Add StaticActivityPublisher (experimental)

Notifier/Notifier.csproj

@@ -140,6 +140,8 @@
       <DesignTime>True</DesignTime>
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
+    <Compile Include="UI\Events\ActivityEventArgs.cs" />
+    <Compile Include="UI\Events\StaticActivityPublisher.cs" />
     <Compile Include="UI\Windows\NotifierTrayIcon.cs" />
     <Compile Include="UI\Windows\NotificationWindow.xaml.cs">
       <DependentUpon>NotificationWindow.xaml</DependentUpon>

Notifier/UI/Events/ActivityEventArgs.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Wokhan.WindowsFirewallNotifier.Notifier.Helpers;
+
+namespace Wokhan.WindowsFirewallNotifier.Notifier.UI.Events
+{
+    public class ActivityEventArgs : EventArgs
+    {
+        public ActivityEnum Activity { get; set; }
+
+        public CurrentConn CurrentConnection { get; set; }
+
+        public DateTime TimeStamp { get; } = DateTime.Now;
+
+        public enum ActivityEnum
+        {
+            Allow, Block, AllowTemp, BlockTemp
+        }
+        public ActivityEventArgs(ActivityEnum activity, CurrentConn currentConnection)
+        {
+            Activity = activity;
+            CurrentConnection = currentConnection;
+        }
+    }
+}

Notifier/UI/Events/StaticActivityPublisher.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Wokhan.WindowsFirewallNotifier.Notifier.Helpers;
+
+namespace Wokhan.WindowsFirewallNotifier.Notifier.UI.Events
+{
+    public interface IActivitySender
+    {
+        string Name { get; set; }
+    }
+
+    /*
+     * Static activity event publisher.
+     * See:
+     * https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/events/how-to-publish-events-that-conform-to-net-framework-guidelines
+     */
+    public static class StaticActivityPublisher
+    {
+        public delegate void ActivityEventHandler<TActivityEventArgs>(IActivitySender sender, ActivityEventArgs args);
+
+        public static event ActivityEventHandler<ActivityEventArgs> ActivityEvent;
+
+        public static void Publish(IActivitySender sender, ActivityEventArgs.ActivityEnum activity, CurrentConn currentConnection)
+        {
+            ActivityEventArgs args = new ActivityEventArgs(activity, currentConnection);
+            OnRaiseActivityEvent(sender, args);
+        }
+
+        public static void Subscribe(ActivityEventHandler<ActivityEventArgs> eventHandler)
+        {
+            ActivityEvent += eventHandler;
+        }
+
+        // Wrap event invocations inside a protected virtual method
+        // to allow derived classes to override the event invocation behavior
+        private static void OnRaiseActivityEvent(IActivitySender sender, ActivityEventArgs args)
+        {
+            //// Make a temporary copy of the event to avoid possibility of
+            //// a race condition if the last subscriber unsubscribes
+            //// immediately after the null check and before the event is raised.
+            //EventHandler<ActivityEventArgs> handler = RaiseActivityEvent;
+
+            //// Event will be null if there are no subscribers
+            //if (handler != null)
+            //{
+            //    //// Format the string to send inside the CustomEventArgs parameter
+            //    //e.Message += $" at {DateTime.Now}";
+
+            //    // Use the () operator to raise the event.
+            //    handler(sender, e);
+            //}
+            ActivityEvent?.Invoke(sender, args);
+        }
+    }
+}