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/*
 * Copyright 2023-2024 wjybxx([email protected])
 *
 * Licensed 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 cn.wjybxx.dson.io;

import cn.wjybxx.base.io.ByteBufferUtils;
import cn.wjybxx.dson.types.Binary;

/**
 * 二进制块
 * 默认编码length对应的部分
 *
 * @author wjybxx
 * date 2023/4/2
 */
public final class DsonChunk {

    private final byte[] buffer;
    /** 有效区域的起始偏移 */
    private int offset;
    /** 有效区域的长度 */
    private int length;
    /** 有效区域已使用长度 */
    private int used;

    public DsonChunk(byte[] buffer) {
        this(buffer, 0, buffer.length);
    }

    /**
     * @param offset 有效区域的起始偏移
     * @param length 有效区域的长度
     */
    public DsonChunk(byte[] buffer, int offset, int length) {
        ByteBufferUtils.checkBuffer(buffer, offset, length);
        this.buffer = buffer;
        this.offset = offset;
        this.length = length;
        this.used = 0;
    }

    /**
     * 重新设置块的有效载荷部分
     *
     * @param offset 有效部分的起始偏移量
     * @param length 有效部分的长度
     */
    public void setOffsetLength(int offset, int length) {
        ByteBufferUtils.checkBuffer(buffer, offset, length);
        this.offset = offset;
        this.length = length;
    }

    /** 设置已使用的块大小 */
    public void setUsed(int used) {
        if (used < 0 || used > length) {
            throw new IllegalArgumentException(String.format("used %d, length %d", used, length));
        }
        this.used = used;
    }

    /** 转换为binary */
    public Binary toBinary() {
        return Binary.copyFrom(buffer, offset, length);
    }

    /** chunk的有效载荷 */
    public byte[] payload() {
        byte[] r = new byte[length];
        System.arraycopy(buffer, offset, r, 0, length);
        return r;
    }

    /** chunk使用的载荷部分 */
    public byte[] usedPayload() {
        byte[] r = new byte[used];
        System.arraycopy(buffer, offset, r, 0, used);
        return r;
    }

    //

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

    public int getOffset() {
        return offset;
    }

    public int getLength() {
        return length;
    }

    public int getUsed() {
        return used;
    }

}