REGEX for Matching img tag within arbitrary number of nested custom tags

Question

I am writing a message board that allows for quoting and quote chaining of other users. The message board allows certain html tags including the <img>. When a message is quoted, I want to find the <img> and replace the picture with a thumbnail. Here is my current code:

<?php
 $pattern = "<quote msgid=\"t,(\d+),(\d+)@(\d+)\" from=\"([A-z0-9_\.-]+)\" posted=\"(\d+)\">(.+)<img src=\"https?:\/\/i\.(minus|imgur)\.com\/([A-z0-9_\.-]+)\.(jpg|gif|png|jpeg)\"( \/)?>";
 $replace = "<div class=\"quoted-message\" msgid=\"t,$1,$2@$3\"><div class=\"message-top\">From: $4 | Posted: $5</div>$6<img src=\"http:\/\/$7.com\/$8s\.$9\" />";
 $encoded = preg_replace($pattern, $replace, $encoded);
?>

The pattern itself works but the problem I am running into is that it does not play nice with nested quotes. For example the data can look like this:

<quote msgid="t,1234,3456@0" from"user" posted="test">Some words here<quote msgid="t,5635,57456@0" from"user2" posted="test">Some more <b>words</b> here<quote msgid="t,1243532,3452@0" from"user" posted="test">Something else here<img src="linktoimage"/></quote>some words can go here</quote>or here</quote>

My current regex will replace the first 3 Opening quote tags with one div tag instead of just matching the most inner tag. I know it has to do with the (.+) but I don't know what else I can do in order to check for preceding data.

Any help would be greatly appreciated.

Answer 1

Regular expressions are not very suitable for your situation (very oddly explained here). You should really use a parser.

Answer 2

(?!<quote.*?<quote)(<quote)

Matches the inner most quote tag.

http://regexr.com?30ng2