/*
 * Copyright 1996-2006 Sun Microsystems, Inc.  All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
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 *
 *
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 *
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 */

package java.util.zip;

import java.nio.ByteBuffer;

/**
 * This class provides support for general purpose compression using the
 * popular ZLIB compression library. The ZLIB compression library was
 * initially developed as part of the PNG graphics standard and is not
 * protected by patents. It is fully described in the specifications at 
 * the <a href="package-summary.html#package_description">java.util.zip
 * package description</a>.
 *
 * <p>The following code fragment demonstrates a trivial compression
 * and decompression of a string using <tt>Deflater</tt> and
 * <tt>Inflater</tt>.
 *
 * <blockquote><pre>
 * try {
 *     // Encode a String into bytes
 *     String inputString = "blahblahblah\u20AC\u20AC";
 *     byte[] input = inputString.getBytes("UTF-8");
 *
 *     // Compress the bytes
 *     byte[] output = new byte[100];
 *     Deflater compresser = new Deflater();
 *     compresser.setInput(input);
 *     compresser.finish();
 *     int compressedDataLength = compresser.deflate(output);
 *
 *     // Decompress the bytes
 *     Inflater decompresser = new Inflater();
 *     decompresser.setInput(output, 0, compressedDataLength);
 *     byte[] result = new byte[100];
 *     int resultLength = decompresser.inflate(result);
 *     decompresser.end();
 *
 *     // Decode the bytes into a String
 *     String outputString = new String(result, 0, resultLength, "UTF-8");
 * } catch(java.io.UnsupportedEncodingException ex) {
 *     // handle
 * } catch (java.util.zip.DataFormatException ex) {
 *     // handle
 * }
 * </pre></blockquote>
 *
 * @see		Inflater
 * @version 	1.51, 05/05/07
 * @author 	David Connelly
 */
public class Deflater
{
	private long strm;
	private byte[] buf = new byte[0];
	private int off, len;
	private int level, strategy;
	private boolean setParams;
	private volatile boolean finish, finished;

	/**
	 * Compression method for the deflate algorithm (the only one currently
	 * supported).
	 */
	public static final int DEFLATED = 8;

	/**
	 * Compression level for no compression.
	 */
	public static final int NO_COMPRESSION = 0;

	/**
	 * Compression level for fastest compression.
	 */
	public static final int BEST_SPEED = 1;

	/**
	 * Compression level for best compression.
	 */
	public static final int BEST_COMPRESSION = 9;

	/**
	 * Default compression level.
	 */
	public static final int DEFAULT_COMPRESSION = -1;

	/**
	 * Compression strategy best used for data consisting mostly of small
	 * values with a somewhat random distribution. Forces more Huffman coding
	 * and less string matching.
	 */
	public static final int FILTERED = 1;

	/**
	 * Compression strategy for Huffman coding only.
	 */
	public static final int HUFFMAN_ONLY = 2;

	/**
	 * Default compression strategy.
	 */
	public static final int DEFAULT_STRATEGY = 0;

	static
	{
		/* Zip library is loaded from System.initializeSystemClass */
		initIDs();
	}

	/**
	 * Creates a new compressor using the specified compression level.
	 * If 'nowrap' is true then the ZLIB header and checksum fields will
	 * not be used in order to support the compression format used in
	 * both GZIP and PKZIP.
	 * @param level the compression level (0-9)
	 * @param nowrap if true then use GZIP compatible compression
	 */
	public Deflater(int level, boolean nowrap)
	{
		this.level = level;
		this.strategy = DEFAULT_STRATEGY;

		strm = init(level, DEFAULT_STRATEGY, nowrap);
	}

	/** 
	 * Creates a new compressor using the specified compression level.
	 * Compressed data will be generated in ZLIB format.
	 * @param level the compression level (0-9)
	 */
	public Deflater(int level)
	{
		this(level, false);
	}

	/**
	 * Creates a new compressor with the default compression level.
	 * Compressed data will be generated in ZLIB format.
	 */
	public Deflater()
	{
		this(DEFAULT_COMPRESSION, false);
	}

	/**
	 * Sets input data for compression. This should be called whenever
	 * needsInput() returns true indicating that more input data is required.
	 * @param b the input data bytes
	 * @param off the start offset of the data
	 * @param len the length of the data
	 * @see Deflater#needsInput
	 */
	public synchronized void setInput(byte[] b, int off, int len)
	{
		rangeCheck(b, off, len);

		this.buf = b;
		this.off = off;
		this.len = len;
	}

	/**
	 * Sets input data for compression. This should be called whenever
	 * needsInput() returns true indicating that more input data is required.
	 * @param b the input data bytes
	 * @see Deflater#needsInput
	 */
	public void setInput(byte[] b)
	{
		setInput(b, 0, b.length);
	}

	/**
	 * Sets preset dictionary for compression. A preset dictionary is used
	 * when the history buffer can be predetermined. When the data is later
	 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
	 * in order to get the Adler-32 value of the dictionary required for
	 * decompression.
	 * @param b the dictionary data bytes
	 * @param off the start offset of the data
	 * @param len the length of the data
	 * @see Inflater#inflate
	 * @see Inflater#getAdler
	 */
	public synchronized void setDictionary(byte[] b, int off, int len)
	{
		rangeCheck(b, off, len);
		setDictionary(strm, b, off, len);
	}

	/**
	 * Sets preset dictionary for compression. A preset dictionary is used
	 * when the history buffer can be predetermined. When the data is later
	 * uncompressed with Inflater.inflate(), Inflater.getAdler() can be called
	 * in order to get the Adler-32 value of the dictionary required for
	 * decompression.
	 * @param b the dictionary data bytes
	 * @see Inflater#inflate
	 * @see Inflater#getAdler
	 */
	public void setDictionary(byte[] b)
	{
		setDictionary(b, 0, b.length);
	}

	/**
	 * Sets the compression strategy to the specified value.
	 * @param strategy the new compression strategy
	 * @exception IllegalArgumentException if the compression strategy is
	 *				           invalid
	 */
	public synchronized void setStrategy(int strategy)
	{
		switch (strategy)
		{
			case DEFAULT_STRATEGY:
			case FILTERED:
			case HUFFMAN_ONLY:
				break;
			default:
				throw new IllegalArgumentException();
		}
		if (this.strategy != strategy)
		{
			this.strategy = strategy;
			setParams = true;
		}
	}

	/**
	 * Sets the current compression level to the specified value.
	 * @param level the new compression level (0-9)
	 * @exception IllegalArgumentException if the compression level is invalid
	 */
	public synchronized void setLevel(int level)
	{
		if ((level < 0 || level > 9) && level != DEFAULT_COMPRESSION)
		{
			throw new IllegalArgumentException("invalid compression level");
		}
		if (this.level != level)
		{
			this.level = level;
			setParams = true;
		}
	}

	/**
	 * Returns true if the input data buffer is empty and setInput()
	 * should be called in order to provide more input.
	 * @return true if the input data buffer is empty and setInput()
	 * should be called in order to provide more input
	 */
	public boolean needsInput()
	{
		return len <= 0;
	}

	/**
	 * When called, indicates that compression should end with the current
	 * contents of the input buffer.
	 */
	public synchronized void finish()
	{
		finish = true;
	}

	/**
	 * Returns true if the end of the compressed data output stream has
	 * been reached.
	 * @return true if the end of the compressed data output stream has
	 * been reached
	 */
	public synchronized boolean finished()
	{
		return finished;
	}

	protected void rangeCheck(byte[] b, int off, int len)
	{
		if (b == null)
		{
			throw new NullPointerException();
		}
		if (off < 0 || len < 0 || off > b.length - len)
		{
			throw new ArrayIndexOutOfBoundsException();
		}
	}

	
	public synchronized int deflate(byte[] outBuf, int outOff, int outLen)
	{
		rangeCheck(outBuf, outOff, outLen);
		return deflateBytes(strm, outBuf, outOff, outLen, this.buf, this.off, this.len, setParams, finish);
	}

	/**
	 * Fills specified buffer with compressed data. Returns actual number
	 * of bytes of compressed data. A return value of 0 indicates that
	 * needsInput() should be called in order to determine if more input
	 * data is required.
	 * @param b the buffer for the compressed data
	 * @return the actual number of bytes of compressed data
	 */
	public int deflate(byte[] b)
	{
		return deflate(b, 0, b.length);
	}

	/**
	 * Returns the ADLER-32 value of the uncompressed data.
	 * @return the ADLER-32 value of the uncompressed data
	 */
	public synchronized int getAdler()
	{
		ensureOpen();
		return getAdler(strm);
	}

	/**
	 * Returns the total number of uncompressed bytes input so far.
	 *
	 * <p>Since the number of bytes may be greater than
	 * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
	 * the preferred means of obtaining this information.</p>
	 *
	 * @return the total number of uncompressed bytes input so far
	 */
	public int getTotalIn()
	{
		return (int) getBytesRead();
	}

	/**
	 * Returns the total number of uncompressed bytes input so far.</p>
	 *
	 * @return the total (non-negative) number of uncompressed bytes input so far
	 * @since 1.5
	 */
	public synchronized long getBytesRead()
	{
		ensureOpen();
		return getBytesRead(strm);
	}

	/**
	 * Returns the total number of compressed bytes output so far.
	 *
	 * <p>Since the number of bytes may be greater than
	 * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
	 * the preferred means of obtaining this information.</p>
	 *
	 * @return the total number of compressed bytes output so far
	 */
	public int getTotalOut()
	{
		return (int) getBytesWritten();
	}

	/**
	 * Returns the total number of compressed bytes output so far.</p>
	 *
	 * @return the total (non-negative) number of compressed bytes output so far
	 * @since 1.5
	 */
	public synchronized long getBytesWritten()
	{
		ensureOpen();
		return getBytesWritten(strm);
	}

	/**
	 * Resets deflater so that a new set of input data can be processed.
	 * Keeps current compression level and strategy settings.
	 */
	public synchronized void reset()
	{
		ensureOpen();
		reset(strm);
		finish = false;
		finished = false;
		off = len = 0;
	}

	/**
	 * Closes the compressor and discards any unprocessed input.
	 * This method should be called when the compressor is no longer
	 * being used, but will also be called automatically by the
	 * finalize() method. Once this method is called, the behavior
	 * of the Deflater object is undefined.
	 */
	public synchronized void end()
	{
		if (strm != 0)
		{
			end(strm);
			strm = 0;
			buf = null;
		}
	}

	/**
	 * Closes the compressor when garbage is collected.
	 */
	protected void finalize()
	{
		end();
	}

	private void ensureOpen()
	{
		if (strm == 0)
			throw new NullPointerException();
	}

	private static native void initIDs();

	private native static long init(int level, int strategy, boolean nowrap);

	private native static void setDictionary(long strm, byte[] b, int off, int len);
	
	private native int deflateBytes(long strm, byte[] writeBuf, int writeOff, int writeLen, byte[] readBuf, int readOff, int readLen, boolean setParamIDs, boolean finish);

	private native static int getAdler(long strm);

	private native static long getBytesRead(long strm);

	private native static long getBytesWritten(long strm);

	private native static void reset(long strm);

	private native static void end(long strm);
}