Secret! (#8276)

Co-authored-by: moonheart08 <moonheart08@users.noreply.github.com>

Content.Server/GameTicking/Rules/SecretRuleSystem.cs

@@ -0,0 +1,42 @@
+using System.Linq;
+using Content.Server.GameTicking.Presets;
+using Content.Shared.Random;
+using Content.Shared.Random.Helpers;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Random;
+
+namespace Content.Server.GameTicking.Rules;
+
+public sealed class SecretRuleSystem : GameRuleSystem
+{
+    [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+    [Dependency] private readonly IRobustRandom _random = default!;
+    [Dependency] private readonly GameTicker _ticker = default!;
+
+    public override string Prototype => "Secret";
+
+    public override void Started()
+    {
+        PickRule();
+    }
+
+    public override void Ended()
+    {
+        // noop
+        // Preset should already handle it.
+        return;
+    }
+
+    private void PickRule()
+    {
+        // TODO: This doesn't consider what can't start due to minimum player count, but currently there's no way to know anyway.
+        // as they use cvars.
+        var preset = _prototypeManager.Index<WeightedRandomPrototype>("Secret").Pick(_random);
+        Logger.InfoS("gamepreset", $"Selected {preset} for secret.");
+
+        foreach (var rule in _prototypeManager.Index<GamePresetPrototype>(preset).Rules)
+        {
+            _ticker.AddGameRule(_prototypeManager.Index<GameRulePrototype>(rule));
+        }
+    }
+}