os/hosts/droppie/backup-autostop.nix

{pkgs, ...}: let
  shutdownWaitMinutes = 10;
  shutdownScript = pkgs.writeShellScriptBin "shutdown-wait" ''


    if [ -n "''${running}" ] && [ "''${running}" = "yes" ]; then
      echo "backups are still running"
      exit 1
    fi

    echo "WARNING: System will be shut down within the next ${builtins.toString shutdownWaitMinutes} minutes" | ${pkgs.util-linux}/bin/wall

    sleep 10

    shutdown -P +${builtins.toString shutdownWaitMinutes}
  '';
in {
  systemd.services."shutdown-after-backup" = {
    enable = true;
    serviceConfig = {
      ExecStart = "${shutdownScript}/bin/shutdown-wait";
      Type = "oneshot";
    };
  };

  systemd.timers."shutdown-after-backup" = {
    enable = true;
    timerConfig = {
      OnCalendar = "*-*-* 02..09:00,15,30,45:00 Etc/UTC";
    };
    wantedBy = ["timers.target"];
    partOf = ["shutdown-after-backup.service"];
  };
}