#!/usr/bin/perl

use strict;
use warnings "all";
use Fcntl;

$0 = 'acpid.pl';
my $debug = 0;

sub logger ($) {
	if ($debug != 0) {
		my $msg = shift;
		$msg = localtime() . ' ' . $msg;
		syswrite STDOUT, $msg;
	}
}

my $base = '/sys/class/power_supply/BAT0';

unless(-f "$base/present") {
	logger("Battery info at /sys/class/BAT0/present not found, quitting.\n");
	exit 0;
}

my $battery_present = 2;
my $battery_check = 2;
my $charging = 2;

while ( sleep(180) ) {
# check that battery is in place
	open(ACPI, "$base/present") or next;
	my $buf = '';

	if (read(ACPI, $buf, 1)) {
		if ($battery_check == 0) {
			logger("Ability to read from /sys/class/BAT0/present restored\n");
			$battery_check = 1;
		}

		if ($buf == '0') {
			if ($battery_present != 0) {
				logger("We have no battery, skipping charge level polling until it appears\n");
				$battery_present = 0;
			}

			close ACPI;
			next;
		}
	} else {
		if ($battery_check != 0) {
			logger("Unable to read from /sys/class/BAT0/present\n");
			$battery_check = 0;
		}

		close ACPI;
		next;
	}

	close ACPI;
	$battery_present = 1;

# check status, we have no need to poll battery if it charging/charged
	unless (-f "$base/status") {
		logger("Something broken in /sys, unable to find $base/status, quitting\n");
		exit 1;
	}

# TODO: file access save state and print on change
	open(STATUS, "$base/status") or do {
		logger("Unable to open $base/status\n");
		next;
	};

	$buf = <STATUS>;
	close STATUS;

	chomp($buf);

	if ($buf ne 'Discharging') {
		if ($charging != 1) {
			logger("Battery charging.\n");
			$charging = 1;
		}
		next;
	} else {
		if ($charging != 0) {
			logger("Battery discharging.\n");
			$charging = 0;
		}
	}

# read charge state
	unless (-f "$base/capacity") {
		logger("Something broken in /sys, unable to find $base/capacity, quitting\n");
		exit 1;
	}

# TODO: file access save state and print on change
	open(CHARGE, "$base/capacity") or do {
		logger("Unable to open $base/capacity\n");
		next;
	};

	read(CHARGE, $buf, 3) or do {
		logger("Unable to read $base/capacity\n");
		next;
	};

	chomp($buf);
	
	if ($buf < 10) {
		logger("Battery charge is less than 10%, hibernating\n");
		`dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Hibernate`;
	} else {
		logger("Charge is $buf%\n");
	}
}