Added UmbracoBuilderExtensions.AddNotificationsFromAssembly to help all notifications from within an Assembly

src/Umbraco.Core/Extensions/UmbracoBuilderExtensions.cs

@@ -0,0 +1,100 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.DependencyInjection;
+using Umbraco.Cms.Core.DependencyInjection;
+using Umbraco.Cms.Core.Events;
+
+namespace Umbraco.Cms.Core.Extensions
+{
+    public static class UmbracoBuilderExtensions
+    {
+        /// <summary>
+        /// Registers all <see cref="INotificationHandler{TNotification}"/> within an assembly
+        /// </summary>
+        /// <param name="self"><see cref="IUmbracoBuilder"/></param>
+        /// <typeparam name="T">Type contained within the targeted assembly</typeparam>
+        /// <returns></returns>
+        public static IUmbracoBuilder AddNotificationsFromAssembly<T>(this IUmbracoBuilder self)
+        {
+            AddNotificationHandlers<T>(self);
+            AddAsyncNotificationHandlers<T>(self);
+
+            return self;
+        }
+
+        private static void AddNotificationHandlers<T>(IUmbracoBuilder self)
+        {
+            var notificationHandlers = GetNotificationHandlers<T>();
+            foreach (var notificationHandler in notificationHandlers)
+            {
+                var handlerImplementations = GetNotificationHandlerImplementations<T>(notificationHandler);
+                foreach (var implementation in handlerImplementations)
+                {
+                    RegisterNotificationHandler(self, implementation, notificationHandler);
+                }
+            }
+        }
+
+        private static List<Type> GetNotificationHandlers<T>() =>
+            typeof(T).Assembly.GetTypes()
+                .Where(x => x.IsAssignableToGenericType(typeof(INotificationHandler<>)))
+                .ToList();
+
+        private static List<Type> GetNotificationHandlerImplementations<T>(Type handlerType) =>
+            handlerType
+                .GetInterfaces()
+                .Where(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(INotificationHandler<>))
+                .ToList();
+
+        private static void AddAsyncNotificationHandlers<T>(IUmbracoBuilder self)
+        {
+            var notificationHandlers = GetAsyncNotificationHandlers<T>();
+            foreach (var notificationHandler in notificationHandlers)
+            {
+                var handlerImplementations = GetAsyncNotificationHandlerImplementations<T>(notificationHandler);
+                foreach (var handler in handlerImplementations)
+                {
+                    RegisterNotificationHandler(self, handler, notificationHandler);
+                }
+            }
+        }
+
+        private static List<Type> GetAsyncNotificationHandlers<T>() =>
+            typeof(T).Assembly.GetTypes()
+                .Where(x => x.IsAssignableToGenericType(typeof(INotificationAsyncHandler<>)))
+                .ToList();
+
+        private static List<Type> GetAsyncNotificationHandlerImplementations<T>(Type handlerType) =>
+            handlerType
+                .GetInterfaces()
+                .Where(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(INotificationAsyncHandler<>))
+                .ToList();
+
+        private static void RegisterNotificationHandler(IUmbracoBuilder self, Type notificationHandlerType, Type implementingHandlerType)
+        {
+            var descriptor = new UniqueServiceDescriptor(notificationHandlerType, implementingHandlerType, ServiceLifetime.Transient);
+            if (!self.Services.Contains(descriptor))
+            {
+                self.Services.Add(descriptor);
+            }
+        }
+
+        private static bool IsAssignableToGenericType(this Type givenType, Type genericType)
+        {
+            var interfaceTypes = givenType.GetInterfaces();
+
+            foreach (var it in interfaceTypes)
+            {
+                if (it.IsGenericType && it.GetGenericTypeDefinition() == genericType)
+                    return true;
+            }
+
+            if (givenType.IsGenericType && givenType.GetGenericTypeDefinition() == genericType)
+                return true;
+
+            var baseType = givenType.BaseType;
+            return baseType != null && IsAssignableToGenericType(baseType, genericType);
+        }
+    }
+}