/*

 * Copyright 1996-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.util.zip;

/**

 * 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

 * @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 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) {

        if (b== null) {

            throw new NullPointerException();

        }

        if (off < 0 || len < 0 || off > b.length - len) {

            throw new ArrayIndexOutOfBoundsException();

        }

        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) {

        if (strm == 0 || b == null) {

            throw new NullPointerException();

        }

        if (off < 0 || len < 0 || off > b.length - len) {

            throw new ArrayIndexOutOfBoundsException();

        }

        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;

    }

    /**

     * 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

     * @param off the start offset of the data

     * @param len the maximum number of bytes of compressed data

     * @return the actual number of bytes of compressed data

     */

    public synchronized int deflate(byte[] b, int off, int len) {

        if (b == null) {

            throw new NullPointerException();

        }

        if (off < 0 || len < 0 || off > b.length - len) {

            throw new ArrayIndexOutOfBoundsException();

        }

        return deflateBytes(b, off, len);

    }

    /**

     * 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(byte[] b, int off, int len);

    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);

}