#!/usr/bin/perl

my $battery = "/proc/acpi/battery/BAT0/state";
my $timer = "/proc/interrupts";

my $pm = {
    mamps	=> 0,
    volts	=> 0,
    capacity	=> 0,
    mwatts	=> 0,
    time_left	=> 0,
    ticks	=> 0,
    last_ticks	=> 0,
};

sub get_battery_status() {
	my $buf = "";
	open(IN, "<$battery") or printf "Could not read battery: $!\n";
	read(IN, $buf, 256);
	#printf("Buf: %s\n", $buf);
	close(IN);
	my @rows = split("\n", $buf);
	foreach my $row (@rows) {
		$row =~ s/ +/ /g;
		my ($tag, $val) = split(": ", $row);
		#printf("%s =  %s\n", $tag, $val);
		if ($tag eq "present rate") {
			($pm->{mamps}) = split(" mA", $val);
			next;
		}
		if ($tag eq "remaining capacity") {
			($pm->{capacity}) = split(" mAh", $val);
			next;
		}
		if ($tag eq "present voltage") {
			($pm->{volts}) = split(" mV", $val);
			next;
		}

	}

	$pm->{mwatts} = $pm->{mamps} * $pm->{volts};
	if ($pm->{mamps} > 0) {
		$pm->{time_left} = ($pm->{capacity} * 60 ) / $pm->{mamps};
	}
	#printf("mamps: %i volts: %i capacity: %i mwats: %i time_left: %i\n",
	#       $pm->{mamps}, $pm->{volts}, $pm->{capacity}, $pm->{mwatts}, $pm->{time_left});
}

sub read_timer_ticks() {
	my $buf = "";
	open(IN, "<$timer") or die "Could not open timer: $!";
	read(IN, $buf, 128);
	close(IN);
	my @rows = split("\n", $buf);
	foreach my $row (@rows) {
		$row =~ s/ +/ /g;
		my ($tag, $val) = split(": ", $row);
		$tag =~ s/ +//g;
		#printf("%s =  %s\n", $tag, $val);
		($val) = split(" ", $val);
		if ($tag eq "0") {
			return($val);
		}
	}
	return 0;
}

my ($rate) = @ARGV;

if ($rate eq "") {
	printf("Usage: %s interval_in_seconds\n", $0);
	exit(1);
}

my $mamps_sum = 0;
my $volts_sum = 0;
my $mwatts_sum = 0;
my $measure_count = 0;

sub end_up {
    if ($mamps_sum > 0 && $measure_count > 0){
	printf("\nAverage the last %d seconds:\n",
	       $measure_count*$rate);
	printf("Current: %imA\n", $mamps_sum/$measure_count);
	printf("Volts:   %.2fV\n", $volts_sum/($measure_count * 1000));
	printf("mWatts:  %.2fmW\n", $mwatts_sum/($measure_count * 1000000));
	exit(0);
    }
    else{
        die ("Could not determine battery averages");
    }
}

$SIG{TERM} = 'end_up';
$SIG{INT} = 'end_up';
$SIG{QUIT} = 'end_up';

my $last_ticks = 0;

while (1) {
	get_battery_status();
	$pm->{ticks} = read_timer_ticks();
	my $delta_ticks = ($pm->{ticks} - $pm->{last_ticks}) / $rate;
	if ($pm->{last_ticks} == 0) {
		$delta_ticks = 0; 
	}
	$pm->{last_ticks} = $pm->{ticks};

	my $hours = $pm->{time_left} / 60;
	my $mins = $pm->{time_left} % 60;

	printf("Current: %imA Voltage: %.2fV Power: %.2fW %imAh ".
	       "Time: %02i:%02ih Ticks: %iHZ\n",
	       $pm->{mamps},
	       $pm->{volts} / 1000,
	       $pm->{mwatts} / 1000000,
	       $pm->{capacity},
	       $hours,
	       $mins,
	       $delta_ticks);
	$mamps_sum += $pm->{mamps};
	$volts_sum += $pm->{volts};
	$mwatts_sum += $pm->{mwatts};
	$measure_count++;
	sleep $rate;
}