using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Newtonsoft.Json;
using Microsoft.AspNetCore.Authorization;
using Shentun.Utilities.Encrypt;
using NPOI.SS.Formula.Functions;
using Shentun.Utilities.Enums;

namespace Shentun.WebApi.Service
{
    public class JwtHelper
    {
        public string SecurityKey;
        public JwtHelper()
        {
            var jwtConfig = new JwtConfig();
            SecurityKey = jwtConfig.SecurityKey;
        }
        public double GetExpiration(ClientAppType clientAppType)
        {
            var jwtConfig = new JwtConfig();

            // 过期时间
            double expMin;
            switch (clientAppType)
            {
                case ClientAppType.Web:
                    expMin = jwtConfig.WebExpiration;
                    break;
                case ClientAppType.Mobile:
                    expMin = jwtConfig.MobileExpiration;
                    break;
                case ClientAppType.Mini:
                    expMin = jwtConfig.MiniExpiration;
                    break;
                case ClientAppType.SelfMachine:
                    expMin = jwtConfig.SelfMachineExpiration;
                    break;
                case ClientAppType.Desktop:
                    expMin = jwtConfig.DesktopExpiration;
                    break;
                default:
                    expMin = jwtConfig.OtherExpiration;
                    break;
                    
            }
            return expMin;
        }
        /// <summary>
        /// 获取JWT令牌
        /// </summary>
        /// <param name="claims"></param>
        /// <param name="clientAppType"></param>
        /// <returns></returns>
        public string GetJwt(IEnumerable<Claim> claims,ClientAppType clientAppType,bool isRefreshToken = false)
        {
            var dateTime = DateTime.UtcNow;//世界时间
            //秘钥
            var jwtConfig = new JwtConfig();
            var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(SecurityKey));
            var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
           
            
            // 过期时间
            double expMin;
            switch (clientAppType)
            {
                case ClientAppType.Web:
                    expMin = jwtConfig.WebExpiration;
                    break;
                case ClientAppType.Mobile:
                    expMin = jwtConfig.MobileExpiration;
                    break;
                case ClientAppType.Mini:
                    expMin = jwtConfig.MiniExpiration;
                    break;
                case ClientAppType.SelfMachine:
                    expMin = jwtConfig.SelfMachineExpiration;
                    break;
                case ClientAppType.Desktop:
                    expMin = jwtConfig.DesktopExpiration;
                    break;
                default:
                    expMin = jwtConfig.OtherExpiration;
                    break;
            }
            if (isRefreshToken)
            {
                expMin = expMin * 2;
            }
            DateTime expTime = dateTime.AddMinutes(expMin);
            var jwt = new JwtSecurityToken(
                issuer: jwtConfig.Issuer,//颁发者
                audience: jwtConfig.Audience,//颁发给
                claims: claims, //声明集合
                notBefore: dateTime,//生效时间，这里必须使用世界时间
                expires: expTime,//过期时间，这里必须使用世界时间
                signingCredentials: creds);
            
            var jwtHandler = new JwtSecurityTokenHandler();
            var encodedJwt = jwtHandler.WriteToken(jwt);

            
            encodedJwt = $"{JwtBearerDefaults.AuthenticationScheme} {encodedJwt}";
            //encodedJwt = AESHelper.Encode(encodedJwt, SecurityKey.Substring(0,16));
            return encodedJwt;
        }
        /// <summary>
        /// 获取TokenValidationParameters
        /// </summary>
        /// <returns></returns>
        public  TokenValidationParameters GetTokenValidationParameters()
        {
            var jwtConfig = new JwtConfig();
            TokenValidationParameters tokenValidationParameters = new TokenValidationParameters
            {
                ValidIssuer = jwtConfig.Issuer,//颁发者
                ValidAudience = jwtConfig.Audience,//颁发给
                IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(SecurityKey)),

                /***********************************TokenValidationParameters的参数默认值***********************************/
                RequireSignedTokens = true,
                // SaveSigninToken = false,
                // ValidateActor = false,
                // 将下面两个参数设置为false，可以不验证Issuer和Audience，但是不建议这样做。
                ValidateAudience = true,//颁发给验证
                ValidateIssuer = true,//颁发者验证
                ValidateIssuerSigningKey = true,
                // 是否要求Token的Claims中必须包含 Expires
                RequireExpirationTime = true,
                // 允许的服务器时间偏移量
                ClockSkew = TimeSpan.FromSeconds(1),
                // 是否验证Token有效期，使用当前时间与Token的Claims中的NotBefore和Expires对比
                ValidateLifetime = true
            };
            return tokenValidationParameters;
        }
        public  JwtSecurityToken GetValidatedToken(string jwtStr)
        {
            
            var jwtHandler = new JwtSecurityTokenHandler();
            if (jwtStr.StartsWith(JwtBearerDefaults.AuthenticationScheme))
                jwtStr = jwtStr.ToString().Substring(JwtBearerDefaults.AuthenticationScheme.Length).Trim();

            jwtHandler.ValidateToken(jwtStr, GetTokenValidationParameters(), out SecurityToken validatedToken);

            var jwtToken = (JwtSecurityToken)validatedToken;
            return jwtToken;
        }
        
    }
}