using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Runtime.Caching;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;
using Sony.Filtr.AppleMusicAPI.Models;

namespace Sony.Filtr.AppleMusicAPI
{
    public class AppleMusicAuthClientCredentialsHttpMessageHandler : DelegatingHandler
    {
        private readonly string _clientId;
        private readonly string _clientSecret;
        private static readonly SemaphoreSlim SyncLock = new SemaphoreSlim(1);

        public AppleMusicAuthClientCredentialsHttpMessageHandler(string clientId, string clientSecret, HttpMessageHandler httpMessageHandler): base(httpMessageHandler)
        {
            _clientId = clientId;
            _clientSecret = clientSecret;
        }

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            if (request.Headers.Authorization == null)
            {
                request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", await GetAuthenticationTokenAsync());
            }
            return await base.SendAsync(request, cancellationToken);
        }

        private async Task<string> GetAuthenticationTokenAsync()
        {
            var cacheKey = "AppleMusicWebApiSession-Token" + _clientId;

            //Locking for token?
            //var token = MemoryCache.Default.Get(cacheKey) as string;
            //if (token == null)
            //{
            //    SyncLock.Wait();
            //    try
            //    {
            //        token = MemoryCache.Default.Get(cacheKey) as string;
            //        if (token == null)
            //        {
            //            var timeBeforeRequest = DateTime.Now;

            //            var response = await GetAuthenticationTokenResponse();

            //            

            //            var expireTime = timeBeforeRequest.AddSeconds(Convert.ToInt32(response.expires_in));
            //            MemoryCache.Default.Set(cacheKey, token, new DateTimeOffset(expireTime));
            //        }
            //    }
            //    finally
            //    {
            //        SyncLock.Release();
            //    }
            //}

            return await GetAuthenticationTokenResponse();

            //return token;
        }

        public static string Base64Encode(string plainText)
        {
            var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
            return Convert.ToBase64String(plainTextBytes);
        }

        private async Task<string> GetAuthenticationTokenResponse()
        {
            HttpClient client = new HttpClient();

            var content = new FormUrlEncodedContent(new[] 
            {
                new KeyValuePair<string, string>("grant_type", "client_credentials")
                //new KeyValuePair<string, string>("scope", "")
            });


            var authHeader = Base64Encode(_clientId + ":" + _clientSecret);

            var jwtToken = GetJwtToken();

            var requestMessage = new HttpRequestMessage(HttpMethod.Post, "https://accounts.spotify.com/api/token");
            requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Basic", authHeader);
            requestMessage.Content = content;

            var response = await client.SendAsync(requestMessage);
            var responseString = await response.Content.ReadAsStringAsync();

            return responseString;
            //var authenticationResponse = JsonConvert.DeserializeObject<AutenticationResponse>(responseString);
            //return authenticationResponse;
        }

        private string GetJwtToken()
        {
            //jose-jwt
            //var header = JsonConvert.SerializeObject(new JwtHeader()
            //{
            //    alg = "ES256",
            //    kid = "9K26W5TDWH"
            //});

            //var unixEpochTimeSpan = (DateTime.UtcNow – new DateTime(1970, 1, 1));

            //var expiresAt = (long)t.TotalSeconds;

            //var payload = JsonConvert.SerializeObject(new JwtPayload()
            //{
            //    iss = "Y38Y7276CK",
            //    exp = DateTime.Now.Ticks
            //    iat = ""
            //});

            //return $"{header} {payload}";

            var payload = new Dictionary<string, object>()
            {
                { "iss", "Y38Y7276CK" },
   
            };

            var privateKey = new X509Certificate2("ecc-key.p12", "password").GetECDsaPrivateKey();

            string token = Jose.JWT.Encode(payload, privateKey, JwsAlgorithm.ES256);

            return null;
        }
    }
}