{ config, pkgs, lib, flakeRoot, ... }:
let
  # Repo folder that gets copied to ~/nixos_conf/wallpaperstuff
  repoWallpaperDir = flakeRoot + "/assets/conf/desktop/wallpaper";

  userRelRoot = "nixos_conf/wallpaperstuff";
  userAbsRoot = "${config.home.homeDirectory}/${userRelRoot}";

  # Your actual layout:
  #   ~/nixos_conf/wallpaperstuff/pictures/wallpaper{1..9}.jpg
  picturesDir = "${userAbsRoot}/pictures";
  stateDir = "${userAbsRoot}/current";
  symlinkPath = "${stateDir}/workspace.jpg";

  scriptRel = "hypr/scripts/wpaperd-workspace-1to9.sh";
  wpaperdConfRel = "wpaperd/config.toml";
in
{
  home.packages = [
    pkgs.wpaperd
    pkgs.socat
    pkgs.jq
  ];

  # Copy wallpapers from repo → ~/nixos_conf/wallpaperstuff (includes pictures/)
  home.file."${userRelRoot}" = {
    source = repoWallpaperDir;
    recursive = true;
  };

  # Ensure wpaperd config points to the global symlink (not per-monitor, not rotating)
  xdg.configFile."${wpaperdConfRel}".text = ''
    [default]
    mode = "stretch"

    [any]
    path = "${symlinkPath}"
  '';

  # Script: global wallpaper per workspace (focused workspace), via symlink + reload-wallpaper
  xdg.configFile."${scriptRel}" = {
    executable = true;
    text = ''
      #!/usr/bin/env bash
      set -euo pipefail

      log() { echo "[wpaperd-ws] $*" >&2; }

      PICTURES_DIR="${picturesDir}"
      STATE_DIR="${stateDir}"
      SYMLINK="${symlinkPath}"

      XDG_CONFIG_HOME="''${XDG_CONFIG_HOME:-$HOME/.config}"
      WPAPERD_DIR="$XDG_CONFIG_HOME/wpaperd"
      CONF="$WPAPERD_DIR/config.toml"

      : "''${XDG_RUNTIME_DIR:?XDG_RUNTIME_DIR not set}"
      : "''${HYPRLAND_INSTANCE_SIGNATURE:?HYPRLAND_INSTANCE_SIGNATURE not set}"
      SOCK="''${XDG_RUNTIME_DIR}/hypr/''${HYPRLAND_INSTANCE_SIGNATURE}/.socket2.sock"

      mkdir -p "$STATE_DIR" "$WPAPERD_DIR"

      # Wait for Hyprland socket so we don't exit too early
      for i in $(seq 1 120); do
        [[ -S "$SOCK" ]] && break
        sleep 0.1
      done
      [[ -S "$SOCK" ]] || { log "Hyprland socket not found: $SOCK"; exit 1; }

      ws_num() {
        local w="''${1%%:*}"
        [[ "$w" =~ ^[0-9]+$ ]] || return 1
        printf '%s\n' "$w"
      }

      img_for_ws() {
        local n="$1"
        case "$n" in
          1|2|3|4|5|6|7|8|9) printf '%s/wallpaper%s.jpg\n' "$PICTURES_DIR" "$n" ;;
          *) return 1 ;;
        esac
      }

      ensure_config() {
        # keep config stable and always pointing to the symlink
        cat >"$CONF" <<EOF
      [default]
      mode = "stretch"

      [any]
      path = "$SYMLINK"
      EOF
      }

      reload_wallpaper() {
        ${pkgs.wpaperd}/bin/wpaperctl reload-wallpaper >/dev/null 2>&1 || true
      }

      apply_workspace() {
        local ws_raw="$1"
        local n img

        n="$(ws_num "$ws_raw")" || { log "Ignoring non-numeric workspace: $ws_raw"; return 0; }
        img="$(img_for_ws "$n")" || return 0

        if [[ ! -f "$img" ]]; then
          log "Missing image for ws=$n: $img"
          return 0
        fi

        # If already set, skip
        if [[ -L "$SYMLINK" ]] && [[ "$(readlink -f "$SYMLINK")" == "$(readlink -f "$img")" ]]; then
          return 0
        fi

        ln -sf "$img" "$SYMLINK"
        log "Workspace $n -> $img"
        ensure_config
        reload_wallpaper
      }

      apply_initial() {
        local ws
        ws="$(${pkgs.hyprland}/bin/hyprctl -j monitors | ${pkgs.jq}/bin/jq -r '.[] | select(.focused==true) | .activeWorkspace.name' | head -n1)"
        if [[ -n "$ws" && "$ws" != "null" ]]; then
          apply_workspace "$ws"
        else
          log "Could not determine initial focused workspace"
        fi
      }

      handle_line() {
        case "$1" in
          workspace\>\>*)
            apply_workspace "''${1#workspace>>}"
            ;;
          workspacev2\>\>*)
            local payload="''${1#workspacev2>>}"
            apply_workspace "''${payload#*,}"
            ;;
          focusedmon\>\>*)
            local payload="''${1#focusedmon>>}"
            local ws="''${payload#*,}"
            apply_workspace "$ws"
            ;;
        esac
      }

      ensure_config
      apply_initial

      log "Listening on $SOCK"
      exec ${pkgs.socat}/bin/socat -U - "UNIX-CONNECT:$SOCK" \
        | while IFS= read -r line; do
            handle_line "$line" || true
          done
    '';
  };

  # wpaperd daemon
  systemd.user.services.wpaperd = {
    Unit = {
      Description = "wpaperd wallpaper daemon";
      After = [ "graphical-session.target" ];
      PartOf = [ "graphical-session.target" ];
    };
    Service = {
      ExecStart = "${pkgs.wpaperd}/bin/wpaperd";
      Restart = "on-failure";
      RestartSec = 1;
    };
    Install.WantedBy = [ "graphical-session.target" ];
  };

  # listener
  systemd.user.services.wpaperd-workspace-wallpaper = {
    Unit = {
      Description = "Global wallpaper per workspace (1..9)";
      After = [ "graphical-session.target" "wpaperd.service" ];
      PartOf = [ "graphical-session.target" ];
    };
    Service = {
      ExecStart = "${pkgs.bash}/bin/bash ${config.xdg.configHome}/${scriptRel}";
      Restart = "on-failure";
      RestartSec = 1;
    };
    Install.WantedBy = [ "graphical-session.target" ];
  };
}