php parse_url reverse -- parsed url

These are the two functions I use for decomposing and rebuilding URLs:

function http_parse_query($query) {
    $parameters = array();
    $queryParts = explode('&', $query);
    foreach ($queryParts as $queryPart) {
        $keyValue = explode('=', $queryPart, 2);
        $parameters[$keyValue[0]] = $keyValue[1];
    }
    return $parameters;
}

function build_url(array $parts) {
    return (isset($parts['scheme']) ? "{$parts['scheme']}:" : '') . 
        ((isset($parts['user']) || isset($parts['host'])) ? '//' : '') . 
        (isset($parts['user']) ? "{$parts['user']}" : '') . 
        (isset($parts['pass']) ? ":{$parts['pass']}" : '') . 
        (isset($parts['user']) ? '@' : '') . 
        (isset($parts['host']) ? "{$parts['host']}" : '') . 
        (isset($parts['port']) ? ":{$parts['port']}" : '') . 
        (isset($parts['path']) ? "{$parts['path']}" : '') . 
        (isset($parts['query']) ? "?{$parts['query']}" : '') . 
        (isset($parts['fragment']) ? "#{$parts['fragment']}" : '');
}

// Example
$parts = parse_url($url);

if (isset($parts['query'])) {
    $parameters = http_parse_query($parts['query']);
    foreach ($parameters as $key => $value) {
        $parameters[$key] = $value; // do stuff with $value
    }
    $parts['query'] = http_build_query($parameters);
}

$url = build_url($parts);

This function should do the trick:

function unparse_url(array $parsed): string {
    $pass      = $parsed['pass'] ?? null;
    $user      = $parsed['user'] ?? null;
    $userinfo  = $pass !== null ? "$user:$pass" : $user;
    $port      = $parsed['port'] ?? 0;
    $scheme    = $parsed['scheme'] ?? "";
    $query     = $parsed['query'] ?? "";
    $fragment  = $parsed['fragment'] ?? "";
    $authority = (
        ($userinfo !== null ? "$userinfo@" : "") .
        ($parsed['host'] ?? "") .
        ($port ? ":$port" : "")
    );
    return (
        (\strlen($scheme) > 0 ? "$scheme:" : "") .
        (\strlen($authority) > 0 ? "//$authority" : "") .
        ($parsed['path'] ?? "") .
        (\strlen($query) > 0 ? "?$query" : "") .
        (\strlen($fragment) > 0 ? "#$fragment" : "")
    );
}

Here is a short test for it:

function unparse_url_test() {
    foreach ([
        '',
        'foo',
        'http://www.google.com/',
        'http://u:p@foo:1/path/path?q#frag',
        'http://u:p@foo:1/path/path?#',
        'ssh://root@host',
        '://:@:1/?#',
        'http://:@foo:1/path/path?#',
        'http://@foo:1/path/path?#',
    ] as $url) {
        $parsed1 = parse_url($url);
        $parsed2 = parse_url(unparse_url($parsed1));

        if ($parsed1 !== $parsed2) {
            print var_export($parsed1, true) . "\n!==\n" . var_export($parsed2, true) . "\n\n";
        }
    }
}

unparse_url_test();

Another implemention:

function build_url(array $elements) {
    $e = $elements;
    return
        (isset($e['host']) ? (
            (isset($e['scheme']) ? "$e[scheme]://" : '//') .
            (isset($e['user']) ? $e['user'] . (isset($e['pass']) ? ":$e[pass]" : '') . '@' : '') .
            $e['host'] .
            (isset($e['port']) ? ":$e[port]" : '')
        ) : '') .
        (isset($e['path']) ? $e['path'] : '/') .
        (isset($e['query']) ? '?' . (is_array($e['query']) ? http_build_query($e['query'], '', '&') : $e['query']) : '') .
        (isset($e['fragment']) ? "#$e[fragment]" : '')
    ;
}

The results should be:

{
    "host": "example.com"
}
/* //example.com/ */

{
    "scheme": "https",
    "host": "example.com"
}
/* https://example.com/ */

{
    "scheme": "http",
    "host": "example.com",
    "port": 8080,
    "path": "/x/y/z"
}
/* http://example.com:8080/x/y/z */

{
    "scheme": "http",
    "host": "example.com",
    "port": 8080,
    "user": "anonymous",
    "query": "a=b&c=d",
    "fragment": "xyz"
}
/* http://[email protected]:8080/?a=b&c=d#xyz */

{
    "scheme": "http",
    "host": "example.com",
    "user": "root",
    "pass": "stupid",
    "path": "/x/y/z",
    "query": {
        "a": "b",
        "c": "d"
    }
}
/* http://root:[email protected]/x/y/z?a=b&c=d */

{
    "path": "/x/y/z",
    "query": "a=b&c=d"
}
/* /x/y/z?a=b&c=d */

You should be able to do

http_build_url($parse)

NOTE: http_build_url is only available by installing pecl_http.

According to the docs it's designed specifically to handle the output from parse_url. Both functions handle anchors, query params, etc so there are no "other properties not mentioned on the $url".

To add http:// when it's missing, use a basic check before parsing it:

if (strpos($url, "http://") != 0)
    $url = "http://$url";