Merge two urls using PHP

merge_urls.php

<?php

/**
 * Combine two urls.
 *
 * The urls can be either a string or url parts that consist of:
 *
 *     scheme, host, port, user, pass, path, query, fragment
 *
 * If passed in as parts in an array, the query parameter can be either
 * a string or an array of name/value key pairs.  The query parameters
 * will be added on to the ones from the original url.  If you want to
 * remove query parameters, or any other parts of the url, you need to
 * pass the value in as null.
 *
 * Examples:
 *
 *     urlMerge(
 *         '/tests/section/people?id=9405',
 *         array('query' => array('found' => true, 'id' => null))
 *     );
 *
 *     urlMerge(
 *         'http://www.example.com/',
 *         array('scheme' => 'https', 'query' => 'foo=bar&test=1'
 *     );
 *
 *     urlMerge(
 *         array('path' => '/tests/item', 'query' => 'id=9405'),
 *         'http://www.example.com'
 *     );
 *
 * @param  string|array $original
 * @param  string|array $new
 * @return string
 */
function urlMerge($original, $new)
{
    if (is_string($original)) {
        $original = parse_url($original);
    }
    if (is_string($new)) {
        $new = parse_url($new);
    }
    $qs = null;
    if (!empty($original['query']) && is_string($original['query'])) {
        parse_str($original['query'], $original['query']);
    }
    if (!empty($new['query']) && is_string($new['query'])) {
        parse_str($new['query'], $new['query']);
    }
    if (isset($original['query']) || isset($new['query'])) {
        if (!isset($original['query'])) {
            $qs = $new['query'];
        } elseif (!isset($new['query'])) {
            $qs = $original['query'];
        } else {
            $qs = array_merge($original['query'], $new['query']);
        }
    }
    $result = array_merge($original, $new);
    $result['query'] = $qs;
    foreach ($result as $k => $v) {
        if ($v === null) {
            unset($result[$k]);
        }
    }
    if (!empty($result['query'])) {
        $result['query'] = http_build_query($result['query']);
    }
    if ($result['path'][0] != '/') {
        $result['path'] = "/{$result['path']}";
    }
    return (isset($result['scheme']) ? "{$result['scheme']}://" : '')
        . (isset($result['user']) ? $result['user']
            . (isset($result['pass']) ? ":{$result['pass']}" : '').'@' : '')
        . (isset($result['host']) ? $result['host'] : '')
        . (isset($result['port']) ? ":{$result['port']}" : '')
        . (isset($result['path']) ? $result['path'] : '')
        . (!empty($result['query']) ? "?{$result['query']}" : '')
        . (isset($result['fragment']) ? "#{$result['fragment']}" : '');
}