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package org.onetwo.apache.io.output;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;

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];
    }

    /**
     * Writes the specified byte to this byte array output stream. 
     *
     * @param   b   the byte to be written.
     */
    public synchronized void write(int b) {
	int newcount = count + 1;
	if (newcount > buf.length) {
            buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
	}
	buf[count] = (byte)b;
	count = newcount;
    }

    /**
     * Writes len bytes from the specified byte array 
     * starting at offset 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) || ((off + len) < 0)) {
	    throw new IndexOutOfBoundsException();
	} else if (len == 0) {
	    return;
	}
        int newcount = count + len;
        if (newcount > buf.length) {
            buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
        }
        System.arraycopy(b, off, buf, count, len);
        count = newcount;
    }

    /**
     * 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 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 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 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 String
     * is a function of the character set, and hence may not be equal to the 
     * size of the buffer.
     *
     *  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  JDK1.1
     */
    public synchronized String toString() {
	return new String(buf, 0, count);
    }
    
    /**
     * Converts the buffer's contents into a string by decoding the bytes using
     * the specified {@link java.nio.charset.Charset charsetName}. The length of
     * the new String is a function of the charset, and hence may not be
     * equal to the length of the byte array.
     *
     *  This method always replaces malformed-input and unmappable-character
     * sequences with this 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  charsetName  the name of a supported
     *		    {@linkplain java.nio.charset.Charset charset}
     * @return String decoded from the buffer's contents.
     * @exception  UnsupportedEncodingException
     *             If the named charset is not supported
     * @since   JDK1.1
     */
    public synchronized String toString(String charsetName)
	throws UnsupportedEncodingException
    {
	return new String(buf, 0, count, charsetName);
    }

    /**
     * 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 c in the resulting string is 
     * constructed from the corresponding element b in the byte 
     * array such that:
     * 
     *     c == (char)(((hibyte & 0xff) << 8) | (b & 0xff))
     * 

     *
     * @deprecated This method does not properly convert bytes into characters.
     * As of JDK 1.1, the preferred way to do this is via the
     * toString(String enc) method, which takes an encoding-name
     * argument, or the 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 ByteArrayOutputStream has no effect. The methods in
     * this class can be called after the stream has been closed without
     * generating an IOException.
     * 
     *
     */
    public void close() throws IOException {
    }

}