Syntriax.Engine/Engine.Physics2D/Collider2DBehaviourBase.cs

using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;
using Syntriax.Engine.Physics2D.Abstract;

namespace Syntriax.Engine.Physics2D;

public abstract class Collider2DBehaviourBase : Behaviour, ICollider2D
{
    public event ICollider2D.OnCollisionDetectedDelegate? OnCollisionDetected = null;
    public event ICollider2D.OnCollisionResolvedDelegate? OnCollisionResolved = null;
    public event ICollider2D.OnTriggeredDelegate? OnTriggered = null;


    protected bool NeedsRecalculation { get; private set; } = true;
    protected IRigidBody2D? _rigidBody2D = null;

    public IRigidBody2D? RigidBody2D => _rigidBody2D;
    public bool IsTrigger { get; set; } = false;

    ITransform IAssignableTransform.Transform => Transform;
    public event IAssignableTransform.OnTransformAssignedDelegate? OnTransformAssigned { add => GameObject.OnTransformAssigned += value; remove => GameObject.OnTransformAssigned -= value; }

    bool IAssignableTransform.Assign(ITransform transform) => GameObject.Assign(transform);

    public void Recalculate()
    {
        if (!NeedsRecalculation)
            return;

        CalculateCollider();
        NeedsRecalculation = false;
    }

    public abstract void CalculateCollider();

    protected override void OnInitialize()
    {
        BehaviourController.TryGetBehaviourInParent(out _rigidBody2D);

        BehaviourController.OnBehaviourAdded += OnBehaviourAddedToController;
        BehaviourController.OnBehaviourRemoved += OnBehaviourRemovedFromController;

        Transform.OnPositionChanged += SetNeedsRecalculation;
        Transform.OnRotationChanged += SetNeedsRecalculation;
        Transform.OnScaleChanged += SetNeedsRecalculation;
        Transform.OnParentChanged += UpdateRigidBody2D;
    }

    private void UpdateRigidBody2D(ITransform _1, ITransform? _2)
    {
        BehaviourController.TryGetBehaviourInParent(out _rigidBody2D);
    }

    private void OnBehaviourAddedToController(IBehaviourController _, IBehaviour behaviour)
    {
        if (behaviour is IRigidBody2D rigidBody)
            _rigidBody2D = rigidBody;
    }

    private void OnBehaviourRemovedFromController(IBehaviourController _, IBehaviour behaviour)
    {
        if (behaviour is IRigidBody2D _)
            _rigidBody2D = null;
    }

    private void SetNeedsRecalculation(ITransform transform) => NeedsRecalculation = true;

    protected override void OnFinalize()
    {
        BehaviourController.OnBehaviourAdded -= OnBehaviourAddedToController;
        BehaviourController.OnBehaviourRemoved -= OnBehaviourRemovedFromController;
        Transform.OnScaleChanged -= SetNeedsRecalculation;

        Transform.OnPositionChanged -= SetNeedsRecalculation;
        Transform.OnRotationChanged -= SetNeedsRecalculation;
    }

    public void Detect(CollisionDetectionInformation collisionDetectionInformation) => OnCollisionDetected?.Invoke(this, collisionDetectionInformation);
    public void Resolve(CollisionDetectionInformation collisionDetectionInformation) => OnCollisionResolved?.Invoke(this, collisionDetectionInformation);
    public void Trigger(ICollider2D initiator) => OnTriggered?.Invoke(this, initiator);
}