PHP string replace when string is not
<p>When href="something/blah/" I need to add the domain $site/something/blah</p>

<p>When href="/someething/blah" I need to add the domain $site/something/blah</p>

<p>when href="http:// I need to do nothing.</p>

<p>when href="www.blah.com I need to add http://</p>

<p><strong>Updated for more specific situation</strong></p>

<p>Simply showing me code to add http:// when it does not exist will not help as there are to many case situations that don't apply to just http://</p>