GodotComponentTest/systems/InteractionSystem.cs

using Godot;
using System;
using System.Collections.Generic;
using Godot.Collections;
using GodotComponentTest.components;
using GodotComponentTest.entities;
using Array = System.Array;
using NodePair = System.Tuple<Godot.Node, Godot.Node>;

public class InteractionSystem : Node
{
    private List<InteractionComponent> _activeInteractions;

    // Called when the node enters the scene tree for the first time.
    public override void _Ready()
    {
        _activeInteractions = new List<InteractionComponent>();
    }

    public override void _Process(float delta)
    {
        base._Process(delta);

        List<NodePair> invalidInteractionPairs = new List<NodePair>();
        List<InteractionComponent> endedInteractions = new List<InteractionComponent>();

        foreach (InteractionComponent interaction in _activeInteractions)
        {
            Spatial owningEntity = interaction.OwningEntity;
            Spatial targetEntity = interaction.TargetEntity;

            if (owningEntity == null || owningEntity.IsQueuedForDeletion() || targetEntity == null || targetEntity.IsQueuedForDeletion())
            {
                interaction.hasStopped = true;
            }
            
            if (interaction.hasStopped)
            {
                IInteractionInterface interactableA = owningEntity as IInteractionInterface;
                if (interactableA != null)
                {
                    interactableA.OnInteractionEnd();
                    interactableA.InteractionComponent = null;
                }
                
                IInteractionInterface interactableB = targetEntity as IInteractionInterface;
                if (interactableB != null)
                {
                    interactableB.OnInteractionEnd();
                    interactableB.InteractionComponent = null;
                }
                
                endedInteractions.Add(interaction);
            }
        }
        
        foreach (InteractionComponent interaction in endedInteractions)
        {
            _activeInteractions.Remove(interaction);
        }
    }

    public void OnStartInteraction(Entity owningEntity, Entity targetEntity)
    {
        InteractionComponent interactionComponent = new InteractionComponent();
        interactionComponent.OwningEntity = owningEntity;
        interactionComponent.TargetEntity = targetEntity;
        
        ConnectInteractionSignals(owningEntity, interactionComponent);
        ConnectInteractionSignals(targetEntity, interactionComponent);
        
        interactionComponent.EmitSignal("InteractionStart");

        _activeInteractions.Add(interactionComponent);
    }

    private static void ConnectInteractionSignals(Entity entity, InteractionComponent interactionComponent)
    {
        IInteractionInterface interactable = entity as IInteractionInterface;
        if (interactable != null)
        {
            interactable.InteractionComponent = interactionComponent;
            interactionComponent.Connect("InteractionStart", entity, nameof(interactable.OnInteractionStart));
            interactionComponent.Connect("InteractionEnd", entity, nameof(interactable.OnInteractionEnd));
        }
    }
}