package component;

import encoding.*;
/*
 * @Author: Wang Feng
 * @Description: 表示签名的元数据，包含：签名类型、用于签名的证书或公钥的位置
//	1. 格式如下：
//		SignatureInfo = 201 TLV-LENGTH
//                <SignatureType>
//                [KeyLocator]
//	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: 20:26 2021/3/15
 * @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 SignatureInfo implements TlvComponentBase, IEncodingAble {
    private SignatureType signatureType;
    private KeyLocator keyLocator;

    public SignatureInfo(){
        signatureType=new SignatureType();
        keyLocator=new KeyLocator();
    }

    /**
     * 根据签名值类型创建一个 SignatureInfo
     * @param value
     */
    public SignatureInfo(SignatureAlgorithm value){
        signatureType=new SignatureType();
        keyLocator=new KeyLocator();
        this.buildSignatureInfoBySignatureTypeValue(value);
    }

    /**
     * 根据签名值类型和 KeyLocator 创建一个 SignatureInfo
     * @param value
     * @param locator
     */
    public SignatureInfo(SignatureAlgorithm value,KeyLocator locator){
        this.buildSignatureInfoBySignatureTypeValueAndKeyLocator(value,locator);
    }

    /**
     * 根据 TLV Block 创建一个 SignatureInfo
     * @param block
     */
    public SignatureInfo(Block block) throws ComponentException {
        this.buildSignatureInfoByBlock(block);
    }

    /**
     * 根据签名类型值初始化当前 SignatureInfo
     * @param signatureTypeValue
     * @return
     */
    public boolean buildSignatureInfoBySignatureTypeValue(SignatureAlgorithm signatureTypeValue){
        return this.signatureType.buildSignatureTypeByValue(signatureTypeValue);
    }

    /**
     * 根据签名类型值和 KeyLocator 初始化当前 SignatureInfo
     * @param value
     * @param locator
     * @return
     */
    public boolean buildSignatureInfoBySignatureTypeValueAndKeyLocator(SignatureAlgorithm value,KeyLocator locator){
        if(!this.signatureType.buildSignatureTypeByValue(value)){
            return false;
        }

        if(!this.keyLocator.buildKeyLocatorByIdentifier(keyLocator.getIdentifier())){
            return false;
        }

        return true;
    }

    /**
     * 根据 TLV Block 初始化当前 SignatureInfo
     * @param block
     * @return
     */
    public boolean buildSignatureInfoByBlock(Block block) throws ComponentException {
        return this.wireDecode(block);
    }

    /**
     * 获得签名类型
     * @return
     */
    public SignatureType getSignatureType() {
        return signatureType;
    }

    /**
     * 获得 KeyLocator
     * @return
     */
    public KeyLocator getKeyLocator() {
        return keyLocator;
    }

    /**
     * 将 SignatureInfo 线速编码为 TLV
     * @param encoder
     * @return
     */
    @Override
    public int wireEncode(Encoder encoder) throws ComponentException {
        int totalLength=0;
        // 编码 TLV-VALUE
        if(!this.keyLocator.isValid()){
            // KeyLocator 是可选的，如果当前 SignatureInfo 对象有一个有效的 KeyLocator，则对其进行编码
            int tmplen= 0;
            try {
                tmplen = this.keyLocator.wireEncode(encoder);
            } catch (ComponentException e) {
                throw new ComponentException("SignatureInfo.wireEncode: "+e.getMessage());
            }
            if(tmplen<=0){
                return -1;
            }
            totalLength+=tmplen;
        }
        int tmplen= 0;
        tmplen = this.signatureType.wireEncode(encoder);
        if(tmplen<=0){
            return -1;
        }
        totalLength+=tmplen;

        // 编码 TLV-LENGTH
        try {
            tmplen=encoder.prependVarNumber(new VlInt(totalLength));
        } catch (EncoderException e) {
            throw new ComponentException("SignatureInfo.wireEncode: "+e.getMessage());
        }
        if(tmplen<=0){
            return -1;
        }
        totalLength+=tmplen;

        // 编码 TLV-TYPE
        try {
            tmplen=encoder.prependVarNumber(new VlInt(TLV.TlvSignatureInfo));
        } catch (EncoderException e) {
            throw new ComponentException("SignatureInfo.wireEncode: "+e.getMessage());
        }
        if(tmplen<=0){
            return -1;
        }
        totalLength+=tmplen;

        return totalLength;
    }

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

        // 解析子 TLV
        try {
            if(!block.parseSubElements()){
                return false;
            }
        } catch (BlockException e) {
            throw new ComponentException("SignatureInfo.wireDecode: "+e.getMessage());
        }

        boolean findSignatureType=false;
        int elementSize=block.getSubElements().length();
        for (int i=0;i<elementSize;i++) {
            Block cacheBlock= null;
            try {
                cacheBlock = block.getSubElements().getBlock(i);
            } catch (BlockException e) {
                throw new ComponentException("SignatureInfo.wireDecode:"+e.getMessage());
            }
            int type= 0;
            try {
                type = cacheBlock.getType().getVlIntValue2Int();
            } catch (VlIntException e) {
                e.printStackTrace();
            }
            switch (type){
                case TLV.TlvSignatureType:
                    if(!this.signatureType.wireDecode(cacheBlock)){
                        return false;
                    }
                    findSignatureType=true;
                case TLV.TlvKeyLocator:
                    if(!this.keyLocator.wireDecode(cacheBlock)){
                        return false;
                    }
                default:
                    throw new ComponentException("SignatureInfo.wireDecode: SignatureInfo sub element type error");
//                    return false;

            }
        }

        // 缺失必要的 SignatureType 子TLV
        if(!findSignatureType){
            throw new Error("SignatureInfo.wireDecode: Parse SignatureInfo error, require SignatureType sub-element");
        }

        return true;
    }
}