nixos/home/common/optional/desktop/wayland/swww-wallpaper-changer.nix

{
  pkgs,
  ...
}:
{
  systemd.user.services.wallpaper-changer = {
    Unit = {
      Description = "Script to change wallpaper using swww";
       PartOf = [ "hyprland-session.target" ];
       After = [ "hyprland-session.target" ]; # or "wayland.target", depending on your system setup
    };
    Install = {
      WantedBy = [ "default.target" ];
    };
    Service = {
      Type = [ "simple" ];
      ExecStart = "${pkgs.writeShellScript "swww-wallpaper-changer" ''
        export WAYLAND_DISPLAY="wayland-1"
        wallpaper_dir="$HOME/.local/share/bg/"
        [ -d "$wallpaper_dir" ] || mkdir -p "$wallpaper_dir"

        # Allow some time for desktop to start
        sleep 3
        echo "starting daemon..."
        ${pkgs.swww}/bin/swww-daemon &

        while true; do
            find "$wallpaper_dir" -type f -follow \( -iname \*.jpg -o -iname \*.png -o -iname \*.gif -o -iname \*.bmp \) | shuf | while read -r file; do
                ${pkgs.swww}/bin/swww img "$file" --transition-step 10 --transition-fps 60
                [ $? != 0 ] && echo "swww failed, reloading daemon" && ${pkgs.swww}/bin/swww-daemon &
                sleep 600
            done
        done
      ''}";
    };
  };
}