/*
 * Copyright (C) 1995, 1996, 1997 By Radu Sion 
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by Radu Sion (radus@cs.pub.ro)
 *
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * (radus@cs.pub.ro, http://www.dsp.pub.ro/radu.html)
 *
 */

import	java.io.*;
import	util;
import	MessageConstants;


/**
 * A class designed to be used as a general network byte message wrapping class.<br><br>
 * For a Message to be valid, it should be created using some <a href="MessageCreator.html">MessageCreator</a>
 * method and then parsed using the <a href="MessageParser.html">MessageParser</a>. It's not enough to create
 * a Message with it's constructor and just feed it further. You should use the <a href="MessageCreator.html">MessageCreator</a>
 * for any message you create. The simplicity is the same. <br>
 * [IN WORK: Implementing Extensive Validity]<br><br>
 * Written: <a href="http://www.dsp.pub.ro/radu.html">Radu Sion</a><br>
 * Version: 0.21<br>
 * Source: <a href="src/Message.java">Message.java</a>
 * @see	MessageCreator
 * @see MessageParser
 */
class 
Message
extends Object
{
byte data[];

/**
 * Constructs a null message based on a given length. 
 * No checkings are performed on parameters.
 * @param 	len	Length in bytes of the new null initialized message
 */
public 
Message(int len)
	{
	data = new byte[len];
	}

/**
 * Constructs a message based on a bytes array. 
 * No checkings are performed on parameters.
 * @param	oo[]	Bytesarray used to initialize the message 
 */
public
Message(byte oo[])
	{
	data = oo;
	}


/**
 * Constructs a message based on a string. 
 * No checkings are performed on parameters.
 * The the string is used only as ASCII so you will loose extra 
 * EBDIC information. (for now) 
 * @param	ss	String used to initialize the message
 */
public
Message(String ss)
	{
	data = new byte[ss.length()];
	ss.getBytes(0,ss.length(),data,0);
	}


/**
 * Constructs a message based on another message, it is just like duplicating.
 * No checkings are performed on parameters.
 * @param msg Original message to copy
 */
public
Message(Message msg)
	{
	data = msg.getBytes();
	}


/**
 * Reads a message from a DataInputStream.
 * Assumes the stream is open & running.
 * No parameter checkings performed.
 * @param dis The InputStream
 * @return null if error, a new Message if ok.
 * @exception IOException If some error occured at the stream.
 */
public static Message
readDataInputStream(DataInputStream dis)
throws IOException
	{
	int len = dis.readInt();
	byte[] buff = new byte[len];
	dis.readFully(buff);
	return new Message(buff);
	}

/** 
 * Writes a message to a DataOutputStream. It might block !!!
 * Assumes stream open & running.
 * No parameter checkings performed.
 * @padram dos The DataOutputStream
 * @param msg Message to send
 * @return true if ok, false otherwise
 * @exception IOException If some error occured at the stream.
 */
public static boolean
writeDataOutputStream(DataOutputStream dos, Message msg)
throws IOException
	{
	dos.writeInt(msg.length());
	byte[] buff = msg.getBytes();
	dos.write(buff); /** blocking ... **/
	//dos.flush();
	return true;
	}	

/**
 * Returns a integer representing two bytes starting at the given index
 * interpreted lo, hi as a integer.
 * No parameter checkings performed.
 * @param index Start index, index of the hi byte
 */
public int
getInt(int index)
	{
	return (data[index+1]*128 + data[index]);
	}


/**
 * Sets two bytes of the message, to represent a integer value as lo, hi.
 * This is the opposite of .getInt().
 * No parameter checkings performed.
 * @param index Index of first (hi) byte
 */
public void
setInt(int index, int value)
	{
	data[index] = (byte)(value % 128);
	data[index+1] = (byte)(value / 128);
	}

/**
 * Returns a character at a given index in the Message. 
 * No checkings are performed on parameters.
 * @param	index	Index in the Message
 */
public char
charAt(int index)
	{
	return (char)data[index];
	}


/**
 * Returns a byte at a given index in the Message.
 * No checkings are performed on parameters.
 * @param	index	Index in the Message
 */
public byte
byteAt(int index)
	{
	return data[index];
	}

/**
 * Sets a byte at a given index in the Message, with a specified value. 
 * No checkings are performed on parameters.
 * @param	index	Index in the Message
 * @param	value	Value to set 
 */
public void
byteAt(int index,int value)
	{
	data[index] = (byte)value;
	}

/**
 * Gives the length of the Message. 
 * @return The length of the Message
 */
public int
length()
	{
	return data.length;
	}

/**
 * Gives a byte reprezentation of the Message.
 * @return A byte array reprezenting the Message.
 */
public byte[]
getBytes()
	{
	return data;
	}

/**
 * Gives a String reprezenting the Message. 
 * It just uses getBytes() to construct a ASCII String.
 */
public String
getString()
	{
	return new String(data,0);
	}

}
/*eoc*/