<?php
/**
 * Class Minify_CSS_UriRewriter 
 * @package Minify
 */

/**
 * Rewrite file-relative URIs as root-relative in CSS files
 *
 * @package Minify
 * @author Stephen Clay <steve@mrclay.org>
 */
class Minify_CSS_UriRewriter {
 
 /**
 * rewrite() and rewriteRelative() append debugging information here
 *
 * @var string
 */
 public static $debugText = '';
 
 /**
 * In CSS content, rewrite file relative URIs as root relative
 * 
 * @param string $css
 * 
 * @param string $currentDir The directory of the current CSS file.
 * 
 * @param string $docRoot The document root of the web site in which 
 * the CSS file resides (default = $_SERVER['DOCUMENT_ROOT']).
 * 
 * @param array $symlinks (default = array()) If the CSS file is stored in 
 * a symlink-ed directory, provide an array of link paths to
 * target paths, where the link paths are within the document root. Because 
 * paths need to be normalized for this to work, use "//" to substitute 
 * the doc root in the link paths (the array keys). E.g.:
 * <code>
 * array('//symlink' => '/real/target/path') // unix
 * array('//static' => 'D:\\staticStorage') // Windows
 * </code>
 * 
 * @return string
 */
 public static function rewrite($css, $currentDir, $docRoot = null, $symlinks = array()) 
 {
 self::$_docRoot = self::_realpath(
 $docRoot ? $docRoot : $_SERVER['DOCUMENT_ROOT']
 );
 self::$_currentDir = self::_realpath($currentDir);
 self::$_symlinks = array();
 
 // normalize symlinks
 foreach ($symlinks as $link => $target) {
 $link = ($link === '//')
 ? self::$_docRoot
 : str_replace('//', self::$_docRoot . '/', $link);
 $link = strtr($link, '/', DIRECTORY_SEPARATOR);
 self::$_symlinks[$link] = self::_realpath($target);
 }
 
 self::$debugText .= "docRoot : " . self::$_docRoot . "\n"
 . "currentDir : " . self::$_currentDir . "\n";
 if (self::$_symlinks) {
 self::$debugText .= "symlinks : " . var_export(self::$_symlinks, 1) . "\n";
 }
 self::$debugText .= "\n";
 
 $css = self::_trimUrls($css);
 
 // rewrite
 $css = preg_replace_callback('/@import\\s+([\'"])(.*?)[\'"]/'
 ,array(self::$className, '_processUriCB'), $css);
 $css = preg_replace_callback('/url\\(\\s*([^\\)\\s]+)\\s*\\)/'
 ,array(self::$className, '_processUriCB'), $css);

 return $css;
 }
 
 /**
 * In CSS content, prepend a path to relative URIs
 * 
 * @param string $css
 * 
 * @param string $path The path to prepend.
 * 
 * @return string
 */
 public static function prepend($css, $path)
 {
 self::$_prependPath = $path;
 
 $css = self::_trimUrls($css);
 
 // append
 $css = preg_replace_callback('/@import\\s+([\'"])(.*?)[\'"]/'
 ,array(self::$className, '_processUriCB'), $css);
 $css = preg_replace_callback('/url\\(\\s*([^\\)\\s]+)\\s*\\)/'
 ,array(self::$className, '_processUriCB'), $css);

 self::$_prependPath = null;
 return $css;
 }
 
 /**
 * Get a root relative URI from a file relative URI
 *
 * <code>
 * Minify_CSS_UriRewriter::rewriteRelative(
 * '../img/hello.gif'
 * , '/home/user/www/css' // path of CSS file
 * , '/home/user/www' // doc root
 * );
 * // returns '/img/hello.gif'
 * 
 * // example where static files are stored in a symlinked directory
 * Minify_CSS_UriRewriter::rewriteRelative(
 * 'hello.gif'
 * , '/var/staticFiles/theme'
 * , '/home/user/www'
 * , array('/home/user/www/static' => '/var/staticFiles')
 * );
 * // returns '/static/theme/hello.gif'
 * </code>
 * 
 * @param string $uri file relative URI
 * 
 * @param string $realCurrentDir realpath of the current file's directory.
 * 
 * @param string $realDocRoot realpath of the site document root.
 * 
 * @param array $symlinks (default = array()) If the file is stored in 
 * a symlink-ed directory, provide an array of link paths to
 * real target paths, where the link paths "appear" to be within the document 
 * root. E.g.:
 * <code>
 * array('/home/foo/www/not/real/path' => '/real/target/path') // unix
 * array('C:\\htdocs\\not\\real' => 'D:\\real\\target\\path') // Windows
 * </code>
 * 
 * @return string
 */
 public static function rewriteRelative($uri, $realCurrentDir, $realDocRoot, $symlinks = array())
 {
 // prepend path with current dir separator (OS-independent)
 $path = strtr($realCurrentDir, '/', DIRECTORY_SEPARATOR) 
 . DIRECTORY_SEPARATOR . strtr($uri, '/', DIRECTORY_SEPARATOR);
 
 self::$debugText .= "file-relative URI : {$uri}\n"
 . "path prepended : {$path}\n";
 
 // "unresolve" a symlink back to doc root
 foreach ($symlinks as $link => $target) {
 if (0 === strpos($path, $target)) {
 // replace $target with $link
 $path = $link . substr($path, strlen($target));
 
 self::$debugText .= "symlink unresolved : {$path}\n";
 
 break;
 }
 }
 // strip doc root
 $path = substr($path, strlen($realDocRoot));
 
 self::$debugText .= "docroot stripped : {$path}\n";
 
 // fix to root-relative URI
 $uri = strtr($path, '/\\', '//');
 $uri = self::removeDots($uri);
 
 self::$debugText .= "traversals removed : {$uri}\n\n";
 
 return $uri;
 }

 /**
 * Remove instances of "./" and "../" where possible from a root-relative URI
 *
 * @param string $uri
 *
 * @return string
 */
 public static function removeDots($uri)
 {
 $uri = str_replace('/./', '/', $uri);
 // inspired by patch from Oleg Cherniy
 do {
 $uri = preg_replace('@/[^/]+/\\.\\./@', '/', $uri, 1, $changed);
 } while ($changed);
 return $uri;
 }
 
 /**
 * Defines which class to call as part of callbacks, change this
 * if you extend Minify_CSS_UriRewriter
 *
 * @var string
 */
 protected static $className = 'Minify_CSS_UriRewriter';

 /**
 * Get realpath with any trailing slash removed. If realpath() fails,
 * just remove the trailing slash.
 * 
 * @param string $path
 * 
 * @return mixed path with no trailing slash
 */
 protected static function _realpath($path)
 {
 $realPath = realpath($path);
 if ($realPath !== false) {
 $path = $realPath;
 }
 return rtrim($path, '/\\');
 }

 /**
 * Directory of this stylesheet
 *
 * @var string
 */
 private static $_currentDir = '';

 /**
 * DOC_ROOT
 *
 * @var string
 */
 private static $_docRoot = '';

 /**
 * directory replacements to map symlink targets back to their
 * source (within the document root) E.g. '/var/www/symlink' => '/var/realpath'
 *
 * @var array
 */
 private static $_symlinks = array();

 /**
 * Path to prepend
 *
 * @var string
 */
 private static $_prependPath = null;

 /**
 * @param string $css
 *
 * @return string
 */
 private static function _trimUrls($css)
 {
 return preg_replace('/
 url\\( # url(
 \\s*
 ([^\\)]+?) # 1 = URI (assuming does not contain ")")
 \\s*
 \\) # )
 /x', 'url(1ドル)', $css);
 }

 /**
 * @param array $m
 *
 * @return string
 */
 private static function _processUriCB($m)
 {
 // $m matched either '/@import\\s+([\'"])(.*?)[\'"]/' or '/url\\(\\s*([^\\)\\s]+)\\s*\\)/'
 $isImport = ($m[0][0] === '@');
 // determine URI and the quote character (if any)
 if ($isImport) {
 $quoteChar = $m[1];
 $uri = $m[2];
 } else {
 // $m[1] is either quoted or not
 $quoteChar = ($m[1][0] === "'" || $m[1][0] === '"')
 ? $m[1][0]
 : '';
 $uri = ($quoteChar === '')
 ? $m[1]
 : substr($m[1], 1, strlen($m[1]) - 2);
 }
 // analyze URI
 if ('/' !== $uri[0] // root-relative
 && false === strpos($uri, '//') // protocol (non-data)
 && 0 !== strpos($uri, 'data:') // data protocol
 ) {
 // URI is file-relative: rewrite depending on options
 if (self::$_prependPath === null) {
 $uri = self::rewriteRelative($uri, self::$_currentDir, self::$_docRoot, self::$_symlinks);
 } else {
 $uri = self::$_prependPath . $uri;
 if ($uri[0] === '/') {
 $root = '';
 $rootRelative = $uri;
 $uri = $root . self::removeDots($rootRelative);
 } elseif (preg_match('@^((https?\:)?//([^/]+))/@', $uri, $m) && (false !== strpos($m[3], '.'))) {
 $root = $m[1];
 $rootRelative = substr($uri, strlen($root));
 $uri = $root . self::removeDots($rootRelative);
 }
 }
 }
 return $isImport
 ? "@import {$quoteChar}{$uri}{$quoteChar}"
 : "url({$quoteChar}{$uri}{$quoteChar})";
 }
}