/*
    *  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.
   *
   */
  package org.apache.mina.filter.codec.serialization;
  
  import java.io.DataInput;
  import java.io.DataInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInput;
  import java.io.StreamCorruptedException;
  
  import org.apache.mina.core.buffer.BufferDataException;
  import org.apache.mina.core.buffer.IoBuffer;
  
  /**
   * An {@link ObjectInput} and {@link InputStream} that can read the objects encoded
   * by {@link ObjectSerializationEncoder}.
   *
   * @author The Apache MINA Project (dev@mina.apache.org)
   */
  public class ObjectSerializationInputStream extends InputStream implements
          ObjectInput {
  
      private final DataInputStream in;
  
      private final ClassLoader classLoader;
  
      private int maxObjectSize = 1048576;
  
      public ObjectSerializationInputStream(InputStream in) {
          this(in, null);
      }
  
      public ObjectSerializationInputStream(InputStream in,
              ClassLoader classLoader) {
          if (in == null) {
              throw new NullPointerException("in");
          }
          if (classLoader == null) {
              classLoader = Thread.currentThread().getContextClassLoader();
          }
  
          if (in instanceof DataInputStream) {
              this.in = (DataInputStream) in;
          } else {
              this.in = new DataInputStream(in);
          }
  
          this.classLoader = classLoader;
      }
  
      /**
       * Returns the allowed maximum size of the object to be decoded.
       * If the size of the object to be decoded exceeds this value, this
       * decoder will throw a {@link BufferDataException}.  The default
       * value is <tt>1048576</tt> (1MB).
       */
      public int getMaxObjectSize() {
          return maxObjectSize;
      }
  
      /**
       * Sets the allowed maximum size of the object to be decoded.
       * If the size of the object to be decoded exceeds this value, this
       * decoder will throw a {@link BufferDataException}.  The default
       * value is <tt>1048576</tt> (1MB).
       */
      public void setMaxObjectSize(int maxObjectSize) {
          if (maxObjectSize <= 0) {
              throw new IllegalArgumentException("maxObjectSize: "
                      + maxObjectSize);
          }
  
          this.maxObjectSize = maxObjectSize;
      }
  
      @Override
      public int read() throws IOException {
          return in.read();
      }
  
      public Object readObject() throws ClassNotFoundException, IOException {
         int objectSize = in.readInt();
         if (objectSize <= 0) {
             throw new StreamCorruptedException("Invalid objectSize: "
                     + objectSize);
         }
         if (objectSize > maxObjectSize) {
             throw new StreamCorruptedException("ObjectSize too big: "
                     + objectSize + " (expected: <= " + maxObjectSize + ')');
         }
 
         IoBuffer buf = IoBuffer.allocate(objectSize + 4, false);
         buf.putInt(objectSize);
         in.readFully(buf.array(), 4, objectSize);
         buf.position(0);
         buf.limit(objectSize + 4);
 
         return buf.getObject(classLoader);
     }
 
     public boolean readBoolean() throws IOException {
         return in.readBoolean();
     }
 
     public byte readByte() throws IOException {
         return in.readByte();
     }
 
     public char readChar() throws IOException {
         return in.readChar();
     }
 
     public double readDouble() throws IOException {
         return in.readDouble();
     }
 
     public float readFloat() throws IOException {
         return in.readFloat();
     }
 
     public void readFully(byte[] b) throws IOException {
         in.readFully(b);
     }
 
     public void readFully(byte[] b, int off, int len) throws IOException {
         in.readFully(b, off, len);
     }
 
     public int readInt() throws IOException {
         return in.readInt();
     }
 
     /**
      * @see DataInput#readLine()
      * @deprecated
      */
     @Deprecated
     public String readLine() throws IOException {
         return in.readLine();
     }
 
     public long readLong() throws IOException {
         return in.readLong();
     }
 
     public short readShort() throws IOException {
         return in.readShort();
     }
 
     public String readUTF() throws IOException {
         return in.readUTF();
     }
 
     public int readUnsignedByte() throws IOException {
         return in.readUnsignedByte();
     }
 
     public int readUnsignedShort() throws IOException {
         return in.readUnsignedShort();
     }
 
     public int skipBytes(int n) throws IOException {
         return in.skipBytes(n);
     }
 }