/*
    *    Copyright 2012-2022 the original author or authors.
    *
    *    Licensed 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
    *
    *       https://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.
   */
  package org.mybatis.caches.memcached;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.Closeable;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.util.zip.GZIPInputStream;
  import java.util.zip.GZIPOutputStream;
  
  import net.spy.memcached.CachedData;
  import net.spy.memcached.transcoders.Transcoder;
  
  import org.apache.ibatis.cache.CacheException;
  
  /**
   * The Transcoder that compress and decompress the stored objects using the GZIP compression algorithm.
   *
   * @author Simone Tripodi
   */
  final class CompressorTranscoder implements Transcoder<Object> {
  
    /**
     * The serialized and compressed flag.
     */
    private static final int SERIALIZED_COMPRESSED = 3;
  
    /**
     * {@inheritDoc}
     */
    @Override
    public boolean asyncDecode(final CachedData cachedData) {
      return false;
    }
  
    /**
     * {@inheritDoc}
     */
    @Override
    public Object decode(final CachedData cachedData) {
      byte[] buffer = cachedData.getData();
  
      ByteArrayInputStream bais = new ByteArrayInputStream(buffer);
      GZIPInputStream gzis = null;
      ObjectInputStream ois = null;
      Object ret = null;
  
      try {
        gzis = new GZIPInputStream(bais);
        ois = new ObjectInputStream(gzis);
        ret = ois.readObject();
      } catch (Exception e) {
        throw new CacheException("Impossible to decompress cached object, see nested exceptions", e);
      } finally {
        closeQuietly(ois);
        closeQuietly(gzis);
        closeQuietly(bais);
      }
      return ret;
    }
  
    /**
     * {@inheritDoc}
     */
    @Override
    public CachedData encode(final Object object) {
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      GZIPOutputStream gzops = null;
      ObjectOutputStream oos = null;
  
      try {
        gzops = new GZIPOutputStream(baos);
        oos = new ObjectOutputStream(gzops);
        oos.writeObject(object);
      } catch (IOException e) {
        throw new CacheException("Impossible to compress object [" + object + "], see nested exceptions", e);
      } finally {
        closeQuietly(oos);
        closeQuietly(gzops);
        closeQuietly(baos);
      }
  
     byte[] buffer = baos.toByteArray();
     return new CachedData(SERIALIZED_COMPRESSED, buffer, CachedData.MAX_SIZE);
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public int getMaxSize() {
     return Integer.MAX_VALUE;
   }
 
   /**
    * Unconditionally close an {@link InputStream}.
    *
    * @param closeable
    *          the InputStream to close, may be null or already closed.
    */
   private static void closeQuietly(final Closeable closeable) {
     if (closeable != null) {
       try {
         closeable.close();
       } catch (IOException e) {
         // do nothing
       }
     }
   }
 
 }