package XML::FOAF::Utils;
##############################################################################

use strict;
use vars qw($VERSION $MAX_DEPTH);
use XML::FOAF;

$MAX_DEPTH = 7;
$VERSION   = 0.1;

my $Digest;

BEGIN {
	$Digest = 'Digest::SHA';
	eval q| require Digest::SHA |;
	if($@ and $@ =~ /Can't locate/){
		require Digest::SHA::PurePerl;
		$Digest = 'Digest::SHA::PurePerl';
	}
}

BEGIN {
	*{XML::FOAF::Person::seeAlso} = sub {
		$_[0]->get("http://www.w3.org/2000/01/rdf-schema#seeAlso");
	} unless(XML::FOAF::Person->can('seeAlso'));
}


##############################################################################


sub new {
	my $class = shift;
	my %opt   = @_;
	my $self  = {};
	bless $self,$class;

	$self->{_digest} = $Digest->new(1);
	$self->depth(0);
	$self->max_depth( defined $opt{MAX_DEPTH} ? $opt{MAX_DEPTH}
	                                              : $MAX_DEPTH || 0 );
	$self;
}


sub max_depth {
	$_[0]->{_max_depth} = $_[1] if(@_ > 1);
	$_[0]->{_max_depth};
}


sub depth {
	$_[0]->{_depth} = $_[1] if(@_ > 1);
	$_[0]->{_depth};
}


sub traverse {
	my $self  = shift;
	my $code  = shift;
	my @foafs = @_;
	my $max   = $self->max_depth;
	my $depth = $self->depth;

	for my $foaf (@foafs){
		my $p = $foaf->person;
		$code->($self,$p) if($p);
		$self->_traverse($code,$foaf);
	}

	$self;
}


sub _traverse {
	my $self  = shift;
	my $code  = shift;
	my $foaf  = shift;
	my $max   = $self->max_depth;
	my $depth = $self->depth;

	$self->depth(++$depth);

	if($depth > $max){
		$self->depth($depth - 1);
		return;
	}

	for my $p ( @{$foaf->person->knows} ){

		$code->($self,$p) or next;

		if(my $ref = $p->seeAlso){
			my $foaf = XML::FOAF->new( URI->new($ref) );
			$self->_traverse($code,$foaf) if($foaf);
		}
	}

	$self->depth($depth - 1);
}


sub finger {
	my $self  = shift;
	my $mbox  = shift || return;
	my @foafs = @_;
	my $searched = {};
	my $sha1sum;
	my $found;

	if($mbox !~ /^mailto:/ and $mbox =~ /@/){
		$mbox = 'mailto:' . $mbox;
		$sha1sum = $self->{_digest}->add($mbox)->hexdigest;
	}
	else{
		$sha1sum = $mbox;
		$mbox   = '';
	}


	$self->traverse(sub {
		return 0 if($found);

		my $utils    = shift;
		my $person   = shift;
		my $_mbox    = $person->mbox || '';
		my $_sha1sum = $person->mbox_sha1sum || '';
		my $seeAlso  = $person->seeAlso;

		$searched->{$seeAlso}++ if($seeAlso);

		return 0 if($searched->{$seeAlso} and $searched->{$seeAlso} > 1);

		if($sha1sum eq $_sha1sum){
			$found = $person;
		}
		elsif($mbox and $_mbox eq $mbox){
			$found = $person;
		}

		! $found;
	},@foafs);

	$found;
}


1;