{
  description = "Flake to define configurations of 'elss' - ellmauthaler stefan's systems";

  inputs = {
    
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.11";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";

    nix = {
      url = "github:NixOS/nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nixos-hardware = {
      url = "github:NixOS/nixos-hardware/master";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    home-manager = {
      url = "github:nix-community/home-manager/release-21.11";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    flake-utils-plus = {
      url = "github:gytis-ivaskevicius/flake-utils-plus";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    
    emacs-overlay = {
      url = "github:nix-community/emacs-overlay";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    simple-nixos-mailserver.url = "gitlab:simple-nixos-mailserver/nixos-mailserver/nixos-21.11";

    sops-nix = {
      url = "github:Mic92/sops-nix/master";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    dwarffs = {
      url = "github:edolstra/dwarffs";
      inputs = {
        nix.follows = "nix";
        nixpkgs.follows = "nixpkgs";
      };
    };
  };

  outputs = {self, nixpkgs, flake-utils-plus, ...}@inputs:
    let
      extended-lib = nixpkgs.lib.extend
        (final: prev: {
          elss = (import ./lib {lib = final; }) prev;
        });
      inherit (extended-lib.elss) discoverModules moduleNames;
    in
      flake-utils-plus.lib.mkFlake rec{
        inherit self inputs;
        supportedSystems = [ "x86_64-linux" ];

        lib = extended-lib;

        channelsConfig = {
          allowUnfreePredicate = pkg: builtins.elem (extended-lib.getName pkg) [
            "steam"
            "steam-original"
            "steam-runtime"
            "skypeforlinux"
            "teams"
            "zoom"
          ];
        };

        channels.nixpkgs.overlaysBuilder = channels: [
          (final: prev: {
            unstable = channels.nixpkgs-unstable;
          })
          inputs.nix.overlay
          inputs.emacs-overlay.overlay
        ];

        hostDefaults = {
          system = "x86_64-linux";
          channelName = "nixpkgs";
          modules = [
            inputs.home-manager.nixosModules.home-manager
            inputs.dwarffs.nixosModules.dwarffs
          ] ++ (map (name: ./modules + "/${name}") (moduleNames ./modules));
          specialArgs = {
            nixos-hardware = inputs.nixos-hardware.nixosModules;
            inherit inputs;
          };
          extraArgs = { inherit homeConfigurations; };
        };

        hosts = discoverModules ./machines (name: {
          modules = [ (./machines + "/${name}") ];
          specialArgs = { lib = extended-lib; };
        });

        homeConfigurations = discoverModules ./users
        (name:
          let
            username = extended-lib.removeSuffix ".nix" name;
          in
            inputs.home-manager.lib.homeManagerConfiguration {
              configuration = import (./users + "/${name}");
              inherit username;
              system = "x86_64-linux";
              homeDirectory = "/home/${username}";
              stateVersion = "21.05";
            });        
      };
}