#!/bin/bash

SLEEP_SECS=600
WAKE_SECS=30
LOCK_DIR="/tmp/sleepwalk"

start_deep_sleep() {
	led_sleep
	echo mem > /sys/power/state 2>/dev/null
	return $?
}

wait_for_notifications() {
	secs=$WAKE_SECS
	is_led_on=0
	while [ $secs -ge 0 ]; do
		sleep 1
		if [ $is_led_on == 0 ]; then
			led_wake
			is_led_on=1
		else
			led_disable
			is_led_on=0
		fi

		if is_screen_on; then
			break
		fi
		secs=$(($secs-1))
	done
	led_disable
}

schedule_wake_time() {
	rtcwake -m no --date "+${SLEEP_SECS}s" 2>&1 >/dev/null
}

reset_wake_time() {
	led_wake
	> /sys/class/rtc/rtc0/wakealarm
}

is_screen_on() {
	return "$(cat /sys/class/backlight/backlight/bl_power)"
}

led_sleep() {
	echo 1 > /sys/class/leds/green\:indicator/brightness
	echo 0 > /sys/class/leds/red\:indicator/brightness
	echo 0 > /sys/class/leds/blue\:indicator/brightness
}

led_wake() {
	echo 0 > /sys/class/leds/green\:indicator/brightness
	echo 1 > /sys/class/leds/red\:indicator/brightness
	echo 0 > /sys/class/leds/blue\:indicator/brightness
}

led_disable() {
	echo 0 > /sys/class/leds/green\:indicator/brightness
	echo 0 > /sys/class/leds/red\:indicator/brightness
	echo 0 > /sys/class/leds/blue\:indicator/brightness
}

if [ $EUID -ne 0 ]; then
	echo "Needs root" >&2
	exit 1
fi

if [ -z "$1" ] || [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
	cat <<-EOF >&2
		Usage: sleepwalk [start/stop]
		Commands:
			 start		Start sleep cycle
			 stop		Stop sleep cycle
	EOF
	exit
fi

if [ "$1" == "start" ]; then
	if [ -d "$LOCK_DIR" ] || ! mkdir "$LOCK_DIR"; then
		echo "sleepwalk is already running - run 'sleepwalk stop' to stop it" >&2
		exit 1
	fi
	trap "$0 stop" EXIT

	while [ -d "$LOCK_DIR" ]; do
		while is_screen_on; do
			sleep 60
		done

		reset_wake_time
		schedule_wake_time

		while ! start_deep_sleep; do
			reset_wake_time
			echo "Failed going to sleep, try again in $WAKE_SECS seconds ..." >&2
			wait_for_notifications
			schedule_wake_time
			if is_screen_on; then
				break
			fi
		done
		wait_for_notifications
	done
elif [ "$1" == "stop" ]; then
	reset_wake_time
	led_disable
	rmdir "$LOCK_DIR" 2>/dev/null
else
	echo "Unknown command: $1" >&2
	exit 1
fi