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A partial port of the Bouncycastle J2ME crypto library with parts taken from GWTx.
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/*
 *  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.
 */

package com.googlecode.gwt.crypto.gwtx.io;

import com.googlecode.gwt.crypto.util.Sys;

/**
 * ByteArrayOutputStream is a class whose underlying stream is represented by a
 * byte array. As bytes are written to this stream, the local byte array may be
 * expanded to hold more bytes.
 * 
 * @see ByteArrayInputStream
 */
public class ByteArrayOutputStream extends OutputStream {
	/**
	 * The byte array containing the bytes written.
	 */
	protected byte[] buf;

	/**
	 * The number of bytes written.
	 */
	protected int count;

	/**
	 * Constructs a new ByteArrayOutputStream with a default size of 32 bytes.
	 * If more than 32 bytes are written to this instance, the underlying byte
	 * array will expand to accommodate.
	 * 
	 */
	public ByteArrayOutputStream() {
		super();
		buf = new byte[32];
	}

	/**
	 * Constructs a new ByteArrayOutputStream with a default size of
	 * size bytes. If more than size bytes are
	 * written to this instance, the underlying byte array will expand to
	 * accommodate.
	 * 
	 * @param size
	 *            an non-negative integer representing the initial size for the
	 *            underlying byte array.
	 */
	public ByteArrayOutputStream(int size) {
		super();
		if (size >= 0) {
            buf = new byte[size];
        } else {
            throw new IllegalArgumentException("K005e: " + size); //$NON-NLS-1$
        }
	}

	/**
	 * Close this ByteArrayOutputStream. This implementation releases System
	 * resources used for this stream.
	 * 
	 * @throws IOException
	 *             If an error occurs attempting to close this OutputStream.
	 */
    @Override
	public void close() throws IOException {
		/**
		 * Although the spec claims "A closed stream cannot perform output
		 * operations and cannot be reopened.", this implementation must do
		 * nothing.
		 */
		super.close();
	}

	private void expand(int i) {
		/* Can the buffer handle @i more bytes, if not expand it */
		if (count + i <= buf.length) {
            return;
        }

		byte[] newbuf = new byte[(count + i) * 2];
		Sys.arraycopy(buf, 0, newbuf, 0, count);
        buf = newbuf;
	}

    /**
	 * Reset this ByteArrayOutputStream to the beginning of the underlying byte
	 * array. All subsequent writes will overwrite any bytes previously stored
	 * in this stream.
	 * 
	 */
	public synchronized void reset() {
		count = 0;
	}

	/**
	 * Answers the total number of bytes written to this stream thus far.
	 * 
	 * @return the number of bytes written to this Stream.
	 */
	public int size() {
		return count;
	}

	/**
	 * Answer the contents of this ByteArrayOutputStream as a byte array. Any
	 * changes made to the receiver after returning will not be reflected in the
	 * byte array returned to the caller.
	 * 
	 * @return this streams current contents as a byte array.
	 */
	public synchronized byte[] toByteArray() {
		byte[] newArray = new byte[count];
		Sys.arraycopy(buf, 0, newArray, 0, count);
		return newArray;
	}

	/**
	 * Answer the contents of this ByteArrayOutputStream as a String. Any
	 * changes made to the receiver after returning will not be reflected in the
	 * String returned to the caller.
	 * 
	 * @return this streams current contents as a String.
	 */
    @Override
	public String toString() {
        char[] c = new char[count];
        for (int i=0; i < count; i++) {
            c[i] = (char)buf[i];
        }
        return new String(c);
	}

	/**
	 * Answer the contents of this ByteArrayOutputStream as a String. Each byte
	 * b in this stream is converted to a character
	 * c using the following function:
	 * c == (char)(((hibyte & 0xff) << 8) | (b & 0xff)). This
	 * method is deprecated and either toString(), or toString(enc) should be
	 * used.
	 * 
	 * @param hibyte
	 *            the high byte of each resulting Unicode character
	 * @return this streams current contents as a String with the high byte set
	 *         to hibyte
	 * 
	 * @deprecated Use toString()
	 */
    public String toString(int hibyte) {
		char[] newBuf = new char[size()];
		for (int i = 0; i < newBuf.length; i++) {
            newBuf[i] = (char) (((hibyte & 0xff) << 8) | (buf[i] & 0xff));
        }
		return new String(newBuf);
	}

	/**
     * Encoding is ignored.
	 * Answer the contents of this ByteArrayOutputStream as a String converted
	 * using the encoding declared in enc.
	 * 
	 * @param enc
	 *            A String representing the encoding to use when translating
	 *            this stream to a String.
	 * @return this streams current contents as a String.
	 * 
	 * @throws UnsupportedEncodingException
	 *             If declared encoding is not supported
	 */
	public String toString(String enc) throws UnsupportedEncodingException {
		return toString();
	}

	/**
	 * Writes count bytes from the byte array
	 * buffer starting at offset index to the
	 * ByteArrayOutputStream.
	 * 
	 * @param buffer
	 *            the buffer to be written
	 * @param offset
	 *            offset in buffer to get bytes
	 * @param len
	 *            number of bytes in buffer to write
	 * 
	 * @throws NullPointerException
	 *             If buffer is null.
	 * @throws IndexOutOfBoundsException
	 *             If offset or count are outside of bounds.
	 */
    @Override
	public synchronized void write(byte[] buffer, int offset, int len) {
		/* Unsure what to do here, spec is unclear */
		if (buf == null) {
            return;
        }
		if (buffer != null) {
			// avoid int overflow
			if (0 <= offset && offset <= buffer.length && 0 <= len
					&& len <= buffer.length - offset) {
				/* Expand if necessary */
				expand(len);
				Sys.arraycopy(buffer, offset, buf, this.count, len);
				this.count += len;
			} else {
                throw new IndexOutOfBoundsException(); //$NON-NLS-1$
            }
		} else {
            throw new NullPointerException("buffer must not be null"); //$NON-NLS-1$
        }
	}

	/**
	 * Writes the specified byte oneByte to the OutputStream.
	 * Only the low order byte of oneByte is written.
	 * 
	 * @param oneByte
	 *            the byte to be written
	 */
    @Override
	public synchronized void write(int oneByte) {
		try {
			buf[count] = (byte) oneByte;
			count++;
		} catch (IndexOutOfBoundsException e) {
			// Expand when necessary
			expand(1);
			buf[count++] = (byte) oneByte;
		} catch (NullPointerException e) {
		}
	}

	/**
	 * Take the contents of this stream and write it to the output stream
	 * out.
	 * 
	 * @param out
	 *            An OutputStream on which to write the contents of this stream.
	 * 
	 * @throws IOException
	 *             If an error occurs when writing to output stream
	 */
	public void writeTo(OutputStream out) throws IOException {
		out.write(buf, 0, count);
	}
}