{ pkgs, ... }:
let
  readlink = "${pkgs.coreutils}/bin/readlink";
  notify-send = "${pkgs.libnotify}/bin/notify-send";
in {
  systemd = {
    services = {
      clean-keychain = {
        description = "Clean up .keychain on boot";
        wantedBy = [ "multi-user.target" ];
        serviceConfig = {
          Type = "oneshot";
          ExecStart = "${pkgs.coreutils-full}/bin/rm -rf /home/don/.keychain";
        };
      };
    };
    user = {
      services = {
        detect-reboot-for-upgrade = {
          script = ''
            set -eu -o pipefail
            booted="$(${readlink} /run/booted-system/{initrd,kernel,kernel-modules})"
            built="$(${readlink} /nix/var/nix/profiles/system/{initrd,kernel,kernel-modules})"
            if [[ "''${booted}" != "''${built}" ]];
            then
              echo "Looks like we need a reboot!"
              ${notify-send} --urgency=low --icon=system-reboot "Reboot is needed for a NixOS upgrade."
            fi
          '';
          serviceConfig = { Type = "oneshot"; };
        };
      };
      timers = {
        detect-reboot-for-upgrade = {
          wantedBy = [ "timers.target" ];
          partOf = [ "detect-reboot-for-upgrade.service" ];
          timerConfig = {
            OnCalendar = "hourly";
            Unit = "detect-reboot-for-upgrade.service";
          };
        };
      };
    };
  };
}