#!/usr/bin/perl -w

use strict;
use warnings;
use Getopt::Std;

getopts('pieh', \my %opts);

# help requested?
usage() && exit if $opts{h};

# get the current desktop & background image (if any)
my $desktop = getCurrentDesktop();
my $currentImage = getCurrentImage($desktop);

# set up the location of the artwork directory and index file
my $backgroundDir = "/home/dave/BackgroundArt";
my $indexfile = "$backgroundDir/.index.txt";

# Setup complete, now take an action based on the flags passed in

# info request for current image?
info($currentImage) && exit if $opts{i};

# edit request for current image?
edit($currentImage) && exit if $opts{e};

# otherwise we must be changing to a new image -- assume going forward unless -p specified
my $direction = $opts{p} ? -1 : +1;

# figure out the next image from the index file
my $nextImage = getNextImage($currentImage, $direction);

# change the wallpaper for the current desktop 
`dcop kdesktop KBackgroundIface setWallpaper $desktop $nextImage  4`;

# thats it...
exit 0;

###########################################
sub info {
###########################################
	my ( $currentImage ) = @_;
	my $infofile = getInfoFile($currentImage);
	my @data = readFile($infofile);
	if ( @data )
	{
		`kdialog --passivepopup "@data" 60`;
	}
	return 1;
}

###########################################
sub edit {
###########################################
	my ( $currentImage ) = @_;
	my $infofile = getInfoFile($currentImage);

	my @data = readFile($infofile);
	my $rv = `kdialog --title "Add/Edit" --textinputbox "Add/Edit details for $currentImage" "@data"`;

	# Now save the resulting text back to the info file
	writeFile($infofile, $rv);

	return 1;
}

###########################################
sub getInfoFile {
###########################################
	my ( $infofile ) = @_;
	$infofile =~ s#^(.*)/(.*)#$1/.info/$2.txt#;
	return $infofile;	
}

###########################################
sub readFile {
###########################################
 	my ($filename ) = @_;
	my @data;
	if ( -e $filename )
	{
		open (FILE, "< $filename") or die "Error: couldn't open file $filename: $!\n";
		@data = <FILE>;
		close FILE;
	}
	return @data;
}

###########################################
sub writeFile {
###########################################
	my ( $filename, $data ) = @_;
	open ( FILE, "> $filename");
	print FILE $data;
	close FILE;
}

###########################################
sub getCurrentDesktop {
###########################################
	my $rv = `dcop kwin KWinInterface currentDesktop`;
	chomp $rv;
	return $rv;
}

###########################################
sub getCurrentImage {
###########################################
	my ( $desktop ) = @_;
	my $wallpaper = `dcop kdesktop KBackgroundIface currentWallpaper $desktop`;
	chomp $wallpaper;

	# return a dummy value if no image currently set
	$wallpaper = "_noimage_" if !$wallpaper;
	return $wallpaper;
}

###########################################
sub getNextImage {
###########################################
	my ( $currentImage, $direction ) = @_;
	# first get the index of this image in the indexfile
	my $index = `grep -n $currentImage $indexfile | cut -d':' -f1`;	
	chomp $index;
	# set to 0 if not found, since there may be either no image or one we haven't got listed
	$index = 0 if !$index;

	# we'll need to know the number of lines so we can wrap around if required
	my $length = `wc -l $indexfile | cut -d' ' -f1`;
	chomp $length;

	# increment/decrement index, wrapping around if required
	$index += $direction;
	$index = 1 if $index > $length;
	$index = $length if $index <= 0;

	# get the filename corresponding to this new index
	my $newBackground = `head -$index $indexfile | tail -1`;
	chomp $newBackground;

	return $newBackground;
}

###########################################
sub usage {
###########################################
	 print <<"END";
usage: wallpaper <option>
Options:
(default): 	Next image
-p: 		Prev image
-i: 		show Info
-e: 		Edit info
-h: 		Help

END
}