{ pkgs, ... }:
let
  update_time = "10m";
  backgrounds_directory = "$HOME/Immagini/Sfondi/1080+/1440+";
  update_script = pkgs.writeShellScriptBin "wl-update-background" ''
    set -e
    if [ $# -eq 0 ]; then
      image=`${pkgs.findutils}/bin/find ${backgrounds_directory} -type f | ${pkgs.gnugrep}/bin/grep -v "/\." | ${pkgs.coreutils}/bin/shuf -n 1`
    else
      image="$1"
    fi
    echo "image: $image"
    ${pkgs.swww}/bin/swww img "$image"
  '';
in
{
  home.packages = [ update_script ];

  systemd.user.services."wl-update-background" = {
    Unit = {
      Description = "Set random desktop background using swww";
      After = [ "graphical-session.pre.target" ];
      PartOf = [ "graphical-session.target" ];
      RequiresMountsFor = [ "/home/bertof/Immagini" ];
    };
    Install = { WantedBy = [ "graphical-session.target" ]; };
    Service = {
      Type = "oneshot";
      IOSchedulingClass = "idle";
      ExecStart = "${update_script}/bin/wl-update-background";
    };
  };

  systemd.user.timers."wl-update-background" = {
    Unit = { Description = "Set random desktop background using swww"; };
    Timer = { OnUnitActiveSec = update_time; };
    Install = { WantedBy = [ "timers.target" ]; };
  };
}