{ config, pkgs, lib, flakeRoot, ... }:
let
  repoWallpaperDir  = flakeRoot + "/assets/conf/desktop/wallpaper";
  repoWallpaperConf = flakeRoot + "/assets/conf/desktop/wallpaper/wallpaper.conf";
  userRelRoot  = "nixos_conf/wallpaperstuff";
  userAbsRoot  = "${config.home.homeDirectory}/${userRelRoot}";
  userConfPath = "${userAbsRoot}/wallpaper.conf";
  userWsScriptPath = "${userAbsRoot}/wpaperd-workspace-1to9.sh";
  # Exclude wallpaper.conf so HM does NOT manage it (avoids backup collisions)
  repoWallpapersOnly = lib.cleanSourceWith {
    src = repoWallpaperDir;
    filter = path: type:
      (builtins.baseNameOf path) != "wallpaper.conf";
  };
  wsScript = ''
    #!/usr/bin/env bash
    set -euo pipefail
    ROOT_DIR="''${1:?usage: wpaperd-workspace-1to9.sh /path/to/wallpaper-dir}"
    : "''${XDG_RUNTIME_DIR:?XDG_RUNTIME_DIR not set}"
    : "''${HYPRLAND_INSTANCE_SIGNATURE:?HYPRLAND_INSTANCE_SIGNATURE not set}"
    SOCK="''${XDG_RUNTIME_DIR}/hypr/''${HYPRLAND_INSTANCE_SIGNATURE}/.socket2.sock"
    [[ -S "$SOCK" ]] || { echo "Hyprland socket not found: $SOCK" >&2; exit 1; }
    set_for_ws() {
      local ws_raw="$1"
      # Hyprland workspace name may look like "1" or "1:foo" — take the numeric prefix
      local ws="''${ws_raw%%:*}"
      [[ "$ws" =~ ^[1-9]$ ]] || return 0
      local img="$ROOT_DIR/wallpaper$ws.jpg"
      if [[ -f "$img" ]]; then
        ${pkgs.wpaperd}/bin/wpaperctl set "$img" >/dev/null 2>&1 || true
      fi
    }
    # Apply once at start (best effort): ask hyprctl for active workspace name
    if command -v ${pkgs.hyprland}/bin/hyprctl >/dev/null 2>&1; then
      cur="$(${pkgs.hyprland}/bin/hyprctl activeworkspace -j 2>/dev/null | ${pkgs.jq}/bin/jq -r '.name // empty' || true)"
      [[ -n "''${cur:-}" ]] && set_for_ws "$cur" || true
    fi
    exec ${pkgs.socat}/bin/socat -u "UNIX-CONNECT:$SOCK" - | while IFS= read -r line; do
      case "$line" in
        workspace\>\>*)
          ws="''${line#workspace>>}"
          set_for_ws "$ws"
          ;;
      esac
    done
  '';
in
{
  home.packages = [
    pkgs.wpaperd
    pkgs.socat
    pkgs.jq
    pkgs.hyprland
  ];
  # Sync everything *except* wallpaper.conf into ~/nixos_conf/wallpaperstuff
  # Put wallpaper1.jpg .. wallpaper9.jpg in your repo wallpaper dir and they’ll be copied here.
  home.file."${userRelRoot}" = {
    source = repoWallpapersOnly;
    recursive = true;
  };
  # Now safely overwrite the config every activation (no HM collision)
  home.activation.wallpaperConfForce =
    lib.hm.dag.entryAfter [ "writeBoundary" ] ''
      set -euo pipefail
      mkdir -p "${userAbsRoot}"
      install -m 0644 "${repoWallpaperConf}" "${userConfPath}"
    '';
  # Install the listener script
  home.file."${userRelRoot}/wpaperd-workspace-1to9.sh" = {
    text = wsScript;
    executable = true;
  };
  # wpaperd daemon
  systemd.user.services.wpaperd = {
    Unit = {
      Description = "wpaperd wallpaper daemon";
      After = [ "default.target" ];
    };
    Service = {
      Type = "simple";
      ExecStart = "${pkgs.wpaperd}/bin/wpaperd --config ${userConfPath}";
      Restart = "on-failure";
      RestartSec = 1;
    };
    Install.WantedBy = [ "default.target" ];
  };
  # Workspace listener: switches wallpaper when workspace changes (1..9)
  systemd.user.services.wpaperd-workspace-1to9 = {
    Unit = {
      Description = "Set wallpaper1..9.jpg per Hyprland workspace (wpaperctl)";
      After = [ "wpaperd.service" "graphical-session.target" ];
      PartOf = [ "graphical-session.target" ];
    };
    Service = {
      Type = "simple";
      ExecStart = "${pkgs.bash}/bin/bash ${userWsScriptPath} ${userAbsRoot}";
      Restart = "on-failure";
      RestartSec = 1;
    };
    Install.WantedBy = [ "default.target" ];
  };
}