package com.kmall.admin.haikong.utils;

import cn.hutool.core.map.MapUtil;
import org.apache.commons.lang.StringUtils;

import java.io.UnsupportedEncodingException;
import java.math.BigDecimal;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.Map;

/**
 * 仓库系统签名工具类
 * @author lhm
 * @createDate 2021-11-01
 */
public class WareSysSignUtils {

    private WareSysSignUtils() {}

    private static Map<String, String> formatUrl(String url) {
        Map<String, String> map = MapUtil.newHashMap();
        if (org.springframework.util.StringUtils.isEmpty(url)) {
            return map;
        }
        int i = url.lastIndexOf("?");
        String paramStr = url.substring(i+1);
        String[] strings = paramStr.split("&");
        for (String string : strings) {
            int j = string.indexOf("=");
            String key = string.substring(0, j);
            if (!"sign".equalsIgnoreCase(key)) {
                String value = string.substring(j + 1);
                map.put(key, value);
            }
        }
        return map;
    }

    public static String getSignRequest(String url, String body, String secretKey) throws Exception {
        String sign = signRequest(formatUrl(url), body, secretKey);
        return url + "&sign=" + sign;
    }


    public static String signRequest(Map<String,String> params, String body, String secretKey) throws Exception {
        // 1. 第一步，确保参数已经排序
        String[] keys = params.keySet().toArray(new String[0]);
        Arrays.sort(keys);
        // 2. 第二步，把所有参数名和参数值拼接在一起(包含body体)
        String joinedParams = joinRequestParams(params, body, secretKey, keys);
        // 3. 第三步，使用加密算法进行加密（目前仅支持md5算法）
        byte[] abstractMesaage = digest(joinedParams);
        // 4. 把二进制转换成大写的十六进制
        return byte2Hex(abstractMesaage);
    }

    private static String byte2Hex(byte[] bytes) {
        char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        int j = bytes.length;
        char[] str = new char[j * 2];
        int k = 0;
        for (byte byte0 : bytes) {
            str[k++] = hexDigits[byte0 >>> 4 & 0xf];
            str[k++] = hexDigits[byte0 & 0xf];
        }
        return new String(str);
    }

    private static byte[] digest(String message) throws Exception {
        MessageDigest md5Instance = MessageDigest.getInstance("MD5");
        md5Instance.update(message.getBytes(StandardCharsets.UTF_8));
        return md5Instance.digest();
    }

    private static String joinRequestParams(Map<String, String> params, String body, String secretKey, String[] sortedKes) {
        StringBuilder sb = new StringBuilder(secretKey); // 前面加上secretKey
        for (String key : sortedKes) {
            if ("sign".equals(key)) {
                continue; // 签名时不计算sign本身
            } else {
                String value = params.get(key);
                if (StringUtils.isNotEmpty(key) && StringUtils.isNotEmpty(value)) {
                    sb.append(key).append(value);
                }
            }
        }
        // 拼接body体
        sb.append(body);
        // 最后加上secretKey
        sb.append(secretKey);
        return sb.toString();
    }
}