UTF-8";
      LC_IDENTIFICATION = "zh_CN.UTF-8";
      LC_MEASUREMENT = "zh_CN.UTF-8";
      LC_MONETARY = "zh_CN.UTF-8";
      LC_NAME = "zh_CN.UTF-8";
      LC_NUMERIC = "zh_CN.UTF-8";
      LC_PAPER = "zh_CN.UTF-8";
      LC_TELEPHONE = "zh_CN.UTF-8";
      LC_TIME = "zh_CN.UTF-8";
    };
  };

  nix.settings = {
    auto-optimise-store = true;
    experimental-features = [
      "nix-command"
      "flakes"
    ];

    substituters = [
      "https://mirrors.ustc.edu.cn/nix-channels/store" # 中科大
      "https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store" # 清华
      "https://mirrors.bfsu.edu.cn/nix-channels/store" # 北外
      "https://mirror.sjtu.edu.cn/nix-channels/store" # 交大
      "https://nixos-cn.cachix.org"
      "https://cache.nixos.org/"
    ];

    trusted-users = [
      "root"
      "@wheel"
    ];
  };

  nix.gc = {
    automatic = true;
    dates = "weekly";
    options = "--delete-older-than 1w";
  };
}