check string for youtube link or image - php

Question

I have a small piece of code that checks a string for a url and adds the < a href> tag to create a link. I also have it check the string for a youtube link and then add rel="youtube" to the < a> tag.
How can I get the code to only add rel to the youtube links?
How can I get it to add a different rel to any type of image link?
$text = "http://site.com a site www.anothersite.com/ http://www.youtube.com/watch?v=UyxqmghxS6M here is another site";
$linkstring = preg_replace( '/(http|ftp)+(s)?:(\/\/)((\w|\.)+)(\/)?(\S+)?/i', '\4', $text );
if(preg_match('/http:\/\/www\.youtube\.com\/watch\?v=[^&]+/', $linkstring, $vresult)) {
$linkstring = preg_replace( '/(http|ftp)+(s)?:(\/\/)((\w|\.)+)(\/)?(\S+)?/i', '<a rel="youtube" href="\0">\4</a>', $text );
$type= 'youtube';
}
else {
$type = 'none';
}
echo $text;
echo $linkstring, "<br />";
echo $type, "<br />";

Answer 1

Try http://simplehtmldom.sourceforge.net/.
Code:
<?php
include('simple_html_dom.php');
$html = str_get_html('Link');
$html->find('a', 0)->rel = 'youtube';
echo $html;
Output:
[username#localhost dom]$ php dom.php
Link
You can build an entire page DOM or a simple single link with this library.
Detecting hostname of URL:
Pass the url to parse_url. parse_url returns an array of the URL parts.
Code:
print_r(parse_url('http://www.youtube.com/watch?v=UyxqmghxS6M'));
Output:
Array
(
[scheme] => http
[host] => www.youtube.com
[path] => /watch
[query] => v=UyxqmghxS6M
)

Answer 2

Try the following:
//text
$text = "http://site.com/bounty.png a site www.anothersite.com/ http://www.youtube.com/watch?v=UyxqmghxS6M&featured=true here is another site";
//Youtube links
$pattern = "/(http:\/\/){0,1}(www\.){0,1}youtube\.com\/watch\?v=([a-z0-9\-_\|]{11})[^\s]*/i";
$replacement = '<a rel="youtube" href="http://www.youtube.com/watch?v=\3">\0</a>';
$text = preg_replace($pattern, $replacement, $text);
//image links
$pattern = "/(http:\/\/){0,1}(www\.){0,1}[^\/]+\/[^\s]+\.(png|jpg|jpeg|bmp|gif)[^\s]*/i";
$replacement = '<a rel="image" href="\0">\0</a>';
$text = preg_replace($pattern, $replacement, $text);
note that the latter can only detect links to images which have an extension. As such, links like www.example.com?image=3 will not be detected.