// 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 org.apache.doris.common.io;

import java.io.InputStream;
import java.io.OutputStream;

/**
 * ByteArrayOutputStream implementation that doesn't synchronize methods
 * and doesn't copy the data on toByteArray().
 * http://javatechniques.com/blog/faster-deep-copies-of-java-objects/
 */
public class FastByteArrayOutputStream extends OutputStream {
    /**
     * Buffer and size
     */
    protected byte[] buf = null;
    protected int size = 0;

    /**
     * Constructs a stream with buffer capacity size 5K
     */
    public FastByteArrayOutputStream() {
        this(5 * 1024);
    }

    /**
     * Constructs a stream with the given initial size
     */
    public FastByteArrayOutputStream(int initSize) {
        this.size = 0;
        this.buf = new byte[initSize];
    }

    /**
     * Ensures that we have a large enough buffer for the given size.
     */
    private void verifyBufferSize(int sz) {
        if (sz > buf.length) {
            byte[] old = buf;
            buf = new byte[Math.max(sz, 2 * buf.length)];
            System.arraycopy(old, 0, buf, 0, old.length);
            old = null;
        }
    }

    public int getSize() {
        return size;
    }

    /**
     * Returns the byte array containing the written data. Note that this
     * array will almost always be larger than the amount of data actually
     * written.
     */
    public byte[] getByteArray() {
        return buf;
    }

    public final void write(byte[] b) {
        verifyBufferSize(size + b.length);
        System.arraycopy(b, 0, buf, size, b.length);
        size += b.length;
    }

    public final void write(byte[] b, int off, int len) {
        verifyBufferSize(size + len);
        System.arraycopy(b, off, buf, size, len);
        size += len;
    }

    public final void write(int b) {
        verifyBufferSize(size + 1);
        buf[size++] = (byte) b;
    }

    public void reset() {
        size = 0;
    }

    /**
     * Returns a ByteArrayInputStream for reading back the written data
     */
    public InputStream getInputStream() {
        return new FastByteArrayInputStream(buf, size);
    }

}
