using System;
using System.Collections.Generic;

using Syntriax.Engine.Core.Abstract;

namespace Syntriax.Engine.Core;

public class BehaviourCacher<T> : IAssignableGameManager where T : IBehaviour
{
    public Action<IAssignable>? OnUnassigned { get; set; } = null;
    public Action<IAssignableGameManager>? OnGameManagerAssigned { get; set; } = null;

    public Action<BehaviourCacher<T>, T>? OnCached { get; set; } = null;
    public Action<BehaviourCacher<T>, T>? OnUncached { get; set; } = null;

    private readonly List<T> _behaviours = new(32);

    public IReadOnlyList<T> Behaviours => _behaviours;
    public IGameManager GameManager { get; private set; } = null!;

    public BehaviourCacher() { }
    public BehaviourCacher(IGameManager gameManager) => Assign(gameManager);

    private void OnGameObjectRegistered(GameManager manager, IGameObject gameObject)
    {
        gameObject.BehaviourController.OnBehaviourAdded += OnBehaviourAdded;
        gameObject.BehaviourController.OnBehaviourRemoved += OnBehaviourRemoved;
    }

    private void OnGameObjectUnregistered(GameManager manager, IGameObject gameObject)
    {
        gameObject.BehaviourController.OnBehaviourAdded -= OnBehaviourAdded;
        gameObject.BehaviourController.OnBehaviourRemoved -= OnBehaviourRemoved;
    }

    private void OnBehaviourAdded(IBehaviourController controller, IBehaviour behaviour)
    {
        if (behaviour is not T tBehaviour)
            return;

        _behaviours.Add(tBehaviour);
        OnCached?.Invoke(this, tBehaviour);
    }

    private void OnBehaviourRemoved(IBehaviourController controller, IBehaviour behaviour)
    {
        if (behaviour is not T tBehaviour)
            return;

        if (!_behaviours.Remove(tBehaviour))
            return;

        OnUncached?.Invoke(this, tBehaviour);
    }

    public bool Assign(IGameManager gameManager)
    {
        if (GameManager is not null)
            return false;

        gameManager.OnGameObjectRegistered += OnGameObjectRegistered;
        gameManager.OnGameObjectUnRegistered += OnGameObjectUnregistered;

        GameManager = gameManager;
        return true;
    }

    public bool Unassign()
    {
        if (GameManager is null)
            return false;

        GameManager.OnGameObjectRegistered -= OnGameObjectRegistered;
        GameManager.OnGameObjectUnRegistered -= OnGameObjectUnregistered;

        GameManager = null!;
        return true;
    }
}