#!/bin/bash
# Usage:
# - setmonitor dp-brightness [increase|decrease|min|max]
# - setmonitor night-light [increase|decrease|day|night]
set -e

if [ $# -ne 2 ]; then
	echo 'Check setmonitor source for usage'
	exit 1
fi

MONITORS="$(xrandr --listactivemonitors | tail -n +2 | cut -d'+' -f2 | cut -d' ' -f1 | sed 's/^\*//')"
EXTERNAL_MONITORS="$(echo $MONITORS | tr ' ' '\n' | grep -v eDP)"

# Usage: brightness MONITOR
brightness () {
	echo "$(xrandr --verbose | grep "^$1" -A5 | grep Brightness | cut -d':' -f2 | sed 's/\s*//')"
}

# Usage: dp_brightness [increase|decrease|min|max] MONITOR
dp_brightness () {
	STEP=5
	BRIGHTNESS="$(bc <<< "$(brightness "$2")*100")"

	case "$1" in
		increase) BRIGHTNESS="$(bc <<< "$BRIGHTNESS+$STEP")" ;;
		decrease) BRIGHTNESS="$(bc <<< "$BRIGHTNESS-$STEP")" ;;
		min) BRIGHTNESS=0 ;;
		max) BRIGHTNESS=100 ;;
		*)
			echo "Invalid argument '$1'"
			exit 1
			;;
	esac

	BRIGHTNESS="$(bc <<< "scale=2; $BRIGHTNESS/100")"

	xrandr --output "$MONITOR" --brightness "$BRIGHTNESS"
}

# Usage: nightlight [increase|decrease|day|night]
nightlight () {
	TMPFILE=/tmp/.night-light-index

	# https://askubuntu.com/a/1061304
	STEPS=(
		"1:0.18172716:0.00000001" "1:0.42322816:0.00000001" "1:0.54360078:0.08679949"
		"1:0.64373109:0.28819679" "1:0.71976951:0.42860152" "1:0.77987699:0.54642268"
		"1:0.82854786:0.64816570" "1:0.86860704:0.73688797" "1:0.90198230:0.81465502"
		"1:0.93853986:0.88130458" "1:0.97107439:0.94305985" "1:1:1"
	)

	CUR=$((${#STEPS[@]}-1))
	if [ -f $TMPFILE ]; then
		CUR=$(cat $TMPFILE)
	fi

	case "$1" in
		increase) NEW=$(($CUR >= ${#STEPS[@]} ? $CUR : $CUR+1)) ;;
		decrease) NEW=$(($CUR <= 0 ? $CUR : $CUR-1)) ;;
		day) NEW=$((${#STEPS[@]}-1)) ;;
		night) NEW=0 ;;
		*)
			echo "Invalid argument '$1'"
			exit 1
			;;
	esac

	echo $NEW > $TMPFILE

	for MONITOR in $MONITORS; do
		BRIGHTNESS=$(brightness "$MONITOR")
		xrandr --output "$MONITOR" --gamma "${STEPS[$NEW]}" --brightness "$BRIGHTNESS" || true
	done
}

case "$1" in
	dp-brightness)
		for MONITOR in $EXTERNAL_MONITORS; do
			dp_brightness "$2" "$MONITOR"
		done
		;;
	night-light)
		nightlight "$2"
		;;
	*)
		echo 'Check setmonitor source for usage'
		exit 1
esac