#!/bin/sh

# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.

main()
{
	# Handle opts
	while getopts ":h" opt
	do
		case "$opt" in
			h) usage && exit 0 ;;
			*)
				printf "Invalid option passed: %s\n" "$OPTARG" >&2
				;;
		esac
	done

	shift $(( OPTIND - 1 ))

	[ $# -lt 1 ] && usage && exit 1

	case "$1" in
		inc)
			brightnessctl set +${2:-5}%
			notify="Brightness increased to $(brightness_level)%"
			;;
		dec)
			if [ $(brightness_level) -lt $(( ${2:-5} + 1 )) ]
			then
				brightnessctl set 1
			else
				brightnessctl set ${2:-5}%-
			fi

			notify="Brightness lowered to $(brightness_level)%"
			;;
		set)
			[ -z "$2" ] && usage && exit 1

			brightnessctl set $2%
			notify="Brightness set to $(brightness_level)%"
			;;
	esac

	notify-send -n 57492 -s -t 2 -i "$(brightness_icon)" "Backlight" "$notify"
}

brightness_level()
{
	awk "BEGIN { printf(\"%d\", ($(brightnessctl get) / $(brightnessctl max)) * 100) }"
}

brightness_icon()
{
	[ $(brightness_level) -lt 10 ] && printf "notification-display-brightness-off" && return
	[ $(brightness_level) -lt 35 ] && printf "notification-display-brightness-low" && return
	[ $(brightness_level) -lt 70 ] && printf "notification-display-brightness-medium" && return
	[ $(brightness_level) -lt 95 ] && printf "notification-display-brightness-high" && return

	printf "notification-display-brightness-full"
}

usage()
{
	cat <<EOF
Usage:
	${0##*/} -h
	${0##*/} inc [level]
	${0##*/} dec [level]
	${0##*/} set <level>

Alter the backlight intensity.

Subcommands:
	inc     Increase the volume by level, defaults to 5.
	dec     Decrease the volume by level, defaults to 5.
	set     Set the volume to level.

Options:
	-h  Show this help text and exit.
EOF
}

main "$@"