function save_text_to_html($string) {
$string = strip_tags(trim($string));
$string= htmlspecialchars($string);
$string= text_to_html($string);
$string = preg_replace(“/[\r\n]{2,}/”, “

\n”, $string);
return $string;
}

function text_to_html($string) {
return preg_replace(‘/([hf][tps]{2,4}:\/\/[^ \t\n\r]+[^ .\t,\n\r\(\)"\'])/’, ‘‘, $string);
}

fonte: www.sastgroup.com