Merge Domain Event Dispatcher with Command and Query Dispatcher

src/Monolith/ClassifiedAds.Application/ApplicationServicesExtensions.cs

@@ -5,7 +5,6 @@
 using ClassifiedAds.Application.SmsMessages.Services;
 using ClassifiedAds.Application.Users.Services;
 using ClassifiedAds.Domain.Entities;
-using ClassifiedAds.Domain.Events;
 using System;
 using System.Linq;
 using System.Reflection;
@@ -16,11 +15,7 @@ public static class ApplicationServicesExtensions
 {
     public static IServiceCollection AddApplicationServices(this IServiceCollection services, Action<Type, Type, ServiceLifetime> configureInterceptor = null)
     {
-        DomainEvents.RegisterHandlers(Assembly.GetExecutingAssembly(), services);
-
-        services
-            .AddScoped<IDomainEvents, DomainEvents>()
-            .AddScoped(typeof(ICrudService<>), typeof(CrudService<>))
+        services.AddScoped(typeof(ICrudService<>), typeof(CrudService<>))
             .AddScoped<IUserService, UserService>()
             .AddScoped<IProductService, ProductService>()
             .AddScoped<EmailMessageService>()
@@ -46,7 +41,9 @@ public static IServiceCollection AddMessageHandlers(this IServiceCollection serv
     {
         services.AddScoped<Dispatcher>();
 
-        var assemblyTypes = Assembly.GetExecutingAssembly().GetTypes();
+        var assembly = Assembly.GetExecutingAssembly();
+
+        var assemblyTypes = assembly.GetTypes();
 
         foreach (var type in assemblyTypes)
         {
@@ -91,6 +88,8 @@ public static IServiceCollection AddMessageHandlers(this IServiceCollection serv
             }
         }
 
+        Dispatcher.RegisterEventHandlers(assembly, services);
+
         return services;
     }
 }

src/Monolith/ClassifiedAds.Application/Common/Dispatcher.cs

@@ -1,4 +1,9 @@
-using System;
+using ClassifiedAds.Domain.Events;
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -8,6 +13,22 @@ public class Dispatcher
 {
     private readonly IServiceProvider _provider;
 
+    private static List<Type> _eventHandlers = new List<Type>();
+
+    public static void RegisterEventHandlers(Assembly assembly, IServiceCollection services)
+    {
+        var types = assembly.GetTypes()
+                            .Where(x => x.GetInterfaces().Any(y => y.IsGenericType && y.GetGenericTypeDefinition() == typeof(IDomainEventHandler<>)))
+                            .ToList();
+
+        foreach (var type in types)
+        {
+            services.AddTransient(type);
+        }
+
+        _eventHandlers.AddRange(types);
+    }
+
     public Dispatcher(IServiceProvider provider)
     {
         _provider = provider;
@@ -34,4 +55,21 @@ public async Task<T> DispatchAsync<T>(IQuery<T> query, CancellationToken cancell
 
         return await result;
     }
+
+    public async Task DispatchAsync(IDomainEvent domainEvent, CancellationToken cancellationToken = default)
+    {
+        foreach (Type handlerType in _eventHandlers)
+        {
+            bool canHandleEvent = handlerType.GetInterfaces()
+                .Any(x => x.IsGenericType
+                    && x.GetGenericTypeDefinition() == typeof(IDomainEventHandler<>)
+                    && x.GenericTypeArguments[0] == domainEvent.GetType());
+
+            if (canHandleEvent)
+            {
+                dynamic handler = _provider.GetService(handlerType);
+                await handler.HandleAsync((dynamic)domainEvent, cancellationToken);
+            }
+        }
+    }
 }

src/Monolith/ClassifiedAds.Application/Common/Services/CrudService.cs

@@ -15,13 +15,13 @@ public class CrudService<T> : ICrudService<T>
 {
     private readonly IUnitOfWork _unitOfWork;
     protected readonly IRepository<T, Guid> _repository;
-    private readonly IDomainEvents _domainEvents;
+    protected readonly Dispatcher _dispatcher;
 
-    public CrudService(IRepository<T, Guid> repository, IDomainEvents domainEvents)
+    public CrudService(IRepository<T, Guid> repository, Dispatcher dispatcher)
     {
         _unitOfWork = repository.UnitOfWork;
         _repository = repository;
-        _domainEvents = domainEvents;
+        _dispatcher = dispatcher;
     }
 
     public Task<List<T>> GetAsync(CancellationToken cancellationToken = default)
@@ -51,20 +51,20 @@ public async Task AddAsync(T entity, CancellationToken cancellationToken = defau
     {
         await _repository.AddAsync(entity, cancellationToken);
         await _unitOfWork.SaveChangesAsync(cancellationToken);
-        await _domainEvents.DispatchAsync(new EntityCreatedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
+        await _dispatcher.DispatchAsync(new EntityCreatedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
     }
 
     public async Task UpdateAsync(T entity, CancellationToken cancellationToken = default)
     {
         await _repository.UpdateAsync(entity, cancellationToken);
         await _unitOfWork.SaveChangesAsync(cancellationToken);
-        await _domainEvents.DispatchAsync(new EntityUpdatedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
+        await _dispatcher.DispatchAsync(new EntityUpdatedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
     }
 
     public async Task DeleteAsync(T entity, CancellationToken cancellationToken = default)
     {
         _repository.Delete(entity);
         await _unitOfWork.SaveChangesAsync(cancellationToken);
-        await _domainEvents.DispatchAsync(new EntityDeletedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
+        await _dispatcher.DispatchAsync(new EntityDeletedEvent<T>(entity, DateTime.UtcNow), cancellationToken);
     }
 }

src/Monolith/ClassifiedAds.Application/Products/Services/ProductService.cs

@@ -1,5 +1,4 @@
 using ClassifiedAds.Domain.Entities;
-using ClassifiedAds.Domain.Events;
 using ClassifiedAds.Domain.Identity;
 using ClassifiedAds.Domain.Repositories;
 using System;
@@ -8,8 +7,8 @@ namespace ClassifiedAds.Application.Products.Services;
 
 public class ProductService : CrudService<Product>, IProductService
 {
-    public ProductService(IRepository<Product, Guid> productRepository, IDomainEvents domainEvents, ICurrentUser currentUser)
-        : base(productRepository, domainEvents)
+    public ProductService(IRepository<Product, Guid> productRepository, Dispatcher dispatcher, ICurrentUser currentUser)
+        : base(productRepository, dispatcher)
     {
     }
 }

src/Monolith/ClassifiedAds.Application/Users/Services/UserService.cs

@@ -1,14 +1,13 @@
 using ClassifiedAds.Domain.Entities;
-using ClassifiedAds.Domain.Events;
 using ClassifiedAds.Domain.Repositories;
 using System;
 
 namespace ClassifiedAds.Application.Users.Services;
 
 public class UserService : CrudService<User>, IUserService
 {
-    public UserService(IRepository<User, Guid> userRepository, IDomainEvents domainEvents)
-        : base(userRepository, domainEvents)
+    public UserService(IRepository<User, Guid> userRepository, Dispatcher dispatcher)
+        : base(userRepository, dispatcher)
     {
     }
 }

src/Monolith/ClassifiedAds.BackgroundServer/Program.cs

@@ -48,7 +48,8 @@ public static void Main(string[] args)
             services.AddDateTimeProvider();
             services.AddPersistence(appSettings.ConnectionStrings.ClassifiedAds)
                     .AddDomainServices()
-                    .AddApplicationServices();
+                    .AddApplicationServices()
+                    .AddMessageHandlers();
 
             services.AddMessageBusSender<FileUploadedEvent>(appSettings.MessageBroker);
             services.AddMessageBusSender<FileDeletedEvent>(appSettings.MessageBroker);

src/Monolith/ClassifiedAds.UnitTests/Application/Services/UserServiceTests.cs

@@ -1,7 +1,7 @@
+using ClassifiedAds.Application;
 using ClassifiedAds.Application.Users.Services;
 using ClassifiedAds.CrossCuttingConcerns.Exceptions;
 using ClassifiedAds.Domain.Entities;
-using ClassifiedAds.Domain.Events;
 using ClassifiedAds.Domain.Repositories;
 using Moq;
 using System;
@@ -20,8 +20,9 @@ public class UserServiceTests
     public UserServiceTests()
     {
         _userRepository = new Mock<IRepository<User, Guid>>();
-        var domainEvents = new Mock<IDomainEvents>();
-        _userService = new UserService(_userRepository.Object, domainEvents.Object);
+        var serviceProvider = new Mock<IServiceProvider>();
+        var dispatcher = new Dispatcher(serviceProvider.Object);
+        _userService = new UserService(_userRepository.Object, dispatcher);
     }
 
     [Fact]