package component;

import encoding.*;

/*
 * @Author: Wang Feng
 * @Description: 表示一个签名值 TLV
//	1. 格式如下：
//		SignatureValue = 200 TLV-LENGTH *OCTET
//	2. 详情参见：http://gitea.qjm253.cn/PKUSZ-future-network-lab/minlib/src/branch/master/docs/PacketFormat.md#4-signature
 * @Version: 1.0.0
 * @Date: 21:45 2021/3/12
 * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
 */
public class SignatureValue implements TlvComponentBase, IEncodingAble {
    private byte[] value;

    /**
     * 根据签名值字节数组创建一个 SignatureValue
     * @param value
     */
    public SignatureValue(byte[] value) throws ComponentException {
        if(!this.buildSignatureValueByByteArray(value)){
            throw new ComponentException("Signature(byte[] value): value invalid");
        }
    }

    /**
     * 根据 TLV Block 创建一个 SignatureValue
     * @param block
     */
    public SignatureValue(Block block) throws ComponentException {
        if(!this.buildSignatureValueByBlock(block)){
            throw new ComponentException("Signature(Block block): block invalid");
        }
    }

    /**
     * 根据签名值字节数组初始化一个 SignatureValue
     * @param value
     * @return
     */
    public boolean buildSignatureValueByByteArray(byte[] value){
        this.value=new byte[value.length];
        System.arraycopy(value,0,this.value,0,value.length);
        return true;
    }

    /**
     * 根据 TLV Block 初始化一个 SignatureValue
     * @param block
     * @return
     */
    public boolean buildSignatureValueByBlock(Block block) throws ComponentException {
        return this.wireDecode(block);
    }

    /**
     * 得到签名值的字节数组
     * @return
     */
    public byte[] getValue(){
        return this.value;
    }

    /**
     * 对 SignatureValue 进行线速编码为TLV
     * @param encoder
     * @return
     */
    @Override
    public int wireEncode(Encoder encoder) throws ComponentException {
        try {
            int totalLength = 0;
            // 编码 TLV-VALUE
            int tmplen = encoder.prependByteArray(this.value, new SizeT(this.value.length));
            if (tmplen <= 0) {
                return -1;
            }
            totalLength += tmplen;

            // 编码 TLV-LENGTH
            tmplen = encoder.prependVarNumber(new VlInt(totalLength));
            if (tmplen <= 0) {
                return -1;
            }
            totalLength += tmplen;

            // 编码 TLV-TYPE
            tmplen = encoder.prependVarNumber(new VlInt(TLV.TlvSignatureValue));
            if (tmplen <= 0) {
                return -1;
            }
            totalLength += tmplen;

            return totalLength;
        } catch (EncoderException e) {
            throw new ComponentException("SignatureValue.wireEncode: "+e.getMessage());
        }
    }

    /**
     * 从 TLV Block 中解码出一个 SignatureValue
     * @param block
     * @return
     */
    @Override
    public boolean wireDecode(Block block) throws ComponentException {
        try {
            // 检查 Type 是否正确
            if (!TLV.expectType(block.getType(), new VlInt(TLV.TlvSignatureValue))) {
                return false;
            }

            int len = block.getLength().getVlIntValue2Int();
            this.value = new byte[len];
            System.arraycopy(block.getValue(), 0, this.value, 0, len);
            return true;
        } catch (VlIntException e) {
            throw new ComponentException("SignatureValue.wireDecode: "+e.getMessage());
        }
    }
}