using Microsoft.AspNet.SignalR.Client;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;

namespace SignalRClientPOS
{
    class Program
    {
        // callback data as received from PayWiser
        private class Callback
        {
            public string Type { get; set; }
            public string Data { get; set; }
            public string HMAC { get; set; }
        }

        // innser callback data for pos payment as received from PayWiser
        private class POSPaymentCallback
        {
            public string PGReferenceID { get; set; }
            public string CustomerReferenceID { get; set; }
            public int TransactionType { get; set; }
            public int PaymentStatus { get; set; }
            public string PaymentDescription { get; set; }
            public string CardScheme { get; set; }
            public string CardType { get; set; }
            public string TerminalID { get; set; }
            public string TerminalIP { get; set; }
            public string TerminalPort { get; set; }
        }

        // innser callback data for pos refund as received from PayWiser
        private class POSRefundCallback: POSPaymentCallback
        {
        }

        private static HubConnection hubConnection = null;
        private static IHubProxy hubProxy = null;
        private static bool isClosing = false;

        private static string confirmationString = "1234qwertz";

        static void Main(string[] args)
        {
            InitializeConnection();

            Console.Read();
            isClosing = true;
            hubConnection.Stop();
        }

        private static void InitializeConnection()
        {
            if (hubConnection != null)
                hubConnection.Closed -= OnDisconnected;

            var querystringData = new Dictionary<string, string>();
            // for getting all transactions callbacks, specify just ApiKey
            querystringData.Add("ApiKey", "TestMerchant-26365011-38a3-40ff-9ecb-57582a28098b");
            // for getting just one payment callback, specify PGReferenceID as well
            querystringData.Add("PGReferenceID", "d7bceab3-b1f9-4d97-af5c-eb18863c1134");

            hubConnection = new HubConnection("https://gateway.paywiser.eu:8094/", querystringData);
            hubConnection.Error += ex => Console.WriteLine("SignalR error: {0}", ex.Message);
            hubConnection.Closed += OnDisconnected;

            hubProxy = hubConnection.CreateHubProxy("pOSPaymentsSignal");

            hubProxy.On<string>("PGPOSPaymentMessage", (paymentData) =>
            {
                // deserialize data
                Callback callback = JsonConvert.DeserializeObject<Callback>(paymentData);
                
                // deserialize inner callback data
                if (callback.Type.Equals("pos_payment"))
                {
                    POSPaymentCallback posPayment = JsonConvert.DeserializeObject<POSPaymentCallback>(callback.Data);
                    // your logic goes here
                }
                else if (callback.Type.Equals("pos_refund"))
                {
                    POSRefundCallback posRefund = JsonConvert.DeserializeObject<POSRefundCallback>(callback.Data);
                    // your logic goes here
                }

                // calculate HMAC
                string calculatedHMAC = CalculateHMAC(callback.Data, confirmationString);

                Console.WriteLine("Message: "+paymentData);
                Console.WriteLine("HMAC from data: " + callback.HMAC);
                Console.WriteLine("HMAC calculated: " + calculatedHMAC);
                Console.WriteLine("");
            });

            ConnectWithRetry();
        }

        static void OnDisconnected()
        {
            Console.WriteLine("Disconnected");
            if (!isClosing)
                InitializeConnection();
        }

        private static void ConnectWithRetry()
        {
            hubConnection.Start().ContinueWith(task => {
                if (task.IsFaulted)
                {
                    Console.WriteLine("There was an error opening the connection:{0}", task.Exception.GetBaseException());
                }
                else
                {
                    Console.WriteLine("Connected");
                }

            }).Wait();
        }

        private static string CalculateHMAC(string payload, string confirmationSequence)
        {
            if (String.IsNullOrWhiteSpace(payload) || String.IsNullOrWhiteSpace(confirmationSequence))
                return "";

            var data = Encoding.UTF8.GetBytes(payload);
            var key = Encoding.UTF8.GetBytes(confirmationSequence);

            // Create HMAC-MD5 Algorithm;
            var hmac = new HMACMD5(key);

            // Compute hash.
            var hashBytes = hmac.ComputeHash(data);

            // Convert to HEX string.
            return System.BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
        }
    }
}