#!/usr/bin/perl

use strict;
use warnings;
use X11::Protocol;

# Nummer des Desktops auf den man wechseln will
my $desktop_nr=shift(@ARGV) || 0;
# ein Paar Konstante
my @const = ('AnyPropertyType', 0, -1, 0);

my $x = X11::Protocol->new();
my $root=$x->root;

# Anzahl der verfügbaren Desktops
my $desktops=unpack('L',($x->GetProperty($root, $x->atom('_NET_NUMBER_OF_DESKTOPS'), @const))[0]);
# Namen der Desktops
my @desktop_names=split("\000",($x->GetProperty($root, $x->atom('_NET_DESKTOP_NAMES'), @const))[0]);
# Nummer des gerade Aktiven Desktops
my $desktop_now=unpack('L',($x->GetProperty($root, $x->atom('_NET_CURRENT_DESKTOP'), @const))[0]);

print "Desktops: ".$desktops."\n";
print "Names: ".join(' | ',@desktop_names)."\n";
print "Active: ".$desktop_now."\n";

$desktop_nr-=$desktops while($desktop_nr>=$desktops);
$desktop_nr+=$desktops while($desktop_nr<0);

# Desktop wechseln
# Ziehmlich schlecht Dokumentiert das ganze.
# habe einen Tag gebraucht um die nötigen Informationen zusammen zu suchen...
$x->SendEvent(
  $root, 0,
  $x->pack_event_mask('SubstructureNotify', 'SubstructureRedirect'),
  $x->pack_event(
    name=>'ClientMessage',
    format=>32,
    window=>$root,
    type=>$x->atom('_NET_CURRENT_DESKTOP'),
    data=>pack('LLxxxxxxxxxxxx',$desktop_nr,time())
  )
);

use strict;
use Tk;
use Tk::Xlib;

my $desktop_nr = shift; !defined $desktop_nr and die;

my $mw = new MainWindow;
$mw->withdraw;

sub _root_property {
    my($prop) = @_;
    my(undef, @vals) = eval {
	$mw->property("get", "_NET_" . uc($prop), "root");
    };
    warn $@ if $@;
    @vals;
}

for my $prop (qw(number_of_desktops current_desktop)) {
    no strict 'refs';
    *{$prop} = sub {
	my($val) = _root_property($prop);
	$val;
    };
}

sub desktop_names {
    my($names) = eval {
	$mw->property("get", "_NET_DESKTOP_NAMES", "root");
    };
    warn $@ if $@;
    split /\0/, $names;
}

print "Desktops: " . number_of_desktops() . "\n";
print "Names: " . join(" | ", desktop_names()) . "\n";
print "Active: " . current_desktop() . "\n";

my $root = $mw->Display->RootWindow;
# Hier scheitert es:
$mw->SendClientMessage('_NET_CURRENT_DESKTOP', $$root, 32, pack('LLxxxxxxxxxxxx',$desktop_nr,time()));

print "Active now: " . current_desktop() . "\n";


__END__

$x->flush();