package com.hx.util;

import java.util.Base64;
import java.util.Date;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.ExpiredJwtException;
import io.jsonwebtoken.JwtBuilder;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.SignatureException;

/**
 * 生成token （登录，或者其他）
 * @author chenjiahe
 * @Data 20200609
 */
public class JwtTool {
	
    /**
     * 签发JWT
     * @param id 标识
     * @param subject 可以是JSON数据 尽可能少
     * @param ttlMillis 有效时间长度(秒)，为空你认证时间
     * @return  String
     *
     */
    public static String createJWT(String id, String subject, long ttlMillis) {
        SignatureAlgorithm signatureAlgorithm = SignatureAlgorithm.HS256;
        long nowMillis = System.currentTimeMillis();
        Date now = new Date(nowMillis);
        SecretKey secretKey = generalKey();
        JwtBuilder builder = Jwts.builder()
                .setId(id)
                .setSubject(subject)   // 主题
                .setIssuer("user")     // 签发者
                .setIssuedAt(now)      // 签发时间
                .signWith(signatureAlgorithm, secretKey); // 签名算法以及密匙
        if (SimpleTool.checkNotNull(ttlMillis)&&ttlMillis >= 0) {
            long expMillis = nowMillis + ttlMillis*1000;
            Date expDate = new Date(expMillis);
            builder.setExpiration(expDate); // 过期时间
        }
        return builder.compact();
    }
    /**
     * 验证JWT
     * @param jwtStr
     * @return JwtConstant
     */
    public static JwtConstant validateJWT(String jwtStr) {
    	JwtConstant checkResult = new JwtConstant();
        Claims claims = null;
        try {
            claims = parseJWT(jwtStr);
            checkResult.setSuccess(true);
            checkResult.setClaims(claims);
        } catch (ExpiredJwtException e) {
            checkResult.setErrCode(JwtConstant.JWT_ERRCODE_EXPIRE);
            checkResult.setSuccess(false);
        } catch (SignatureException e) {
            checkResult.setErrCode(JwtConstant.JWT_ERRCODE_FAIL);
            checkResult.setSuccess(false);
        } catch (Exception e) {
            checkResult.setErrCode(JwtConstant.JWT_ERRCODE_FAIL);
            checkResult.setSuccess(false);
        }
        return checkResult;
    }
    
    public static SecretKey generalKey() {
        byte[] encodedKey = Base64.getDecoder().decode(JwtConstant.JWT_SECERT);
        SecretKey key = new SecretKeySpec(encodedKey, 0, encodedKey.length, "AES");
        return key;
    }
    
    /**
     * 
     * 解析JWT字符串
     * @param jwt
     * @return
     * @throws Exception
     */
    public static Claims parseJWT(String jwt) throws Exception {
        SecretKey secretKey = generalKey();
        return Jwts.parser()
            .setSigningKey(secretKey)
            .parseClaimsJws(jwt)
            .getBody();
    }
}