/*

 * Copyright (c) 1994, 2017, 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.io;

import java.nio.charset.Charset;

import java.util.Arrays;

/**

 * This class implements an output stream in which the data is

 * written into a byte array. The buffer automatically grows as data

 * is written to it.

 * The data can be retrieved using {@code toByteArray()} and

 * {@code toString()}.

 * <p>

 * Closing a {@code ByteArrayOutputStream} has no effect. The methods in

 * this class can be called after the stream has been closed without

 * generating an {@code IOException}.

 *

 * @author  Arthur van Hoff

 * @since   1.0

 */

public class ByteArrayOutputStream extends OutputStream {

    /**

     * The buffer where data is stored.

     */

    protected byte buf[];

    /**

     * The number of valid bytes in the buffer.

     */

    protected int count;

    /**

     * Creates a new byte array output stream. The buffer capacity is

     * initially 32 bytes, though its size increases if necessary.

     */

    public ByteArrayOutputStream() {

        this(32);

    }

    /**

     * Creates a new byte array output stream, with a buffer capacity of

     * the specified size, in bytes.

     *

     * @param   size   the initial size.

     * @exception  IllegalArgumentException if size is negative.

     */

    public ByteArrayOutputStream(int size) {

        if (size < 0) {

            throw new IllegalArgumentException("Negative initial size: "

                                               + size);

        }

        buf = new byte[size];

    }

    /**

     * Increases the capacity if necessary to ensure that it can hold

     * at least the number of elements specified by the minimum

     * capacity argument.

     *

     * @param minCapacity the desired minimum capacity

     * @throws OutOfMemoryError if {@code minCapacity < 0}.  This is

     * interpreted as a request for the unsatisfiably large capacity

     * {@code (long) Integer.MAX_VALUE + (minCapacity - Integer.MAX_VALUE)}.

     */

    private void ensureCapacity(int minCapacity) {

        // overflow-conscious code

        if (minCapacity - buf.length > 0)

            grow(minCapacity);

    }

    /**

     * The maximum size of array to allocate.

     * Some VMs reserve some header words in an array.

     * Attempts to allocate larger arrays may result in

     * OutOfMemoryError: Requested array size exceeds VM limit

     */

    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

    /**

     * Increases the capacity to ensure that it can hold at least the

     * number of elements specified by the minimum capacity argument.

     *

     * @param minCapacity the desired minimum capacity

     */

    private void grow(int minCapacity) {

        // overflow-conscious code

        int oldCapacity = buf.length;

        int newCapacity = oldCapacity << 1;

        if (newCapacity - minCapacity < 0)

            newCapacity = minCapacity;

        if (newCapacity - MAX_ARRAY_SIZE > 0)

            newCapacity = hugeCapacity(minCapacity);

        buf = Arrays.copyOf(buf, newCapacity);

    }

    private static int hugeCapacity(int minCapacity) {

        if (minCapacity < 0) // overflow

            throw new OutOfMemoryError();

        return (minCapacity > MAX_ARRAY_SIZE) ?

            Integer.MAX_VALUE :

            MAX_ARRAY_SIZE;

    }

    /**

     * Writes the specified byte to this byte array output stream.

     *

     * @param   b   the byte to be written.

     */

    public synchronized void write(int b) {

        ensureCapacity(count + 1);

        buf[count] = (byte) b;

        count += 1;

    }

    /**

     * Writes {@code len} bytes from the specified byte array

     * starting at offset {@code off} to this byte array output stream.

     *

     * @param   b     the data.

     * @param   off   the start offset in the data.

     * @param   len   the number of bytes to write.

     */

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

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

            ((off + len) - b.length > 0)) {

            throw new IndexOutOfBoundsException();

        }

        ensureCapacity(count + len);

        System.arraycopy(b, off, buf, count, len);

        count += len;

    }

    /**

     * Writes the complete contents of this byte array output stream to

     * the specified output stream argument, as if by calling the output

     * stream's write method using {@code out.write(buf, 0, count)}.

     *

     * @param      out   the output stream to which to write the data.

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

     */

    public synchronized void writeTo(OutputStream out) throws IOException {

        out.write(buf, 0, count);

    }

    /**

     * Resets the {@code count} field of this byte array output

     * stream to zero, so that all currently accumulated output in the

     * output stream is discarded. The output stream can be used again,

     * reusing the already allocated buffer space.

     *

     * @see     java.io.ByteArrayInputStream#count

     */

    public synchronized void reset() {

        count = 0;

    }

    /**

     * Creates a newly allocated byte array. Its size is the current

     * size of this output stream and the valid contents of the buffer

     * have been copied into it.

     *

     * @return  the current contents of this output stream, as a byte array.

     * @see     java.io.ByteArrayOutputStream#size()

     */

    public synchronized byte[] toByteArray() {

        return Arrays.copyOf(buf, count);

    }

    /**

     * Returns the current size of the buffer.

     *

     * @return  the value of the {@code count} field, which is the number

     *          of valid bytes in this output stream.

     * @see     java.io.ByteArrayOutputStream#count

     */

    public synchronized int size() {

        return count;

    }

    /**

     * Converts the buffer's contents into a string decoding bytes using the

     * platform's default character set. The length of the new {@code String}

     * is a function of the character set, and hence may not be equal to the

     * size of the buffer.

     *

     * <p> This method always replaces malformed-input and unmappable-character

     * sequences with the default replacement string for the platform's

     * default character set. The {@linkplain java.nio.charset.CharsetDecoder}

     * class should be used when more control over the decoding process is

     * required.

     *

     * @return String decoded from the buffer's contents.

     * @since  1.1

     */

    public synchronized String toString() {

        return new String(buf, 0, count);

    }

    /**

     * Converts the buffer's contents into a string by decoding the bytes using

     * the named {@link java.nio.charset.Charset charset}.

     *

     * <p> This method is equivalent to {@code #toString(charset)} that takes a

     * {@link java.nio.charset.Charset charset}.

     *

     * <p> An invocation of this method of the form

     *

     * <pre> {@code

     *      ByteArrayOutputStream b = ...

     *      b.toString("UTF-8")

     *      }

     * </pre>

     *

     * behaves in exactly the same way as the expression

     *

     * <pre> {@code

     *      ByteArrayOutputStream b = ...

     *      b.toString(StandardCharsets.UTF_8)

     *      }

     * </pre>

     *

     *

     * @param      charsetName  the name of a supported

     *             {@link java.nio.charset.Charset charset}

     * @return     String decoded from the buffer's contents.

     * @exception  UnsupportedEncodingException

     *             If the named charset is not supported

     * @since      1.1

     */

    public synchronized String toString(String charsetName)

        throws UnsupportedEncodingException

    {

        return new String(buf, 0, count, charsetName);

    }

    /**

     * Converts the buffer's contents into a string by decoding the bytes using

     * the specified {@link java.nio.charset.Charset charset}. The length of the new

     * {@code String} is a function of the charset, and hence may not be equal

     * to the length of the byte array.

     *

     * <p> This method always replaces malformed-input and unmappable-character

     * sequences with the charset's default replacement string. The {@link

     * java.nio.charset.CharsetDecoder} class should be used when more control

     * over the decoding process is required.

     *

     * @param      charset  the {@linkplain java.nio.charset.Charset charset}

     *             to be used to decode the {@code bytes}

     * @return     String decoded from the buffer's contents.

     * @since      10

     */

    public synchronized String toString(Charset charset) {

        return new String(buf, 0, count, charset);

    }

    /**

     * Creates a newly allocated string. Its size is the current size of

     * the output stream and the valid contents of the buffer have been

     * copied into it. Each character <i>c</i> in the resulting string is

     * constructed from the corresponding element <i>b</i> in the byte

     * array such that:

     * <blockquote><pre>{@code

     *     c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))

     * }</pre></blockquote>

     *

     * @deprecated This method does not properly convert bytes into characters.

     * As of JDK 1.1, the preferred way to do this is via the

     * {@link #toString(String charsetName)} or {@link #toString(Charset charset)}

     * method, which takes an encoding-name or charset argument,

     * or the {@code toString()} method, which uses the platform's default

     * character encoding.

     *

     * @param      hibyte    the high byte of each resulting Unicode character.

     * @return     the current contents of the output stream, as a string.

     * @see        java.io.ByteArrayOutputStream#size()

     * @see        java.io.ByteArrayOutputStream#toString(String)

     * @see        java.io.ByteArrayOutputStream#toString()

     */

    @Deprecated

    public synchronized String toString(int hibyte) {

        return new String(buf, hibyte, 0, count);

    }

    /**

     * Closing a {@code ByteArrayOutputStream} has no effect. The methods in

     * this class can be called after the stream has been closed without

     * generating an {@code IOException}.

     */

    public void close() throws IOException {

    }

}