using System; 
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Configuration;
using Microsoft.IdentityModel.Tokens;
using Newtonsoft.Json;
using QualityControlPlatform.Helpers.Response;
using static QualityControlPlatform.Helpers.Response.ResponseHelper;

namespace QualityControlPlatform.Middleware
{ 
    public class JwtMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly JwtSecurityTokenHandler _jwtSecurityTokenHandler = new JwtSecurityTokenHandler();
        private static IConfiguration Configuration { get; set; }
        public JwtMiddleware(RequestDelegate next, IConfiguration config)
        {
            _next = next;
            Configuration = config;
        }

        public async Task Invoke(HttpContext context)
        {
            if (context == null) throw new ArgumentNullException(nameof(context));
            var tokenStr = context.Request.Headers["Authorization"].ToString();
            //未携带token请求不需要授权页面,让其直接通过，用方法名上面的校验来判断
            if (!string.IsNullOrEmpty(tokenStr))
            {
                //携带了token，判断token，回传失效，过期，或者续期
                var setting = new JsonSerializerSettings
                {
                    ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver()
                };
                //token 是否合规
                if (!IsCanReadToken(ref tokenStr))
                {
                    var result = new ResultModel() { Message = "invalid token", Code = Convert.ToInt32(ErrorEnum.TokenError) };
                    await context.Response.WriteAsync( JsonConvert.SerializeObject(result, setting), Encoding.UTF8);
                    return;
                }
                // token是否超过有效期
                if (IsExp(tokenStr))
                {
                    var result = new ResultModel() { Message = "token expired", Code = Convert.ToInt32(ErrorEnum.TokenError) };
                    await context.Response.WriteAsync( JsonConvert.SerializeObject(result, setting), Encoding.UTF8);
                    return;
                }
                var claims = new[]
                {
                    new Claim("userCode",GetJwtSecurityToken(tokenStr)?.Claims.FirstOrDefault(p=>p.Type.Equals("userCode"))?.Value) ,
                    new Claim("userName",GetJwtSecurityToken(tokenStr)?.Claims.FirstOrDefault(p=>p.Type.Equals("userName"))?.Value),
                    new Claim("deptCode",GetJwtSecurityToken(tokenStr)?.Claims.FirstOrDefault(p=>p.Type.Equals("deptCode"))?.Value) ,
                    new Claim("deptName",GetJwtSecurityToken(tokenStr)?.Claims.FirstOrDefault(p=>p.Type.Equals("deptName"))?.Value)
                };
                // 获取SecurityKey
                var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration.GetSection("Authentication")["SecurityKey"]));
                var token = new JwtSecurityToken(
                    issuer: Configuration.GetSection("Authentication")["IsSure"],                    // 发布者
                    audience: Configuration.GetSection("Authentication")["Audience"],                // 接收者
                    notBefore: DateTime.Now,                                                          // token签发时间
                    expires: DateTime.Now.AddMinutes(30),                                             // token过期时间
                    claims: claims,                                                                   // 该token内存储的自定义字段信息
                    signingCredentials: new SigningCredentials(key, SecurityAlgorithms.HmacSha256)    // 用于签发token的秘钥算法
                );
                // 返回成功信息，写出token
                var data = new JwtSecurityTokenHandler().WriteToken(token);
                context.Response.Headers.Add("newToken", data);
            }
            await _next(context);
        }

        /// <summary>
        /// Token是否是符合要求的标准 Json Web 令牌
        /// </summary>
        /// <param name="tokenStr"></param>
        /// <returns></returns>
        public bool IsCanReadToken(ref string tokenStr)
        {
            tokenStr = tokenStr.Replace("Bearer ", string.Empty);
            var key = Encoding.UTF8.GetBytes(Configuration.GetSection("Authentication")["SecurityKey"]);
            var tokenValidationParameters = new TokenValidationParameters
            {
                ValidIssuer = Configuration.GetSection("Authentication")["IsSure"],
                ValidAudience = Configuration.GetSection("Authentication")["Audience"],
                IssuerSigningKey = new SymmetricSecurityKey(key),
                RequireExpirationTime = true,
                ClockSkew = TimeSpan.Zero
            };
            // 验证token是否有效，如果过期，报错SecurityTokenExpiredException
            // 报错信息：IDX10223 : Lifetime validation failed
            try
            {
                var principal = _jwtSecurityTokenHandler.ValidateToken(tokenStr, tokenValidationParameters, out var securityToken);
                return principal != null;
            }
            catch (Exception)
            {
                return false;
            }
        }

        /// <summary>
        /// 从Token解密出JwtSecurityToken,JwtSecurityToken : SecurityToken
        /// </summary>
        /// <param name="tokenStr"></param>
        /// <returns></returns>
        public JwtSecurityToken GetJwtSecurityToken(string tokenStr)
        {
            var jwt = _jwtSecurityTokenHandler.ReadJwtToken(tokenStr);
            return jwt;
        }
        /// <summary>
        /// 判断token是否过期
        /// </summary>
        /// <param name="token"></param>
        /// <returns></returns>
        public bool IsExp(string token)
        {
            return GetDateTime(Convert.ToDouble(GetJwtSecurityToken(token)?.Claims.First(c => c.Type == JwtRegisteredClaimNames.Exp)?.Value)) < DateTime.Now;
        }
        private static DateTime GetDateTime(double timeStamp)// 时间戳Timestamp转换成日期
        {
            var dateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
            dateTime = dateTime.AddSeconds(timeStamp).ToLocalTime();
            return dateTime;
        }
    }
}