#!/usr/bin/perl
use XML::FOAF;
use URI;
my $uri = $ARGV[0];
my $file = $ARGV[1];
my $rdfs='http://www.w3.org/2000/01/rdf-schema#';
die "Usage $0 <url>; eg $0 http://www.livejournal.com/users/danbri/data/foaf" unless $uri;

# I'm messing around with XML::FOAF based on some code from crschmidt and ben trott
# danbri@w3.org

# Further playing leads to a script which will go out and fetch all your friends
# recursively out to a certain level, and print name/nick/mbox/mbox_sha1sum, along 
# with level.

# Implements some very simple caching (nothing stored locally, just a "seen" cache)
# This script is very rough. I don't recommend anyone using it.
#crschmid@uiuc.edu

%uris;
%bigarray;
my $p = personFromURI($uri);
$uris{$uri} = 1;

die "No person described in FOAF data" unless $p;

personBlurb($p, 1);
knowsSummary($p, 1);

foreach (%bigarray) {
    print $_->{level} . " " . $_->{nick} . " " . $_->{name} . " " . $_->{mbox} . " " . $_->{mbox_sha1sum} .  "\n" if $_->{mbox_sha1sum};
    
}

##### Misc utilities

sub dataRefs {
  my $p=shift;
  my @data=();
  foreach my $mate (@{$p->knows}) {
    my $sa=$mate->get($rdfs.'seeAlso');
    push (@data, $sa);
  }
  return \@data;
}

sub personBlurb {
    my $p=shift;
    my $level = shift;
    if ($p) {
        $bigarray{$p->nick}->{'name'} = $p->name if $p->name;
        $bigarray{$p->nick}->{'nick'} = $p->nick if $p->nick;
        $bigarray{$p->nick}->{'mbox_sha1sum'} = $p->mbox_sha1sum if $p->mbox_sha1sum;
        $bigarray{$p->nick}->{'mbox'} = $p->mbox if $p->mbox;
        $bigarray{$p->nick}->{'level'} = $level;
    }
}

sub knowsSummary {
   my $p = shift;
   my $level = shift;
   if ($p) {
      foreach my $mate (@{$p->knows}) {
         personBlurb($mate, $level);
         if ($level < 3){ 
            my @d= @{dataRefs($p)};
            print  STDERR "reading friends of ".$mate->nick.", at level $level\n";
            foreach my $uri (@d) {
               print STDERR "FOAF from: $uri\n";
               if (!$uris{$uri}) {
                  my $p2=personFromURI($uri);
                  $uris{$uri} = 1;
                  personBlurb($p2, $level);
                  knowsSummary($p2, $level + 1);
               } else { print STDERR "Seen $uri, skipping.\n"; }
            }
         }
      }
   }
}

sub personFromURI {
  my $uri = shift;
  my $foaf = XML::FOAF->new(URI->new($uri), "FOAF-Fetch, danbri+fetchfoaf\@w3.org");
  my $p = $foaf->person if $foaf; # replace with PPD code?   see end of doc for snippet
  return $p;
}

sub allSeeAlso {
  my $p=shift;
  ## Get all rdfs:seeAlso arcs in the foaf graph:
  # this shows a 'raw RDF' style of interaction with the data.
  my @res=[];
  my $enum = $foaf->{model}->getStmts(undef,RDF::Core::Resource->new($rdfs.'seeAlso'),undef);
  my $statement = $enum->getFirst;
  while (defined $statement) {
    push @res, $statement->getObject->getLabel."\n";
    $statement = $enum->getNext
  }
  $enum->close;
  return @res;
}