Knockout-Lite/app/BbCode/Tag/Youtube.php

<?php

namespace App\BbCode\Tag;

use Knockout\BbCode\Tag\TagInterface;
use Knockout\BbCode\Tokenizer\Tag as TokenTag;

class Youtube implements TagInterface
{

    public function format(TokenTag $tokenTag): string
    {
        $url = $tokenTag->getText();
        return "<a href=\"{$url}\" target=\"_blank\">[Youtube Embed]</a>";
    }

    public function getName(): string
    {
        return 'youtube';
    }

    public function getOriginalText(TokenTag $tokenTag) : string
    {
        return "[youtube]{$tokenTag->getText()}[/youtube]";
    }
}