HTML indenting with Perl

I have a variable (ex. $content) with HTML code (without line breaks - removed before). How to process HTML code with adding TAB indent after each open tag and decrease indent level after each closing tag?

P.S. I don't need external script or programm (like tidy). I need to make this in my own script.

For example: source content:

<!DOCTYPE html><html><head><title>test</title></head>   <body>  <h1>hello!</h1><p>It works!</p></body></html>

needed result:

<!DOCTYPE html>
<html>
    <head>
        <title>test</title>
    </head>
    <body>
        <h1>hello!</h1>
        <p>It works!</p>
    </body>
</html>

Solution

use HTML::HTML5::Parser qw();
use HTML::HTML5::Writer qw();
use XML::LibXML::PrettyPrint qw();

print HTML::HTML5::Writer->new(
    start_tags => 'force',
    end_tags => 'force',
)->document(
    XML::LibXML::PrettyPrint->new_for_html(
        indent_string => "\t"
    )->pretty_print(
        HTML::HTML5::Parser->new->parse_string(
            '<!DOCTYPE html><html><head><title>test</title></head>   <body>  <h1>hello!</h1><p>It works!</p></body></html>'
        )
    )
);

<!DOCTYPE html><html>
    <head>
        <title>test</title>
    </head>
    <body>
        <h1>hello!</h1>
        <p>It works!</p>
    </body>
</html>