multiCats.nix

{ config, lib, pkgs, ... }:
with lib;
let

  cfg = config.services.netcat;

  makeService = n: {
    name = "netcat${toString n}";
    value = {
      enable = true;
      description = "Netcat ${toString n}";
      serviceConfig = {
        ExecStart = ''
	  ${pkgs.netcat}/bin/nc -l ${toString (config.services.netcat.basePort +  n)}
	'';
        Restart = "on-failure";
      };
    };
  };


in {

  options = {

    services.netcat = {

      enable = mkOption {
        type = types.bool;
        default = false;
        description = "Whether to start some pointless netcat processes";
      };

      count = mkOption {
        type = types.int;
        default = 1;
        description = "How many pointless netcat processes to start";
      };

      basePort = mkOption {
        type = types.int;
        default = 999;
        description = "The base port number";
      };

    };
  };

  config = mkIf cfg.enable {
    systemd.user.services = builtins.listToAttrs (map makeService (lib.range 1 cfg.count));
  };
}