{ config, pkgs, ... }:

let
  shell = "${pkgs.dash}/bin/dash";
  wallpapers = "${config.home.homeDirectory}/Images/wallpapers/enabled";
  find = "${pkgs.findutils}/bin/find";
  shuf = "${pkgs.coreutils}/bin/shuf";
  swaybg = "${pkgs.swaybg}/bin/swaybg";
  setbg = pkgs.writeScriptBin "setbg" ''
    #!/${shell}
    BG="$(${find} "${wallpapers}" -type f | ${shuf} -n 1)"
    ${swaybg} --image $BG --mode fill
  '';
in {
  systemd.user.services.setbg = {
    Unit = {
      Description = "set background using swaybg";
      BindsTo = [ "river-session.target" ];
    };
    Service = {
      Type = "simple";
      ExecStart = "${setbg}/bin/setbg";
    };
    Install = { WantedBy = [ "river-session.target" ]; };
  };
}