package com.walker.pay.payunk.util;

import com.walker.infrastructure.ApplicationRuntimeException;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.collections4.MapUtils;
import org.apache.commons.io.IOUtils;
import sun.misc.BASE64Encoder;
import sun.security.util.DerInputStream;
import sun.security.util.DerValue;

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.RSAPrivateCrtKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;

public class SignUtils {

    /**
     * 生成签名
     *
     * @param params 参数个数
     * @return {@link String}
     */
    public static String signature(Map<String, Object> params) {
        String signatures = "";
        try {
            List<String> paramsStr = new ArrayList<>();
            for (String key1 : params.keySet()) {
                if (null != params.get(key1) && !"".equals(params.get(key1)) && !"sign".equals(key1)) {
                    paramsStr.add(key1);
                }
            }
            Collections.sort(paramsStr);
            StringBuilder sbff = new StringBuilder();
            for (String kk : paramsStr) {
                if (params.get(kk) == null) {
                    continue;
                }
                String value = params.get(kk).toString();
                if ("".equals(sbff.toString())) {
                    sbff.append(kk).append("=").append(value);
                } else {
                    sbff.append("&").append(kk).append("=").append(value);
                }
            }
            String str = String.valueOf(sbff);
            System.out.println(str);
            signatures = encryptionSign(str);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return signatures;
    }

    /**
     * RSA私钥加密
     *
     * @param content 内容
     * @return {@link String}
     */
    public static String encryptionSign(String content) {
        try {
            Signature signature = Signature.getInstance("SHA1WithRSA");
            String publicKeyBase64Str = IOUtils.toString(Thread.currentThread().getContextClassLoader().getResourceAsStream("rsa.pri"));
            PrivateKey privateKey = pkcs1ToPrivateKey(publicKeyBase64Str);
            signature.initSign(privateKey);
            signature.update(content.getBytes(StandardCharsets.UTF_8));
            byte[] signed = signature.sign();
            return byte2Base64(signed);
        } catch (Exception e) {
            throw new ApplicationRuntimeException("加载'rsa.pri'文件错误，可能文件不存在或解析格式错误：" + e.getMessage(), e);
        }
    }

    public static String byte2Base64(byte[] bytes) {
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(bytes);
//        return Base64.encodeBase64String(bytes);
    }


    /**
     * 读取文件中的私钥
     *
     * @param keyBase64 关键base64
     * @return {@link PrivateKey}
     * @throws Exception 异常
     */
    public static PrivateKey pkcs1ToPrivateKey(String keyBase64) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        DerInputStream derReader = new DerInputStream(java.util.Base64.getMimeDecoder().decode(keyBase64));
        DerValue[] seq = derReader.getSequence(0);
        BigInteger modulus = seq[1].getBigInteger();
        BigInteger publicExp = seq[2].getBigInteger();
        BigInteger privateExp = seq[3].getBigInteger();
        BigInteger prime1 = seq[4].getBigInteger();
        BigInteger prime2 = seq[5].getBigInteger();
        BigInteger exp1 = seq[6].getBigInteger();
        BigInteger exp2 = seq[7].getBigInteger();
        BigInteger crtCoef = seq[8].getBigInteger();
        RSAPrivateCrtKeySpec keySpec = new RSAPrivateCrtKeySpec(modulus, publicExp, privateExp, prime1, prime2, exp1, exp2, crtCoef);
        return keyFactory.generatePrivate(keySpec);

//         读取私钥
//        FileInputStream privateKeyFileIn = new FileInputStream("E:\video\\privateKey.dat");
//        ObjectInputStream privateKeyObjIn = new ObjectInputStream(privateKeyFileIn);
//        PrivateKey privateKey = (PrivateKey) privateKeyObjIn.readObject();
//        privateKeyObjIn.close();
    }

    /**
     * 读取文件中的公钥
     *
     * @return {@link PublicKey}
     * @throws Exception 异常
     */
    public static PublicKey getPublicKey() throws Exception {
        String publicKeyBase64Str = IOUtils.toString(Thread.currentThread().getContextClassLoader().getResourceAsStream("rsa.pub"));
        byte[] decodeBase64 = Base64.decodeBase64(publicKeyBase64Str);
        // 公钥的规则 X509EncodedKeySpec
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(decodeBase64);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePublic(x509EncodedKeySpec);
    }

    /**
     * 验证签名
     *
     * @param params 参数个数
     * @return {@link String}
     */
    public static String verify(Map<String, Object> params) {
        String signatures = "";
        try {
            List<String> paramsStr = new ArrayList<>();
            for (String key1 : params.keySet()) {
                if (null != params.get(key1) && !"".equals(params.get(key1)) && !"sign".equals(key1)) {
                    paramsStr.add(key1);
                }
            }
            Collections.sort(paramsStr);
            StringBuilder sbff = new StringBuilder();
            for (String kk : paramsStr) {
                if (params.get(kk) == null) {
                    continue;
                }
                String value = params.get(kk).toString();
                if ("".equals(sbff.toString())) {
                    sbff.append(kk).append("=").append(value);
                } else {
                    sbff.append("&").append(kk).append("=").append(value);
                }
            }
            String str = String.valueOf(sbff);
//            BASE64Decoder decoder = new BASE64Decoder();
//            byte[] signed = decoder.decodeBuffer(MapUtils.getString(params, "sign"));
            byte[] signed = Base64.decodeBase64(MapUtils.getString(params, "sign"));
                    Signature sign = Signature.getInstance("SHA1withRSA");
            sign.initVerify(getPublicKey());
            sign.update(str.getBytes(StandardCharsets.UTF_8));
            if (sign.verify(signed)) {
                return "success";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "error";
    }
}