BREAKING CHANGE: renamed original Behaviour class to BehaviourInternal, and replaced it with BehaviourBase

Original Behaviour was using old methods for detecting entering/exiting universe,
they are now all under the same hood and the original is kept for UniverseEntranceManager
because it needs to enter the universe without itself. The internal behaviour kept under
a subnamespace of "Core.Internal" for the purpose that it might come in handy for other use cases.

Engine.Core/Behaviour.cs

@@ -1,50 +1,103 @@
 namespace Engine.Core;
 
-public abstract class Behaviour : BehaviourBase
+[System.Diagnostics.DebuggerDisplay("{GetType().Name, nq}, Priority: {Priority}, Initialized: {Initialized}")]
+public abstract class Behaviour : BaseEntity, IBehaviour
 {
-    private readonly Event<IUniverseObject, IUniverseObject.EnteredUniverseArguments>.EventHandler delegateEnteredUniverse = null!;
-    private readonly Event<IUniverseObject, IUniverseObject.ExitedUniverseArguments>.EventHandler delegateExitedUniverse = null!;
+    public Event<IBehaviour, IBehaviour.PriorityChangedArguments> OnPriorityChanged { get; } = new();
+    public Event<IActive, IActive.ActiveChangedArguments> OnActiveChanged { get; } = new();
+    public Event<IHasBehaviourController> OnBehaviourControllerAssigned { get; } = new();
 
-    public Behaviour()
+    private readonly Event<IHasUniverseObject>.EventHandler delegateOnUniverseObjectAssigned = null!;
+    private readonly Event<IActive, IActive.ActiveChangedArguments>.EventHandler delegateOnUniverseObjectActiveChanged = null!;
+    private readonly Event<IStateEnable, IStateEnable.EnabledChangedArguments>.EventHandler delegateOnStateEnabledChanged = null!;
+
+    public IUniverse Universe => BehaviourController.UniverseObject.Universe;
+    public IUniverseObject UniverseObject => BehaviourController.UniverseObject;
+
+    private IBehaviourController _behaviourController = null!;
+    public IBehaviourController BehaviourController => _behaviourController;
+
+    private int _priority = 0;
+    public int Priority
     {
-        OnInitialized.AddListener(OnInitialize);
-        OnFinalized.AddListener(OnFinalize);
-        OnUnassigned.AddListener(OnUnassign);
+        get => _priority;
+        set
+        {
+            if (value == _priority)
+                return;
 
-        delegateEnteredUniverse = EnteredUniverse;
-        delegateExitedUniverse = ExitedUniverse;
+            int previousPriority = _priority;
+            _priority = value;
+            OnPriorityChanged?.Invoke(this, new(previousPriority));
+        }
     }
 
-    protected virtual void OnUnassign() { }
-    protected void OnUnassign(IAssignable assignable) => OnUnassign();
+    private bool _isActive = false;
+    public bool IsActive => _isActive;
 
-    protected virtual void OnInitialize() { }
-    protected void OnInitialize(IInitializable _)
+    protected virtual void OnAssign(IBehaviourController behaviourController) { }
+    public bool Assign(IBehaviourController behaviourController)
     {
-        BehaviourController.UniverseObject.OnEnteredUniverse.AddListener(delegateEnteredUniverse);
-        BehaviourController.UniverseObject.OnExitedUniverse.AddListener(delegateExitedUniverse);
+        if (IsInitialized)
+            return false;
 
-        OnInitialize();
-
-        if (UniverseObject.IsInUniverse)
-            EnteredUniverse(UniverseObject, new(Universe));
+        _behaviourController = behaviourController;
+        OnAssign(behaviourController);
+        behaviourController.OnUniverseObjectAssigned.AddListener(delegateOnUniverseObjectAssigned);
+        behaviourController.StateEnable.OnEnabledChanged.AddListener(delegateOnStateEnabledChanged);
+        if (behaviourController.UniverseObject is not null)
+            OnUniverseObjectAssigned(behaviourController);
+        OnBehaviourControllerAssigned?.Invoke(this);
+        return true;
     }
 
-    protected virtual void OnFinalize() { }
-    protected void OnFinalize(IInitializable _)
+    private void OnUniverseObjectAssigned(IHasUniverseObject sender)
     {
-        BehaviourController.UniverseObject.OnEnteredUniverse.RemoveListener(delegateEnteredUniverse);
-        BehaviourController.UniverseObject.OnExitedUniverse.RemoveListener(delegateExitedUniverse);
-
-        OnFinalize();
-
-        if (UniverseObject.IsInUniverse)
-            ExitedUniverse(UniverseObject, new(Universe));
+        sender.UniverseObject.OnActiveChanged.AddListener(delegateOnUniverseObjectActiveChanged);
+        UpdateActive();
     }
 
-    protected virtual void OnEnteredUniverse(IUniverse universe) { }
-    protected void EnteredUniverse(IUniverseObject sender, IUniverseObject.EnteredUniverseArguments args) => OnEnteredUniverse(args.Universe);
+    protected override void OnAssign(IStateEnable stateEnable)
+    {
+        base.OnAssign(stateEnable);
 
-    protected virtual void OnExitedUniverse(IUniverse universe) { }
-    protected void ExitedUniverse(IUniverseObject sender, IUniverseObject.ExitedUniverseArguments args) => OnExitedUniverse(args.Universe);
+        stateEnable.OnEnabledChanged.AddListener(delegateOnStateEnabledChanged);
+    }
+
+    protected override void UnassignInternal()
+    {
+        BehaviourController.UniverseObject.OnActiveChanged.RemoveListener(delegateOnUniverseObjectActiveChanged);
+        StateEnable.OnEnabledChanged.RemoveListener(delegateOnStateEnabledChanged);
+        BehaviourController.OnUniverseObjectAssigned.RemoveListener(delegateOnUniverseObjectAssigned);
+        BehaviourController.StateEnable.OnEnabledChanged.RemoveListener(delegateOnStateEnabledChanged);
+        base.UnassignInternal();
+        _behaviourController = null!;
+    }
+
+    protected override void InitializeInternal()
+    {
+        Debug.Assert.AssertBehaviourControllerAssigned(this);
+        Debug.Assert.AssertStateEnableAssigned(this);
+
+        UpdateActive();
+    }
+
+    private void OnStateEnabledChanged(IStateEnable sender, IStateEnable.EnabledChangedArguments args) => UpdateActive();
+    private void OnUniverseObjectActiveChanged(IActive sender, IActive.ActiveChangedArguments args) => UpdateActive();
+
+    private void UpdateActive()
+    {
+        bool previousActive = IsActive;
+        _isActive = StateEnable.Enabled && _behaviourController.StateEnable.Enabled && _behaviourController.UniverseObject.IsActive;
+
+        if (previousActive != IsActive)
+            OnActiveChanged?.Invoke(this, new(previousActive));
+    }
+
+    protected Behaviour()
+    {
+        delegateOnUniverseObjectAssigned = OnUniverseObjectAssigned;
+        delegateOnUniverseObjectActiveChanged = OnUniverseObjectActiveChanged;
+        delegateOnStateEnabledChanged = OnStateEnabledChanged;
+    }
 }