use HTML::Parser;

use warnings;
use strict;

my $p = HTML::Parser->new(
    api_version => 3,
    start_h   => [\&start, 'tagname, attr, attrseq, text'],
    end_h     => [\&end,   'tagname, text'],
    comment_h => [\&comm,  'text' ],
    default_h => [ sub {print shift}, 'text'],
);
$p->unbroken_text(1);

my $file = shift;
$p->parse_file($file);

my ($pending, $link);

sub start {
    my($tag, $attr, $attrseq, $text) = @_;
    for my $k (keys %$attr) {
        if ($attr->{$k} =~ /\!/) {
            ($attr->{$k},$link) = transform_comments($attr->{$k});
        }
    }
    $pending++;
    my $a = join ' ',
          map {
            $_ eq '/' ? $_ :
            "$_=\"$attr->{$_}\""
          } @$attrseq;
    print "<$tag", $a ? " $a>" : '>';
}
sub end {
    my ($tag,$text) = @_;
    print $text;
    if ($pending) {
        print $link;
        $pending = $link = '';
    }
}
sub comm {
    my $text;
    ($text,$link) = transform_comments($_[0]);
    print $text;
    print $link unless $pending;
}

sub transform_comments {
    my $str = shift;
    if ($str =~ /(\S+) --!>([^<]+?)<!-- (\1)/) {
        my ($key,$text) = ($1,$2);
        # return value of hash and link
        my $val  = "fake-$text-translated";
        my $link = '<a href=\'foo\'>foo</a>';
        return $val,$link;
    }
    $str;
}