/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.util;

import java.io.Serializable;

A resizable byte array.
Since:
4.0/**
 * A resizable byte array.
 *
 * @since 4.0
 */
public final class ByteArrayBuffer implements Serializable {

    private static final long serialVersionUID = 4359112959524048036L;

    private byte[] buffer;
    private int len;

    
Creates an instance of ByteArrayBuffer with the given initial capacity. 
Params:
capacity – the capacity/**
     * Creates an instance of {@link ByteArrayBuffer} with the given initial
     * capacity.
     *
     * @param capacity the capacity
     */
    public ByteArrayBuffer(final int capacity) {
        super();
        Args.notNegative(capacity, "Buffer capacity");
        this.buffer = new byte[capacity];
    }

    private void expand(final int newlen) {
        final byte newbuffer[] = new byte[Math.max(this.buffer.length << 1, newlen)];
        System.arraycopy(this.buffer, 0, newbuffer, 0, this.len);
        this.buffer = newbuffer;
    }

    
Appends len bytes to this buffer from the given source array starting at index off. The capacity of the buffer is increased, if necessary, to accommodate all len bytes. 
Params:
b –        the bytes to be appended.
off –      the index of the first byte to append.
len –      the number of bytes to append.
Throws:
IndexOutOfBoundsException – if off if out of range, len is negative, or off + len is out of range./**
     * Appends {@code len} bytes to this buffer from the given source
     * array starting at index {@code off}. The capacity of the buffer
     * is increased, if necessary, to accommodate all {@code len} bytes.
     *
     * @param   b        the bytes to be appended.
     * @param   off      the index of the first byte to append.
     * @param   len      the number of bytes to append.
     * @throws IndexOutOfBoundsException if {@code off} if out of
     * range, {@code len} is negative, or
     * {@code off} + {@code len} is out of range.
     */
    public void append(final byte[] b, final int off, final int len) {
        if (b == null) {
            return;
        }
        if ((off < 0) || (off > b.length) || (len < 0) ||
                ((off + len) < 0) || ((off + len) > b.length)) {
            throw new IndexOutOfBoundsException("off: "+off+" len: "+len+" b.length: "+b.length);
        }
        if (len == 0) {
            return;
        }
        final int newlen = this.len + len;
        if (newlen > this.buffer.length) {
            expand(newlen);
        }
        System.arraycopy(b, off, this.buffer, this.len, len);
        this.len = newlen;
    }

    
Appends b byte to this buffer. The capacity of the buffer is increased, if necessary, to accommodate the additional byte. 
Params:
b –        the byte to be appended./**
     * Appends {@code b} byte to this buffer. The capacity of the buffer
     * is increased, if necessary, to accommodate the additional byte.
     *
     * @param   b        the byte to be appended.
     */
    public void append(final int b) {
        final int newlen = this.len + 1;
        if (newlen > this.buffer.length) {
            expand(newlen);
        }
        this.buffer[this.len] = (byte)b;
        this.len = newlen;
    }

    
Appends len chars to this buffer from the given source array starting at index off. The capacity of the buffer is increased if necessary to accommodate all len chars. 

The chars are converted to bytes using simple cast.
Params:
b –        the chars to be appended.
off –      the index of the first char to append.
len –      the number of bytes to append.
Throws:
IndexOutOfBoundsException – if off if out of range, len is negative, or off + len is out of range./**
     * Appends {@code len} chars to this buffer from the given source
     * array starting at index {@code off}. The capacity of the buffer
     * is increased if necessary to accommodate all {@code len} chars.
     * <p>
     * The chars are converted to bytes using simple cast.
     *
     * @param   b        the chars to be appended.
     * @param   off      the index of the first char to append.
     * @param   len      the number of bytes to append.
     * @throws IndexOutOfBoundsException if {@code off} if out of
     * range, {@code len} is negative, or
     * {@code off} + {@code len} is out of range.
     */
    public void append(final char[] b, final int off, final int len) {
        if (b == null) {
            return;
        }
        if ((off < 0) || (off > b.length) || (len < 0) ||
                ((off + len) < 0) || ((off + len) > b.length)) {
            throw new IndexOutOfBoundsException("off: "+off+" len: "+len+" b.length: "+b.length);
        }
        if (len == 0) {
            return;
        }
        final int oldlen = this.len;
        final int newlen = oldlen + len;
        if (newlen > this.buffer.length) {
            expand(newlen);
        }

        for (int i1 = off, i2 = oldlen; i2 < newlen; i1++, i2++) {
            final int c = b[i1];
            if ((c >= 0x20 && c <= 0x7E) || // Visible ASCII
                (c >= 0xA0 && c <= 0xFF) || // Visible ISO-8859-1
                c == 0x09) {                // TAB
                this.buffer[i2] = (byte) c;
            } else {
                this.buffer[i2] = '?';
            }
        }
        this.len = newlen;
    }

    
Appends len chars to this buffer from the given source char array buffer starting at index off. The capacity of the buffer is increased if necessary to accommodate all len chars. 

The chars are converted to bytes using simple cast.
Params:
b –        the chars to be appended.
off –      the index of the first char to append.
len –      the number of bytes to append.
Throws:
IndexOutOfBoundsException – if off if out of range, len is negative, or off + len is out of range./**
     * Appends {@code len} chars to this buffer from the given source
     * char array buffer starting at index {@code off}. The capacity
     * of the buffer is increased if necessary to accommodate all
     * {@code len} chars.
     * <p>
     * The chars are converted to bytes using simple cast.
     *
     * @param   b        the chars to be appended.
     * @param   off      the index of the first char to append.
     * @param   len      the number of bytes to append.
     * @throws IndexOutOfBoundsException if {@code off} if out of
     * range, {@code len} is negative, or
     * {@code off} + {@code len} is out of range.
     */
    public void append(final CharArrayBuffer b, final int off, final int len) {
        if (b == null) {
            return;
        }
        append(b.buffer(), off, len);
    }

    
Clears content of the buffer. The underlying byte array is not resized.
/**
     * Clears content of the buffer. The underlying byte array is not resized.
     */
    public void clear() {
        this.len = 0;
    }

    
Converts the content of this buffer to an array of bytes.
Returns:
byte array/**
     * Converts the content of this buffer to an array of bytes.
     *
     * @return byte array
     */
    public byte[] toByteArray() {
        final byte[] b = new byte[this.len];
        if (this.len > 0) {
            System.arraycopy(this.buffer, 0, b, 0, this.len);
        }
        return b;
    }

    
Returns the byte value in this buffer at the specified index. The index argument must be greater than or equal to 0, and less than the length of this buffer. 
Params:
i –   the index of the desired byte value.
Throws:
IndexOutOfBoundsException –  if index is negative or greater than or equal to length().
Returns:
    the byte value at the specified index./**
     * Returns the {@code byte} value in this buffer at the specified
     * index. The index argument must be greater than or equal to
     * {@code 0}, and less than the length of this buffer.
     *
     * @param      i   the index of the desired byte value.
     * @return     the byte value at the specified index.
     * @throws     IndexOutOfBoundsException  if {@code index} is
     *             negative or greater than or equal to {@link #length()}.
     */
    public int byteAt(final int i) {
        return this.buffer[i];
    }

    
Returns the current capacity. The capacity is the amount of storage
available for newly appended bytes, beyond which an allocation
will occur.
Returns:
 the current capacity/**
     * Returns the current capacity. The capacity is the amount of storage
     * available for newly appended bytes, beyond which an allocation
     * will occur.
     *
     * @return  the current capacity
     */
    public int capacity() {
        return this.buffer.length;
    }

    
Returns the length of the buffer (byte count).
Returns:
 the length of the buffer/**
     * Returns the length of the buffer (byte count).
     *
     * @return  the length of the buffer
     */
    public int length() {
        return this.len;
    }

    
Ensures that the capacity is at least equal to the specified minimum. If the current capacity is less than the argument, then a new internal array is allocated with greater capacity. If the required argument is non-positive, this method takes no action. 
Params:
required –   the minimum required capacity.
Since:
4.1/**
     * Ensures that the capacity is at least equal to the specified minimum.
     * If the current capacity is less than the argument, then a new internal
     * array is allocated with greater capacity. If the {@code required}
     * argument is non-positive, this method takes no action.
     *
     * @param   required   the minimum required capacity.
     *
     * @since 4.1
     */
    public void ensureCapacity(final int required) {
        if (required <= 0) {
            return;
        }
        final int available = this.buffer.length - this.len;
        if (required > available) {
            expand(this.len + required);
        }
    }

    
Returns reference to the underlying byte array.
Returns:
the byte array./**
     * Returns reference to the underlying byte array.
     *
     * @return the byte array.
     */
    public byte[] buffer() {
        return this.buffer;
    }

    
Sets the length of the buffer. The new length value is expected to be less than the current capacity and greater than or equal to 0. 
Params:
len –   the new length
Throws:
IndexOutOfBoundsException –  if the len argument is greater than the current capacity of the buffer or less than 0./**
     * Sets the length of the buffer. The new length value is expected to be
     * less than the current capacity and greater than or equal to
     * {@code 0}.
     *
     * @param      len   the new length
     * @throws     IndexOutOfBoundsException  if the
     *               {@code len} argument is greater than the current
     *               capacity of the buffer or less than {@code 0}.
     */
    public void setLength(final int len) {
        if (len < 0 || len > this.buffer.length) {
            throw new IndexOutOfBoundsException("len: "+len+" < 0 or > buffer len: "+this.buffer.length);
        }
        this.len = len;
    }

    
Returns true if this buffer is empty, that is, its length() is equal to 0. 
Returns:
true if this buffer is empty, false otherwise./**
     * Returns {@code true} if this buffer is empty, that is, its
     * {@link #length()} is equal to {@code 0}.
     * @return {@code true} if this buffer is empty, {@code false}
     *   otherwise.
     */
    public boolean isEmpty() {
        return this.len == 0;
    }

    
Returns true if this buffer is full, that is, its length() is equal to its capacity(). 
Returns:
true if this buffer is full, false otherwise./**
     * Returns {@code true} if this buffer is full, that is, its
     * {@link #length()} is equal to its {@link #capacity()}.
     * @return {@code true} if this buffer is full, {@code false}
     *   otherwise.
     */
    public boolean isFull() {
        return this.len == this.buffer.length;
    }

    
Returns the index within this buffer of the first occurrence of the specified byte, starting the search at the specified beginIndex and finishing at endIndex. If no such byte occurs in this buffer within the specified bounds, -1 is returned. 
 There is no restriction on the value of beginIndex and endIndex. If beginIndex is negative, it has the same effect as if it were zero. If endIndex is greater than length(), it has the same effect as if it were length(). If the beginIndex is greater than the endIndex, -1 is returned. 
Params:
b –            the byte to search for.
from –         the index to start the search from.
to –           the index to finish the search at.
Returns:
 the index of the first occurrence of the byte in the buffer within the given bounds, or -1 if the byte does not occur.
Since:
4.1/**
     * Returns the index within this buffer of the first occurrence of the
     * specified byte, starting the search at the specified
     * {@code beginIndex} and finishing at {@code endIndex}.
     * If no such byte occurs in this buffer within the specified bounds,
     * {@code -1} is returned.
     * <p>
     * There is no restriction on the value of {@code beginIndex} and
     * {@code endIndex}. If {@code beginIndex} is negative,
     * it has the same effect as if it were zero. If {@code endIndex} is
     * greater than {@link #length()}, it has the same effect as if it were
     * {@link #length()}. If the {@code beginIndex} is greater than
     * the {@code endIndex}, {@code -1} is returned.
     *
     * @param   b            the byte to search for.
     * @param   from         the index to start the search from.
     * @param   to           the index to finish the search at.
     * @return  the index of the first occurrence of the byte in the buffer
     *   within the given bounds, or {@code -1} if the byte does
     *   not occur.
     *
     * @since 4.1
     */
    public int indexOf(final byte b, final int from, final int to) {
        int beginIndex = from;
        if (beginIndex < 0) {
            beginIndex = 0;
        }
        int endIndex = to;
        if (endIndex > this.len) {
            endIndex = this.len;
        }
        if (beginIndex > endIndex) {
            return -1;
        }
        for (int i = beginIndex; i < endIndex; i++) {
            if (this.buffer[i] == b) {
                return i;
            }
        }
        return -1;
    }

    
Returns the index within this buffer of the first occurrence of the specified byte, starting the search at 0 and finishing at length(). If no such byte occurs in this buffer within those bounds, -1 is returned. 
Params:
b –   the byte to search for.
Returns:
 the index of the first occurrence of the byte in the buffer, or -1 if the byte does not occur.
Since:
4.1/**
     * Returns the index within this buffer of the first occurrence of the
     * specified byte, starting the search at {@code 0} and finishing
     * at {@link #length()}. If no such byte occurs in this buffer within
     * those bounds, {@code -1} is returned.
     *
     * @param   b   the byte to search for.
     * @return  the index of the first occurrence of the byte in the
     *   buffer, or {@code -1} if the byte does not occur.
     *
     * @since 4.1
     */
    public int indexOf(final byte b) {
        return indexOf(b, 0, this.len);
    }
}