Introduce INotificationHandler

BTCPayServer/Controllers/NotificationsController.cs

@@ -27,13 +27,19 @@ namespace BTCPayServer.Controllers
         private readonly ApplicationDbContext _db;
         private readonly NotificationSender _notificationSender;
         private readonly UserManager<ApplicationUser> _userManager;
+        private readonly NotificationManager _notificationManager;
 
-        public NotificationsController(BTCPayServerEnvironment env, ApplicationDbContext db, NotificationSender notificationSender, UserManager<ApplicationUser> userManager)
+        public NotificationsController(BTCPayServerEnvironment env,
+            ApplicationDbContext db,
+            NotificationSender notificationSender,
+            UserManager<ApplicationUser> userManager,
+            NotificationManager notificationManager)
         {
             _env = env;
             _db = db;
             _notificationSender = notificationSender;
             _userManager = userManager;
+            _notificationManager = notificationManager;
         }
 
         [HttpGet]
@@ -50,7 +56,7 @@ namespace BTCPayServer.Controllers
                     .OrderByDescending(a => a.Created)
                     .Skip(skip).Take(count)
                     .Where(a => a.ApplicationUserId == userId)
-                    .Select(a => a.ToViewModel())
+                    .Select(a => _notificationManager.ToViewModel(a))
                     .ToList(),
                 Total = _db.Notifications.Where(a => a.ApplicationUserId == userId).Count()
             };

BTCPayServer/Hosting/BTCPayServerServices.cs

@@ -47,6 +47,7 @@ using Serilog;
 using BTCPayServer.Security.GreenField;
 using BTCPayServer.Services.Labels;
 using BTCPayServer.Services.Notifications;
+using BTCPayServer.Services.Notifications.Blobs;
 
 namespace BTCPayServer.Hosting
 {
@@ -220,6 +221,7 @@ namespace BTCPayServer.Hosting
             services.AddSingleton<IBackgroundJobClient, BackgroundJobClient>();
             services.AddScoped<IAuthorizationHandler, CookieAuthorizationHandler>();
             services.AddScoped<IAuthorizationHandler, BitpayAuthorizationHandler>();
+            services.AddSingleton<INotificationHandler, NewVersionNotification.Handler>();
 
             services.TryAddSingleton<ExplorerClientProvider>();
             services.TryAddSingleton<Bitpay>(o =>

BTCPayServer/Models/NotificationViewModels/IndexViewModel.cs

@@ -27,31 +27,4 @@ namespace BTCPayServer.Models.NotificationViewModels
         public string ActionLink { get; set; }
         public bool Seen { get; set; }
     }
-
-    public static class NotificationViewModelExt
-    {
-        static Dictionary<string, Type> _NotificationTypes;
-        static NotificationViewModelExt()
-        {
-            _NotificationTypes = Assembly.GetExecutingAssembly()
-                    .GetTypes()
-                    .Select(t => (t, NotificationType: t.GetCustomAttribute<NotificationAttribute>()?.NotificationType))
-                    .Where(t => t.NotificationType is string)
-                    .ToDictionary(o => o.NotificationType, o => o.t);
-        }
-
-        public static NotificationViewModel ToViewModel(this NotificationData data)
-        {
-            var casted = (BaseNotification)JsonConvert.DeserializeObject(ZipUtils.Unzip(data.Blob), _NotificationTypes[data.NotificationType]);
-            var obj = new NotificationViewModel
-            {
-                Id = data.Id,
-                Created = data.Created,
-                Seen = data.Seen
-            };
-            casted.FillViewModel(obj);
-
-            return obj;
-        }
-    }
 }

BTCPayServer/Services/Notifications/Blobs/BaseNotification.cs

@@ -1,15 +0,0 @@
-using System;
-using BTCPayServer.Data;
-using BTCPayServer.Models.NotificationViewModels;
-using Newtonsoft.Json;
-
-namespace BTCPayServer.Services.Notifications.Blobs
-{
-    // Make sure to keep all Blob Notification classes in same namespace
-    // because of dependent initialization and parsing to view models logic
-    // IndexViewModel.cs#32
-    public abstract class BaseNotification
-    {
-        public abstract void FillViewModel(NotificationViewModel data);
-    }
-}

BTCPayServer/Services/Notifications/Blobs/NewVersionNotification.cs

@@ -4,9 +4,17 @@ using Newtonsoft.Json;
 
 namespace BTCPayServer.Services.Notifications.Blobs
 {
-    [Notification("newversion")]
+    internal class NewVersionNotification
-    internal class NewVersionNotification : BaseNotification
     {
+        internal class Handler : NotificationHandler<NewVersionNotification>
+        {
+            public override string NotificationType => "newversion";
+            protected override void FillViewModel(NewVersionNotification notification, NotificationViewModel vm)
+            {
+                vm.Body = $"New version {notification.Version} released!";
+                vm.ActionLink = $"https://github.com/btcpayserver/btcpayserver/releases/tag/v{notification.Version}";
+            }
+        }
         public NewVersionNotification()
         {
 
@@ -16,11 +24,5 @@ namespace BTCPayServer.Services.Notifications.Blobs
             Version = version;
         }
         public string Version { get; set; }
-
-        public override void FillViewModel(NotificationViewModel vm)
-        {
-            vm.Body = $"New version {Version} released!";
-            vm.ActionLink = $"https://github.com/btcpayserver/btcpayserver/releases/tag/v{Version}";
-        }
     }
 }

BTCPayServer/Services/Notifications/Blobs/NotificationAttribute.cs

@@ -1,17 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-
-namespace BTCPayServer.Services.Notifications.Blobs
-{
-    [AttributeUsage(AttributeTargets.Class)]
-    public class NotificationAttribute : Attribute
-    {
-        public NotificationAttribute(string notificationType)
-        {
-            NotificationType = notificationType;
-        }
-        public string NotificationType { get; }
-    }
-}

BTCPayServer/Services/Notifications/INotificationHandler.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using BTCPayServer.Models.NotificationViewModels;
+
+namespace BTCPayServer.Services.Notifications
+{
+    public interface INotificationHandler
+    {
+        string NotificationType { get; }
+        Type NotificationBlobType { get; }
+        void FillViewModel(object notification, NotificationViewModel vm);
+    }
+    public abstract class NotificationHandler<TNotification> : INotificationHandler
+    {
+        public abstract string NotificationType { get; }
+        Type INotificationHandler.NotificationBlobType => typeof(TNotification);
+        void INotificationHandler.FillViewModel(object notification, NotificationViewModel vm)
+        {
+            FillViewModel((TNotification)notification, vm);
+        }
+        protected abstract void FillViewModel(TNotification notification, NotificationViewModel vm);
+    }
+}

BTCPayServer/Services/Notifications/NotificationManager.cs

@@ -6,8 +6,10 @@ using System.Text;
 using System.Threading.Tasks;
 using BTCPayServer.Data;
 using BTCPayServer.Models.NotificationViewModels;
+using Google.Apis.Storage.v1.Data;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.Extensions.Caching.Memory;
+using Newtonsoft.Json;
 
 namespace BTCPayServer.Services.Notifications
 {
@@ -16,12 +18,16 @@ namespace BTCPayServer.Services.Notifications
         private readonly ApplicationDbContextFactory _factory;
         private readonly UserManager<ApplicationUser> _userManager;
         private readonly IMemoryCache _memoryCache;
+        private readonly Dictionary<string, INotificationHandler> _handlersByNotificationType;
+        private readonly Dictionary<Type, INotificationHandler> _handlersByBlobType;
 
-        public NotificationManager(ApplicationDbContextFactory factory, UserManager<ApplicationUser> userManager, IMemoryCache memoryCache)
+        public NotificationManager(ApplicationDbContextFactory factory, UserManager<ApplicationUser> userManager, IMemoryCache memoryCache, IEnumerable<INotificationHandler> handlers)
         {
             _factory = factory;
             _userManager = userManager;
             _memoryCache = memoryCache;
+            _handlersByNotificationType = handlers.ToDictionary(h => h.NotificationType);
+            _handlersByBlobType = handlers.ToDictionary(h => h.NotificationBlobType);
         }
 
         private const int _cacheExpiryMs = 5000;
@@ -55,7 +61,7 @@ namespace BTCPayServer.Services.Notifications
                             .Where(a => a.ApplicationUserId == userId && !a.Seen)
                             .OrderByDescending(a => a.Created)
                             .Take(5)
-                            .Select(a => a.ToViewModel())
+                            .Select(a => ToViewModel(a))
                             .ToList();
                     }
                     catch (System.IO.InvalidDataException)
@@ -77,6 +83,33 @@ namespace BTCPayServer.Services.Notifications
 
             return resp;
         }
+
+        public NotificationViewModel ToViewModel(NotificationData data)
+        {
+            var handler = GetHandler(data.NotificationType);
+            var notification = JsonConvert.DeserializeObject(ZipUtils.Unzip(data.Blob), handler.NotificationBlobType);
+            var obj = new NotificationViewModel
+            {
+                Id = data.Id,
+                Created = data.Created,
+                Seen = data.Seen
+            };
+            handler.FillViewModel(notification, obj);
+            return obj;
+        }
+
+        public INotificationHandler GetHandler(string notificationId)
+        {
+            if (_handlersByNotificationType.TryGetValue(notificationId, out var h))
+                return h;
+            throw new InvalidOperationException($"No INotificationHandler found for {notificationId}");
+        }
+        public INotificationHandler GetHandler(Type blobType)
+        {
+            if (_handlersByBlobType.TryGetValue(blobType, out var h))
+                return h;
+            throw new InvalidOperationException($"No INotificationHandler found for {blobType.Name}");
+        }
     }
 
     public class NotificationSummaryViewModel

BTCPayServer/Services/Notifications/NotificationSender.cs

@@ -16,15 +16,17 @@ namespace BTCPayServer.Services.Notifications
         private readonly ApplicationDbContextFactory _contextFactory;
         private readonly UserManager<ApplicationUser> _userManager;
         private readonly EventAggregator _eventAggregator;
+        private readonly NotificationManager _notificationManager;
 
-        public NotificationSender(ApplicationDbContextFactory contextFactory, UserManager<ApplicationUser> userManager, EventAggregator eventAggregator)
+        public NotificationSender(ApplicationDbContextFactory contextFactory, UserManager<ApplicationUser> userManager, EventAggregator eventAggregator, NotificationManager notificationManager)
         {
             _contextFactory = contextFactory;
             _userManager = userManager;
             _eventAggregator = eventAggregator;
+            _notificationManager = notificationManager;
         }
 
-        public async Task SendNotification(NotificationScope scope, BaseNotification notification)
+        public async Task SendNotification(NotificationScope scope, object notification)
         {
             if (scope == null)
                 throw new ArgumentNullException(nameof(scope));
@@ -41,25 +43,16 @@ namespace BTCPayServer.Services.Notifications
                         Id = Guid.NewGuid().ToString(),
                         Created = DateTimeOffset.UtcNow,
                         ApplicationUserId = uid,
-                        NotificationType = GetNotificationTypeString(notification.GetType()),
+                        NotificationType = _notificationManager.GetHandler(notification.GetType()).NotificationType,
                         Blob = ZipUtils.Zip(obj),
                         Seen = false
                     };
                     db.Notifications.Add(data);
                 }
-
                 await db.SaveChangesAsync();
             }
         }
 
-        private string GetNotificationTypeString(Type type)
-        {
-            var str =  type.GetCustomAttribute<NotificationAttribute>()?.NotificationType;
-            if (str is null)
-                throw new NotSupportedException($"{type} is not a notification");
-            return str;
-        }
-
         private async Task<string[]> GetUsers(NotificationScope scope)
         {
             if (scope is AdminScope)