Add Online system base

Source/Engine/Online/Online.h

@@ -0,0 +1,35 @@
+// Copyright (c) 2012-2022 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Core/Delegate.h"
+#include "Engine/Scripting/ScriptingType.h"
+
+class IOnlinePlatform;
+
+/// <summary>
+/// The online system for communicating with various multiplayer services such as player info, achievements, game lobby or in-game store.
+/// </summary>
+API_CLASS(Static, Namespace="FlaxEngine.Online") class FLAXENGINE_API Online
+{
+    DECLARE_SCRIPTING_TYPE_NO_SPAWN(Online);
+public:
+    /// <summary>
+    /// The current online platform.
+    /// </summary>
+    API_FIELD(ReadOnly) static IOnlinePlatform* Platform;
+
+    /// <summary>
+    /// Event called when current online platform gets changed.
+    /// </summary>
+    API_EVENT() static Action PlatformChanged;
+
+public:
+    /// <summary>
+    /// Initializes the online system with a given online platform implementation.
+    /// </summary>
+    /// <remarks>Destroys the current platform (in any already in-use).</remarks>
+    /// <param name="platform">The online platform object.</param>
+    /// <returns>True if failed, otherwise false.</returns>
+    API_FUNCTION() static bool Initialize(IOnlinePlatform* platform);
+};