#!/bin/bash
# zephyrus-backlight + | - | PERCENT — step or set the internal panel's backlight, never below 1 %.
# Shipped by the mesh's asus-zephyrus-g14 module; edit the catalogue.
#
# The panel is the backlight beneath the eDP connector, not a name: in hybrid mode this model also
# registers the discrete GPU's backlight (nvidia_0), which moves nothing. Writable by the video group
# through the module's udev rule, so the vendor-key trigger needs no root.
set -u
STEP=5
dev=""
for d in /sys/class/backlight/*; do
	[ -e "$d" ] || continue
	case "$(readlink -f "$d")" in *-eDP-*) dev=$d; break ;; esac
done
if [ -z "$dev" ]; then
	for d in /sys/class/backlight/*; do [ -e "$d" ] && { dev=$d; break; }; done
fi
[ -n "$dev" ] || { echo "zephyrus-backlight: no backlight" >&2; exit 1; }
cur=$(cat "$dev/brightness")
max=$(cat "$dev/max_brightness")
pct=$(( cur * 100 / max ))
case "${1:-}" in
	+|up|Up) pct=$(( pct + STEP )) ;;
	-|down|Down) pct=$(( pct - STEP )) ;;
	''|*[!0-9]*) echo "usage: zephyrus-backlight + | - | PERCENT" >&2; exit 2 ;;
	*) pct=$1 ;;
esac
(( pct < 1 )) && pct=1
(( pct > 100 )) && pct=100
new=$(( max * pct / 100 ))
(( new < 1 )) && new=1
printf '%s' "$new" >"$dev/brightness" || exit 1
exec "$(dirname "$0")/zephyrus-notify" 5555 "Brightness: ${pct}%"