{ config, pkgs, lib, flakeRoot, ... }:

let
  username     = config.users.users."traveldroid".name or "traveldroid";
  homeDir      = "/home/${username}";
  wallpaperSrc = "${flakeRoot}/assets/Wallpapers";
  wallpaperDst = "${homeDir}/Wallpapers";
  scriptFile   = "${wallpaperDst}/set-wallpapers-at-logon.sh";
in
{
  ############################
  # Systemwide packages
  ############################
  environment.systemPackages = with pkgs; [
    swww
    waypaper
    jq
    rsync
  ];

  ############################
  # User systemd service to start swww, sync wallpapers, and run the script
  ############################
  systemd.user.services.wallpaperSync = {
    description = "Start swww, sync Wallpapers and run set-wallpapers-at-logon.sh";
    wants = [ "graphical-session.target" ];
    after = [ "graphical-session.target" ];

    serviceConfig.Type = "oneshot";
    serviceConfig.ExecStart = ''
      # Start swww daemon if not running
      pgrep swww >/dev/null 2>&1 || swww &

      # Ensure destination exists
      mkdir -p ${wallpaperDst}

      # Copy wallpapers: overwrite newer files, do not delete existing
      rsync -au --ignore-existing ${wallpaperSrc}/ ${wallpaperDst}/
      rsync -au ${wallpaperSrc}/ ${wallpaperDst}/

      # Execute the logon wallpaper script
      ${scriptFile}
    '';
    serviceConfig.Restart = "on-failure";
  };

  ############################
  # Timer to run the service every 15 minutes
  ############################
  systemd.user.timers.wallpaperSyncTimer = {
    description = "Run wallpaperSync service every 15 minutes";
    wantedBy = [ "timers.target" ];
    timerConfig.OnBootSec = "1min";      # run soon after login
    timerConfig.OnUnitActiveSec = "15min";
    timerConfig.Persistent = true;
  };
}