//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.server.handler.gzip;
  
  import static org.eclipse.jetty.http.GzipHttpContent.ETAG_GZIP_QUOTE;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.Set;
  import java.util.zip.Deflater;
  
  import javax.servlet.ServletContext;
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.http.GzipHttpContent;
  import org.eclipse.jetty.http.HttpField;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.HttpVersion;
  import org.eclipse.jetty.http.MimeTypes;
  import org.eclipse.jetty.http.pathmap.PathSpecSet;
  import org.eclipse.jetty.server.HttpOutput;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.handler.HandlerWrapper;
  import org.eclipse.jetty.util.IncludeExclude;
  import org.eclipse.jetty.util.RegexSet;
  import org.eclipse.jetty.util.StringUtil;
  import org.eclipse.jetty.util.URIUtil;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  
  /**
   * A Handler that can dynamically GZIP compress responses.   Unlike 
   * previous and 3rd party GzipFilters, this mechanism works with asynchronously
   * generated responses and does not need to wrap the response or it's output
   * stream.  Instead it uses the efficient {@link org.eclipse.jetty.server.HttpOutput.Interceptor} mechanism.
   * <p>
   * The handler can be applied to the entire server (a gzip.mod is included in
   * the distribution) or it may be applied to individual contexts.
   * </p>
   */
  public class GzipHandler extends HandlerWrapper implements GzipFactory
  {
      private static final Logger LOG = Log.getLogger(GzipHandler.class);
  
      public final static String GZIP = "gzip";
      public final static String DEFLATE = "deflate";
      public final static int DEFAULT_MIN_GZIP_SIZE=16;
      private int _minGzipSize=DEFAULT_MIN_GZIP_SIZE;
      private int _compressionLevel=Deflater.DEFAULT_COMPRESSION;
      private boolean _checkGzExists = true;
      private boolean _syncFlush = false;
      
      // non-static, as other GzipHandler instances may have different configurations
      private final ThreadLocal<Deflater> _deflater = new ThreadLocal<Deflater>();
  
      private final IncludeExclude<String> _agentPatterns=new IncludeExclude<>(RegexSet.class);
      private final IncludeExclude<String> _methods = new IncludeExclude<>();
      private final IncludeExclude<String> _paths = new IncludeExclude<>(PathSpecSet.class);
      private final IncludeExclude<String> _mimeTypes = new IncludeExclude<>();
      
      private HttpField _vary;
  
  
      /* ------------------------------------------------------------ */
      /**
       * Instantiates a new gzip handler.
       * The excluded Mime Types are initialized to common known 
       * images, audio, video and other already compressed types.
       * The included methods is initialized to GET.
       * The excluded agent patterns are set to exclude MSIE 6.0
       */
      public GzipHandler()
      {
          _methods.include(HttpMethod.GET.asString());
          for (String type:MimeTypes.getKnownMimeTypes())
          {
              if ("image/svg+xml".equals(type))
                  _paths.exclude("*.svgz");
              else if (type.startsWith("image/")||
                 type.startsWith("audio/")||
                 type.startsWith("video/"))
                 _mimeTypes.exclude(type);
         }
         _mimeTypes.exclude("application/compress");
         _mimeTypes.exclude("application/zip");
         _mimeTypes.exclude("application/gzip");
         _mimeTypes.exclude("application/bzip2");
         _mimeTypes.exclude("application/x-rar-compressed");
         LOG.debug("{} mime types {}",this,_mimeTypes);
         
         _agentPatterns.exclude(".*MSIE 6.0.*");
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param patterns Regular expressions matching user agents to exclude
      */
     public void addExcludedAgentPatterns(String... patterns)
     {
         _agentPatterns.exclude(patterns);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param methods The methods to exclude in compression
      */
     public void addExcludedMethods(String... methods)
     {
         for (String m : methods)
             _methods.exclude(m);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the mime types.
      * @param types The mime types to exclude (without charset or other parameters).
      * For backward compatibility the mimetypes may be comma separated strings, but this
      * will not be supported in future versions.
      */
     public void addExcludedMimeTypes(String... types)
     {
         for (String t : types)
             _mimeTypes.exclude(StringUtil.csvSplit(t));
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param pathspecs Path specs (as per servlet spec) to exclude. If a 
      * ServletContext is available, the paths are relative to the context path,
      * otherwise they are absolute.
      * For backward compatibility the pathspecs may be comma separated strings, but this
      * will not be supported in future versions.
      */
     public void addExcludedPaths(String... pathspecs)
     {
         for (String p : pathspecs)
             _paths.exclude(StringUtil.csvSplit(p));
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param patterns Regular expressions matching user agents to exclude
      */
     public void addIncludedAgentPatterns(String... patterns)
     {
         _agentPatterns.include(patterns);
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @param methods The methods to include in compression
      */
     public void addIncludedMethods(String... methods)
     {
         for (String m : methods)
             _methods.include(m);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @return True if {@link Deflater#SYNC_FLUSH} is used, else {@link Deflater#NO_FLUSH}
      */
     public boolean isSyncFlush()
     {
         return _syncFlush;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * <p>Set the {@link Deflater} flush mode to use.  {@link Deflater#SYNC_FLUSH}
      * should be used if the application wishes to stream the data, but this may
      * hurt compression performance.
      * @param syncFlush True if {@link Deflater#SYNC_FLUSH} is used, else {@link Deflater#NO_FLUSH}
      */
     public void setSyncFlush(boolean syncFlush)
     {
         _syncFlush = syncFlush;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Add included mime types. Inclusion takes precedence over
      * exclusion.
      * @param types The mime types to include (without charset or other parameters)
      * For backward compatibility the mimetypes may be comma separated strings, but this
      * will not be supported in future versions.
      */
     public void addIncludedMimeTypes(String... types)
     {
         for (String t : types)
             _mimeTypes.include(StringUtil.csvSplit(t));
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Add path specs to include. Inclusion takes precedence over exclusion.
      * @param pathspecs Path specs (as per servlet spec) to include. If a 
      * ServletContext is available, the paths are relative to the context path,
      * otherwise they are absolute
      * For backward compatibility the pathspecs may be comma separated strings, but this
      * will not be supported in future versions.
      */
     public void addIncludedPaths(String... pathspecs)
     {
         for (String p : pathspecs)
             _paths.include(StringUtil.csvSplit(p));
     }
     
     /* ------------------------------------------------------------ */
     @Override
     protected void doStart() throws Exception
     {
         _vary=(_agentPatterns.size()>0)?GzipHttpOutputInterceptor.VARY_ACCEPT_ENCODING_USER_AGENT:GzipHttpOutputInterceptor.VARY_ACCEPT_ENCODING;
         super.doStart();
     }
 
     /* ------------------------------------------------------------ */
     public boolean getCheckGzExists()
     {
         return _checkGzExists;
     }
 
     /* ------------------------------------------------------------ */
     public int getCompressionLevel()
     {
         return _compressionLevel;
     }
     
     /* ------------------------------------------------------------ */
     @Override
     public Deflater getDeflater(Request request, long content_length)
     {
         String ua = request.getHttpFields().get(HttpHeader.USER_AGENT);
         if (ua!=null && !isAgentGzipable(ua))
         {
             LOG.debug("{} excluded user agent {}",this,request);
             return null;
         }
         
         if (content_length>=0 && content_length<_minGzipSize)
         {
             LOG.debug("{} excluded minGzipSize {}",this,request);
             return null;
         }
 
         // If not HTTP/2, then we must check the accept encoding header
         if (request.getHttpVersion()!=HttpVersion.HTTP_2)
         {
             HttpField accept = request.getHttpFields().getField(HttpHeader.ACCEPT_ENCODING);
 
             if (accept==null)
             {
                 LOG.debug("{} excluded !accept {}",this,request);
                 return null;
             }
             boolean gzip = accept.contains("gzip");
 
             if (!gzip)
             {
                 LOG.debug("{} excluded not gzip accept {}",this,request);
                 return null;
             }
         }
         
         Deflater df = _deflater.get();
         if (df==null)
             df=new Deflater(_compressionLevel,true);        
         else
             _deflater.set(null);
         
         return df;
     }
     
     /* ------------------------------------------------------------ */
     public String[] getExcludedAgentPatterns()
     {
         Set<String> excluded=_agentPatterns.getExcluded();
         return excluded.toArray(new String[excluded.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getExcludedMethods()
     {
         Set<String> excluded=_methods.getExcluded();
         return excluded.toArray(new String[excluded.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getExcludedMimeTypes()
     {
         Set<String> excluded=_mimeTypes.getExcluded();
         return excluded.toArray(new String[excluded.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getExcludedPaths()
     {
         Set<String> excluded=_paths.getExcluded();
         return excluded.toArray(new String[excluded.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getIncludedAgentPatterns()
     {
         Set<String> includes=_agentPatterns.getIncluded();
         return includes.toArray(new String[includes.size()]);
     }
     
     /* ------------------------------------------------------------ */
     public String[] getIncludedMethods()
     {
         Set<String> includes=_methods.getIncluded();
         return includes.toArray(new String[includes.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getIncludedMimeTypes()
     {
         Set<String> includes=_mimeTypes.getIncluded();
         return includes.toArray(new String[includes.size()]);
     }
 
     /* ------------------------------------------------------------ */
     public String[] getIncludedPaths()
     {
         Set<String> includes=_paths.getIncluded();
         return includes.toArray(new String[includes.size()]);
     }
 
     /* ------------------------------------------------------------ */
     @Deprecated
     public String[] getMethods()
     {
         return getIncludedMethods();
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Get the minimum reponse size.
      *
      * @return minimum reponse size
      */
     public int getMinGzipSize()
     {
         return _minGzipSize;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see org.eclipse.jetty.server.handler.HandlerWrapper#handle(java.lang.String, org.eclipse.jetty.server.Request, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
      */
     @Override
     public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
     {
         ServletContext context = baseRequest.getServletContext();
         String path = context==null?baseRequest.getRequestURI():URIUtil.addPaths(baseRequest.getServletPath(),baseRequest.getPathInfo());
         LOG.debug("{} handle {} in {}",this,baseRequest,context);
         
         HttpOutput out = baseRequest.getResponse().getHttpOutput();   
         // Are we already being gzipped?
         HttpOutput.Interceptor interceptor = out.getInterceptor();
         while (interceptor!=null)
         {
             if (interceptor instanceof GzipHttpOutputInterceptor)
             {
                 LOG.debug("{} already intercepting {}",this,request);
                 _handler.handle(target,baseRequest, request, response);
                 return;
             }
             interceptor=interceptor.getNextInterceptor();
         }
         
         // If not a supported method - no Vary because no matter what client, this URI is always excluded
         if (!_methods.matches(baseRequest.getMethod()))
         {
             LOG.debug("{} excluded by method {}",this,request);
             _handler.handle(target,baseRequest, request, response);
             return;
         }
         
         // If not a supported URI- no Vary because no matter what client, this URI is always excluded
         // Use pathInfo because this is be
         if (!isPathGzipable(path))
         {
             LOG.debug("{} excluded by path {}",this,request);
             _handler.handle(target,baseRequest, request, response);
             return;
         }
 
         // Exclude non compressible mime-types known from URI extension. - no Vary because no matter what client, this URI is always excluded
         String mimeType = context==null?null:context.getMimeType(path);
         if (mimeType!=null)
         {
             mimeType = MimeTypes.getContentTypeWithoutCharset(mimeType);
             if (!isMimeTypeGzipable(mimeType))
             {
                 LOG.debug("{} excluded by path suffix mime type {}",this,request);
                 // handle normally without setting vary header
                 _handler.handle(target,baseRequest, request, response);
                 return;
             }
         }
         
         if (_checkGzExists && context!=null)
         {
             String realpath=request.getServletContext().getRealPath(path);
             if (realpath!=null)
             {
                 File gz=new File(realpath+".gz");
                 if (gz.exists())
                 {
                     LOG.debug("{} gzip exists {}",this,request);
                     // allow default servlet to handle
                     _handler.handle(target,baseRequest, request, response);
                     return;
                 }
             }
         }
         
         // Special handling for etags
         String etag = baseRequest.getHttpFields().get(HttpHeader.IF_NONE_MATCH); 
         if (etag!=null)
         {
             int i=etag.indexOf(ETAG_GZIP_QUOTE);
             if (i>0)
             {
                 while (i>=0)
                 {
                     etag=etag.substring(0,i)+etag.substring(i+GzipHttpContent.ETAG_GZIP.length());
                     i=etag.indexOf(ETAG_GZIP_QUOTE,i);
                 }
                 baseRequest.getHttpFields().put(new HttpField(HttpHeader.IF_NONE_MATCH,etag));
             }
         }
 
         // install interceptor and handle
         out.setInterceptor(new GzipHttpOutputInterceptor(this,_vary,baseRequest.getHttpChannel(),out.getInterceptor(),_syncFlush));
         if (_handler!=null)
             _handler.handle(target,baseRequest, request, response);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Checks to see if the userAgent is excluded
      *
      * @param ua the user agent
      * @return boolean true if excluded
      */
     protected boolean isAgentGzipable(String ua)
     {
         if (ua == null)
             return false;
         
         return _agentPatterns.matches(ua);
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public boolean isMimeTypeGzipable(String mimetype)
     {
         return _mimeTypes.matches(mimetype);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Checks to see if the path is included or not excluded 
      *
      * @param requestURI
      *            the request uri
      * @return boolean true if gzipable
      */
     protected boolean isPathGzipable(String requestURI)
     {
         if (requestURI == null)
             return true;
         
         return _paths.matches(requestURI);
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public void recycle(Deflater deflater)
     {
         deflater.reset();
         if (_deflater.get()==null)
             _deflater.set(deflater);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param checkGzExists If true, check if a static gz file exists for
      * the resource that the DefaultServlet may serve as precompressed.
      */
     public void setCheckGzExists(boolean checkGzExists)
     {
         _checkGzExists = checkGzExists;
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @param compressionLevel  The compression level to use to initialize {@link Deflater#setLevel(int)}
      */
     public void setCompressionLevel(int compressionLevel)
     {
         _compressionLevel = compressionLevel;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param patterns Regular expressions matching user agents to exclude
      */
     public void setExcludedAgentPatterns(String... patterns)
     {
         _agentPatterns.getExcluded().clear();
         addExcludedAgentPatterns(patterns);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param method to exclude
      */
     public void setExcludedMethods(String... method)
     {
         _methods.getExcluded().clear();
         _methods.exclude(method);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the mime types.
      * @param types The mime types to exclude (without charset or other parameters)
      */
     public void setExcludedMimeTypes(String... types)
     {
         _mimeTypes.getExcluded().clear();
         _mimeTypes.exclude(types);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param pathspecs Path specs (as per servlet spec) to exclude. If a 
      * ServletContext is available, the paths are relative to the context path,
      * otherwise they are absolute.
      */
     public void setExcludedPaths(String... pathspecs)
     {
         _paths.getExcluded().clear();
         _paths.exclude(pathspecs);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param patterns Regular expressions matching user agents to include
      */
     public void setIncludedAgentPatterns(String... patterns)
     {
         _agentPatterns.getIncluded().clear();
         addIncludedAgentPatterns(patterns);
     }
     
     /* ------------------------------------------------------------ */
     /**
      * @param methods The methods to include in compression
      */
     public void setIncludedMethods(String... methods)
     {
         _methods.getIncluded().clear();
         _methods.include(methods);
     }
     
     /* ------------------------------------------------------------ */
     /**
      * Set included mime types. Inclusion takes precedence over
      * exclusion.
      * @param types The mime types to include (without charset or other parameters)
      */
     public void setIncludedMimeTypes(String... types)
     {
         _mimeTypes.getIncluded().clear();
         _mimeTypes.include(types);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the path specs to include. Inclusion takes precedence over exclusion.
      * @param pathspecs Path specs (as per servlet spec) to include. If a 
      * ServletContext is available, the paths are relative to the context path,
      * otherwise they are absolute
      */
     public void setIncludedPaths(String... pathspecs)
     {
         _paths.getIncluded().clear();
         _paths.include(pathspecs);
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Set the minimum response size to trigger dynamic compresssion
      *
      * @param minGzipSize minimum response size in bytes
      */
     public void setMinGzipSize(int minGzipSize)
     {
         _minGzipSize = minGzipSize;
     }
 }