#!/usr/bin/perl
#
# A motion sensor monitor for mon. Requires "pnmpsnr" from netpbm
# distribution. You will need to modify this to obtain the image from
# your image sensor. I use a D-Link DCS-900W, which allows me to simply
# fetch the current image via HTTP.
#
# Jim Trocki
#
# Copyright 2007 Jim Trocki
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#


sub getimage;
sub debug;

$SECS = 0;
$TOLERANCE = 3;
$COUNT = 2000;

$lastY = undef;
$Y = undef;
$movement = 0;

$prev_img = "a.pnm";
$cur_img = "b.pnm";

getimage ($prev_img);

sleep $SECS;

#
# this will run until $COUNT images are sampled or until a change
# in the image is identified
#
for ($i = 0; $i < $COUNT; $i++)
{
   getimage ($cur_img);
   $output = `pnmpsnr $prev_img $cur_img 2>&1`;

   die if ($output !~ /Y\s+color\s+component:\s+(\d+(\.\d+)?)/ims);
   $Y = $1;

   $diff = abs ($Y - $lastY);

   debug "y=$Y diff=$diff";

   if (defined $lastY && $diff > $TOLERANCE)
   {
	$movement++;
	last;
   }

   system ("mv $cur_img $prev_img");
   $lastY = $Y;

   sleep $SECS;
}

# eventually give the mon server a status update
if ($movement)
{
#    mkdir ("motion-$s");
#    system ("mv $cur_img $prev_img motion-$s");
    my @t = localtime;
    my $f = sprintf ('motion-%04d%02d%02d-%02d%02d%02d.jpg', $t[5] + 1900, $t[4] + 1, @t[3,2,1,0]);
    system ("pnmtojpeg $cur_img > $f");
    print "motion detected\n";
}

else
{
    print "no motion detected\n";
}

exit ($movement);


sub getimage
{
    my $name = shift;
    
    debug "wgetting $name";
    system ("wget -O- -q --http-user=root --http-passwd='roots' " .
            "http://cam:8080/IMAGE.JPG | " .
	    "jpegtopnm > $name 2>/dev/null");
}

sub debug
{
    my $d = shift;

    print STDERR "$d\n";
}