<?php
 /**
  * 完整调用示例:
  * 1、combine.php?t=j&b=public&fs=jslib.jquery,function
  *
  * 该例子调用的是网站根目录下的public/jslib/jquery.js和public/function.js
  *
  * 2、combine.php?t=j&fs=jslib.jquery,function
  *
  * 该例子调用的是网站根目录下的jslib/jquery.js和function.js
  *
  * 3、combine.php?t=c&b=public.css&fs=common,index
  *
  * 该例子调用的是网站根目录下的public/css/common.css和public/css/index.css
  *
  * 4、combine.php?t=c&fs=css.common
  * 该例子调用的是网站根目录下的css/common.css
  *
  * 注:多个文件名之间用,分隔;只有一个文件名最后不要有,
  *  用,分隔的多个文件会被压缩进一个文件，一次性传给浏览器
  **/
 $is_bad_request=false;
 $cache = true;
 $doc_root_uri=$_SERVER['DOCUMENT_ROOT'].'/';
 $cachedir = $doc_root_uri . 'public/cache';
 //文件类型，j为js，c为css
 $type=isset($_GET['t'])?($_GET['t']=='j'||$_GET['t']=='c'?$_GET['t']:''):'';
 //存放js和css文件的基目录, 例如:?b=public.js 代表的是/public/js文件夹，出发点是网站根目录
 //基目录参数不是必须的，如果有基目录那么这个基目录就会附加在文件名之前
 $base =isset($_GET['b'])?($doc_root_uri.str_replace('.','/',$_GET['b'])):$doc_root_uri;
 //文件名列表，文件名不带后缀名.比如基目录是
 //文件名的格式是 :基目录(如果有)+文件包名+文件名
 //例如:类型是j,
 //  文件名public.js.jquery
 //  如果有基路径且为public，
 //  那么转换后的文件名就是/public/public/js/jquery.js
 //  如果没有基路径
 //  那么转换后的文件名就是/public/js/jquery.js
 //多个文件名之间用,分隔
 $fs=isset($_GET['fs'])?str_replace('.','/',$_GET['fs']):'';
 $fs=str_replace(',','.'.($type=='j'?'js,':'css,'),$fs);
 $fs=$fs.($type=='j'?'.js':'.css');
 if($type==''||$fs==''){$is_bad_request=true;}
 //die($base);
 if($is_bad_request){header ("HTTP/1.0 503 Not Implemented");}
 $file_type=$type=='j'?'javascript':'css';
 $elements = explode(',',preg_replace('/([^?]*).*/', '\1', $fs));
 // Determine last modification date of the files
 $lastmodified = 0;
 while (list(,$element) = each($elements)) {
   $path =$base . '/' . $element;
   if (($type == 'j' && substr($path, -3) != '.js') ||
     ($type == 'c' && substr($path, -4) != '.css')) {
     header ("HTTP/1.0 403 Forbidden");
     exit;
   }
   if (substr($path, 0, strlen($base)) != $base || !file_exists($path)) {
     header ("HTTP/1.0 404 Not Found");
     exit;
   }
   $lastmodified = max($lastmodified, filemtime($path));
 }
 // Send Etag hash
 $hash = $lastmodified . '-' . md5($fs);
 header ("Etag: \"" . $hash . "\"");
 if (isset($_SERVER['HTTP_IF_NONE_MATCH']) &&
   stripslashes($_SERVER['HTTP_IF_NONE_MATCH']) == '"' . $hash . '"')
 {
   // Return visit and no modifications, so do not send anything
   header ("HTTP/1.0 304 Not Modified");
   header ("Content-Type: text/" . $file_type);
   header ('Content-Length: 0');
 }
 else
 {
   // First time visit or files were modified
   if ($cache)
   {
     // Determine supported compression method
     $gzip = strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip');
     $deflate = strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'deflate');
     // Determine used compression method
     $encoding = $gzip ? 'gzip' : ($deflate ? 'deflate' : 'none');
     // Check for buggy versions of Internet Explorer
     if (!strstr($_SERVER['HTTP_USER_AGENT'], 'Opera') &&
       preg_match('/^Mozilla\/4\.0 \(compatible; MSIE ([0-9]\.[0-9])/i', $_SERVER['HTTP_USER_AGENT'], $matches)) {
       $version = floatval($matches[1]);
       if ($version < 6)
         $encoding = 'none';
       if ($version == 6 && !strstr($_SERVER['HTTP_USER_AGENT'], 'EV1'))
         $encoding = 'none';
     }
     // Try the cache first to see if the combined files were already generated
     $cachefile = 'cache-' . $hash . '.' . $file_type . ($encoding != 'none' ? '.' . $encoding : '');
     if (file_exists($cachedir . '/' . $cachefile)) {
       if ($fp = fopen($cachedir . '/' . $cachefile, 'rb')) {
         if ($encoding != 'none') {
           header ("Content-Encoding: " . $encoding);
         }
         header ("Content-Type: text/" . $file_type);
         header ("Content-Length: " . filesize($cachedir . '/' . $cachefile));
         fpassthru($fp);
         fclose($fp);
         exit;
       }
     }
   }
   // Get contents of the files
   $contents = '';
   reset($elements);
   while (list(,$element) = each($elements)) {
     $path = $base . '/' . $element;
     $contents .= "\n\n" . file_get_contents($path);
   }
   // Send Content-Type
   header ("Content-Type: text/" . $file_type);
   if (isset($encoding) && $encoding != 'none')
   {
     // Send compressed contents
     $contents = gzencode($contents, 9, $gzip ? FORCE_GZIP : FORCE_DEFLATE);
     header ("Content-Encoding: " . $encoding);
     header ('Content-Length: ' . strlen($contents));
     echo $contents;
   }
   else
   {
     // Send regular contents
     header ('Content-Length: ' . strlen($contents));
     echo $contents;
   }
   // Store cache
   if ($cache) {
     if ($fp = fopen($cachedir . '/' . $cachefile, 'wb')) {
       fwrite($fp, $contents);
       fclose($fp);
     }
   }
 }