using Newtonsoft.Json;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

public class Program

{

    static async Task Main(string[] args)

        {

            var _subscriptionsManager = new RequestReplyBusSubscriptionsManager();

            _subscriptionsManager.AddSubscription<ReplyMessageExample, GetElevatorRequest, GetExampeRequestHandler>("get_elevators");

​

            IEnumerable<SubscriptionInfo> subscriptions = _subscriptionsManager.GetSubscriptionsForEvent("get_elevators");

            foreach (var subscription in subscriptions)

            {

                var handler = new GetExampeRequestHandler();

                Type concreteType = typeof(IRequestMessageHandler<,>).MakeGenericType(subscription.RequestType, subscription.ReplyType);

                object integrationEvent = JsonConvert.DeserializeObject("{\"equipmentNumber\":\"AT9512CA\"}", subscription.RequestType);

​

                Type concreteType2 = typeof(Task<>).MakeGenericType(subscription.ReplyType);

​

                var reply = await (Task<dynamic>)concreteType.GetMethod("Handle")?.Invoke(handler, new[] { integrationEvent });

            }

​

            Console.WriteLine("Done");

        }

    public class GetElevatorRequest

    {

        public string EquipmentNumber { get; set; }

    }

​

    public interface IReplyMessage

    {

    }

​

    public class ReplyMessageExample : IReplyMessage

    {

        public string EquipmentNumber { get; set; }

        public bool Connected { get; set; }

    }

​

    public class GetExampeRequestHandler : IRequestMessageHandler<GetElevatorRequest, ReplyMessageExample>

    {

        public Task<ReplyMessageExample> Handle(GetElevatorRequest request)

        {

            Console.WriteLine("Processing request for elevator");

​

            var reply = new ReplyMessageExample

            {

                EquipmentNumber = request.EquipmentNumber,

                Connected = new Random().Next() % 2 == 0

            };

​

            return Task.FromResult(reply);

        }

    }

​

    public interface IRequestMessageHandler<in TRequest, TReply>

    {

        Task<TReply> Handle(TRequest request);

    }

​

    public sealed class RequestReplyBusSubscriptionsManager

    {

        private readonly Dictionary<string, List<SubscriptionInfo>> _subscriptions;

​

        public RequestReplyBusSubscriptionsManager()

        {

            _subscriptions = new Dictionary<string, List<SubscriptionInfo>>();

        }

​

        public bool HasSubscriptionsForRequest(string eventType)

        {

            return _subscriptions.ContainsKey(eventType);

        }

​

        public void AddSubscription<TReply, TRequest, TRequestHandler>(string requestName)

            where TReply : class

            where TRequest : class

            where TRequestHandler : IRequestMessageHandler<TRequest, TReply>

        {

            Type handlerType = typeof(TRequestHandler);

            if (!HasSubscriptionsForRequest(requestName))

            {

                _subscriptions.Add(requestName, new List<SubscriptionInfo>());

            }

            else if (_subscriptions[requestName].Any(t => t.HandlerType == handlerType))

            {

                throw new ArgumentException($"Handler Type { handlerType.Name } already registered for '{requestName}' with reply type '{typeof(TReply)}'");

            }

            _subscriptions[requestName].Add(new SubscriptionInfo(typeof(TReply), typeof(TRequest), handlerType));

        }

​

        public IEnumerable<SubscriptionInfo> GetSubscriptionsForEvent(string eventType)

        {

            return _subscriptions[eventType];

        }

    }

​

    public sealed class SubscriptionInfo

    {

        public SubscriptionInfo(Type replyType, Type requestType, Type handlerType)

        {

            ReplyType = replyType;

            RequestType = requestType;

            HandlerType = handlerType;

        }

​

        public Type ReplyType { get; }

        public Type HandlerType { get; }

        public Type RequestType { get; }

    }

}