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/*
 Licensed to Diennea S.r.l. under one
 or more contributor license agreements. See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership. Diennea S.r.l. 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 herddb.utils;

import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.Arrays;

/**
 * Simple ByteArrayOutputStream which exposes the internal array
 *
 * @author enrico.olivelli
 */
@SuppressFBWarnings("EI_EXPOSE_REP")
public class VisibleByteArrayOutputStream extends OutputStream {

    byte buf[];

    int count;

    public VisibleByteArrayOutputStream() {
        this(32);
    }

    public VisibleByteArrayOutputStream(int size) {
        if (size < 0) {
            throw new IllegalArgumentException("Negative initial size: " + size);
        }
        buf = new byte[size];
    }

    private void ensureCapacity(int minCapacity) {
        // overflow-conscious code
        if (minCapacity - buf.length > 0) {
            grow(minCapacity);
        }
    }

    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

    /**
     * Increases the capacity to ensure that it can hold at least the number of
     * elements specified by the minimum capacity argument.
     *
     * @param minCapacity the desired minimum capacity
     */
    private void grow(int minCapacity) {
        // overflow-conscious code
        int oldCapacity = buf.length;
        int newCapacity = oldCapacity << 1;
        if (newCapacity - minCapacity < 0) {
            newCapacity = minCapacity;
        }
        if (newCapacity - MAX_ARRAY_SIZE > 0) {
            newCapacity = hugeCapacity(minCapacity);
        }
        buf = Arrays.copyOf(buf, newCapacity);
    }

    private static int hugeCapacity(int minCapacity) {
        if (minCapacity < 0) {
            // overflow
            throw new OutOfMemoryError();
        }
        return (minCapacity > MAX_ARRAY_SIZE)
                ? Integer.MAX_VALUE
                : MAX_ARRAY_SIZE;
    }

    @Override
    public void write(int b) {
        ensureCapacity(count + 1);
        buf[count] = (byte) b;
        count += 1;
    }

    @Override
    public void write(byte b[], int off, int len) {
        if ((off < 0) || (off > b.length) || (len < 0)
                || ((off + len) - b.length > 0)) {
            throw new IndexOutOfBoundsException();
        }
        ensureCapacity(count + len);
        System.arraycopy(b, off, buf, count, len);
        count += len;
    }

    @Override
    public void write(byte b[]) {
        write(b, 0, b.length);
    }

    public void writeTo(OutputStream out) throws IOException {
        out.write(buf, 0, count);
    }

    public void reset() {
        count = 0;
    }

    public byte[] xxhash64() {
        return XXHash64Utils.digest(buf, 0, count);
    }

    public byte[] toByteArray() {
        return Arrays.copyOf(buf, count);
    }

    /**
     * Return the internal buffer or perform a copy
     * @return the internal buffer or a copy
     */
    public byte[] toByteArrayNoCopy() {
        if (count == buf.length) {
            return buf;
        }
        return Arrays.copyOf(buf, count);
    }

    public int size() {
        return count;
    }

    public byte[] getBuffer() {
        return buf;
    }

    public ByteBuffer toByteBuffer() {
        return ByteBuffer.wrap(buf, 0, count);
    }

    public String toString(Charset charset) {
        return new String(buf, 0, count, charset);
    }

    @Override
    public void close() {
    }

}