{
  description = "NixOS configuration for GPD Win Max";

  nixConfig = rec {
    auto-optimise-store = true;
    experimental-features = [ "nix-command" "flakes" ];
    trusted-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/"
    ];
    substituters = trusted-substituters;

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

  inputs = {
    nixpkgs.url = "nixpkgs/nixos-23.05";
    impermanence.url = "github:nix-community/impermanence";

    home-manager = {
      url = "github:nix-community/home-manager/release-23.05";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nixos-cn = {
      url = "github:nixos-cn/flakes";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = { self, nixpkgs, home-manager, nixos-cn, impermanence, ... }: {
    nixosConfigurations.gpd = nixpkgs.lib.nixosSystem rec {
      system = "x86_64-linux";

      specialArgs = {
        pkgs = import nixpkgs {
          system = system;
          config.allowUnfree = true;
          overlays = [
            (self: super: {
              waybar = super.waybar.overrideAttrs (oldAttrs: {
                # enable hyprland support
                mesonFlags = oldAttrs.mesonFlags ++ [ "-Dexperimental=true" ];
              });
              vaapiIntel = super.vaapiIntel.overrideAttrs (oldAttrs: {
                enableHybridCodec = true;
              });
            })
          ];
        };

        cn-pkgs = import nixos-cn {
          system = system;
          config.allowUnfree = true;
        };
      };

      modules = [
        ./configuration.nix
        impermanence.nixosModules.impermanence
        nixos-cn.nixosModules.nixos-cn-registries
        nixos-cn.nixosModules.nixos-cn

        home-manager.nixosModules.home-manager
        {
          home-manager.useGlobalPkgs = true;
          home-manager.useUserPackages = true;
          home-manager.users = import ./home;
        }
      ];
    };
  };
}