//
   //  ========================================================================
   //  Copyright (c) 1995-2013 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.client.util;
  
  import java.io.UnsupportedEncodingException;
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.charset.UnsupportedCharsetException;
  import java.util.Locale;
  
  import org.eclipse.jetty.client.api.Response;
  import org.eclipse.jetty.client.api.Result;
  import org.eclipse.jetty.http.HttpFields;
  import org.eclipse.jetty.http.HttpHeader;
  
  /**
   * <p>Implementation of {@link Response.Listener} that buffers the content up to a maximum length
   * specified to the constructors.</p>
   * <p>The content may be retrieved from {@link #onSuccess(Response)} or {@link #onComplete(Result)}
   * via {@link #getContent()} or {@link #getContentAsString()}.</p>
   */
  public abstract class BufferingResponseListener extends Response.Listener.Empty
  {
      private final int maxLength;
      private volatile byte[] buffer = new byte[0];
      private volatile String encoding;
  
      /**
       * Creates an instance with a default maximum length of 2 MiB.
       */
      public BufferingResponseListener()
      {
          this(2 * 1024 * 1024);
      }
  
      /**
       * Creates an instance with the given maximum length
       *
       * @param maxLength the maximum length of the content
       */
      public BufferingResponseListener(int maxLength)
      {
          this.maxLength = maxLength;
      }
  
      @Override
      public void onHeaders(Response response)
      {
          HttpFields headers = response.getHeaders();
          long length = headers.getLongField(HttpHeader.CONTENT_LENGTH.asString());
          if (length > maxLength)
          {
              response.abort(new IllegalArgumentException("Buffering capacity exceeded"));
          }
          else
          {
              String contentType = headers.get(HttpHeader.CONTENT_TYPE);
              if (contentType != null)
              {
                  String charset = "charset=";
                  int index = contentType.toLowerCase(Locale.ENGLISH).indexOf(charset);
                  if (index > 0)
                  {
                      String encoding = contentType.substring(index + charset.length());
                      // Sometimes charsets arrive with an ending semicolon
                      index = encoding.indexOf(';');
                      if (index > 0)
                          encoding = encoding.substring(0, index);
                      this.encoding = encoding;
                  }
              }
          }
      }
  
      @Override
      public void onContent(Response response, ByteBuffer content)
      {
          long newLength = buffer.length + content.remaining();
          if (newLength > maxLength)
          {
              response.abort(new IllegalArgumentException("Buffering capacity exceeded"));
          }
         else
         {
             byte[] newBuffer = new byte[(int)newLength];
             System.arraycopy(buffer, 0, newBuffer, 0, buffer.length);
             content.get(newBuffer, buffer.length, content.remaining());
             buffer = newBuffer;
         }
     }
 
     @Override
     public abstract void onComplete(Result result);
 
     public String getEncoding()
     {
         return encoding;
     }
 
     /**
      * @return the content as bytes
      * @see #getContentAsString()
      */
     public byte[] getContent()
     {
         return buffer;
     }
 
     /**
      * @return the content as a string, using the "Content-Type" header to detect the encoding
      *         or defaulting to UTF-8 if the encoding could not be detected.
      * @see #getContentAsString(String)
      */
     public String getContentAsString()
     {
         String encoding = this.encoding;
         if (encoding == null)
             return getContentAsString(StandardCharsets.UTF_8);
         return getContentAsString(encoding);
     }
 
     /**
      * @param encoding the encoding of the content bytes
      * @return the content as a string, with the specified encoding
      * @see #getContentAsString()
      */
     public String getContentAsString(String encoding)
     {
         try
         {
             return new String(getContent(), encoding);
         }
         catch (UnsupportedEncodingException x)
         {
             throw new UnsupportedCharsetException(encoding);
         }
     }
 
     /**
      * @param encoding the encoding of the content bytes
      * @return the content as a string, with the specified encoding
      * @see #getContentAsString()
      */
     public String getContentAsString(Charset encoding)
     {
         return new String(getContent(), encoding);
     }
 }