IM_NEW/MessageService.WebApi/Application/EventHandlers/MessageHandler.cs

using IM.Commons.IntegrationEvents;
using MassTransit;
using MediatR;
using MessageService.Domain.Events;
using MessageService.Domain.IReposities;
using MessageService.Infrastructure;

namespace MessageService.WebApi.Application.EventHandlers
{
    public class MessageHandler : INotificationHandler<MessageCreatedDomainEvent>, INotificationHandler<MessageWithdrawDomainEvent>
    {
        private readonly IPublishEndpoint endpoint;
        private readonly IConversationReposity reposity;
        private readonly MessageDbContext messageDb;

        public MessageHandler(IPublishEndpoint endpoint, IConversationReposity reposity, MessageDbContext messageDb)
        {
            this.endpoint = endpoint;
            this.reposity = reposity;
            this.messageDb = messageDb;
        }

        public async Task Handle(MessageCreatedDomainEvent notification, CancellationToken cancellationToken)
        {
            var message = notification.Message;

            var conversations = await reposity.FindByStreamKeyAsync(message.StreamKey, cancellationToken);
            foreach (var conversation in conversations)
            {
                conversation.UpdateLastMessage(message.Content.Fallback, message.CreationTime);
                if (conversation.UserId == message.SenderId)
                {
                    conversation.SetLastReadSequence(message.SequenceId);
                }
                else
                {
                    conversation.IncrementUnread();
                }
            }

            messageDb.Conversations.UpdateRange(conversations);
            await messageDb.SaveChangesAsync(cancellationToken);

            await endpoint.Publish(message.ToIntegrationEvent(), cancellationToken);
        }

        public async Task Handle(MessageWithdrawDomainEvent notification, CancellationToken cancellationToken)
        {
            var message = notification.Message;
            await endpoint.Publish(new MsgWithdrawEvent(message.Id, message.State.ToString(), message.StreamKey), cancellationToken);
        }
    }
}