/*

 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.util.zip;

/**

 * This class provides support for general purpose decompression 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         Deflater

 * @author      David Connelly

 *

 */

public

class Inflater {

    private final ZStreamRef zsRef;

    private byte[] buf = defaultBuf;

    private int off, len;

    private boolean finished;

    private boolean needDict;

    private static final byte[] defaultBuf = new byte[0];

    static {

        /* Zip library is loaded from System.initializeSystemClass */

        initIDs();

    }

    /**

     * Creates a new decompressor. If the parameter 'nowrap' is true then

     * the ZLIB header and checksum fields will not be used. This provides

     * compatibility with the compression format used by both GZIP and PKZIP.

     * <p>

     * Note: When using the 'nowrap' option it is also necessary to provide

     * an extra "dummy" byte as input. This is required by the ZLIB native

     * library in order to support certain optimizations.

     *

     * @param nowrap if true then support GZIP compatible compression

     */

    public Inflater(boolean nowrap) {

        zsRef = new ZStreamRef(init(nowrap));

    }

    /**

     * Creates a new decompressor.

     */

    public Inflater() {

        this(false);

    }

    /**

     * Sets input data for decompression. 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 input data

     * @param len the length of the input data

     * @see Inflater#needsInput

     */

    public 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();

        }

        synchronized (zsRef) {

            this.buf = b;

            this.off = off;

            this.len = len;

        }

    }

    /**

     * Sets input data for decompression. Should be called whenever

     * needsInput() returns true indicating that more input data is

     * required.

     * @param b the input data bytes

     * @see Inflater#needsInput

     */

    public void setInput(byte[] b) {

        setInput(b, 0, b.length);

    }

    /**

     * Sets the preset dictionary to the given array of bytes. Should be

     * called when inflate() returns 0 and needsDictionary() returns true

     * indicating that a preset dictionary is required. The method getAdler()

     * can be used to get the Adler-32 value of the dictionary needed.

     * @param b the dictionary data bytes

     * @param off the start offset of the data

     * @param len the length of the data

     * @see Inflater#needsDictionary

     * @see Inflater#getAdler

     */

    public void setDictionary(byte[] b, int off, int len) {

        if (b == null) {

            throw new NullPointerException();

        }

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

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            ensureOpen();

            setDictionary(zsRef.address(), b, off, len);

            needDict = false;

        }

    }

    /**

     * Sets the preset dictionary to the given array of bytes. Should be

     * called when inflate() returns 0 and needsDictionary() returns true

     * indicating that a preset dictionary is required. The method getAdler()

     * can be used to get the Adler-32 value of the dictionary needed.

     * @param b the dictionary data bytes

     * @see Inflater#needsDictionary

     * @see Inflater#getAdler

     */

    public void setDictionary(byte[] b) {

        setDictionary(b, 0, b.length);

    }

    /**

     * Returns the total number of bytes remaining in the input buffer.

     * This can be used to find out what bytes still remain in the input

     * buffer after decompression has finished.

     * @return the total number of bytes remaining in the input buffer

     */

    public int getRemaining() {

        synchronized (zsRef) {

            return len;

        }

    }

    /**

     * Returns true if no data remains in the input buffer. This can

     * be used to determine if #setInput should be called in order

     * to provide more input.

     * @return true if no data remains in the input buffer

     */

    public boolean needsInput() {

        synchronized (zsRef) {

            return len <= 0;

        }

    }

    /**

     * Returns true if a preset dictionary is needed for decompression.

     * @return true if a preset dictionary is needed for decompression

     * @see Inflater#setDictionary

     */

    public boolean needsDictionary() {

        synchronized (zsRef) {

            return needDict;

        }

    }

    /**

     * Returns true if the end of the compressed data stream has been

     * reached.

     * @return true if the end of the compressed data stream has been

     * reached

     */

    public boolean finished() {

        synchronized (zsRef) {

            return finished;

        }

    }

    /**

     * Uncompresses bytes into specified buffer. Returns actual number

     * of bytes uncompressed. A return value of 0 indicates that

     * needsInput() or needsDictionary() should be called in order to

     * determine if more input data or a preset dictionary is required.

     * In the latter case, getAdler() can be used to get the Adler-32

     * value of the dictionary required.

     * @param b the buffer for the uncompressed data

     * @param off the start offset of the data

     * @param len the maximum number of uncompressed bytes

     * @return the actual number of uncompressed bytes

     * @exception DataFormatException if the compressed data format is invalid

     * @see Inflater#needsInput

     * @see Inflater#needsDictionary

     */

    public int inflate(byte[] b, int off, int len)

        throws DataFormatException

    {

        if (b == null) {

            throw new NullPointerException();

        }

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

            throw new ArrayIndexOutOfBoundsException();

        }

        synchronized (zsRef) {

            ensureOpen();

            return inflateBytes(zsRef.address(), b, off, len);

        }

    }

    /**

     * Uncompresses bytes into specified buffer. Returns actual number

     * of bytes uncompressed. A return value of 0 indicates that

     * needsInput() or needsDictionary() should be called in order to

     * determine if more input data or a preset dictionary is required.

     * In the latter case, getAdler() can be used to get the Adler-32

     * value of the dictionary required.

     * @param b the buffer for the uncompressed data

     * @return the actual number of uncompressed bytes

     * @exception DataFormatException if the compressed data format is invalid

     * @see Inflater#needsInput

     * @see Inflater#needsDictionary

     */

    public int inflate(byte[] b) throws DataFormatException {

        return inflate(b, 0, b.length);

    }

    /**

     * Returns the ADLER-32 value of the uncompressed data.

     * @return the ADLER-32 value of the uncompressed data

     */

    public int getAdler() {

        synchronized (zsRef) {

            ensureOpen();

            return getAdler(zsRef.address());

        }

    }

    /**

     * Returns the total number of compressed 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 compressed bytes input so far

     */

    public int getTotalIn() {

        return (int) getBytesRead();

    }

    /**

     * Returns the total number of compressed bytes input so far.</p>

     *

     * @return the total (non-negative) number of compressed bytes input so far

     * @since 1.5

     */

    public long getBytesRead() {

        synchronized (zsRef) {

            ensureOpen();

            return getBytesRead(zsRef.address());

        }

    }

    /**

     * Returns the total number of uncompressed 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 uncompressed bytes output so far

     */

    public int getTotalOut() {

        return (int) getBytesWritten();

    }

    /**

     * Returns the total number of uncompressed bytes output so far.</p>

     *

     * @return the total (non-negative) number of uncompressed bytes output so far

     * @since 1.5

     */

    public long getBytesWritten() {

        synchronized (zsRef) {

            ensureOpen();

            return getBytesWritten(zsRef.address());

        }

    }

    /**

     * Resets inflater so that a new set of input data can be processed.

     */

    public void reset() {

        synchronized (zsRef) {

            ensureOpen();

            reset(zsRef.address());

            buf = defaultBuf;

            finished = false;

            needDict = false;

            off = len = 0;

        }

    }

    /**

     * Closes the decompressor and discards any unprocessed input.

     * This method should be called when the decompressor is no longer

     * being used, but will also be called automatically by the finalize()

     * method. Once this method is called, the behavior of the Inflater

     * object is undefined.

     */

    public void end() {

        synchronized (zsRef) {

            long addr = zsRef.address();

            zsRef.clear();

            if (addr != 0) {

                end(addr);

                buf = null;

            }

        }

    }

    /**

     * Closes the decompressor when garbage is collected.

     */

    protected void finalize() {

        end();

    }

    private void ensureOpen () {

        assert Thread.holdsLock(zsRef);

        if (zsRef.address() == 0)

            throw new NullPointerException("Inflater has been closed");

    }

    boolean ended() {

        synchronized (zsRef) {

            return zsRef.address() == 0;

        }

    }

    private native static void initIDs();

    private native static long init(boolean nowrap);

    private native static void setDictionary(long addr, byte[] b, int off,

                                             int len);

    private native int inflateBytes(long addr, byte[] b, int off, int len)

            throws DataFormatException;

    private native static int getAdler(long addr);

    private native static long getBytesRead(long addr);

    private native static long getBytesWritten(long addr);

    private native static void reset(long addr);

    private native static void end(long addr);

}