#
# SAX Filter to follow XLinks and basically
# transform them into XIncludes.
#
# code by Brad Lhotsky <brad@divisionbyzero.net>
#
package XML::Expander::Filter::XLink;

use 5.006;
use strict;
use warnings;

use base qw(XML::SAX::Base);

use XML::Expander;
use LWP::Simple;
use Data::Dumper;

our $VERSION = 0.01;
our $DEBUG = 1;
#our $AUTOLOAD;

XML::Expander::Filter::XLink->_debug("USED ME");

sub start_element {
        my ($self,$el) = @_;
        $self->_debug("starting an element $el->{LocalName}");
        my $attrs = $el->{Attributes};
        my $xlink = undef;
        my %link = ();
        foreach my $a (keys %$attrs) {
                next unless $attrs->{$a}{NamespaceURI} eq 'http://www.w3.org/1999/xlink';
                $link{$attrs->{$a}{LocalName}} = $attrs->{$a}{Value};
                $xlink ||= $el->{LocalName};
        }
        return $self->SUPER::start_element($el) unless $xlink;
        $self->_debug("* found an xlink");
        print Dumper ( \%link );
        #
        # this where we incorporate the rest of the document if its
        # an xlink and stuff
        $self->{xlink_linked} = 1;
        my @lnx = qw/simple locator/;
        if($link{href}) {
                delete $self->{xlink_linked};
                my $parser = XML::SAX::ParserFactory->parser( { Handler => $self} );
                my $content = $self->retrieve($link{href});

                print $content;

                $parser->parse_string( $content );
                $self->{xlink_linked} = 1;
                return;
        }
        #
        # we should only get here if we have an xlinked we don't
        # understand, so lets make this safe
        delete $self->{xlink_linked};
        return $self->SUPER::start_element($el);
}

sub end_element {
        my $self = shift;
        if($self->{xlink_linked}) {
                delete $self->{xlink_linked};
                return;
        }
        $self->SUPER::end_element(@_);
}

sub characters {
        my $self = shift;
        return if $self->{xlink_linked};
        $self->SUPER::characters(@_);
}

sub retrieve {
        my ($self,$uri) = @_;
        return get($uri);
}

#sub AUTOLOAD {
#       my ($self) = shift;
#       $self->_debug("Attempting to AUTOLOAD $AUTOLOAD");
#       my $func = 'SUPER::' . (split /\:\:/, $AUTOLOAD)[-1];
#       $self->_debug("fucntion: $func");
#       #no strict 'refs';
#       #$self->$func(@_);
#}

sub _debug {
        return unless $DEBUG;
        my ($self,@msgs) = @_;
        my $time = join ':', map { unless( /^\d\d$/ ) { s/^/0/; }  $_; } (localtime)[2,1,0];
        for(@msgs) {
                chomp;
                print STDERR "$time DEBUG> $_\n";
        }
}

1;