/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.tools;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;

import com.rapidminer.example.ExampleSet;


/**
 * 
 * @author Simon Fischer
 *
 */
public class IOObjectSerializer {

	public static final byte[] MAGIC_NUMBER = { (byte)0x2A, (byte)0x71, (byte)0xD1 } ;

	private static final IOObjectSerializer INSTANCE = new IOObjectSerializer();
	
	public static IOObjectSerializer getInstance() {
		return INSTANCE;
	}
	

	/** Serializes the object with a default type appropriate for the given object. */
	public void serialize(OutputStream out, Object object) throws IOException {
		SerializationType type;
		if (object instanceof ExampleSet) {
			type = SerializationType.STREAMED_EXAMPLE_SET_DENSE_CURRENT_VERSION;
		} else {
			type = SerializationType.JAVA_BINARY;
		}
		serialize(out, object, type);
	}
	

	public void writeHeader(OutputStream out, SerializationType serializationType) throws IOException {
		out.write(MAGIC_NUMBER);
		out.flush();
		DataOutputStream dout = new DataOutputStream(out);
		dout.writeInt(serializationType.ordinal());
		dout.flush();
	}

	/** Serializes the object to the stream, using the given serialization type. */
	public void serialize(OutputStream out, Object object, SerializationType serializationType) throws IOException {
		writeHeader(out, serializationType);
		serializationType.getBodySerializer().serialize(object, out);
		out.flush();
	}

	public SerializationType deserializeHeader(InputStream in) throws IOException {
		byte[] magicRead = new byte[MAGIC_NUMBER.length];
		int offset = 0;
		int length;
		do {
			length = in.read(magicRead, offset, MAGIC_NUMBER.length - offset);
			if (length == -1) {
				throw new IOException("EOF while reading magic number.");
			}
			offset += length;
		}  while (offset < MAGIC_NUMBER.length);
		if (!Arrays.equals(magicRead, MAGIC_NUMBER)) {
			throw new IOException("No magic number found. Make sure you are using RapidMiner 5.0 compatible files.");
		}
		DataInputStream din = new DataInputStream(in);
		int typeIndex = din.readInt();
		if ((typeIndex < 0) || (typeIndex > SerializationType.values().length)) {
			throw new IOException("Illegal serialization type: " + typeIndex);
		}
		return SerializationType.values()[typeIndex];
	}

	/** Deserializes an object serialized by {@link #serialize(OutputStream, Object, SerializationType)}. */
	public Object deserialize(InputStream in) throws IOException {
		SerializationType type = deserializeHeader(in);
		return type.getBodySerializer().deserialize(in);
	}
		
	/** Serializes the object into a byte buffer. */
	public byte[] serializeToBuffer(Object o) throws IOException {
		ByteArrayOutputStream bufOut = new ByteArrayOutputStream();
		try {
			serialize(bufOut, o);
			bufOut.flush();
			return bufOut.toByteArray();
		} finally {
			bufOut.close();
		}		
	}
	
	/** Deserializes the object from a byte buffer created by {@link #serializeToBuffer(Object)}. */
	public Object deserializeFromBuffer(byte[] buffer) throws IOException, ClassNotFoundException {
		ByteArrayInputStream bufIn = new ByteArrayInputStream(buffer);
		try {
			return deserialize(bufIn);
		} finally {
			bufIn.close();
		}		
	}
}