Regular expressions in PHP / find "<a> </a>" - php

Question

I want to check a textarea. If the user enter some links in the textarea, php should automatically tag the links. I'm using this code:
$message = "text with some link within";
$url = '#(?!<a[^>]*?>)(http)?(s)?(://)?(([a-zA-Z])([-\w]+\.)+([^\s\.]+[^\s]*)+[^,.\s])(?![^<]*?</a>)#';
if(preg_match($url, $message) == 1){
$message = preg_replace($url, '$0', $message);
}
The problem is, when there's already a tagged link (with an "a" tag), regex is destroying the link.
Here is an example:
first input from textarea: Hello .... test.com
changed by regex: Hello ... test.com
this is working fine, but if you update this:
Hello ... http://test.com" target="_blank" rel="nofollow" title="test.com" target="_blank" rel="nofollow" title="test.com">test.com">test.com">test.com
Thanks for your help!

Answer 1

I'm not familiar with PHP and maybe this is not a good pattern for url validation, but the point is if there is already an "a" tag, the text is not replaced.
<?php
$message = array(
'Hello ... test.com',
"Hello .... http://www.test.com ..."
);
$url = '#(<a[^>]*>[^<]+</a>|((https?://)?[\w\.-]+\.[a-zA-Z]{2,3}[^\s\W]*))#';
foreach ($message as $msg) {
preg_match($url, $msg, $matches);
if(preg_match($url, $msg) == 1 && count($matches) > 2) {
$msg = preg_replace($url, '$0', $msg);
}
echo $msg.PHP_EOL;
}
// Output:
// Hello ... test.com
// Hello .... http://www.test.com ...
Hope it helps.