using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using JWT;
using JWT.Algorithms;
using JWT.Exceptions;
using JWT.Serializers;
using Newtonsoft.Json;

namespace VueWebApi.Tools
{
    public class JwtTools
    {
        public static string Key { get; set; } = "Hello World"; //不要泄密
        //加密
        public static string Encode(Dictionary<string, object> payLoad, string key = null)
        {
            if (string.IsNullOrEmpty(key))
            {
                key = Key;
            }

            IJwtAlgorithm algorithm = new HMACSHA256Algorithm();
            IJsonSerializer serializer = new JsonNetSerializer();
            IBase64UrlEncoder urlEncoder = new JwtBase64UrlEncoder();
            IJwtEncoder encoder = new JwtEncoder(algorithm, serializer, urlEncoder);
            //添加一个Jwt时效串
            payLoad.Add("timeout", DateTime.Now.AddDays(1));
            return encoder.Encode(payLoad, key);
        }

        //解密
        public static Dictionary<string, object> Decode(string jwtstr, string key = null)
        {
            if (string.IsNullOrEmpty(key))
            {
                key = Key;
            }
            try
            {
                IJsonSerializer serializer = new JsonNetSerializer();
                IDateTimeProvider provider = new UtcDateTimeProvider();
                IJwtValidator validator = new JwtValidator(serializer, provider);
                IBase64UrlEncoder urlEncoder = new JwtBase64UrlEncoder();
                IJwtAlgorithm algorithm = new HMACSHA256Algorithm();
                IJwtDecoder decoder = new JwtDecoder(serializer, validator, urlEncoder, algorithm);

                var json = decoder.Decode(jwtstr, key, verify: true);//token为之前生成的字符串

                //string---->Dictionary
                //把一个字符串反向生成对应的对象内容 
                var result = JsonConvert.DeserializeObject<Dictionary<string, object>>(json);
                if ((DateTime)result["timeout"] < DateTime.Now)
                {
                    throw new Exception(message:"Jwt已过期,请重新登录");
                }
                result.Remove(key: "timeout");
                return result;
            }
            catch (TokenExpiredException)
            {

                throw;  //请求超时
            }
            catch (SignatureVerificationException)
            {
                throw; //签名验证失败，数据可能被篡改
            }
        }

        //校验登录
        //public static string key = "123456";
        //public static string ValideLogined(HttpRequest req)
        //{
        //    if (req.Headers["token"] == null)
        //        throw new Exception(message: "请登录!");
        //    return Decode(token: req.Headers["token"], key);
        //}
    }
}