<?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);
      }
    }
  }