Regex PHP - Auto-detect YouTube, image and “regular” links

Question

I want to make it so that in my chat-application, links to websites can be clickable and links to YouTube and images automatically gets embedded.

I\'ve made this cod

Answer 1

Here is a solution I came up with:

$str = 'This is an image: google.ca/images/srpr/logo3w.png

YouTube: http://www.youtube.com/watch?v=V2b8ilapFrI&feature=related

Stackoverflow:  http://stackoverflow.com/';

$str = preg_replace_callback('#(?:https?://\S+)|(?:www.\S+)|(?:\S+\.\S+)#', function($arr)
{
    if(strpos($arr[0], 'http://') !== 0)
    {
        $arr[0] = 'http://' . $arr[0];
    }
    $url = parse_url($arr[0]);

    // images
    if(preg_match('#\.(png|jpg|gif)$#', $url['path']))
    {
        return '';
    }
    // youtube
    if(in_array($url['host'], array('www.youtube.com', 'youtube.com'))
      && $url['path'] == '/watch'
      && isset($url['query']))
    {
        parse_str($url['query'], $query);
        return sprintf('', $query['v']);
    }
    //links
    return sprintf('%1$s', $arr[0]);
}, $str);

Let me know if you need me to clarify anything for you.