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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2013-2014 sagyf Yang. The Four Group.
 */

package goja.core.kits.stream;


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

/**
 * 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 toByteArray() and
 * toString().
 * 

 * Closing a FastByteArrayOutputStream has no effect. The methods in
 * this class can be called after the stream has been closed without
 * generating an IOException.
 * 
 * This is an alternative implementation of the java.io.FastByteArrayOutputStream
 * class. The original implementation only allocates 32 bytes at the beginning.
 * As this class is designed for heavy duty it starts at 1024 bytes. In contrast
 * to the original it doesn't reallocate the whole memory block but allocates
 * additional buffers. This way no buffers need to be garbage collected and
 * the contents don't have to be copied to the new buffer. This class is
 * designed to behave exactly like the original. The only exception is the
 * depreciated toString(int) method that has been ignored.
 */
public class FastByteArrayOutputStream extends OutputStream {

    private final FastByteBuffer buffer;

    /**
     * Creates a new byte array output stream. The buffer capacity is
     * initially 1024 bytes, though its size increases if necessary.
     */
    public FastByteArrayOutputStream() {
        this(1024);
    }

    /**
     * Creates a new byte array output stream, with a buffer capacity of
     * the specified size, in bytes.
     *
     * @param size the initial size.
     * @throws IllegalArgumentException if size is negative.
     */
    public FastByteArrayOutputStream(int size) {
        buffer = new FastByteBuffer(size);
    }

    /**
     * @see java.io.OutputStream#write(byte[], int, int)
     */
    @Override
    public void write(byte[] b, int off, int len) {
        buffer.append(b, off, len);
    }

    /**
     * Writes single byte.
     */
    @Override
    public void write(int b) {
        buffer.append((byte) b);
    }

    /**
     * @see java.io.ByteArrayOutputStream#size()
     */
    public int size() {
        return buffer.size();
    }

    /**
     * Closing a FastByteArrayOutputStream has no effect. The methods in
     * this class can be called after the stream has been closed without
     * generating an IOException.
     */
    @Override
    public void close() {
        //nop
    }

    /**
     * @see java.io.ByteArrayOutputStream#reset()
     */
    public void reset() {
        buffer.clear();
    }

    /**
     * @see java.io.ByteArrayOutputStream#writeTo(java.io.OutputStream)
     */
    public void writeTo(OutputStream out) throws IOException {
        int index = buffer.index();
        for (int i = 0; i < index; i++) {
            byte[] buf = buffer.array(i);
            out.write(buf);
        }
        out.write(buffer.array(index), 0, buffer.offset());
    }

    /**
     * @see java.io.ByteArrayOutputStream#toByteArray()
     */
    public byte[] toByteArray() {
        return buffer.toArray();
    }

    /**
     * @see java.io.ByteArrayOutputStream#toString()
     */
    @Override
    public String toString() {
        return new String(toByteArray());
    }

    /**
     * @see java.io.ByteArrayOutputStream#toString(String)
     */
    public String toString(String enc) throws UnsupportedEncodingException {
        return new String(toByteArray(), enc);
    }

}