{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixos-hardware.url = "github:NixOS/nixos-hardware";
    nix-index-database.url = "github:Mic92/nix-index-database";
    nix-index-database.inputs.nixpkgs.follows = "nixpkgs";
    darwin.url = "github:lnl7/nix-darwin/master";
    darwin.inputs.nixpkgs.follows = "nixpkgs";
    home-manager.url = "github:nix-community/home-manager";
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
    emacs-overlay.url = "github:nix-community/emacs-overlay";
    emacs-overlay.inputs.nixpkgs.follows = "nixpkgs";
    secrets = {
      flake = false;
    };
    utils.url = "github:numtide/flake-utils";
  };

  outputs =
    inputs@
    { self
    , utils
    , nixpkgs
    , nixos-hardware
    , home-manager
    , darwin
    , nix-index-database
    , secrets
    , emacs-overlay
    , ...
    }:
    let
      mkHomeConfiguration = { modules, system }: home-manager.lib.homeManagerConfiguration {
        pkgs = import nixpkgs { inherit system; };

        inherit modules;
        extraSpecialArgs = {
          inherit inputs system;
        };
      };
    in
    {
      nixosConfigurations.prefect = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./system/prefect.nix
        ] ++ (with nixos-hardware.nixosModules; [
          common-cpu-amd
          common-cpu-amd-pstate
          common-pc-ssd
          common-pc
          common-gpu-nvidia-nonprime
        ]);
      };
      nixosConfigurations.nanopi = nixpkgs.lib.nixosSystem {
        system = utils.lib.system.aarch64-linux;
        modules = [ ./nanopi.nix ];
      };
      darwinConfigurations.mba = darwin.lib.darwinSystem {
        system = utils.lib.system.aarch64-darwin;
        modules = [ ./system/mba.nix ];
      };
      homeConfigurations."alan@mba" = mkHomeConfiguration {
        system = utils.lib.system.aarch64-darwin;
        modules = [
          ./user/mba.nix
          nix-index-database.hmModules.nix-index
          (secrets + "/default.nix")
          (secrets + "/ssh.nix")
          ({ nixpkgs.overlays = [ emacs-overlay.overlay ]; })
        ];
      };
      homeConfigurations."alan@prefect" = mkHomeConfiguration {
        system = utils.lib.system.x86_64-linux;
        modules = [
          ./user/prefect.nix
          nix-index-database.hmModules.nix-index
          (secrets + "/default.nix")
          (secrets + "/ssh.nix")
          ({ nixpkgs.overlays = [ emacs-overlay.overlay ]; })
        ];
      };
      homeConfigurations."alan@nanopi" = mkHomeConfiguration {
        system = utils.lib.system.aarch64-linux;
        modules = [
          ./user/nanopi.nix
          nix-index-database.hmModules.nix-index
          (secrets + "/default.nix")
        ];
      };
      homeConfigurations."alan@linde" = mkHomeConfiguration {
        system = utils.lib.system.aarch64-linux;
        modules = [
          ./user/server.nix
          nix-index-database.hmModules.nix-index
          (secrets + "/default.nix")
        ];
      };
    };
}