use strict;
use warnings;

use HTML::Parser;

# tags with allowable attributes
my %tags = (
    img => { map { $_ => 1 } qw(width height src border) },
    a 	=> { map { $_ => 1 } qw(href target name) },
);

# tags with no attributes
$tags{$_} = {} foreach qw(b i u br p code pre);

my $html = "";

sub safe_html {

	my $p = new HTML::Parser(
		api_version => 3, 
		start_h	=> [ \&_start, 'tagname, attr' ],
		end_h => [ \&_end,   'tagname'],
		text_h => [ \&_text,  'text'   ],
	    );

	$p->parse(shift);

	$html =~ s/\s+/ /g;

	return $html;

}

sub _start {

	my ($tag, $attrs) = @_;
	return unless $tags{$tag};

	$html .= '<' . $tag;

	while (my ($attr, $value) = each %$attrs) {
		if ($tags{$tag}->{$attr}) {
			$html .= sprintf(q{ %s="%s"}, $attr, $value);
		}
	}

	$html .= '>';

}

sub _end {
	my $tag = shift;
	$html .= '</' . $tag . '>' if $tags{$tag};
}

sub _text {
	$html .= shift;
}