/*
 * Copyright (c) 2003,2009 Declarative Engineering LLC.
 * All rights reserved.  This program and the accompanying materials
 * are made available under the terms of the Declarative Engineering LLC
 * verson 1 which accompanies this distribution, and is available at
 * http://declarativeengineering.com/legal/DE_Developer_License_v1.txt
 */
package com.common.io;

import java.io.OutputStream;
import java.io.IOException;
import java.util.zip.*;

public class CompressionOutputStream extends OutputStream implements IOutputStream {
	public static final int DEFAULT_BUFFER_SIZE = 301;
	public static final int MAX_BUFFER_SIZE = 65535;

	protected OutputStream stream = null;
	protected Deflater deflater = null;
	protected byte[] outputBuffer = null;
/**
 * CompressionOutputStream constructor.
 * @param stream The stream that will handle all output from this stream.
 */
public CompressionOutputStream(OutputStream stream) {
	this(stream, null, DEFAULT_BUFFER_SIZE);
}//CompressionOutputStream()//
/**
 * CompressionOutputStream constructor.
 * @param stream The stream that will handle all output from this stream.
 * @param deflater The deflater to be used.
 */
public CompressionOutputStream(OutputStream stream, Deflater deflater) {
	this(stream, deflater, DEFAULT_BUFFER_SIZE);
}//CompressionOutputStream()//
/**
 * CompressionOutputStream constructor.
 * @param stream The stream that will handle all output from this stream.
 * @param deflater The deflater to be used.
 * @param bufferSize The size of the buffer used to read from the deflater.
 */
public CompressionOutputStream(OutputStream stream, Deflater deflater, int bufferSize) {
	//Validate the inputs.//
	if(bufferSize < 1) {
		throw new IllegalArgumentException("Buffer size must be greater than zero.");
	}//if//
	else if(bufferSize > MAX_BUFFER_SIZE) {
		throw new IllegalArgumentException("Buffer size must be less than " + MAX_BUFFER_SIZE + ".");
	}//else if//
	else if(stream == null) {
		throw new IllegalArgumentException("A non-null output stream must be provided.");
	}//else if//
	else if(deflater == null) {
		deflater = new Deflater(Deflater.DEFAULT_COMPRESSION, true);
	}//else if//

	this.stream = stream;
	this.deflater = deflater;
	this.outputBuffer = new byte[bufferSize];
}//CompressionOutputStream()//
/* (non-Javadoc)
 * @see java.io.IOutputStream#canEncrypt()
 */
public boolean canEncrypt() {
	return (stream instanceof IOutputStream) && (((IOutputStream) stream).canEncrypt());
}//canEncrypt()//
/* (non-Javadoc)
 * @see java.io.OutputStream#close()
 */
public void close() throws IOException {
	deflater.finish();
	deflate();
	
	super.close();
}//close()//
/**
 * Deflates the cached data.
 */
private void deflate() throws IOException {
	int count = 0;
	
	while((count = deflater.deflate(outputBuffer, 2, outputBuffer.length - 2)) > 0) {
		StreamSupport.writeShort((short) count, outputBuffer, 0);  //Note: count should never exceed the buffer length and thus should stay within two bytes in size.//
		stream.write(outputBuffer, 0, count + 2);
	}//while//
	
	/* Another way of doing the same thing I think.
	while(!deflater.needsInput()) {
		int count = deflater.deflate(outputBuffer);

		if(count > 0) {
			stream.write(outputBuffer, 0, count);
		}//if//
	}//while//
	*/
}//deflate()//
/* (non-Javadoc)
 * @see java.io.IOutputStream#encrypt(boolean)
 */
public void encrypt(boolean encrypt) throws IOException {
	if(stream instanceof IOutputStream) {
		if(((IOutputStream) stream).canEncrypt()) {
			flush();
			((IOutputStream) stream).encrypt(encrypt);
		}//if//
		else {
			throw new IOException(ERROR_ENCRYPTION_NOT_SUPPORTED);
		}//else//
	}//if//
	else {
		throw new IOException(ERROR_ENCRYPTION_NOT_SUPPORTED);
	}//else//
}//encrypt()//
/* (non-Javadoc)
 * @see java.io.OutputStream#flush()
 */
public void flush() throws IOException {
	if(deflater.getTotalIn() > 0) {
		deflater.finish();
		deflate();
		deflater.reset();
	}//if//
		
	stream.flush();
}//flush()//
/* (non-Javadoc)
 * @see java.io.IOutputStream#isEncrypting()
 */
public boolean isEncrypting() {
	return (stream instanceof IOutputStream) && (((IOutputStream) stream).isEncrypting());
}//isEncrypting()//
/* (non-Javadoc)
 * @see java.io.OutputStream#write(byte[])
 */
public void write(byte[] buffer) throws IOException {
	write(buffer, 0, buffer.length);
}//write()//
/* (non-Javadoc)
 * @see java.io.OutputStream#write(byte[], int, int)
 */
public void write(byte[] buffer, int offset, int length) throws IOException {
	deflater.setInput(buffer, offset, length);
	deflate();
}//write()//
/* (non-Javadoc)
 * @see java.io.OutputStream#write(int)
 */
public void write(int b) throws IOException {
	outputBuffer[0] = (byte) (b & 0xFF);
	write(outputBuffer, 0, 1);
}//write()//
}//CompressionOutputStream//