#!/bin/sh
### BEGIN INIT INFO
# Provides:          brightness
# Required-Start:    $local_fs
# Required-Stop:     $local_fs
# Default-Start:     S
# Default-Stop:      0 6
# Short-Description: Save and restore brightness level between restarts.
# Description:       This script saves the brightness level between restarts.
#                    It is called from the boot, halt and reboot scripts.
### END INIT INFO

readonly SAVEFILE_PREFIX=/var/lib/initscripts/brightness

. /lib/init/vars.sh
. /lib/lsb/init-functions

do_invoke() {
	local rv=0 rc
	# ACPI (without explicit label)
	do_$1 '' \
		/sys/class/backlight/acpi_video0/brightness \
		/sys/class/backlight/acpi_video0/max_brightness
	rc=$?
	[ $rc -lt $rv ] || rv=$rc
	# Intel
	do_$1 intel \
		/sys/class/backlight/intel_backlight/brightness \
		/sys/class/backlight/intel_backlight/max_brightness
	rc=$?
	[ $rc -lt $rv ] || rv=$rc
	# could insert others using the same scheme here
	return $rv
}

do_status() {
	local label=$1 knob=$2 max=$3 file=$SAVEFILE_PREFIX${1:+.$1}
	[ -e "$knob" ] || return 0

	MSG="Current${label:+ $label} brightness level is $(cat "$knob")"
	if [ -f "$file" ]; then
		log_success_msg "${MSG}, saved value is $(cat "$file")"
		return 0
	fi
	log_failure_msg "${MSG}, there is no saved value"
	return 4
}

do_start() {
	local label=$1 knob=$2 max=$3 file=$SAVEFILE_PREFIX${1:+.$1}
	[ -e "$knob" ] || return 0

	[ "$VERBOSE" = "no" ] ||
		log_action_begin_msg Initialising $label brightness level

	if [ -f "$file" ]; then
		cat "$file" >"$knob"
	else
		cat "$max" >"$knob"
	fi
	local rv=$?
	[ "$VERBOSE" = "no" ] || log_action_end_msg $rv
	return $rv
}

do_stop() {
	local label=$1 knob=$2 max=$3 file=$SAVEFILE_PREFIX${1:+.$1}
	[ -e "$knob" ] || return 0

	# If the backlight is off, don't save to avoid blank display after
	# reboot. See Devuan #617.
	[ "$(cat $knob)" -eq 0 ] && return 0

	[ "$VERBOSE" = "no" ] ||
		log_action_begin_msg Saving $label brightness level
	cat "$knob" >"$file"
	local rv=$?
	[ "$VERBOSE" = "no" ] || log_action_end_msg $rv
	return $rv
}

case $1 in
	start | restart | reload | force-reload)
		do_invoke start
		;;
	stop)
		do_invoke stop
		;;
	status)
		do_invoke status
		;;
	*)
		echo >&2 "Usage: $0 {start|stop|restart|reload|force-reload|status}"
		exit 3
		;;
esac
