package com.nova.sankuai.domain.api.doudouqian;

import com.alibaba.fastjson.JSONObject;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.security.Key;
import java.security.KeyFactory;
import java.security.MessageDigest;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.*;

/**
 * <p>
 * 用于加密解密的各种工具集
 * </p>
 *
 * @author Tiangle
 * @since 2022/4/26
 **/
public class DdqSignUtil {

    /**
     * @param bizDataJson 业务数据
     * @param channelCode 机构申请得到的渠道号
     * @param publicKey   公钥
     * @param md5Key      MD5秘钥
     * @return
     * @throws Exception
     */
    public static String buildRequest(String bizDataJson, String channelCode, String publicKey, String md5Key) throws Exception {
        // aesKey
        String aesKey = DdqSignUtil.getRandom(16, true);
        // timeStamp
        String timestamp = System.currentTimeMillis() / 1000 + "";
        // biz_data
        String bizEncryptData = DdqSignUtil.encrypt(bizDataJson, aesKey);
        // secretKey
        String secretKey = DdqSignUtil.encryptByPublicKey(aesKey, publicKey);

        Map<String, String> sortMap = new HashMap<>();
        sortMap.put("channel_code", channelCode);
        sortMap.put("timestamp", timestamp);
        sortMap.put("biz_data", bizEncryptData);
        sortMap.put("secret_key", secretKey);
        String sign = DdqSignUtil.createSign(sortMap, md5Key);

        // 构建请求参数
        JSONObject params = new JSONObject();
        params.put("sign", sign);
        params.put("secret_key", secretKey);
        params.put("biz_data", bizEncryptData);
        params.put("channel_code", channelCode);
        params.put("timestamp", timestamp);
        return params.toString();
    }

    /**
     * 生成指定位数的随机字符串
     *
     * @param length      长度
     * @param useAlphabet 是否使用字母
     * @return String
     */
    public static String getRandom(int length, boolean useAlphabet) {
        StringBuffer buffer = new StringBuffer();
        String s = "0123456789" + (useAlphabet ? "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" : "");
        for (int i = 0; i < length; i++) {
            buffer.append(s.charAt(new Random().nextInt(s.length())));
        }
        return buffer.toString();
    }

    /**
     * AES 加密
     *
     * @param content 待加密内容
     * @param key     秘钥
     * @return String 密文
     * @throws Exception EX
     */
    public static String encrypt(String content, String key) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        byte[] keyBytes = key.getBytes(StandardCharsets.UTF_8);
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(keyBytes, "AES"));
        byte[] bytes = cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));
        return Base64.encodeBase64String(bytes);
    }

    /**
     * AES 解密
     *
     * @param encryptBytes 密文
     * @param key          秘钥
     * @return String 明文
     * @throws Exception EX
     */
    public static String decrypt(String encryptBytes, String key) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        byte[] keyBytes = key.getBytes(StandardCharsets.UTF_8);
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(keyBytes, "AES"));
        byte[] decryptBytes = cipher.doFinal(Base64.decodeBase64(encryptBytes));
        return new String(decryptBytes);
    }

    /**
     * 用公钥加密
     *
     * @param value 要加密数据
     * @param key   密钥
     * @return byte[]
     * @throws Exception RSA异常
     */
    public static String encryptByPublicKey(String value, String key) throws Exception {
        byte[] data = getBytes(value);
        // 对公钥解密
        byte[] keyBytes = Base64.decodeBase64(key);
        // 取公钥
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Key publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return Base64.encodeBase64String(doFinalBySegment(cipher, data, true));
    }

    /**
     * 获取字符串的字节数组
     *
     * @param content 字符串
     * @return byte[]
     */
    public static byte[] getBytes(String content) {
        return content.getBytes(StandardCharsets.UTF_8);
    }

    private static byte[] doFinalBySegment(Cipher cipher, byte[] source, boolean isEncode) throws Exception {
        ByteArrayOutputStream out = null;
        try {
            int blockSize = isEncode ? 117 : 128;
            if (source.length <= blockSize) {
                return cipher.doFinal(source);
            }
            out = new ByteArrayOutputStream();
            int offsetIndex = 0, offset = 0, sourceLength = source.length;
            while (sourceLength - offset > 0) {
                int size = Math.min(sourceLength - offset, blockSize);
                byte[] buffer = cipher.doFinal(source, offset, size);
                out.write(buffer, 0, buffer.length);
                offsetIndex++;
                offset = offsetIndex * blockSize;
            }
            return out.toByteArray();
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * MD5 Encrypt
     *
     * @param info 待加密字符串
     * @return String
     * @throws Exception 加密异常
     */
    public static String md5Encrypt(String info) throws Exception {
        MessageDigest md5 = MessageDigest.getInstance("MD5");
        md5.update(info.getBytes(StandardCharsets.UTF_8));
        byte[] result = md5.digest();
        StringBuffer buffer = new StringBuffer();
        for (byte b : result) {
            String str = Integer.toHexString(b & 0xFF);
            if (str.length() == 1) {
                buffer.append("0");
            }
            buffer.append(str);
        }
        return buffer.toString().toUpperCase();
    }

    /**
     * 创建签名字符串
     *
     * @param sortMap 用于创建签名的参数集合
     * @param md5Key  MD5加密秘钥
     * @return
     * @throws Exception
     */
    public static String createSign(Map<String, String> sortMap, String md5Key) throws Exception {
        // 按ASCII码升序组成签名参数字符串
        SortedMap sortedMap = new TreeMap(sortMap);
        Set<String> set = sortedMap.keySet();
        StringBuffer tempSign = new StringBuffer();
        for (String o : set) {
            tempSign.append(o).append("=").append(sortedMap.get(o));
            tempSign.append("&");
        }
        tempSign.deleteCharAt(tempSign.length() - 1);
        // 获取加密签名字符串
        String sign = md5Encrypt(tempSign + md5Key);
        return sign;
    }

    /**
     * 用私钥解密
     *
     * @param value 密文
     * @param key   密钥
     * @return String
     * @throws Exception RSA异常
     */
    public static String decryptByPrivateKey(String value, String key) throws Exception {
        byte[] data = Base64.decodeBase64(value);
        // 对私钥解密
        byte[] keyBytes = Base64.decodeBase64(key);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        Key privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return getString(doFinalBySegment(cipher, data, false));
    }

    /**
     * 转换字节数组为字符串
     *
     * @param content 字节数组
     * @return String
     */
    public static String getString(byte[] content) {
        return new String(content, StandardCharsets.UTF_8);
    }

    /**
     * 查询参数
     *
     * @param paramMap
     * @param name
     * @return String
     */
    public static String getValue(Map<String, Object> paramMap, String name) {
        if (paramMap == null || paramMap.isEmpty() || StringUtils.isBlank(name) || !paramMap.containsKey(name)) {
            return null;
        }
        Object obj = paramMap.get(name);
        if (obj == null) {
            return null;
        }
        String value = obj.toString();
        return value.trim();
    }
}