package com.blade.kit.io;

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

/**
 * 基于快速缓冲FastByteBuffer的OutputStream，随着数据的增长自动扩充缓冲区
 * <p>
 * 可以通过{@link #toByteArray()}和 {@link #toString()}来获取数据
 * <p>
 * {@link #close()}方法无任何效果，当流被关闭后不会抛出IOException
 * <p>
 * 这种设计避免重新分配内存块而是分配新增的缓冲区，缓冲区不会被GC，数据也不会被拷贝到其他缓冲区。
 *
 * @author	<a href="mailto:biezhi.me@gmail.com" target="_blank">biezhi</a>
 * @since	1.0
 */
public class FastByteArrayOutputStream extends OutputStream {

    private final FastByteBuffer buffer;

    public FastByteArrayOutputStream() {
        this(1024);
    }

    public FastByteArrayOutputStream(int size) {
        buffer = new FastByteBuffer(size);
    }

    @Override
    public void write(byte[] b, int off, int len) {
        buffer.append(b, off, len);
    }

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

    public int size() {
        return buffer.size();
    }

    /**
     * 此方法无任何效果，当流被关闭后不会抛出IOException
     */
    @Override
    public void close() {
        // nop
    }

    public void reset() {
        buffer.reset();
    }

    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());
    }

    public byte[] toByteArray() {
        return buffer.toArray();
    }

    @Override
    public String toString() {
        return new String(toByteArray());
    }

    public String toString(String enc) throws UnsupportedEncodingException {
        return new String(toByteArray(), enc);
    }

}