/*

 * Copyright 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;

import java.io.FilterInputStream;

import java.io.InputStream;

import java.io.IOException;

/**

 * Implements an input stream filter for compressing data in the "deflate"

 * compression format.

 *

 * @since       1.6

 * @author      David R Tribble (david@tribble.com)

 *

 * @see DeflaterOutputStream

 * @see InflaterOutputStream

 * @see InflaterInputStream

 */

public class DeflaterInputStream extends FilterInputStream {

    /** Compressor for this stream. */

    protected final Deflater def;

    /** Input buffer for reading compressed data. */

    protected final byte[] buf;

    /** Temporary read buffer. */

    private byte[] rbuf = new byte[1];

    /** Default compressor is used. */

    private boolean usesDefaultDeflater = false;

    /** End of the underlying input stream has been reached. */

    private boolean reachEOF = false;

    /**

     * Check to make sure that this stream has not been closed.

     */

    private void ensureOpen() throws IOException {

        if (in == null) {

            throw new IOException("Stream closed");

        }

    }

    /**

     * Creates a new input stream with a default compressor and buffer

     * size.

     *

     * @param in input stream to read the uncompressed data to

     * @throws NullPointerException if {@code in} is null

     */

    public DeflaterInputStream(InputStream in) {

        this(in, new Deflater());

        usesDefaultDeflater = true;

    }

    /**

     * Creates a new input stream with the specified compressor and a

     * default buffer size.

     *

     * @param in input stream to read the uncompressed data to

     * @param defl compressor ("deflater") for this stream

     * @throws NullPointerException if {@code in} or {@code defl} is null

     */

    public DeflaterInputStream(InputStream in, Deflater defl) {

        this(in, defl, 512);

    }

    /**

     * Creates a new input stream with the specified compressor and buffer

     * size.

     *

     * @param in input stream to read the uncompressed data to

     * @param defl compressor ("deflater") for this stream

     * @param bufLen compression buffer size

     * @throws IllegalArgumentException if {@code bufLen} is <= 0

     * @throws NullPointerException if {@code in} or {@code defl} is null

     */

    public DeflaterInputStream(InputStream in, Deflater defl, int bufLen) {

        super(in);

        // Sanity checks

        if (in == null)

            throw new NullPointerException("Null input");

        if (defl == null)

            throw new NullPointerException("Null deflater");

        if (bufLen < 1)

            throw new IllegalArgumentException("Buffer size < 1");

        // Initialize

        def = defl;

        buf = new byte[bufLen];

    }

    /**

     * Closes this input stream and its underlying input stream, discarding

     * any pending uncompressed data.

     *

     * @throws IOException if an I/O error occurs

     */

    public void close() throws IOException {

        if (in != null) {

            try {

                // Clean up

                if (usesDefaultDeflater) {

                    def.end();

                }

                in.close();

            } finally {

                in = null;

            }

        }

    }

    /**

     * Reads a single byte of compressed data from the input stream.

     * This method will block until some input can be read and compressed.

     *

     * @return a single byte of compressed data, or -1 if the end of the

     * uncompressed input stream is reached

     * @throws IOException if an I/O error occurs or if this stream is

     * already closed

     */

    public int read() throws IOException {

        // Read a single byte of compressed data

        int len = read(rbuf, 0, 1);

        if (len <= 0)

            return -1;

        return (rbuf[0] & 0xFF);

    }

    /**

     * Reads compressed data into a byte array.

     * This method will block until some input can be read and compressed.

     *

     * @param b buffer into which the data is read

     * @param off starting offset of the data within {@code b}

     * @param len maximum number of compressed bytes to read into {@code b}

     * @return the actual number of bytes read, or -1 if the end of the

     * uncompressed input stream is reached

     * @throws IndexOutOfBoundsException  if {@code len} > {@code b.length -

     * off}

     * @throws IOException if an I/O error occurs or if this input stream is

     * already closed

     */

    public int read(byte[] b, int off, int len) throws IOException {

        // Sanity checks

        ensureOpen();

        if (b == null) {

            throw new NullPointerException("Null buffer for read");

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

            throw new IndexOutOfBoundsException();

        } else if (len == 0) {

            return 0;

        }

        // Read and compress (deflate) input data bytes

        int cnt = 0;

        while (len > 0 && !def.finished()) {

            int n;

            // Read data from the input stream

            if (def.needsInput()) {

                n = in.read(buf, 0, buf.length);

                if (n < 0) {

                    // End of the input stream reached

                    def.finish();

                } else if (n > 0) {

                    def.setInput(buf, 0, n);

                }

            }

            // Compress the input data, filling the read buffer

            n = def.deflate(b, off, len);

            cnt += n;

            off += n;

            len -= n;

        }

        if (cnt == 0 && def.finished()) {

            reachEOF = true;

            cnt = -1;

        }

        return cnt;

    }

    /**

     * Skips over and discards data from the input stream.

     * This method may block until the specified number of bytes are read and

     * skipped. <em>Note:</em> While {@code n} is given as a {@code long},

     * the maximum number of bytes which can be skipped is

     * {@code Integer.MAX_VALUE}.

     *

     * @param n number of bytes to be skipped

     * @return the actual number of bytes skipped

     * @throws IOException if an I/O error occurs or if this stream is

     * already closed

     */

    public long skip(long n) throws IOException {

        if (n < 0) {

            throw new IllegalArgumentException("negative skip length");

        }

        ensureOpen();

        // Skip bytes by repeatedly decompressing small blocks

        if (rbuf.length < 512)

            rbuf = new byte[512];

        int total = (int)Math.min(n, Integer.MAX_VALUE);

        long cnt = 0;

        while (total > 0) {

            // Read a small block of uncompressed bytes

            int len = read(rbuf, 0, (total <= rbuf.length ? total : rbuf.length));

            if (len < 0) {

                break;

            }

            cnt += len;

            total -= len;

        }

        return cnt;

    }

    /**

     * Returns 0 after EOF has been reached, otherwise always return 1.

     * <p>

     * Programs should not count on this method to return the actual number

     * of bytes that could be read without blocking

     * @return zero after the end of the underlying input stream has been

     * reached, otherwise always returns 1

     * @throws IOException if an I/O error occurs or if this stream is

     * already closed

     */

    public int available() throws IOException {

        ensureOpen();

        if (reachEOF) {

            return 0;

        }

        return 1;

    }

    /**

     * Always returns {@code false} because this input stream does not support

     * the {@link #mark mark()} and {@link #reset reset()} methods.

     *

     * @return false, always

     */

    public boolean markSupported() {

        return false;

    }

    /**

     * <i>This operation is not supported</i>.

     *

     * @param limit maximum bytes that can be read before invalidating the position marker

     */

    public void mark(int limit) {

        // Operation not supported

    }

    /**

     * <i>This operation is not supported</i>.

     *

     * @throws IOException always thrown

     */

    public void reset() throws IOException {

        throw new IOException("mark/reset not supported");

    }

}