using System;
using System.Collections.Generic;

namespace Syntriax.Engine.Core;

public class BehaviourCollectorSorted<T> : BehaviourCollector<T> where T : class
{
    private readonly Event<IBehaviour, IBehaviour.PriorityChangedArguments>.EventHandler delegateOnPriorityChanged = null!;

    private IComparer<T>? _sortBy = null;
    public IComparer<T>? SortBy
    {
        get => _sortBy;
        set
        {
            _sortBy = value;

            if (value is not null)
                behaviours.Sort(value);
        }
    }

    protected override void AddBehaviour(T behaviour)
    {
        if (SortBy is null)
        {
            behaviours.Add(behaviour);
            return;
        }

        int insertionIndex = behaviours.BinarySearch(behaviour, SortBy);

        if (insertionIndex < 0)
            insertionIndex = ~insertionIndex;

        behaviours.Insert(insertionIndex, behaviour);
    }

    protected override void OnBehaviourAdd(IBehaviour behaviour)
    {
        behaviour.OnPriorityChanged.AddListener(delegateOnPriorityChanged);
    }

    protected override void OnBehaviourRemove(IBehaviour behaviour)
    {
        behaviour.OnPriorityChanged.RemoveListener(delegateOnPriorityChanged);
    }

    private void OnPriorityChanged(IBehaviour sender, IBehaviour.PriorityChangedArguments args)
    {
        T behaviour = (T)sender;
        behaviours.Remove(behaviour);
        AddBehaviour(behaviour);
    }

    public BehaviourCollectorSorted()
    {
        delegateOnPriorityChanged = OnPriorityChanged;
    }

    public BehaviourCollectorSorted(IUniverse universe, Comparison<T> sortBy) : base(universe)
    {
        delegateOnPriorityChanged = OnPriorityChanged;

        SortBy = Comparer<T>.Create(sortBy);
    }
}