Babushka/scripts/CSharp/Common/CharacterControls/Detector.cs

using System.Collections.Generic;
using Babushka.scripts.CSharp.Common.Services;
using Babushka.scripts.CSharp.Low_Code.Variables;
using Godot;

namespace Babushka.scripts.CSharp.Common.CharacterControls;

/// <summary>
/// Defines an <see cref="Area2D"/> Node with a <see cref="CollisionShape2D"/> used for detecting <see cref="InteractionArea2D"/> nodes.
/// </summary>
public partial class Detector : Area2D
{
    [Export] private bool _active = true;
    [Export] private ShapeCast2D _shapeCast2D;
    [Export] private VariableResource _itemToTriggerResource;
    
    private List<ulong> _areasInDetector = new();
    
    public bool IsActive
    {
        get => _active;
        set
        {
            Visible = value;
            _active = value;
        }
    }

    public override void _Ready()
    {
        AreaEntered += OnEnteredInteractable;
        AreaExited += OnExitedInteractable;
    }

    /// <summary>
    /// Called every time this node enters an Area2D. 
    /// </summary>
    /// <param name="area"></param>
    public void OnEnteredInteractable(Area2D area)
    {
        if (!_active || !InputService.Instance.InputEnabled)
            return;

        PopulateList();
        CalculateClosestInteractable();
    }

    /// <summary>
    /// Called whenever this node exits an Area2D.
    /// </summary>
    /// <param name="area"></param>
    public void OnExitedInteractable(Area2D area)
    {
        if (!_active || !InputService.Instance.InputEnabled)
            return;
        
        PopulateList();
        CalculateClosestInteractable();
    }

    private void PopulateList()
    {
        // repopulate the list of areas in the detector to account for enabled / disabled areas
        var currentOverlap = GetOverlappingAreas();
        _areasInDetector = new List<ulong>();

        foreach (var area2D in currentOverlap)
        {
            if (area2D is DetectableInteractionArea detectable)
            {
                ulong id = detectable.GetInstanceId();
                _areasInDetector.Add(id);
            }
        }
    }
    
    private void CalculateClosestInteractable()
    {
        float smallestDistance = float.MaxValue;
        string closestInteractable = null;
        foreach (var area in _areasInDetector)
        {
            Area2D? area2D = InstanceFromId(area) as Area2D;
            if(area2D == null)
                continue;
            
            float distance = area2D.GlobalPosition.DistanceSquaredTo(ToGlobal(_shapeCast2D.TargetPosition));
            if (distance < smallestDistance)
            {
                closestInteractable = area.ToString();
                smallestDistance = distance;
            }
        }
        _itemToTriggerResource.Payload = closestInteractable;
    }
    
}