/*
 * Copyright 1999-2010 The Apache Software Foundation.
 *
 *  Licensed 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 org.apache.xml.security.utils;

import java.io.OutputStream;

/**
 * A simple Unsynced ByteArrayOutputStream
 * @author raul
 *
 */
public class UnsyncByteArrayOutputStream extends OutputStream  {	

    private static final int INITIAL_SIZE = 8192;
    private static ThreadLocal bufCache = new ThreadLocal() {
        protected synchronized Object initialValue() {
            return new byte[INITIAL_SIZE];
        }
    };

    private byte[] buf;
    private int size = INITIAL_SIZE;
    private int pos = 0;

    public UnsyncByteArrayOutputStream() {
	buf = (byte[])bufCache.get();
    }

    public void write(byte[] arg0) {
	int newPos = pos + arg0.length;
	if (newPos > size) {
	    expandSize(newPos);
	}
	System.arraycopy(arg0, 0, buf, pos, arg0.length);
	pos = newPos;
    }

    public void write(byte[] arg0, int arg1, int arg2) {
	int newPos = pos + arg2;
	if (newPos > size) {
	    expandSize(newPos);
	}
	System.arraycopy(arg0, arg1, buf, pos, arg2);
	pos = newPos;
    }

    public void write(int arg0) {		
        int newPos = pos + 1;
	if (newPos > size) {
	    expandSize(newPos);
	}
	buf[pos++] = (byte)arg0;		
    }

    public byte[] toByteArray() {
	byte result[] = new byte[pos];
	System.arraycopy(buf, 0, result, 0, pos);
	return result;
    }

    public void reset() {
	pos = 0;
    }
	
    private void expandSize(int newPos) {
        int newSize = size;
        while (newPos > newSize) {
            newSize = newSize<<2;
        }
        byte newBuf[] = new byte[newSize];
        System.arraycopy(buf, 0, newBuf, 0, pos);
        buf = newBuf;
        size = newSize;
    }
}
