/*
    * Copyright 2009 Red Hat, Inc.
    *
    * Red Hat 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.
   */
  package org.jboss.netty.handler.codec.serialization;
  
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInputStream;
  import java.io.ObjectStreamClass;
  import java.io.StreamCorruptedException;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
   *
   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
   *
   */
  class CompactObjectInputStream extends ObjectInputStream {
  
      private final Map<String, Class<?>> classCache = new HashMap<String, Class<?>>();
      private final ClassLoader classLoader;
  
      CompactObjectInputStream(InputStream in) throws IOException {
          this(in, null);
      }
  
      CompactObjectInputStream(InputStream in, ClassLoader classLoader) throws IOException {
          super(in);
          this.classLoader = classLoader;
      }
  
      @Override
      protected void readStreamHeader() throws IOException,
              StreamCorruptedException {
          int version = readByte() & 0xFF;
          if (version != STREAM_VERSION) {
              throw new StreamCorruptedException(
                      "Unsupported version: " + version);
          }
      }
  
      @Override
      protected ObjectStreamClass readClassDescriptor()
              throws IOException, ClassNotFoundException {
          int type = read();
          if (type < 0) {
              throw new EOFException();
          }
          switch (type) {
          case CompactObjectOutputStream.TYPE_FAT_DESCRIPTOR:
              return super.readClassDescriptor();
          case CompactObjectOutputStream.TYPE_THIN_DESCRIPTOR:
              String className = readUTF();
              Class<?> clazz = loadClass(className);
              return ObjectStreamClass.lookupAny(clazz);
          default:
              throw new StreamCorruptedException(
                      "Unexpected class descriptor type: " + type);
          }
      }
  
      @Override
      protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
          // Query the cache first.
          String className = desc.getName();
          Class<?> clazz = classCache.get(className);
          if (clazz != null) {
              return clazz;
          }
  
          // And then try to resolve.
          try {
              clazz = loadClass(className);
          } catch (ClassNotFoundException ex) {
              clazz = super.resolveClass(desc);
          }
  
          classCache.put(className, clazz);
          return clazz;
      }
  
      protected Class<?> loadClass(String className) throws ClassNotFoundException {
          // Query the cache first.
         Class<?> clazz;
         clazz = classCache.get(className);
         if (clazz != null) {
             return clazz;
         }
 
         // And then try to load.
         ClassLoader classLoader = this.classLoader;
         if (classLoader == null) {
             classLoader = Thread.currentThread().getContextClassLoader();
         }
 
         if (classLoader != null) {
             clazz = classLoader.loadClass(className);
         } else {
             clazz = Class.forName(className);
         }
 
         classCache.put(className, clazz);
         return clazz;
     }
 }