Text::Summary::MediaWiki - Produce a short summary from MediaWiki markup

    use Text::Summary::MediaWiki;

    my $s = Text::Summary::MediaWiki->new(
      url => "http://en.wikipedia.org/wiki/", # Trailing / is required
      get => sub {
        my($url) = @_;
        # return markup of page at URL
      });

    print $s->get("Perl");

package Text::Summary::MediaWiki;
use strict;

use Carp;
use HTML::Entities;

our $VERSION = '0.02';

my %TMP_WHITELIST = (
  IPA => 1,
  'Lang-ru' => 1,
  'Nihongo' => 1, # not sure about this one

);

sub new {
  my($class, %opt) = @_;

  return bless {
    url => $opt{url} || croak("No URL provided"),
    get => $opt{get} || croak("No get callback provided"),
    redirect_limit => $opt{redirect_limit} || 5,
    approx_length => $opt{approx_length} || 200,
    template_whitelist => {%TMP_WHITELIST, $opt{template_whitelist}},
  }, $class;
}

sub get {
   my($self, $name, $redirects) = @_;

   return "Too many redirects" if defined @$redirects &&
     @$redirects > $self->{redirect_limit};

   $name = _name($name);

   my $text = $self->{get}->($self->{url} . $name);

   return "" unless $text =~ /\w/;

   return $self->format($text, $name, $redirects);
}

sub _name {
   my $name = ucfirst shift;
   $name =~ s/ /_/g;
   return $name;
}

sub format {
   my($self, $text, $title, $redirects) = @_;

   # handle redirects
   if($text =~ /^#REDIRECT[ :]*\[\[(.*?)(?:#.*?)?\]\]/i) {
      push @$redirects, $title;
      return $self->get($1, $redirects);
   }

   # Remove comments and templates (maybe should handle templates..?)
   $text =~ s/{{.*?}}//sg;
   $text =~ s/<!--.*?-->//sg;
   # Don't want references..
   $text =~ s/<ref>.*?<\/ref>//sg;

   my($line, $maybe) = ("", 0);
   for(split /\n/, $text) {
      s/\r//g;
      next if /^\s*$/;

      if(/^\s*(?:[-_#!\t}{:|<=\[]|\W*$)/
        && (!/^\s*\[\[/ || /\[\[Image:/i)) {
        if($maybe == 1 && /[#!{}|]/) { $maybe = 0; }
        next;
      }

      next if /^\s*\*/ and not $line; # lists in templates, etc.
      next if /^\s*\w+\s*=/; # info boxes..

      if($maybe < 1 && /^(?:the\s+)?'/i) { # '''Thing'' is ....
        $line = "" if $maybe == 0;
        $maybe = 2;
      }

      if($maybe == 1) {
        $maybe++;
      } elsif($maybe == 0) {
        $line = "" if $line;
        $maybe = 1;
      }

      s/\t/ /g;

      if(/\*/ || $maybe == 3) {
        $maybe = 3;
        $line =~ s/,$//, last unless /^\*/;
        if(/^\s*\*+\s*\[\[.*?\]\]\s*-(\s*.*?)\.?\s*$/) {
           $line .= "$1,";
        }else{
           /^\s*\*+\s*(.*?)\.?$/;
           my $st = $1;
           $line .= ($st =~ /[;:,.]$/ ? " $st" : " $st,");
        }
        next;
      }else{
        $line =~ s/\.$/. / if $line;
        $line .= $_;
      }

      next if length($line) < $self->{approx_length};
      last;
   }

   if(defined $line) {
      $line =~ s/'''//g;
      $line =~ s/''//g;
      $line =~ s/{{([^|]+)|(.*?)}}/
                exists $self->{template_whitelist}->{_name($1)} ? _tl_fixup($2) : ""/ge;
      $line =~ s/\[\[(.*?)\]\]/_wp_link($1)/ge;
      $line =~ s/\[[^ ]+ (.*?)\]/$1/g;
      $line =~ s/<[^>]+>//g;
      $line =~ s/\{\{(.*?)\}\}//g;
      $line = decode_entities($line);
   }

   if(length($line) > 350) {
      $line = substr($line, 0, 380);
      $line =~ s/ +/ /g;
      if(not($line =~ s/^(.{330}[^\.]+\.).*/$1/)) {
         $line =~ s/^(.{345,}\w+)\W.*/$1/;
      }
      $line =~ s/(?:\.)?\s*$//;
      $line .= "...";
   }

   # fixup places where we've stripped templates
   $line =~ s/\s*,\s*\)/)/g;
   $line =~ s/\(\s*,\s*/(/g;
   $line =~ s/\(\s*\)//g;

   # get rid of extra spacing
   $line =~ s/ +/ /g;
   $line =~ s/(^ | $)//g;

   return $line, "$self->{url}$title" if wantarray;
   return $line;
}

sub _tl_fixup {
  my $name = shift;
  $name =~ s/|/ /g;
  return $name;
}

sub _wp_link {
  my $link = shift;
  my $x = index($link, '|');
  return substr($link, $x + 1) if $x != -1;
  return $link
}

1;
__END__