#!/usr/bin/perl

# use Date::Time;

open LOG, ">>/var/log/powerwatch";
select (LOG);
$| = 1;

&log ("PowerWatch Starting");

my $cpu;
my $brightness;
my $lastremaining;
my @lastremainingreal;
my $shutdown = 0;
my $battery = `/usr/bin/vaiobat`;
if ($battery =~ /(\d+)\.(\d+)\%/) {
    $lastremaining = $1;
    $lastremainingreal[0] = $1 . "." . $2;
}

&log ("Initial State: $battery");

if ($battery =~ /AC/) {
    `/usr/bin/setbrightness 255`;
    $brightness = 255;
    `/usr/bin/crusoe -f`;
    $cpu = 1;
}
else {
    `/usr/bin/setbrightness 0`;
    $brightness = 0;
    `/usr/bin/crusoe -s`;
    $cpu = 0;
}

while (1) {
    sleep (15);

    my $battery = `/usr/bin/vaiobat`;
    my $remaining = 50;
    my $remainingreal = 50.0;
    if ($battery =~ /(\d+)\.(\d+)\%/) {
	$remaining = $1;
	$remainingreal = $1 . "." . $2;
    }

    open STATUS, ">/var/log/vaiobat";
    print STATUS $battery;
    close STATUS;

    if ($battery =~ /AC/) {
	&log ("Using AC Power: $battery");

	# reset our queue of old power levels..
	@lastremainingreal = ();

	# we are plugged in
	if ($shutdown == 1) {
	    &log ("Now plugged in so we can cancel the shutdown.");
	    `/sbin/shutdown -c`;
	    $shutdown = 0;
	}

	if ($cpu == 0) {
	    &log ("Throttle CPU to full speed.");
	    `/usr/bin/crusoe -f`;
	    $cpu = 1;
	}

	if ($brightness < 255) {
	    &log ("Set brightness to full.");
	    `/usr/bin/setbrightness 255`;
	    $brightness = 255;
	}

	if (($remaining == 100) && ($lastremaining < 100)) {
	    &log ("Message users that the battery is charged.");
	    `wall The Battery is now 100% charged.`;
	}
    }
    else {
	# on battery	
	&log ("Using Battery:  $battery");

	# try and calculate the amount of time left based upon the
	# drop in the last 15 seconds.
	if ((defined ($lastremainingreal[scalar(@lastremainingreal)-1])) &&
	    ($lastremainingreal[scalar(@lastremainingreal)-1] > $remainingreal)) {
	    my $timeleft = ((0.25 * scalar(@lastremainingreal) * $remainingreal) /
			    ($lastremainingreal[scalar(@lastremainingreal)-1] - $remainingreal));
	    # round to 1 decimal point
	    $timeleft = (int($timeleft * 10) / 10);
	    &log ("I'm guessing you have about $timeleft minutes left.");
	}

	if ($cpu == 1) {
	    &log ("Throttling CPU to half speed.");
	    `/usr/bin/crusoe -s`;
	    $cpu = 0;
	}

	if ($brightness > 0) {
	    &log ("Setting brightness to 0.");
	    `/usr/bin/setbrightness 0`;
	    $brightness = 0;
	}

	if (($remaining <= 10) && ($remaining >= 5) &&
	    ($lastremaining > 10)) {
	    &log ("Battery has dropped below 10%.");
	    `wall Battery is at $remaining\%..`;
	}
	elsif (($remaining < 5) && ($remaining > 2)) {
	    `wall Battery is at $remaining\%.  Please plug me in!`;
	    &log ("Battery has dropped below 5%.");
	    if (!$shutdown) {
		&log ("Initiating shutdown in ten minutes.");
		`/sbin/shutdown -h 10min &`;
		$shutdown = 1;
	    }
	}
	elsif ($remaining <= 2) {
	    &log ("Battery below 2%.  Initiating immediate shutdown.");
	    `wall Shutting down system due to low battery.`;
	    if ($shutdown) {
		`/sbin/shutdown -c`;
	    }
	    `/sbin/shutdown -h now`;
	    $shutdown = 1;
	    close LOG;
	    exit (0);
	}
    }
    $lastremaining = $remaining;
    unshift @lastremainingreal, $remainingreal;
}

close LOG;

exit (0);

sub log {
    my $message = shift;
    chomp $message;
    $date = `date`;
    chomp $date;
    print LOG "[", $date, "] ", $message , "\n";
}