package org.jboss.resteasy.plugins.interceptors;

import javax.annotation.Priority;
import javax.servlet.ServletContext;
import javax.ws.rs.Priorities;
import javax.ws.rs.ProcessingException;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.ext.Provider;
import javax.ws.rs.ext.ReaderInterceptor;
import javax.ws.rs.ext.ReaderInterceptorContext;

import org.jboss.resteasy.core.interception.jaxrs.ServerReaderInterceptorContext;
import org.jboss.resteasy.plugins.server.servlet.ResteasyContextParameters;
import org.jboss.resteasy.resteasy_jaxrs.i18n.LogMessages;
import org.jboss.resteasy.resteasy_jaxrs.i18n.Messages;
import org.jboss.resteasy.spi.ResteasyProviderFactory;

import java.io.IOException;
import java.io.InputStream;
import java.util.zip.GZIPInputStream;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
@Provider
@Priority(Priorities.ENTITY_CODER)
public class GZIPDecodingInterceptor implements ReaderInterceptor
{
  private static final int DEFAULT_MAX_SIZE = 10000000;
  private int maxSize;
  
  public GZIPDecodingInterceptor(int maxSize)
  {
     this.maxSize = maxSize;
  }
  
  public GZIPDecodingInterceptor()
  {
     this.maxSize = -1;
  }
   
  public static class FinishableGZIPInputStream extends GZIPInputStream
  {
      private int maxSize;
      private int count;
      private boolean server;

      public FinishableGZIPInputStream(final InputStream is) throws IOException
      {
         this(is, true, DEFAULT_MAX_SIZE);
      }
      
      public FinishableGZIPInputStream(final InputStream is, boolean server) throws IOException
      {
         this(is, server, DEFAULT_MAX_SIZE);
      }
      
      public FinishableGZIPInputStream(final InputStream is, boolean server, int maxSize) throws IOException
      {
         super(is);
         this.server = server;
         this.maxSize = maxSize;
      }
      
      public int read(byte[] buf, int off, int len) throws IOException 
      {
         LogMessages.LOGGER.debugf("Interceptor : %s,  Method : read", getClass().getName());
         int n = super.read(buf, off, len);
         if (n > -1)
         {
            count += n;
         }
         if (count > maxSize)
         {
            finish();
            close();
            if (server)
            {
               throw new WebApplicationException(Response.status(Status.REQUEST_ENTITY_TOO_LARGE).entity(Messages.MESSAGES.gzipExceedsMaxSize(maxSize)).build());
            }
            else
            {
               throw new ProcessingException(Messages.MESSAGES.gzipExceedsMaxSize(maxSize));
            }
         }
         return n;
      }

      public void finish()
      {
         inf.end(); // make sure on finish the inflater's end() is called to release the native code pointer
      }
   }

   @Override
   public Object aroundReadFrom(ReaderInterceptorContext context) throws IOException, WebApplicationException
   {
      LogMessages.LOGGER.debugf("Interceptor : %s,  Method : aroundReadFrom", getClass().getName());
      Object encoding = context.getHeaders().getFirst(HttpHeaders.CONTENT_ENCODING);
      if (encoding != null && encoding.toString().equalsIgnoreCase("gzip"))
      {
         InputStream old = context.getInputStream();
         FinishableGZIPInputStream is = new FinishableGZIPInputStream(old, context instanceof ServerReaderInterceptorContext, getMaxSize());
         context.setInputStream(is);
         try
         {
            return context.proceed();
         }
         finally
         {
            // Don't finish() an InputStream - TODO this still will require a garbage collect to finish the stream
            // see RESTEASY-554 for more details
            if (!context.getType().equals(InputStream.class)) is.finish();
            context.setInputStream(old);
         }
      }
      else
      {
         return context.proceed();
      }
   }
   
   private int getMaxSize()
   {
      if (maxSize != -1)
      {
         return maxSize;
      }
      
      int size = -1;
      ServletContext context = ResteasyProviderFactory.getContextData(ServletContext.class);
      if (context != null)
      {
         String s = context.getInitParameter(ResteasyContextParameters.RESTEASY_GZIP_MAX_INPUT);
         if (s != null)
         {
            try
            {
               size = Integer.parseInt(s);
            }
            catch (NumberFormatException e)
            {
               LogMessages.LOGGER.invalidFormat(ResteasyContextParameters.RESTEASY_GZIP_MAX_INPUT, Integer.toString(DEFAULT_MAX_SIZE));
            }
         }
      }
      if (size == -1)
      {
         size = DEFAULT_MAX_SIZE;
      }
      
      return size;
   }
}