messengerapi.QueryClient/code/MessengerApi.QueryClient/QueryClient.cs

using portaloggy;
using MessengerApi.Model.Messages;
using MessengerApi.Model;

namespace MessengerApi
{
    public interface IQueryClient : IDisposable
    {
        Task<InboxMessage> Query(OutboxMessage message);
    }

    public class QueryClient : SubscriptionClient, IQueryClient
    {
        private readonly int _timeoutInSeconds;

        public QueryClient(
            Credentials credentials,
            HttpClient httpClient = null, 
            ILogger logger = null,
            int maximumPermittedWaitTimeInSeconds = 10) :base(credentials, httpClient, logger)
        {
            this._timeoutInSeconds = maximumPermittedWaitTimeInSeconds;
        }

        public async Task<InboxMessage> Query(OutboxMessage message)
        {
            try
            {
                var messageTypeMask = $"{message.PayloadType}-{Guid.NewGuid()}";
                var maskedMessage = new OutboxMessage
                {
                    Payload = message.Payload,
                    LifespanInSeconds = message.LifespanInSeconds,
                    PayloadType = messageTypeMask,
                    ToUserId = message.ToUserId
                };
                
                var cts = new CancellationTokenSource(TimeSpan.FromSeconds(this._timeoutInSeconds));
                var sub = this.Subscribe(messageTypeMask);
                var result = (InboxMessage)null;

                sub.OnMessage += (source, message) =>
                {
                    result = message;
                    cts.Cancel();
                };

                this.SendMessage(maskedMessage);

                while (!cts.IsCancellationRequested)
                {
                    await Task.Delay(TimeSpan.FromSeconds(1));
                }

                this.Unsubscribe(sub);

                if (result == null)
                {
                    throw new InvalidOperationException("Couldn't retrieve response.");
                }

                result.PayloadType = message.PayloadType;
                return result;
            }
            catch
            {
                throw;
            }
        }
    }
}