nixos-config/home-manager/roles/night-shutdown.nix

{pkgs, ...}: let
  night-shutdown = pkgs.writeHaskellScript
  {
    name = "night-shutdown";
    imports = [
      "Data.Time.LocalTime"
      "Data.Time.Format"
      "Data.Time.Clock"
      "Control.Concurrent"
      "Data.Functor"
    ];
    bins = [pkgs.libnotify pkgs.systemd];
  } ''
    interval = 5

    main = forever $ do
       time <- getZonedTime
       let tod = localTimeOfDay . zonedTimeToLocalTime$ time
           hour = todHour tod
           minute = todMin tod
           evening = hour == 0
           night = (hour < 6 && hour >= 1)
           action
            | evening = notify_send "Shutdown alert!" ([i|Rechner fährt in #{59-minute} Minuten runter.|]::String)
            | night = systemctl "poweroff"
            | otherwise = pass
       action
       threadDelay $ (interval - (minute `mod` interval)) * 60 * 1000000
  '';
in {
  systemd.user.services.night-shutdown = {
    Unit.Description = "Night Shutdown";
    Service.ExecStart = "${night-shutdown}/bin/night-shutdown";
    Install.WantedBy = ["graphical-session.target"];
  };
}