<?php

/* The HTML code won't be compressed -> Does nothing! */
define('CM_NONE', 0);
/* Compress the HTML in the gzip format. Note that this will also add the header Content-Encoding! */
define('CM_COMPRESS_HTTP_DEFLATE', 2);
define('CM_COMPRESS_HTTP_GZIP', 4);
/* Removes control characters (spaces, tabs, returns,...) from the HTML code */
define('CM_REMOVE_HTML_SPACES', 16);
/* Converts the images to Base64 strings so the images won't be loaded from the server. */
define('CM_ENCODE_HTML_IMAGES', 32);
/* Converts the images in the CSS file to Base64 data URLs */
define('CM_ENCODE_CSS_IMAGES', 64);
/* Executes all compression methods. See the flags CM_GZIP, CM_REMOVESPACES, CM_IMAGEENCODE for further information. */
define('CM_HTML', CM_COMPRESS_HTTP_DEFLATE|CM_REMOVE_HTML_SPACES);
define('CM_CSS', CM_ENCODE_CSS_IMAGES);

define('CM_GZIP_COMPRESSION_LEVEL', 9);
define('CM_DEFLATE_COMPRESSION_LEVEL', 9);


class NRCompress
{
  private static function Callback_EncodeHTMLImages($matches)
  {
    if (!file_exists($matches[1])) return $matches[0].$matches[1]; /* If the file doesn't exists, the return value will be the same as in the HTML code */
    $file = file_get_contents($matches[1]);
    $file_extension = substr($matches[1], strripos($matches[1], ".")+1); /* Extract the file extension (without the point) */
    $base64 = "data:image/".$file_extension.";base64,".base64_encode($file); /* Encodes the image to Base64 */


    $end = str_replace($matches[1], $base64, $matches[0]); /* Assembly the img-tag and the new src-attribute */
    return $end;
  }
  private static function Callback_EncodeCSSImages($matches)
  {
    if (!file_exists($matches[3])) return $matches[0]; /* If the file doesn't exists, the return value will be the same as in the HTML code */
    $file = file_get_contents($matches[3]);
    $file_extension = substr($matches[3], strripos($matches[3], ".")+1); /* Extract the file extension (without the point) */
    $base64 = "data:image/".$file_extension.";base64,".base64_encode($file); /* Encodes the image to Base64 */


    $end = str_replace($matches[3], $base64, $matches[0]); /* Assembly the img-tag and the new src-attribute */
    return $end;
  }

  private static function RemoveSpacesFromHTML($html)
  {
    $control_chars = array("\a", "\t", "\b", "\v", "\f", "\r");
    $nothing = array("",   "",   "",   "",  "","", "", "");
    $html = str_replace($control_chars, $nothing, $html);
    return $html;
  }
  private static function EncodeImagesInHTML($html)
  {
    $pattern = '/<img.+?src\s*=\s*"([^"]+)"/i';
    $html = preg_replace_callback($pattern, "self::Callback_EncodeHTMLImages", $html);
    return $html;
  }
  private static function EncodeImagesInCSS($css)
  {
    $pattern = '/url\(((\'|"|\s?)(.*)(\"|\'|\s?))\)/Usi';
    $css = preg_replace_callback($pattern, "self::Callback_EncodeCSSImages", $css);
    return $css;
  }
  private static function CompressHTTP($code, $compress_methods)
  {
    if (Request::CheckBrowserDeflateSupport() && function_exists("gzdeflate") && $compress_methods & CM_COMPRESS_HTTP_DEFLATE)
    {
      $code = gzdeflate($code, CM_DEFLATE_COMPRESSION_LEVEL);
      return $code;
    }
    if (Request::CheckBrowserGZIPSupport() && function_exists("gzencode") && $compress_methods & CM_COMPRESS_HTTP_GZIP)
    {
      $code = gzencode($code, CM_GZIP_COMPRESSION_LEVEL);
      return $code;
    }
  }
  private static function SetRightHTTPHeader($compress_methods)
  {
    if ($compress_methods & CM_COMPRESS_HTTP_DEFLATE)
    {
      HTTPresponse::addHeader("Content-Encoding", "deflate");
    }
    else if ($compress_methods & CM_COMPRESS_HTTP_GZIP)
    {
      HTTPresponse::addHeader("Content-Encoding", "gzip");
    }
  }
  private static function BuildCacheFilename($code, $compress_methods)
  {
    return ("includes/temp/" . md5($code) . "_" . (string)$compress_methods . ".nrc");
  }

  public static function GetBestHTTPCompression()
  {
    if (Request::CheckBrowserDeflateSupport())
      return CM_COMPRESS_HTTP_DEFLATE;
    else if (Request::CheckBrowserGZIPSupport())
      return CM_COMPRESS_HTTP_GZIP;

    return CM_NONE;
  }


  public static function Compress($code, $compress_methods=CM_ALL, $cache=true)
  {
    if (Core::is_ajax()) return $code;
    if ($compress_methods)

    if ($cache)
    {
      if (file_exists(self::BuildCacheFilename($code, $compress_methods)))
      {
        self::SetRightHTTPHeader($compress_methods);
        return file_get_contents( self::BuildCacheFilename($code, $compress_methods) );
      }
    }

    if ($compress_methods & CM_REMOVE_HTML_SPACES) /* Not working right yet! */
    {
      $code = self::RemoveSpacesFromHTML($code);
    }
    if ($compress_methods & CM_ENCODE_HTML_IMAGES)
    {
      $code = self::EncodeImagesInHTML($code);
    }
    if ($compress_methods & CM_ENCODE_CSS_IMAGES)
    {
      $code = self::EncodeImagesInCSS($code);
    }
    if ($compress_methods & CM_COMPRESS_HTTP_DEFLATE ||
        $compress_methods & CM_COMPRESS_HTTP_GZIP)
    {
      self::CompressHTTP($code, $compress_methods);
      //self::SetRightHTTPHeader($compress_methods);
      HTTPresponse::addHeader("Content-Encoding", "gzip");
    }
    if ($cache)
    {
      $file = fopen(self::BuildCacheFilename($code, $compress_methods), "wb");
      fwrite($file, $code);
      fclose($file);
    }
    return $code;
  }

}

?>