It's also very easy to do with 'simplehtmldom'

include('simple_html_dom.php');
# parse and echo
$html = str_get_html("i'm here <i>and</i> <a href='http://example.com'>this is my site</a>");
$a = $html->find('a');
$a[0]->outertext = "{$a[0]->innertext} ( {$a[0]->href} )";

echo strip_tags($html);

And that produces the code you want in your test case.

The DOM solution:

$dom = new DOMDocument;
$dom->loadHTML($html);
$xpath = new DOMXPath($dom);
foreach($xpath->query('//a[@href]') as $node) {
    $textNode = new DOMText(sprintf('%s (%s)',
        $node->nodeValue, $node->getAttribute('href')));
    $node->parentNode->replaceChild($textNode, $node);
}
echo strip_tags($dom->saveHTML());

and the same without XPath:

$dom = new DOMDocument;
$dom->loadHTML($html);
foreach($dom->getElementsByTagName('a') as $node) {
    if($node->hasAttribute('href')) {
        $textNode = new DOMText(sprintf('%s (%s)',
            $node->nodeValue, $node->getAttribute('href')));
        $node->parentNode->replaceChild($textNode, $node);
    }
}
echo strip_tags($dom->saveHTML());

All it does is load any HTML into a DomDocument instance. In the first case it uses an XPath expression, which is kinda like SQL for XML, and gets all links with an href attribute. It then creates a text node element from the innerHTML and the href attribute and replaces the link. The second version just uses the DOM API and no Xpath.

Yes, it's a few lines more than Regex but this is clean and easy to understand and it won't give you any headaches when you need to add additional logic.

regex do make your life easy here. Just match the URL.

preg_match_all('/href="([^"]+)"/', $text, $m);
$text = str_replace('</a>', ' (' . $m[1][0] . ')', $text);
$text = strip_tags($text);