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/*
 * 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.dubbo.remoting.buffer;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.GatheringByteChannel;
import java.nio.channels.ScatteringByteChannel;

public class HeapChannelBuffer extends AbstractChannelBuffer {

    /**
     * The underlying heap byte array that this buffer is wrapping.
     */
    protected final byte[] array;

    /**
     * Creates a new heap buffer with a newly allocated byte array.
     *
     * @param length the length of the new byte array
     */
    public HeapChannelBuffer(int length) {
        this(new byte[length], 0, 0);
    }

    /**
     * Creates a new heap buffer with an existing byte array.
     *
     * @param array the byte array to wrap
     */
    public HeapChannelBuffer(byte[] array) {
        this(array, 0, array.length);
    }

    /**
     * Creates a new heap buffer with an existing byte array.
     *
     * @param array       the byte array to wrap
     * @param readerIndex the initial reader index of this buffer
     * @param writerIndex the initial writer index of this buffer
     */
    protected HeapChannelBuffer(byte[] array, int readerIndex, int writerIndex) {
        if (array == null) {
            throw new NullPointerException("array");
        }
        this.array = array;
        setIndex(readerIndex, writerIndex);
    }

    @Override
    public boolean isDirect() {
        return false;
    }

    @Override
    public int capacity() {
        return array.length;
    }

    @Override
    public boolean hasArray() {
        return true;
    }

    @Override
    public byte[] array() {
        return array;
    }

    @Override
    public int arrayOffset() {
        return 0;
    }

    @Override
    public byte getByte(int index) {
        return array[index];
    }

    @Override
    public void getBytes(int index, ChannelBuffer dst, int dstIndex, int length) {
        if (dst instanceof HeapChannelBuffer) {
            getBytes(index, ((HeapChannelBuffer) dst).array, dstIndex, length);
        } else {
            dst.setBytes(dstIndex, array, index, length);
        }
    }

    @Override
    public void getBytes(int index, byte[] dst, int dstIndex, int length) {
        System.arraycopy(array, index, dst, dstIndex, length);
    }

    @Override
    public void getBytes(int index, ByteBuffer dst) {
        dst.put(array, index, Math.min(capacity() - index, dst.remaining()));
    }

    @Override
    public void getBytes(int index, OutputStream out, int length) throws IOException {
        out.write(array, index, length);
    }

    public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
        return out.write(ByteBuffer.wrap(array, index, length));
    }

    @Override
    public void setByte(int index, int value) {
        array[index] = (byte) value;
    }

    @Override
    public void setBytes(int index, ChannelBuffer src, int srcIndex, int length) {
        if (src instanceof HeapChannelBuffer) {
            setBytes(index, ((HeapChannelBuffer) src).array, srcIndex, length);
        } else {
            src.getBytes(srcIndex, array, index, length);
        }
    }

    @Override
    public void setBytes(int index, byte[] src, int srcIndex, int length) {
        System.arraycopy(src, srcIndex, array, index, length);
    }

    @Override
    public void setBytes(int index, ByteBuffer src) {
        src.get(array, index, src.remaining());
    }

    @Override
    public int setBytes(int index, InputStream in, int length) throws IOException {
        int readBytes = 0;
        do {
            int localReadBytes = in.read(array, index, length);
            if (localReadBytes < 0) {
                if (readBytes == 0) {
                    return -1;
                } else {
                    break;
                }
            }
            readBytes += localReadBytes;
            index += localReadBytes;
            length -= localReadBytes;
        } while (length > 0);

        return readBytes;
    }

    public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
        ByteBuffer buf = ByteBuffer.wrap(array, index, length);
        int readBytes = 0;

        do {
            int localReadBytes;
            try {
                localReadBytes = in.read(buf);
            } catch (ClosedChannelException e) {
                localReadBytes = -1;
            }
            if (localReadBytes < 0) {
                if (readBytes == 0) {
                    return -1;
                } else {
                    break;
                }
            } else if (localReadBytes == 0) {
                break;
            }
            readBytes += localReadBytes;
        } while (readBytes < length);

        return readBytes;
    }

    @Override
    public ChannelBuffer copy(int index, int length) {
        if (index < 0 || length < 0 || index + length > array.length) {
            throw new IndexOutOfBoundsException();
        }

        byte[] copiedArray = new byte[length];
        System.arraycopy(array, index, copiedArray, 0, length);
        return new HeapChannelBuffer(copiedArray);
    }

    @Override
    public ChannelBufferFactory factory() {
        return HeapChannelBufferFactory.getInstance();
    }

    @Override
    public ByteBuffer toByteBuffer(int index, int length) {
        return ByteBuffer.wrap(array, index, length);
    }
}