home/packages/nct6775-pwm-udev-package.nix

{ pkgs }:

pkgs.stdenv.mkDerivation {
  pname = "nct6775-pwm-udev-rules";
  version = "1.0";

  dontUnpack = true;
  dontBuild = true;

  linkScript = pkgs.writeShellScript "link-nct6775-pwm" ''
    echo "NCT6775 udev rule triggered at $(date): devpath=$1" >> /tmp/udev-nct-debug.log
    # Input: DEVPATH from udev (e.g., /devices/platform/nct6775.656/hwmon/hwmon3)
    DEVPATH="$1"
    HWMON_PATH="/sys$DEVPATH"
    SYMLINK_DIR="/run/hwmon"

    # Ensure the symlink directory exists
    mkdir -p "$SYMLINK_DIR" || { echo "Failed to create $SYMLINK_DIR"; exit 1; }

    # Create symlinks for all attributes in the hwmon directory
    for attr in "$HWMON_PATH"/*; do
      if [ -e "$attr" ]; then
        attr_name=$(basename "$attr")
        echo "Linking $attr_name -> $SYMLINK_DIR/$attr_name" >> /tmp/udev-nct-debug.log
        ln -sf "$attr" "$SYMLINK_DIR/$attr_name" || echo "Failed to create symlink for $attr_name"
      else
        echo "No attributes found in $HWMON_PATH"
      fi
    done

    ls -la /sys/hwmon/ >> /tmp/udev-nct-debug.log 2>/dev/null || true
  '';

  installPhase = ''
    mkdir -p $out/etc/udev/rules.d
    cat > $out/etc/udev/rules.d/99-nct6775-pwm.rules << EOF
    # Create constant paths for NCT6775 PWM controls
    SUBSYSTEM=="hwmon", KERNEL=="hwmon[0-9]*", RUN+="$linkScript %p"
    EOF
  '';

  meta = with pkgs.lib; {
    description = "Udev rules for NCT6775 PWM device symlinks";
    license = licenses.mit;
    platforms = platforms.linux;
  };
}