using System.Collections.Generic;

namespace Engine.Core;

public class UniverseEntranceManager : Behaviour
{
    // We use Ascending order because we are using reverse for loop to call them
    private static Comparer<IBehaviour> SortByAscendingPriority() => Comparer<IBehaviour>.Create((x, y) => x.Priority.CompareTo(y.Priority));

    private readonly ActiveBehaviourCollectorSorted<IEnterUniverse> enterUniverses = new() { SortBy = SortByAscendingPriority() };
    private readonly ActiveBehaviourCollectorSorted<IExitUniverse> exitUniverses = new() { SortBy = SortByAscendingPriority() };

    private readonly List<IEnterUniverse> toCallEnterUniverses = new(32);
    private readonly List<IExitUniverse> toCallExitUniverses = new(32);

    protected override void OnEnteredUniverse(IUniverse universe)
    {
        enterUniverses.Assign(universe);

        foreach (IUniverseObject universeObject in universe.UniverseObjects)
            OnUniverseObjectRegistered(universe, new(universeObject));

        universe.OnUniverseObjectRegistered.AddListener(OnUniverseObjectRegistered);
        universe.OnUniverseObjectUnRegistered.AddListener(OnUniverseObjectUnRegistered);
    }

    protected override void OnExitedUniverse(IUniverse universe)
    {
        enterUniverses.Unassign();

        foreach (IUniverseObject universeObject in universe.UniverseObjects)
            OnUniverseObjectUnRegistered(universe, new(universeObject));

        universe.OnUniverseObjectRegistered.RemoveListener(OnUniverseObjectRegistered);
        universe.OnUniverseObjectUnRegistered.RemoveListener(OnUniverseObjectUnRegistered);
    }

    private void OnUniverseObjectUnRegistered(IUniverse sender, IUniverse.UniverseObjectUnRegisteredArguments args)
    {
        for (int i = toCallExitUniverses.Count - 1; i >= 0; i--)
        {
            toCallExitUniverses[i].ExitUniverse(Universe);
            toCallExitUniverses.RemoveAt(i);
        }
    }

    private void OnUniverseObjectRegistered(IUniverse sender, IUniverse.UniverseObjectRegisteredArguments args)
    {
        for (int i = toCallEnterUniverses.Count - 1; i >= 0; i--)
        {
            toCallEnterUniverses[i].EnterUniverse(Universe);
            toCallEnterUniverses.RemoveAt(i);
        }
    }

    private void OnEnterUniverseCollected(IBehaviourCollector<IEnterUniverse> sender, IBehaviourCollector<IEnterUniverse>.BehaviourCollectedArguments args)
    {
        toCallEnterUniverses.Add(args.BehaviourCollected);
    }

    private void OnExitUniverseCollected(IBehaviourCollector<IExitUniverse> sender, IBehaviourCollector<IExitUniverse>.BehaviourCollectedArguments args)
    {
        toCallExitUniverses.Add(args.BehaviourCollected);
    }

    public UniverseEntranceManager()
    {
        enterUniverses.OnCollected.AddListener(OnEnterUniverseCollected);
        exitUniverses.OnCollected.AddListener(OnExitUniverseCollected);
    }
}