refactored the code, prepared for adding new players

VsDingExtensionProject/WinApiHelper.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace VitaliiGanzha.VsDingExtension
+{
+    public static class WinApiHelper
+    {
+        [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
+        private static extern IntPtr GetForegroundWindow();
+
+        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
+        private static extern int GetWindowThreadProcessId(IntPtr handle, out int processId);
+
+        public static bool ApplicationIsActivated()
+        {
+            var activatedHandle = GetForegroundWindow();
+            if (activatedHandle == IntPtr.Zero)
+            {
+                return false;       // No window is currently activated
+            }
+            var procId = Process.GetCurrentProcess().Id;
+            int activeProcId;
+            GetWindowThreadProcessId(activatedHandle, out activeProcId);
+            return activeProcId == procId;
+        }
+    }
+}