RobustToolbox side of Redial API. (#2804)

* RobustToolbox side of Redial API.

Please be aware that as far as I know testing this code is nigh-impossible until it ships.

* a smidge of paranoia

* paranoia on the paranoia please

Robust.Client/GameController/GameController.Redialler.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Threading;
+using Robust.LoaderApi;
+using Robust.Shared;
+using Robust.Shared.IoC;
+using Robust.Shared.Log;
+using Robust.Shared.Timing;
+using Robust.Shared.Utility;
+
+namespace Robust.Client;
+
+internal partial class GameController
+{
+    // A little paranoia goes a long way.
+    // This is static on purpose - the whole process shouldn't redial more than once, ever.
+    private static int _hasRedialled = 0;
+
+    public void Redial(string address, string? text = null)
+    {
+        // -- ATTENTION, YE WOULD-BE TRESPASSERS! --
+        // This code is the least testable code ever (because it's in-engine code that requires the Launcher), so don't make it do too much.
+        // This checks for some obvious requirements and then forwards to RedialApi which does the actual work.
+        // Testing of RedialApi is doable in the SS14.Launcher project, this is why it has a fake RobustToolbox build.
+        // -- THANK YE, NOW KINDLY MOVE ALONG! --
+
+        // We don't ever want to successfully redial more than once, and we want to shutdown once we've redialled.
+        // Otherwise abuse could happen.
+        DebugTools.AssertNotNull(_mainLoop);
+
+        Logger.Info($"Attempting redial of {address}: {text ?? "no reason given"}");
+
+        if (!_mainLoop!.Running)
+        {
+            throw new Exception("Attempted a redial during shutdown, this is not acceptable - redial first and if you succeed it'll shutdown anyway.");
+        }
+
+        if (_loaderArgs == null)
+        {
+            throw new Exception("Attempted a redial when the game was not run from the launcher (_loaderArgs == null)");
+        }
+
+        if (_loaderArgs!.RedialApi == null)
+        {
+            throw new Exception("Attempted a redial when redialling was not supported by the loader (Outdated launcher?)");
+        }
+
+        if (Interlocked.Increment(ref _hasRedialled) != 1)
+        {
+            // Don't let it overflow or anything
+            Interlocked.Decrement(ref _hasRedialled);
+            throw new Exception("Attempted a redial after one already succeeded or while one is in progress, this is never acceptable");
+        }
+
+        try
+        {
+            _loaderArgs!.RedialApi!.Redial(new Uri(address), text ?? "");
+        }
+        catch (Exception ex)
+        {
+            Interlocked.Decrement(ref _hasRedialled);
+            throw ex;
+        }
+
+        Shutdown("Redial");
+    }
+}
+

Robust.Client/IGameController.cs

@@ -1,9 +1,19 @@
-namespace Robust.Client
-{
-    public interface IGameController
-    {
-        InitialLaunchState LaunchState { get; }
+namespace Robust.Client;
+
+public interface IGameController
+{
+    InitialLaunchState LaunchState { get; }
+
+    void Shutdown(string? reason=null);
+
+    /// <summary>
+    ///     Try to cause the launcher to either reconnect to the same server or connect to a new server.
+    ///     *The engine will shutdown on success.*
+    ///     Will throw an exception if contacting the launcher failed (success indicates it is now the launcher's responsibility).
+    ///     To redial the same server, retrieve the server's address from `LaunchState.Ss14Address`.
+    /// </summary>
+    /// <param name="address">The server address, such as "ss14://localhost:1212/".</param>
+    /// <param name="text">Informational text on the cause of the reconnect. Empty or null gives a default reason.</param>
+    void Redial(string address, string? text = null);
+}
 
-        void Shutdown(string? reason=null);
-    }
-}

Robust.UnitTesting/GameControllerDummy.cs

@@ -16,6 +16,10 @@ namespace Robust.UnitTesting
         {
         }
 
+        public void Redial(string address, string? reason = null)
+        {
+        }
+
         public void SetCommandLineArgs(CommandLineArgs args)
         {
         }