Added online detection handler

MoonlightServers.Daemon/ServerSystem/Handlers/OnlineDetectionHandler.cs

@@ -0,0 +1,85 @@
+using MoonlightServers.Daemon.ServerSystem.Enums;
+using MoonlightServers.Daemon.ServerSystem.Interfaces;
+using MoonlightServers.Daemon.ServerSystem.Models;
+using Stateless;
+
+namespace MoonlightServers.Daemon.ServerSystem.Handlers;
+
+public class OnlineDetectionHandler : IServerStateHandler
+{
+    private readonly ServerContext Context;
+    private IOnlineDetector OnlineDetector => Context.Server.OnlineDetector;
+    private ILogger Logger => Context.Logger;
+
+    private IAsyncDisposable? ConsoleSubscription;
+    private bool IsActive = false;
+
+    public OnlineDetectionHandler(ServerContext context)
+    {
+        Context = context;
+    }
+
+    public async Task ExecuteAsync(StateMachine<ServerState, ServerTrigger>.Transition transition)
+    {
+        if (
+            transition is
+            { Source: ServerState.Offline, Destination: ServerState.Starting, Trigger: ServerTrigger.Start } && !IsActive
+        )
+        {
+            await StartAsync();
+        }
+        else if (transition is { Source: not ServerState.Installing, Destination: ServerState.Offline } && IsActive)
+        {
+            await StopAsync();
+        }
+    }
+
+    private async Task StartAsync()
+    {
+        IsActive = true;
+
+        await OnlineDetector.CreateAsync();
+
+        ConsoleSubscription = await Context.Server.Console.SubscribeStdOutAsync(OnHandleOutput);
+        
+        Logger.LogTrace("Created online detector. Created console subscription");
+    }
+
+    private async ValueTask OnHandleOutput(string line)
+    {
+        if(!IsActive)
+            return;
+        
+        if(!await OnlineDetector.HandleOutputAsync(line))
+            return;
+        
+        if(!Context.Server.StateMachine.CanFire(ServerTrigger.DetectOnline))
+            return;
+
+        Logger.LogTrace("Detected server as online. Destroying online detector");
+        
+        await Context.Server.StateMachine.FireAsync(ServerTrigger.DetectOnline);
+        await StopAsync();
+    }
+
+    private async Task StopAsync()
+    {
+        IsActive = false;
+
+        if (ConsoleSubscription != null)
+        {
+            await ConsoleSubscription.DisposeAsync();
+            ConsoleSubscription = null;
+        }
+
+        await OnlineDetector.DestroyAsync();
+        
+        Logger.LogTrace("Destroyed online detector. Revoked console subscription");
+    }
+
+    public async ValueTask DisposeAsync()
+    {
+        if (ConsoleSubscription != null)
+            await ConsoleSubscription.DisposeAsync();
+    }
+}

MoonlightServers.Daemon/ServerSystem/Handlers/ShutdownHandler.cs

@@ -21,7 +21,7 @@ public class ShutdownHandler : IServerStateHandler
             {
                 Destination: ServerState.Offline,
                 Source: not ServerState.Installing,
-                Trigger: ServerTrigger.Exited
+                Trigger: ServerTrigger.Exited // We don't want to handle the fail event here
             })
             return;
 

MoonlightServers.Daemon/ServerSystem/Handlers/StartupHandler.cs

@@ -30,12 +30,13 @@ public class StartupHandler : IServerStateHandler
         // 4. Run file system checks
         // 5. Create runtime
         // 6. Attach console
-        // 7. Attach statistics collector
-        // 8. Create online detector
-        // 9. Start runtime
+        // 7. Start runtime
 
         // 1. Fetch latest configuration
         // TODO
+        // Consider moving it out of the startup handler, as other handlers might need
+        // the updated config as well or add sorting into the handler registration to ensure they are executing in the correct order.
+        // Sort when building server, not when executing handlers
 
         // 2. Check if file system exists
         if (!await Server.RuntimeFileSystem.CheckExistsAsync())
@@ -65,16 +66,7 @@ public class StartupHandler : IServerStateHandler
 
         await Server.Console.AttachRuntimeAsync();
 
-        // 7. Attach statistics collector
-
-        await Server.Statistics.AttachRuntimeAsync();
-
-        // 8. Create online detector
-
-        await Server.OnlineDetector.CreateAsync();
-        await Server.OnlineDetector.DestroyAsync();
-
-        // 9. Start runtime
+        // 7. Start runtime
 
         await Server.Runtime.StartAsync();
     }

MoonlightServers.Daemon/ServerSystem/ServerFactory.cs

@@ -58,6 +58,7 @@ public class ServerFactory
         // Resolve handlers
         var handlers = new List<IServerStateHandler>();
         
+        handlers.Add(ActivatorUtilities.CreateInstance<OnlineDetectionHandler>(scope.ServiceProvider));
         handlers.Add(ActivatorUtilities.CreateInstance<StartupHandler>(scope.ServiceProvider));
         handlers.Add(ActivatorUtilities.CreateInstance<ShutdownHandler>(scope.ServiceProvider));