/*

 * Copyright (c) 1996, 2019, 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

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 */

package java.util.zip;

import java.io.FilterInputStream;

import java.io.InputStream;

import java.io.IOException;

import java.io.EOFException;

/**

 * This class implements a stream filter for uncompressing data in the

 * "deflate" compression format. It is also used as the basis for other

 * decompression filters, such as GZIPInputStream.

 *

 * @see         Inflater

 * @author      David Connelly

 * @since 1.1

 */

    /**

     * Decompressor for this stream.

     */

    protected Inflater inf;

    /**

     * Input buffer for decompression.

     */

    protected byte[] buf;

    /**

     * Length of input buffer.

     */

    protected int len;

    private boolean closed = false;

    // this flag is set to true after EOF has reached

    private boolean reachEOF = false;

    /**

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

     */

    private void ensureOpen() throws IOException {

        if (closed) {

            throw new IOException("Stream closed");

        }

    }

    /**

     * Creates a new input stream with the specified decompressor and

     * buffer size.

     * @param in the input stream

     * @param inf the decompressor ("inflater")

     * @param size the input buffer size

     * @throws    IllegalArgumentException if {@code size <= 0}

     */

    public InflaterInputStream(InputStream in, Inflater inf, int size) {

        super(in);

        if (in == null || inf == null) {

            throw new NullPointerException();

        } else if (size <= 0) {

            throw new IllegalArgumentException("buffer size <= 0");

        }

        this.inf = inf;

        buf = new byte[size];

    }

    /**

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

     * default buffer size.

     * @param in the input stream

     * @param inf the decompressor ("inflater")

     */

    public InflaterInputStream(InputStream in, Inflater inf) {

        this(in, inf, 512);

    }

    boolean usesDefaultInflater = false;

    /**

     * Creates a new input stream with a default decompressor and buffer size.

     * @param in the input stream

     */

    public InflaterInputStream(InputStream in) {

        this(in, new Inflater());

        usesDefaultInflater = true;

    }

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

    /**

     * Reads a byte of uncompressed data. This method will block until

     * enough input is available for decompression.

     * @return the byte read, or -1 if end of compressed input is reached

     * @throws    IOException if an I/O error has occurred

     */

    public int read() throws IOException {

        ensureOpen();

        return read(singleByteBuf, 0, 1) == -1 ? -1 : Byte.toUnsignedInt(singleByteBuf[0]);

    }

    /**

     * Reads uncompressed data into an array of bytes. If {@code len} is not

     * zero, the method will block until some input can be decompressed; otherwise,

     * no bytes are read and {@code 0} is returned.

     * @param b the buffer into which the data is read

     * @param off the start offset in the destination array {@code b}

     * @param len the maximum number of bytes read

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

     *         compressed input is reached or a preset dictionary is needed

     * @throws     NullPointerException If {@code b} is {@code null}.

     * @throws     IndexOutOfBoundsException If {@code off} is negative,

     * {@code len} is negative, or {@code len} is greater than

     * {@code b.length - off}

     * @throws    ZipException if a ZIP format error has occurred

     * @throws    IOException if an I/O error has occurred

     */

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

        ensureOpen();

        if (b == null) {

            throw new NullPointerException();

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

            throw new IndexOutOfBoundsException();

        } else if (len == 0) {

            return 0;

        }

        try {

            int n;

            while ((n = inf.inflate(b, off, len)) == 0) {

                if (inf.finished() || inf.needsDictionary()) {

                    reachEOF = true;

                    return -1;

                }

                if (inf.needsInput()) {

                    fill();

                }

            }

            return n;

        } catch (DataFormatException e) {

            String s = e.getMessage();

            throw new ZipException(s != null ? s : "Invalid ZLIB data format");

        }

    }

    /**

     * 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     1 before EOF and 0 after EOF.

     * @throws     IOException  if an I/O error occurs.

     *

     */

    public int available() throws IOException {

        ensureOpen();

        if (reachEOF) {

            return 0;

        } else if (inf.finished()) {

            // the end of the compressed data stream has been reached

            reachEOF = true;

            return 0;

        } else {

            return 1;

        }

    }

    private byte[] b = new byte[512];

    /**

     * Skips specified number of bytes of uncompressed data.

     * @param n the number of bytes to skip

     * @return the actual number of bytes skipped.

     * @throws    IOException if an I/O error has occurred

     * @throws    IllegalArgumentException if {@code n < 0}

     */

    public long skip(long n) throws IOException {

        if (n < 0) {

            throw new IllegalArgumentException("negative skip length");

        }

        ensureOpen();

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

        int total = 0;

        while (total < max) {

            int len = max - total;

            if (len > b.length) {

                len = b.length;

            }

            len = read(b, 0, len);

            if (len == -1) {

                reachEOF = true;

                break;

            }

            total += len;

        }

        return total;

    }

    /**

     * Closes this input stream and releases any system resources associated

     * with the stream.

     * @throws    IOException if an I/O error has occurred

     */

    public void close() throws IOException {

        if (!closed) {

            if (usesDefaultInflater)

                inf.end();

            in.close();

            closed = true;

        }

    }

    /**

     * Fills input buffer with more data to decompress.

     * @throws    IOException if an I/O error has occurred

     */

    protected void fill() throws IOException {

        ensureOpen();

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

        if (len == -1) {

            throw new EOFException("Unexpected end of ZLIB input stream");

        }

        inf.setInput(buf, 0, len);

    }

    /**

     * Tests if this input stream supports the {@code mark} and

     * {@code reset} methods. The {@code markSupported}

     * method of {@code InflaterInputStream} returns

     * {@code false}.

     *

     * @return  a {@code boolean} indicating if this stream type supports

     *          the {@code mark} and {@code reset} methods.

     * @see     java.io.InputStream#mark(int)

     * @see     java.io.InputStream#reset()

     */

    public boolean markSupported() {

        return false;

    }

    /**

     * Marks the current position in this input stream.

     *

     * <p> The {@code mark} method of {@code InflaterInputStream}

     * does nothing.

     *

     * @param   readlimit   the maximum limit of bytes that can be read before

     *                      the mark position becomes invalid.

     * @see     java.io.InputStream#reset()

     */

    public synchronized void mark(int readlimit) {

    }

    /**

     * Repositions this stream to the position at the time the

     * {@code mark} method was last called on this input stream.

     *

     * <p> The method {@code reset} for class

     * {@code InflaterInputStream} does nothing except throw an

     * {@code IOException}.

     *

     * @throws     IOException  if this method is invoked.

     * @see     java.io.InputStream#mark(int)

     * @see     java.io.IOException

     */

    public synchronized void reset() throws IOException {

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

    }

}