using JWT;
using JWT.Algorithms;
using JWT.Builder;
using JWT.Serializers;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Claims;
using System.Text;
using System.Threading.Tasks;

namespace Tango.Web.Security
{
    public class WebToken
    {
        public DateTime Issued { get; protected set; }
        public DateTime? Expiration { get; protected set; }
        public String AccessToken { get; protected set; }
        public String RefreshToken { get; protected set; }

        public WebToken()
        {

        }

        public static WebToken CreateNew(String secret, DateTime? expiration = null)
        {
            DateTime issued = DateTime.UtcNow;

            var builder = new JwtBuilder()
                 .WithAlgorithm(new HMACSHA256Algorithm())
                 .WithSecret(secret)
                 .IssuedAt(issued);

            if (expiration != null)
            {
                builder = builder.ExpirationTime(expiration.Value);
            }

            String refreshToken = Guid.NewGuid().ToString();

            builder = builder.AddClaim("object", null);
            builder = builder.AddClaim("refresh-token", refreshToken);

            return new WebToken()
            {
                AccessToken = builder.Build(),
                RefreshToken = refreshToken,
                Expiration = expiration,
                Issued = issued,
            };
        }

        public static void Validate(String secret, String token)
        {
            var json = new JwtBuilder()
                 .WithSecret(secret)
                 .MustVerifySignature()
                 .Decode(token);
        }

        public void Validate(String secret)
        {
            var json = new JwtBuilder()
                        .WithSecret(secret)
                        .MustVerifySignature()
                        .Decode(AccessToken);
        }

        public WebToken Renew(String secret)
        {
            var newToken = CreateNew(secret, DateTime.UtcNow.Add(Expiration.Value - Issued));
            newToken.RefreshToken = RefreshToken;
            return newToken;
        }

        public static WebToken FromToken(String token)
        {
            WebToken webToken = new WebToken();

            var payload = new JwtBuilder()
                  .WithValidator(null)
                  .Decode<IDictionary<string, object>>(token);

            webToken.AccessToken = token;

            if (payload.ContainsKey("exp"))
            {
                long exp = long.Parse(payload["exp"].ToString());
                webToken.Expiration = ConvertEpochToDateTime(exp);
            }

            if (payload.ContainsKey("iat"))
            {
                long iat = long.Parse(payload["iat"].ToString());
                webToken.Issued = ConvertEpochToDateTime(iat);
            }

            if (payload.ContainsKey("refresh-token"))
            {
                webToken.RefreshToken = payload["refresh-token"].ToString();
            }

            return webToken;
        }

        protected static DateTime ConvertEpochToDateTime(long seconds)
        {
            var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
            return epoch.AddSeconds(seconds);
        }
    }

    public class WebToken<T> : WebToken where T : class
    {
        public T Object { get; protected set; }

        private WebToken()
        {

        }

        public static WebToken<T> CreateNew(String secret, T obj = null, DateTime? expiration = null)
        {
            DateTime issued = DateTime.UtcNow;

            var builder = new JwtBuilder()
                 .WithAlgorithm(new HMACSHA256Algorithm())
                 .WithSecret(secret)
                 .IssuedAt(issued);

            if (expiration != null)
            {
                builder = builder.ExpirationTime(expiration.Value);
            }

            String refreshToken = Guid.NewGuid().ToString();

            builder = builder.AddClaim("object", obj);
            builder = builder.AddClaim("refresh-token", refreshToken);

            return new WebToken<T>()
            {
                AccessToken = builder.Build(),
                RefreshToken = refreshToken,
                Expiration = expiration,
                Issued = issued,
                Object = obj,
            };
        }

        public static new WebToken<T> FromToken(String token)
        {
            WebToken<T> webToken = new WebToken<T>();

            var payload = new JwtBuilder()
                  .WithValidator(null)
                  .Decode<IDictionary<string, object>>(token);

            webToken.AccessToken = token;

            if (payload.ContainsKey("exp"))
            {
                long exp = long.Parse(payload["exp"].ToString());
                webToken.Expiration = ConvertEpochToDateTime(exp);
            }

            if (payload.ContainsKey("iat"))
            {
                long iat = long.Parse(payload["iat"].ToString());
                webToken.Issued = ConvertEpochToDateTime(iat);
            }

            if (payload.ContainsKey("refresh-token"))
            {
                webToken.RefreshToken = payload["refresh-token"].ToString();
            }

            webToken.Object = JsonConvert.DeserializeObject<T>(payload["object"].ToString());

            return webToken;
        }

        public new WebToken<T> Renew(String secret)
        {
            var newToken = WebToken<T>.CreateNew(secret, Object, DateTime.UtcNow.Add(Expiration.Value - Issued));
            newToken.RefreshToken = RefreshToken;
            return newToken;
        }
    }
}