{
  description = "Send kvg-kiel bus departures to mqtt";

  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
    nixpkgs.url     = "github:NixOS/nixpkgs/nixos-22.11";
  };

  outputs = { self, nixpkgs, flake-utils }: {

    overlay = final: prev: {

      departures2mqtt = (
        let
          nmqtt = final.fetchFromGitHub {
            owner  = "zevv";
            repo   = "nmqtt";
            rev    = "v1.0.4";
            sha256 = "1by0xyqz754dny19lf8rpkg42passnj0rs6rk3jr763m1zr803mc";
          };

        in final.nimPackages.buildNimPackage {
          name        = "departures2mqtt";
          src         = self;

          buildInputs = [ nmqtt ];

          nimBinOnly  = true;
          nimRelease  = true;
        }
      );

    };

  } // (flake-utils.lib.eachDefaultSystem (system:
    let
      pkgs = import nixpkgs {
        inherit system;
        overlays = [ self.overlay ];
      };

    in rec {

      packages.default         = pkgs.departures2mqtt;
      packages.departures2mqtt = pkgs.departures2mqtt;

      apps.default = {
        type = "app";
        program = "${pkgs.departures2mqtt}/bin/departures2mqtt";
      };

    }
  ));
}