Initial commit

Assets/_Project/Scripts/Code/InteractionLayer/Managers/SelectionManager.cs

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+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.Events;
+
+/// <summary>
+/// Manages selection state for placed interactable objects.
+/// Listens to RayInteractor.OnSelectEvent (which only fires when no ghost is active).
+/// Supports single and multi-select (Ctrl/Shift).
+/// </summary>
+public class SelectionManager : MonoBehaviour
+{
+    private static SelectionManager instance;
+    public static SelectionManager getInstance() => instance;
+
+    private RayInteractor rayInteractor;
+    private BaseInputProvider inputProvider;
+
+    private readonly List<IInteractable> currentSelections = new List<IInteractable>();
+    private bool multiSelectEnabled = false;
+
+    public UnityEvent<IInteractable> SelectionEvent;
+
+    // -------------------------------------------------------------------------
+    // Unity lifecycle
+    // -------------------------------------------------------------------------
+
+    private void Awake()
+    {
+        if (instance == null) instance = this;
+        else Destroy(gameObject);
+    }
+
+    private void Start()
+    {
+        rayInteractor = RayInteractor.getInstance();
+        inputProvider = InputProviderManager.getInstance().getCurrentInputProvider();
+
+        inputProvider.OnEnableMultiSelect.AddListener(() => multiSelectEnabled = true);
+        inputProvider.OnDisableMultiSelect.AddListener(() => multiSelectEnabled = false);
+
+        // RayInteractor only fires this when no ghost is active, so we can safely handle selection here
+        rayInteractor.OnSelectEvent.AddListener(HandleSelect);
+    }
+
+    // -------------------------------------------------------------------------
+    // Selection logic
+    // -------------------------------------------------------------------------
+
+    private void HandleSelect(IInteractable interactable)
+    {
+        if (InputModeManager.Is(InputMode.UI)) return;
+        if (interactable == null)
+        {
+            SelectionEvent?.Invoke(interactable);
+            // Clicked empty space – clear selection unless multi-select is held
+            if (!multiSelectEnabled)
+                ClearSelection();
+            return;
+        }
+
+        if (multiSelectEnabled)
+        {
+            // Toggle the clicked interactable
+            if (currentSelections.Contains(interactable))
+            {
+                currentSelections.Remove(interactable);
+                interactable.highLightOff();
+            }
+            else
+            {
+                currentSelections.Add(interactable);
+                interactable.highLightOn();
+            }
+        }
+        else
+        {
+            // Replace selection with just this interactable
+            bool Exists = currentSelections.Contains(interactable);
+            ClearSelection();
+            if (!Exists) {
+                currentSelections.Add(interactable);
+                interactable.highLightOn();
+            }
+        }
+        SelectionEvent?.Invoke(interactable);
+    }
+
+    // -------------------------------------------------------------------------
+    // Public API
+    // -------------------------------------------------------------------------
+
+    public List<IInteractable> GetCurrentSelections() => currentSelections;
+
+    public void ClearSelection()
+    {
+        foreach (IInteractable selection in currentSelections)
+            selection.highLightOff();
+
+        currentSelections.Clear();
+        SelectionEvent?.Invoke(null);
+    }
+
+    public bool HasOneSelection()
+    {
+        return !(currentSelections.Count > 1 || currentSelections.Count == 0);
+    }
+}