{
  description = "Lgm's NixOS Flake";

  inputs = {
    # There are many ways to reference flake inputs.
    # The most widely used is `github:owner/name/reference`,
    # which represents the GitHub repository URL + branch/commit-id/tag.

    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgs-stable.url = "github:NixOS/nixpkgs/nixos-23.05";
    # nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
    # home-manager, used for managing user configuration
    home-manager = {
      url = "github:nix-community/home-manager/release-23.05";
      # The `follows` keyword in inputs is used for inheritance.
      # Here, `inputs.nixpkgs` of home-manager is kept consistent with
      # the `inputs.nixpkgs` of the current flake,
      # to avoid problems caused by different versions of nixpkgs.
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = inputs@{
    nixpkgs,
    nixpkgs-stable,
    home-manager,
    ...
  }: {
    nixosConfigurations.lgm-nixos = nixpkgs.lib.nixosSystem rec {
      system = "x86_64-linux";
      specialArgs = {
        pkgs-stable = import nixpkgs-stable {
          system = system;
          config.allowUnfree = true;
        };
        secrets = import ./secrets {};
      };
      modules = [
        ./configuration.nix
        ./mounts.nix

        # make home-manager as a module of nixos
        # so that home-manager configuration will be deployed automatically when executing `nixos-rebuild switch`
        home-manager.nixosModules.home-manager
        {
          home-manager.useGlobalPkgs = true;
          home-manager.useUserPackages = true;

          home-manager.users.lgm = import ./home.nix;

          home-manager.extraSpecialArgs = with specialArgs; {
            inherit pkgs-stable;
          };
        }
      ];
    };
  };
}