/**
 * Copyright 2018-2020 stylefeng & fengshuonan (https://gitee.com/stylefeng)
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.stylefeng.guns.sys.core.util;

import cn.stylefeng.guns.sys.core.constant.JwtConstants;
import cn.stylefeng.roses.core.util.ToolUtil;
import io.jsonwebtoken.*;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * <p>jwt token工具类</p>
 * <pre>
 *     jwt的claim里一般包含以下几种数据:
 *         1. iss -- token的发行者
 *         2. sub -- 该JWT所面向的用户
 *         3. aud -- 接收该JWT的一方
 *         4. exp -- token的失效时间
 *         5. nbf -- 在此时间段之前,不会被处理
 *         6. iat -- jwt发布时间
 *         7. jti -- jwt唯一标识,防止重复使用
 * </pre>
 *
 * @author fengshuonan
 * @Date 2017/8/25 10:59
 */
public class JwtTokenUtil {

    /**
     * 获取用户名从token中
     */
    public static String getUsernameFromToken(String token) {
        return getClaimFromToken(token).getSubject();
    }

    /**
     * 获取jwt发布时间
     */
    public static Date getIssuedAtDateFromToken(String token) {
        return getClaimFromToken(token).getIssuedAt();
    }

    /**
     * 获取jwt失效时间
     */
    public static Date getExpirationDateFromToken(String token) {
        return getClaimFromToken(token).getExpiration();
    }

    /**
     * 获取jwt接收者
     */
    public static String getAudienceFromToken(String token) {
        return getClaimFromToken(token).getAudience();
    }

    /**
     * 获取私有的jwt claim
     */
    public static String getPrivateClaimFromToken(String token, String key) {
        return getClaimFromToken(token).get(key).toString();
    }

    /**
     * 获取jwt的payload部分
     */
    public static Claims getClaimFromToken(String token) {
        return Jwts.parser()
                .setSigningKey(JwtConstants.SECRET)
                .parseClaimsJws(token)
                .getBody();
    }

    /**
     * 解析token是否正确,不正确会报异常<br>
     */
    public static void parseToken(String token) throws JwtException {
        Jwts.parser().setSigningKey(JwtConstants.SECRET).parseClaimsJws(token).getBody();
    }

    /**
     * <pre>
     *  验证token是否失效
     *  true:过期   false:没过期
     * </pre>
     */
    public static Boolean isTokenExpired(String token) {
        try {
            final Date expiration = getExpirationDateFromToken(token);
            return expiration.before(new Date());
        } catch (ExpiredJwtException expiredJwtException) {
            return true;
        }
    }

    /**
     * 生成token(通过用户名和签名时候用的随机数)
     */
    public static String generateToken(String userId) {
        Map<String, Object> claims = new HashMap<>();
        return doGenerateToken(claims, userId);
    }

    /**
     * 生成token
     */
    private static String doGenerateToken(Map<String, Object> claims, String subject) {
        final Date createdDate = new Date();
        final Date expirationDate = new Date(createdDate.getTime() + JwtConstants.EXPIRATION * 1000);

        return Jwts.builder()
                .setClaims(claims)
                .setSubject(subject)
                .setIssuedAt(createdDate)
                .setExpiration(expirationDate)
                .signWith(SignatureAlgorithm.HS512, JwtConstants.SECRET)
                .compact();
    }

    /**
     * 获取混淆MD5签名用的随机字符串
     */
    public static String getRandomKey() {
        return ToolUtil.getRandomString(6);
    }
}