cirnogodot/Scripts/Selector.cs

using Godot;
using System;
using System.Collections.Generic;

public partial class Selector : Node2D
{
    private Interactable _lastInteractable;

    private List<Interactable> _interactables = new List<Interactable>();

    private int _selectedInteractable;
    
    [Signal]
    public delegate void SelectedItemInteractableChangedEventHandler(Interactable interactable);
    
    public Interactable SelectedInteractable
    {
        get =>
            _interactables.Count > 0
                ? _selectedInteractable >= _interactables.Count
                    ? _interactables[^1]
                    : _interactables[_selectedInteractable]
                : null;
        set
        {
            // Passing null deselects the interactable
            if (value == null)
            {
                _selectedInteractable = -1;
                NotifyChanged(null);
                return;
            }
            
            // If it's already in the list, set the current one to it, otherwise add it
            if (!_interactables.Contains(value))
            {
                AddInteractable(value);
            }

            _selectedInteractable = _interactables.IndexOf(value);
            NotifyChanged(value);
        }
    }

    public override void _Process(double delta)
    {
        if (Input.IsActionJustPressed("scan"))
        {
            _selectedInteractable += 1;
            if (_selectedInteractable >= _interactables.Count)
            {
                _selectedInteractable = 0;
            }
            
            SelectedInteractable = _interactables[_selectedInteractable];
            UpdatePosition();
            
        }
    }

    private void NotifyChanged(Interactable interactable)
    {
        EmitSignal(nameof(SelectedItemInteractableChanged), interactable);
    }

    public void AddInteractable(Interactable interactable)
    {
        if (!_interactables.Contains(interactable)) {
            _interactables.Add(interactable);

            if (_interactables.Count == 1)
            {
                _selectedInteractable = 0;
            }
            
        }
        UpdatePosition();
    }

    public void RemoveInteractable(Interactable interactable)
    {
        if (_interactables.Contains(interactable))
        {
            _interactables.Remove(interactable);
        }
        UpdatePosition();
    }

    public void Deselect()
    {
        _selectedInteractable = -1;
        this.Visible = false;
    }

    public void UpdatePosition()
    {
        if (SelectedInteractable != null)
        {
            this.Position = SelectedInteractable.Position;
            this.Visible = true;
        }
        else
        {
            this.Visible = false;
        }
    }

}