using System;
using System.Threading.Tasks;
using RabbitMQ.Client.Framing;
using Tapeti.Config;
using Tapeti.Helpers;

namespace Tapeti.Default
{
    public class PublishResultBinding : IBindingMiddleware
    {
        public void Handle(IBindingContext context, Action next)
        {
            next();

            if (context.Result.HasHandler)
                return;

            bool isTask;
            if (context.Result.Info.ParameterType.IsTypeOrTaskOf(t => t.IsClass, out isTask))
            {
                if (isTask)
                {
                    context.Result.SetHandler(async (messageContext, value) =>
                    {
                        var message = await (Task<object>)value;
                        if (message != null)
                            await Reply(message, messageContext);
                    });
                }
                else
                    context.Result.SetHandler((messageContext, value) => 
                        value == null ? null : Reply(value, messageContext));
            }
        }


        private Task Reply(object message, IMessageContext messageContext)
        {
            var publisher = (IInternalPublisher)messageContext.DependencyResolver.Resolve<IPublisher>();
            var properties = new BasicProperties();

            // Only set the property if it's not null, otherwise a string reference exception can occur:
            // http://rabbitmq.1065348.n5.nabble.com/SocketException-when-invoking-model-BasicPublish-td36330.html
            if (messageContext.Properties.IsCorrelationIdPresent())
                properties.CorrelationId = messageContext.Properties.CorrelationId;

            if (messageContext.Properties.IsReplyToPresent())
                return publisher.PublishDirect(message, messageContext.Properties.ReplyTo, properties);

            return publisher.Publish(message, properties);
        }
    }
}