using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using Cysharp.Threading.Tasks;
// ReSharper disable MethodHasAsyncOverload

namespace BITKit
{
    public interface IEntryGroup
    {
  
    }
    public interface IEntryElement
    {
        bool IsEntered { get; set; }
        void Entry();
        UniTask EntryAsync();
        void Entered();
        void Exit();
        UniTask ExitAsync();
        void Exited();
    }

    [System.Serializable]
    public class EntryGroup<T> : IEntryGroup where T : IEntryElement
    {
        public int index = -1;
        public List<T> list = new();
        private int m_index = -1;
        private bool completed=true;
        
        public event Action<T> OnEntry;
        public   event Action<T> OnExit;
        public void Entry(T t)
        {
            if (t is not null)
            {
                list.TryAdd(t);

            }
            index = list.IndexOf(t);
            EnsureConfiguration();
        }
        public void Entry(int index)
        {
            if (index < list.Count)
            {
                this.index = index;
            }
        }
        public void Entry(Func<T,bool> entryFactory)
        {
            var index = list.FindIndex(x => entryFactory.Invoke(x));
            Entry(index);
        }
        public void Entry()
        {
            index = 0;
            EnsureConfiguration();
        }

        public void Exit()
        {
            index = -1;
            EnsureConfiguration();
        }
        public bool TryGetEntried(out T value)
        {
            EnsureConfiguration();
            if (m_index is not -1)
            {
                value = list[m_index];
                return true;
            }
            value = default;
            return false;
        }
        private async void EnsureConfiguration()
        {
            try
            {
                if(completed is false) return;
                completed = false;
                if (index == m_index)
                {

                }
                else
                {
                    var currentIndex = m_index;
                    if (currentIndex is not -1 && list.TryGetElementAt(currentIndex, out var currentElement))
                    {
                        currentElement.Exit();
                        try
                        {
                            await currentElement.ExitAsync();
                        }
                        catch (OperationCanceledException)
                        {
                            return;
                        }
                        catch (Exception e)
                        {
                            BIT4Log.LogException(e);
                        }
                        currentElement.Exited();
                        currentElement.IsEntered = false;
                        OnExit?.Invoke(currentElement);
                    }
                    m_index = index;
                    if (index is not -1 && list.TryGetElementAt(index, out var nextElement))
                    {
                        nextElement.IsEntered = true;
                        OnEntry?.Invoke(nextElement);
                        nextElement.Entry();
                        try
                        {
                            await nextElement.EntryAsync();
                            nextElement.Entered();
                        }
                        catch (OperationCanceledException){}
                        
                    }
                }
                completed = true;
            }
            catch (Exception e)
            {
                #if UNITY_EDITOR
                UnityEngine.Debug.LogException(e);
                #else
                    BIT4Log.LogException(e);
                #endif
            
            }
           
        }
    }
}