#!/bin/bash

usage() {
	cat <<-EOF
	Usage: ${0##*/} [options]

	Options:
	  --reset    reset display to no redshift
	EOF

	if [[ $# -eq 0 ]] ; then
		exit 0
	else
		printf '\nERROR: %s\n' "$*" >&2
		exit 1
	fi
}

rs() {
	exec redshift -m randr "$@"
}

main() {
	cd
	export DISPLAY=:0

	while [[ $# -gt 0 ]] ; do
		case $1 in
		--reset) rs -x ;;
		-h|--help) usage ;;
		*) usage "Unknown option: $1" ;;
		esac
	done

	h=$(date +%H)

	declare -A temps
	temps=(
		[20]=5000
		[21]=4500
		[22]=4000
		[23]=3500
		[00]=3000
		[01]=3000
		[02]=3000
		[03]=3000
		[04]=3000
		[05]=3000
		[06]=3500
		[07]=4000
		[08]=4500
		[09]=5000
	)

	t=${temps[${h}]}
	if [[ -z ${t} ]]; then
		rs -x
	else
		rs -O ${t}k
	fi
}
main "$@"