URL parser

url.php

<?php
function getRedirectTo(string $appBaseUrl, $server, $redirectTo = ''): string {
	$returnUrlData = strlen($redirectTo) > 0
		? parse_url($redirectTo, PHP_URL_SCHEME|PHP_URL_HOST|PHP_URL_PORT|PHP_URL_PATH|PHP_URL_QUERY|PHP_URL_FRAGMENT)
		: []
		;
	$appBaseUrlParsed = parse_url($appBaseUrl, PHP_URL_SCHEME|PHP_URL_HOST|PHP_URL_PORT|PHP_URL_PATH|PHP_URL_QUERY|PHP_URL_FRAGMENT)
	if (!array_key_exists($returnUrlData, 'scheme')) {
		if (array_key_exists($appBaseUrlParsed, 'scheme')) {
			$returnUrlData['scheme'] = $appBaseUrlParsed['scheme'];
		} else {
			$returnUrlData['scheme'] = guessHTTPS($server);
		}
	}
	if (!array_key_exists($returnUrlData, 'host')) {
		if (array_key_exists($appBaseUrlParsed, 'host')) {
			$returnUrlData['host'] = $appBaseUrlParsed['host'];
			if (array_key_exists($appBaseUrlParsed, 'port')) {
				$returnUrlData['port'] = $appBaseUrlParsed['port'];
			}
		} else {
			$returnUrlData['host'] = $server['HTTP_HOST'];
			$returnUrlData['port'] = $server['SERVER_PORT'];
		}
	}
	if (array_key_exists($returnUrlData, 'port')) {
		if ($returnUrlData['port'] == 80 && $returnUrlData['scheme'] === 'http') unset($returnUrlData['port']);
		if ($returnUrlData['port'] == 443 && $returnUrlData['scheme'] === 'https') unset($returnUrlData['port']);
	}
	if (!array_key_exists($returnUrlData, 'path')) {
		if (array_key_exists($appBaseUrlParsed, 'path')) {
			$returnUrlData['path'] = $appBaseUrlParsed['path'];
			$returnUrlData['query'] = $appBaseUrlParsed['query'];
		} else {
			$returnUrlData['path'] = strstr($_SERVER['REQUEST_URI'], '?', true);
			$returnUrlData['query'] = $_SERVER['QUERY_STRING'];
		}
	}

}

function guessHTTPS($server): string {
	if (!array_key_exists($server, 'HTTPS'))
		return 'http';
	if ($server['HTTPS'] === 'off')
		return 'http';
	return empty($server['HTTPS']) ? 'http' : 'https';
}