#!/usr/bin/env perl

# This script takes a default image, and superimposes any number of other
# images on top of it. Then it calls the gconftool to set it as a background
# For example, you can use it to place your mrtg stats in the background,
# while still being able to use gnome icons and semi-transparency
#
#
# Created by Jelte Jansen
# Version 0.1
# Released under the GPL v2, see bottom of the script for the full license
#
# Beneath that, and example .gwallscriptrc can be found
#

use strict;
use Cwd;

my $conf_file = $ENV{HOME}."/.gwallscriptrc";

my $rundir = "/var/run/gwallscript";

my $resultfile = "gwallscript_background.png";

# you could change the next commands to suit your needs, the values enclosed
# in % are filled in by the script
my $getremotecommand = "wget %FILE% -O %OUTPUTFILE%";
my $getlocalcommand = "cp %FILE% ./%OUTPUTFILE%";

my $composecommand = "composite -compose atop -geometry %SIZE%%LOCATION% %FILE1% %FILE2% %OUTPUTFILE%";

my $getcommand = "gconftool-2 --get /desktop/gnome/background/picture_filename";
my $showcommand = "gconftool-2 --type string --set /desktop/gnome/background/picture_filename %OUTPUTFILE%";

my $resizecommand = "convert -resize '%SIZE%!' %IMAGE% %IMAGE%";


my @images = ();
my @imagenames = ();
my @sizes = ();
my @locations = ();

my $base_image = "";
my $interval = -1;

my $verbosity = 1;

sub command($) {
	my $cmd = shift();
	if ($verbosity > 0) {
		print "Executing: '$cmd'\n";
	}
	my $result = system($cmd);
	if ($verbosity > 0) {
		print "Return value: $result\n";
	}
	if ($result != 0) {
		print STDERR "Error executing '$cmd': $result\n";
	}
	return $result;
}

sub prepare_environment($) {
	my $rd = shift();
	# prepare environment
	command("mkdir -p $rd");
	chdir($rd);
}

sub read_config_file($) {
	my $config_file = shift();
	open(CONF, $config_file) || die "Unable to read config file $config_file: $!\n";
	my $image_nr = -1;
	my $linepart;
	foreach my $line (<CONF>) {
		#print $line;
		if ($line =~ s/^Base file:\s+(.*)$//i) {
			$base_image = $1;
		} elsif ($line =~ s/^Interval:\s+(.*)$//i) {
			$linepart = $1;
			if (!($linepart =~ /^[0-9]+$/)) {
				print STDERR "Error: interval value in $config_file not a number\n";
				exit(2);
			} else {
				$interval = $linepart;
			}
		} elsif ($line =~ s/^Rundir:\s+(.*)$//i) {
			$rundir = $1;
		} elsif ($line =~ s/^Image:\s+(.*)$//) {
			$image_nr++;
			$images[$image_nr] = $1;
			$sizes[$image_nr] = "";
			$locations[$image_nr] = "";
		} elsif ($line =~ s/^Size:\s+(.*)$//i) {
			$linepart = $1;
			if (!($linepart =~ /^[0-9]+x[0-9]+$/)) {
				print STDERR "Error: bad size value for image $images[$image_nr]\n";
				exit(3);
			} elsif ($image_nr < 0) {
				print STDERR "Error: Size directive found but no image specified yet\n";
				exit(4);
			} elsif ($sizes[$image_nr] ne "") {
				print STDERR "Error: Multiple Size directives for image $images[$image_nr]\n";
				exit(5);
			} else {
				$sizes[$image_nr] = $linepart;
			}
		} elsif ($line =~ s/^Location:\s+(.*)$//i) {
			$linepart = $1;
			if (!($linepart =~ /^[0-9]+,[0-9]+$/)) {
				print STDERR "Error: bad location value for image $images[$image_nr]\n";
				exit(3);
			} elsif ($image_nr < 0) {
				print STDERR "Error: Location directive found but no image specified yet\n";
				exit(4);
			} elsif ($locations[$image_nr] ne "") {
				print STDERR "Error: Multiple Location directives for image $images[$image_nr]\n";
				exit(5);
			} else {
				$linepart =~ s/,/\+/;
				$linepart = "+" . $linepart;
				$locations[$image_nr] = $linepart;
			}
		}
	}
	
	if ($base_image eq "") {
		print STDERR "Error: no Base file directive in config file\n";
		exit(5);
	}
	if ($interval < 0) {
		print STDERR "Error: no Interval directive in config file\n";
		exit(6);
	}

}

sub get_image($)
{
	my $image = shift();
	my $cmd;
	my $result;
	if ($image =~ /^https?:\/\//) {
		$cmd = $getremotecommand;
	} elsif ($image =~ /^ftp:\/\//) {
		$cmd = $getremotecommand;
	} elsif ($image =~ /^\//) {
		$cmd = $getlocalcommand;
	} else {
		printf STDERR "Warning: don't know how to get $image, skipping\n";
		return 1;
	}
	
	my $outputfile = $image;
	$outputfile =~ s/.*\///;

	$cmd =~ s/%FILE%/$image/;
	$cmd =~ s/%OUTPUTFILE%/$outputfile/;
	
	print $cmd."\n";
	
	if (command($cmd) == 0) {
		# last part is image name
		$result = $outputfile;
	}
	return $result;
}

sub get_images() {
	my $i;
	my $curcompose;
	my $curresize;
	my $imagename;
	$imagename = get_image($base_image);
	if (!$imagename) {
		print STDERR "Error retrieving base image, quitting.\n";
		exit(4);
	}
	command("cp $imagename $resultfile");
	for ($i = 0; $i < (@images); $i++) {
		$imagename = get_image($images[$i]);
		if (!$imagename) {
			print STDERR "Could not determine resulting image file name, skipping\n";
		} else {
			if ($sizes[$i] ne "") {
				$curresize = $resizecommand;
				$curresize =~ s/%SIZE%/$sizes[$i]/g;
				$curresize =~ s/%IMAGE%/\"$imagename\"/g;
				command($curresize);
			}
			$curcompose = $composecommand;
#			$curcompose =~ s/%SIZE%/$sizes[$i]/g;
			$curcompose =~ s/%SIZE%//g;
			$curcompose =~ s/%LOCATION%/$locations[$i]/g;
			$curcompose =~ s/%FILE1%/\"$imagename\"/g;
			$curcompose =~ s/%FILE2%/\"$resultfile\"/g;
			$curcompose =~ s/%OUTPUTFILE%/\"$resultfile\"/g;
			command($curcompose);
		}
	}
}

sub show_background() {
	my $cmd = $showcommand;
	my $cwd = getcwd;
	my $newval = $cwd."/".$resultfile;

	# unfortunately, the name mus change, otherwise the screen is
	# not updated
	my $curval = `$getcommand`;
	chomp($curval);

	if ($curval eq $newval) {
		if ($verbosity > 0) {
			print "Values equal: '$curval' eq '$newval'\n";
		}
		my $changed_newval = $cwd."/1.".$resultfile;
		$cmd = "cp $newval $changed_newval";
		command($cmd);
		$newval = $changed_newval;
	} else {
		if ($verbosity > 0) {
			print "Values differ: '$curval' ne '$newval'\n";
		}
	}
	
	$cmd = $showcommand;
	$cmd =~ s/%OUTPUTFILE%/\"$newval\"/g;
	command($cmd);
}

sub usage() {
	print "Usage: gwallscript.pl [options]\n";
	print "Default settings are read from \$HOME/.gwallscriptrc\n";
	print "Options:\n";
	print "-c <file>:\tUse file as config file\n";
	print "-h:\t\tShow this help\n";
	print "-t:\t\ttest run, only run once (same as setting interval to 0)\n";
	print "-v <nr>:\tVerbosity level\n";
}

# handle command line arguments
my $arg;
my $override_interval;
while ($arg = shift()) {
	if ($arg eq "-c") {
		$conf_file = shift();
		if (!$conf_file) {
			usage();
			exit(1);
		}
	} elsif ($arg eq "-h") {
		usage();
		exit(0);
	} elsif ($arg eq "-t") {
		$override_interval = 1;
	} elsif ($arg eq "-v") {
		$verbosity = shift();
		if (!$verbosity || !($verbosity =~ /^[0-9]+$/)) {
			usage();
			exit(1);
		}
	} else {
		printf "Unknown argument: $arg, use -h for an overview of arguments\n";
		exit(2);
	}
}

# main loop
read_config_file($conf_file);
if ($override_interval) {
	$interval = 0;
}
prepare_environment($rundir);
print $interval."\n";
while (1) {
	get_images();
	show_background();
	if ($interval == 0) {
		exit(0);
	} else {
		sleep($interval);
	}
}



#
# LICENSE
#
#		    GNU GENERAL PUBLIC LICENSE
#		       Version 2, June 1991
#
# Copyright (C) 1989, 1991 Free Software Foundation, Inc.
#                       51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
# Everyone is permitted to copy and distribute verbatim copies
# of this license document, but changing it is not allowed.
#
#			    Preamble
#
#  The licenses for most software are designed to take away your
#freedom to share and change it.  By contrast, the GNU General Public
#License is intended to guarantee your freedom to share and change free
#software--to make sure the software is free for all its users.  This
#General Public License applies to most of the Free Software
#Foundation's software and to any other program whose authors commit to
#using it.  (Some other Free Software Foundation software is covered by
#the GNU Library General Public License instead.)  You can apply it to
#your programs, too.
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#		     END OF TERMS AND CONDITIONS	    How to Apply These Terms to Your New Programs
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#
#    <one line to give the program's name and a brief idea of what it does.>
#    Copyright (C) <year>  <name of author>
#
#    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.
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#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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#Also add information on how to contact you by electronic and paper mail.
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#If the program is interactive, make it output a short notice like this
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#
#    Gnomovision version 69, Copyright (C) year name of author
#    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type how w'.
#    This is free software, and you are welcome to redistribute it
#    under certain conditions; type how c' for details.
#
#The hypothetical commands how w' and how c' should show the appropriate
#parts of the General Public License.  Of course, the commands you use may
#be called something other than how w' and how c'; they could even be
#mouse-clicks or menu items--whatever suits your program.
#
#You should also get your employer (if you work as a programmer) or your
#school, if any, to sign a "copyright disclaimer" for the program, if
#necessary.  Here is a sample; alter the names:
#
#  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
#  Gnomovision' (which makes passes at compilers) written by James Hacker.
#
#  <signature of Ty Coon>, 1 April 1989
#  Ty Coon, President of Vice
#
#This General Public License does not permit incorporating your program into
#proprietary programs.  If your program is a subroutine library, you may
#consider it more useful to permit linking proprietary applications with the
#library.  If this is what you want to do, use the GNU Library General
#Public License instead of this License.
#
#
#

#
# EXAMPLE SETTINGS
#
#
# For images, you can specify a file location (starting with /), or a remote
# location (starting with http:// or ftp://)
#
# Each image has 1 Image: directive, and a few optionals:
# Image: (mandatory) place to get the image from
# Size: (optional) resize the image to this size (<horizontalsize>x<verticalsize>)
# Location: (optional) place the image here (xpos,ypos counting from the top left)
#

#
# General settings, these are mandatory
#

# original full-size wallpaper to impose the images on
#Base file: /home/yourusername/Firefox_wallpaper.png

# interval (in seconds) (this does not include time to download and update)
# if this is 0, run once and exit
# Don't set this too low, it causes quite some delay...
#Interval: 1800


#
# Optional general settings
#

# Temporary files, as well as the result, are stored here
#Rundir: /var/run/gwallscript

#
# Image settings
#

#Image: http://my-site.com/mrtg/firewall-rl0-day.png
#Size: 500x135
#Location: 100,100

#Image: http://my-size.com/munin/bind9_rndc-day.png
#Size: 500x135
#Location: 700,500