ported from perforce

RobotAndDonkey.Game/Modifiers/Modifier.cs

@@ -0,0 +1,43 @@
+using RobotAndDonkey.Game.Execution.Results;
+using RobotAndDonkey.Game.GameState;
+using RobotAndDonkey.Game.Intents;
+
+namespace RobotAndDonkey.Game.Modifiers;
+
+public abstract record Modifier(EModifierKind Kind, EModifierId Id, EModifierDuration Duration)
+{
+    public Modifier DeepClone()
+    {
+        var result = CreateInstance();
+        foreach (var debuffSource in DebuffSources)
+            result.DebuffSources.Add(debuffSource);
+        return result;
+    }
+
+    protected abstract Modifier CreateInstance();
+
+    public virtual void OnAdded(Entity owner, List<Intent> newIntents)
+    {
+    }
+
+    public virtual void Before(Guid requestId, ReadOnlySpan<Intent> intents, CoreLoop coreLoop, Entity owner, List<Intent> newIntents, List<Result> results)
+    {
+    }
+
+    public virtual void After(Guid requestId, ReadOnlySpan<Intent> intents, CoreLoop coreLoop, Entity owner, List<Intent> newIntents, List<Result> results)
+    {
+    }
+
+    public virtual void OnRemoved(Entity owner, List<Intent> newIntents)
+    {
+    }
+
+    public override string ToString()
+    {
+        return "<" + $"{Id}, {Duration}" + (DebuffSources.Count > 0 ? ", debuffed" : "") + ">";
+    }
+
+    public HashSet<Entity> DebuffSources { get; } = [];
+
+    public abstract string ToolTip { get; }
+}