Support subscribing to unmapped events on App and Tray modules

`Electron.App.On("eventName", () => {});` or `Electron.App.On("eventName", obj => {});`

fix #527

ElectronNET.API/App.cs

@@ -1608,5 +1608,35 @@ namespace ElectronNET.API
         }
 
         private bool _preventQuit = false;
+
+        private const string ModuleName = "app";
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="App"/> module.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void On(string eventName, Action fn)
+            => Events.Instance.On(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="App"/> module.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void On(string eventName, Action<object> fn)
+            => Events.Instance.On(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="App"/> module once.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void Once(string eventName, Action fn)
+            => Events.Instance.Once(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="App"/> module once.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void Once(string eventName, Action<object> fn)
+            => Events.Instance.Once(ModuleName, eventName, fn);
     }
 }

ElectronNET.API/Events.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Globalization;
+using Quobject.EngineIoClientDotNet.ComponentEmitter;
+
+namespace ElectronNET.API
+{
+    /// <summary>
+    /// Generic Event Consumers for Electron Modules
+    /// </summary>
+    internal class Events
+    {
+        private static Events _events;
+        private static object _syncRoot = new object();
+        private TextInfo _ti = new CultureInfo("en-US", false).TextInfo;
+        private Events()
+        {
+
+        }
+
+        public static Events Instance
+        {
+            get
+            {
+                if (_events == null)
+                {
+                    lock (_syncRoot)
+                    {
+                        if (_events == null)
+                        {
+                            _events = new Events();
+                        }
+                    }
+                }
+
+                return _events;
+            }
+        }
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        public void On(string moduleName, string eventName, Action fn)
+            => On(moduleName, eventName, new ListenerImpl(fn));
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        public void On(string moduleName, string eventName, Action<object> fn)
+            => On(moduleName, eventName, new ListenerImpl(fn));
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        private void On(string moduleName, string eventName, IListener fn)
+        {
+            var listener = $"{moduleName}{_ti.ToTitleCase(eventName)}Completed";
+            var subscriber = $"register-{moduleName}-on-event";
+            
+            BridgeConnector.Socket.On(listener, fn);
+            BridgeConnector.Socket.Emit(subscriber, eventName, listener);
+        }
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        public void Once(string moduleName, string eventName, Action fn)
+            => Once(moduleName, eventName, new ListenerImpl(fn));
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        public void Once(string moduleName, string eventName, Action<object> fn)
+            => Once(moduleName, eventName, new ListenerImpl(fn));
+
+        /// <summary>
+        /// Subscribe to an unmapped electron event.
+        /// </summary>
+        /// <param name="moduleName">The name of the module, e.g. app, dock, etc...</param>
+        /// <param name="eventName">The name of the event</param>
+        /// <param name="fn">The event handler</param>
+        private void Once(string moduleName, string eventName, IListener fn)
+        {
+            var listener = $"{moduleName}{_ti.ToTitleCase(eventName)}Completed";
+            var subscriber = $"register-{moduleName}-once-event";
+            BridgeConnector.Socket.Once(listener, fn);
+            BridgeConnector.Socket.Emit(subscriber, eventName, listener);
+        }
+
+    }
+}

ElectronNET.API/Tray.cs

@@ -351,5 +351,35 @@ namespace ElectronNET.API
             ContractResolver = new CamelCasePropertyNamesContractResolver(),
             NullValueHandling = NullValueHandling.Ignore
         };
+
+        private const string ModuleName = "tray";
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="Tray"/> module.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void On(string eventName, Action fn)
+            => Events.Instance.On(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="Tray"/> module.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void On(string eventName, Action<object> fn)
+            => Events.Instance.On(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="Tray"/> module once.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void Once(string eventName, Action fn)
+            => Events.Instance.Once(ModuleName, eventName, fn);
+        /// <summary>
+        /// Subscribe to an unmapped event on the <see cref="Tray"/> module once.
+        /// </summary>
+        /// <param name="eventName">The event name</param>
+        /// <param name="fn">The handler</param>
+        public void Once(string eventName, Action<object> fn)
+            => Events.Instance.Once(ModuleName, eventName, fn);
     }
 }