replace any links that don't start with http

linkreplace.php

// replace any links that don't start with http
if (preg_match_all('#<a href="([^"]+)"#', $text, $matches)) {
    foreach ($matches[1] as $key => $match) {
        if (!preg_match('#^https?:#', $match) && !preg_match('#^ftps?:#', $match)) {
            $match = 'http://' . $match;
        }
        $text = preg_replace('#' . preg_quote($matches[0][$key], '#') . '#', '<a href="' . $match . '"', $text, 1);
    }
}