package com.chuanglan.gateway.utils;

import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;

import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

public class SignUtils {

    private static final long *DEFAULT_EXPIRE_MILLIS *= 5 * 60 * 1000L;

    public static Map<String, String> generateSign(String appSecret) {
        String nonce = UUID.*randomUUID*().toString();
        String curTime = String.*valueOf*(System.*currentTimeMillis*()/1000);
        *validateParams*(appSecret, nonce, curTime);
        String signStr = appSecret + nonce + curTime;
        String sign = DigestUtils.*sha1Hex*(signStr).toUpperCase();
        Map<String, String> map = new HashMap<>();
        map.put("sign", sign);
        map.put("nonce", nonce);
        map.put("curTime", curTime);
        return map;
    }

    public static String generateSign(String appSecret, String nonce, String curTime) {
        *validateParams*(appSecret, nonce, curTime);
        String signStr = appSecret + nonce + curTime;
        return DigestUtils.*sha1Hex*(signStr).toUpperCase();
    }

    public static String generateSign(String appSecret, String nonce, long curTime) {
        return *generateSign*(appSecret, nonce, String.*valueOf*(curTime));
    }

    public static boolean verifySign(String appSecret, String nonce, String curTime, String sign) {
        return *verifySign*(appSecret, nonce, curTime, sign, *DEFAULT_EXPIRE_MILLIS*);
    }

    public static boolean verifySign(String appSecret, String nonce, String curTime, String sign, long expireMillis) {
        if (StringUtils.*isBlank*(sign)) {
            return false;
        }
        try {
            *validateParams*(appSecret, nonce, curTime);
        } catch (IllegalArgumentException e) {
            return false;
        }
        if (!*isCurTimeValid*(curTime, expireMillis)) {
            return false;
        }
        String generateSign = *generateSign*(appSecret, nonce, curTime);
        return generateSign.equalsIgnoreCase(sign);
    }

    private static boolean isCurTimeValid(String curTime, long expireMillis) {
        if (!NumberUtils.*isDigits*(curTime)) {
            return false;
        }
        long curTimeLong;
        try {
            curTimeLong = Long.*parseLong*(curTime);
        } catch (NumberFormatException e) {
            return false;
        }
        long now = System.*currentTimeMillis*();
        return (curTimeLong >= now - expireMillis) && (curTimeLong <= now + expireMillis);
    }

    private static void validateParams(String appSecret, String nonce, String curTime) {
        if (StringUtils.*isBlank*(appSecret)) {
            throw new IllegalArgumentException("AppSecret不能为空");
        }
        if (StringUtils.*isBlank*(nonce)) {
            throw new IllegalArgumentException("Nonce不能为空");
        }
        if (StringUtils.*isBlank*(curTime)) {
            throw new IllegalArgumentException("CurTime不能为空");
        }
    }

    public static void main(String[] args) {
        String appId     = "your_app_id";
        String appSecret = "your_app_secret";

        Map<String, String> result = *generateSign*(appSecret);

        System.*out*.println("AppID:    " + appId);
        System.*out*.println("Nonce:    " + result.get("nonce"));
        System.*out*.println("CurTime:  " + result.get("curTime"));
        System.*out*.println("CheckSum: " + result.get("sign"));
    }
}