file-to-http-url.php

<?php

/*

# Example usage:

http_to_file("http://localhost/~robbert/example.com/img/");
// returns "/Users/Robbert/Sites/example.com/img/";

file_to_http("/Users/Robbert/Sites/example.com/style/mobile.css");
// returns "http://localhost/~robbert/example.com/style/mobile.css"

file_to_http("/Users/Robbert/Sites/example.com/../");
// returns "http://localhost/~robbert/"

file_to_http("/Users/Robbert/Sites/example.com/symlink-to-otherwebsite.org-style/");
// returns "http://localhost/~robbert/otherwebsite.org/style/"

*/

function magic($http, $file)
{
  $http_dir = dirname($http);
	$file_dir = dirname($file);

	$http_trail = array_reverse(explode('/', $http_dir));
	$file_trail = array_reverse(explode('/', $file_dir));

	$l = min(count($http_trail), count($file_trail));

	$i = 0;
	while ($i < $l)
	{
		if ($http_trail[$i] !== $file_trail[$i])
		{
			// $i++;
			break;
		}
		$i++;
	}

	$http_root = implode('/', array_reverse(array_slice($http_trail, $i))) . '/';
	$file_root = implode('/', array_reverse(array_slice($file_trail, $i))) . '/';

	return array($http_root, $file_root);
}

function http_to_file($uri)
{
	$roots = magic($_SERVER['SCRIPT_NAME'], $_SERVER['SCRIPT_FILENAME']);

	$parts = parse_url($uri);
	$path = $parts['path'];

	return str_replace($roots[0], $roots[1], $path);
}

function file_to_http($path)
{
	$resolved = realpath($path);

	if ($resolved === false)
		return "";
	else
		$path = $resolved;

	$roots = magic($_SERVER['SCRIPT_NAME'], $_SERVER['SCRIPT_FILENAME']);

	return str_replace($roots[1], $roots[0], $path);
}