/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.http.client.entity;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PushbackInputStream;
  import java.util.zip.Inflater;
  import java.util.zip.InflaterInputStream;
  import java.util.zip.ZipException;
  
  /**
   * Deflate input stream.    This class includes logic needed for various Rfc's in order
   * to reasonably implement the "deflate" compression style.
   */
  public class DeflateInputStream extends InputStream {
  
      private final InputStream sourceStream;
  
      public DeflateInputStream(final InputStream wrapped) throws IOException {
  
          final PushbackInputStream pushback = new PushbackInputStream(wrapped, 2);
          final int i1 = pushback.read();
          final int i2 = pushback.read();
          if (i1 == -1 || i2 == -1) {
              throw new ZipException("Unexpected end of stream");
          }
  
          pushback.unread(i2);
          pushback.unread(i1);
  
          boolean nowrap = true;
          final int b1 = i1 & 0xFF;
          final int compressionMethod = b1 & 0xF;
          final int compressionInfo = b1 >> 4 & 0xF;
          final int b2 = i2 & 0xFF;
          if (compressionMethod == 8 && compressionInfo <= 7 && ((b1 << 8) | b2) % 31 == 0) {
              nowrap = false;
          }
          sourceStream = new DeflateStream(pushback, new Inflater(nowrap));
      }
  
      /**
       * Read a byte.
       */
      @Override
      public int read() throws IOException {
          return sourceStream.read();
      }
  
      /**
       * Read lots of bytes.
       */
      @Override
      public int read(final byte[] b) throws IOException {
          return sourceStream.read(b);
      }
  
      /**
       * Read lots of specific bytes.
       */
      @Override
      public int read(final byte[] b, final int off, final int len) throws IOException {
          return sourceStream.read(b, off, len);
      }
  
      /**
       * Skip
       */
      @Override
      public long skip(final long n) throws IOException {
          return sourceStream.skip(n);
      }
  
      /**
      * Get available.
      */
     @Override
     public int available() throws IOException {
         return sourceStream.available();
     }
 
     /**
      * Mark.
      */
     @Override
     public void mark(final int readLimit) {
         sourceStream.mark(readLimit);
     }
 
     /**
      * Reset.
      */
     @Override
     public void reset() throws IOException {
         sourceStream.reset();
     }
 
     /**
      * Check if mark is supported.
      */
     @Override
     public boolean markSupported() {
         return sourceStream.markSupported();
     }
 
     /**
      * Close.
      */
     @Override
     public void close() throws IOException {
         sourceStream.close();
     }
 
     static class DeflateStream extends InflaterInputStream {
 
         private boolean closed = false;
 
         public DeflateStream(final InputStream in, final Inflater inflater) {
             super(in, inflater);
         }
 
         @Override
         public void close() throws IOException {
             if (closed) {
                 return;
             }
             closed = true;
             inf.end();
             super.close();
         }
 
     }
 
 }