From 005c78a26e52dc905299bb66ba9bff49039ec02a Mon Sep 17 00:00:00 2001
From: Syntriax <syntriax@gmail.com>
Date: Tue, 30 Jan 2024 19:21:45 +0300
Subject: [PATCH] feat: BehaviourCacher<T>

---
 Engine.Core/BehaviourCacher.cs | 102 +++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 Engine.Core/BehaviourCacher.cs

diff --git a/Engine.Core/BehaviourCacher.cs b/Engine.Core/BehaviourCacher.cs
new file mode 100644
index 0000000..57b6ba4
--- /dev/null
+++ b/Engine.Core/BehaviourCacher.cs
@@ -0,0 +1,102 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+using Syntriax.Engine.Core.Abstract;
+
+namespace Syntriax.Engine.Core;
+
+public class BehaviourCacher<T> : IAssignableGameManager, IEnumerable<T>
+{
+    public Action<IAssignable>? OnUnassigned { get; set; } = null;
+    public Action<IAssignableGameManager>? OnGameManagerAssigned { get; set; } = null;
+
+    public Action<BehaviourCacher<T>, T>? OnCached { get; set; } = null;
+    public Action<BehaviourCacher<T>, T>? OnUncached { get; set; } = null;
+
+    private readonly List<T> _behaviours = new(32);
+
+    public IReadOnlyList<T> Behaviours => _behaviours;
+    public IGameManager GameManager { get; private set; } = null!;
+
+    public T this[Index index] => _behaviours[index];
+
+    public BehaviourCacher() { }
+    public BehaviourCacher(IGameManager gameManager) => Assign(gameManager);
+
+    private void OnGameObjectRegistered(IGameManager manager, IGameObject gameObject)
+    {
+        gameObject.BehaviourController.OnBehaviourAdded += OnBehaviourAdded;
+        gameObject.BehaviourController.OnBehaviourRemoved += OnBehaviourRemoved;
+    }
+
+    private void OnGameObjectUnregistered(IGameManager manager, IGameObject gameObject)
+    {
+        gameObject.BehaviourController.OnBehaviourAdded -= OnBehaviourAdded;
+        gameObject.BehaviourController.OnBehaviourRemoved -= OnBehaviourRemoved;
+    }
+
+    private void OnBehaviourAdded(IBehaviourController controller, IBehaviour behaviour)
+    {
+        if (behaviour is not T tBehaviour)
+            return;
+
+        _behaviours.Add(tBehaviour);
+        OnCached?.Invoke(this, tBehaviour);
+    }
+
+    private void OnBehaviourRemoved(IBehaviourController controller, IBehaviour behaviour)
+    {
+        if (behaviour is not T tBehaviour)
+            return;
+
+        if (!_behaviours.Remove(tBehaviour))
+            return;
+
+        OnUncached?.Invoke(this, tBehaviour);
+    }
+
+    public bool Assign(IGameManager gameManager)
+    {
+        if (GameManager is not null)
+            return false;
+
+        foreach (IGameObject gameObject in gameManager)
+        {
+            OnGameObjectRegistered(gameManager, gameObject);
+            foreach (IBehaviour behaviour in gameObject.BehaviourController)
+                OnBehaviourAdded(gameObject.BehaviourController, behaviour);
+        }
+
+        gameManager.OnGameObjectRegistered += OnGameObjectRegistered;
+        gameManager.OnGameObjectUnRegistered += OnGameObjectUnregistered;
+
+        GameManager = gameManager;
+        OnGameManagerAssigned?.Invoke(this);
+
+        return true;
+    }
+
+    public bool Unassign()
+    {
+        if (GameManager is null)
+            return false;
+
+        foreach (IGameObject gameObject in GameManager)
+        {
+            OnGameObjectUnregistered(GameManager, gameObject);
+            foreach (IBehaviour behaviour in gameObject.BehaviourController)
+                OnBehaviourRemoved(gameObject.BehaviourController, behaviour);
+        }
+
+        GameManager.OnGameObjectRegistered -= OnGameObjectRegistered;
+        GameManager.OnGameObjectUnRegistered -= OnGameObjectUnregistered;
+
+        GameManager = null!;
+        OnUnassigned?.Invoke(this);
+        return true;
+    }
+
+    public IEnumerator<T> GetEnumerator() => _behaviours.GetEnumerator();
+    IEnumerator IEnumerable.GetEnumerator() => _behaviours.GetEnumerator();
+}