using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using BITKit.Mod;
using BITKit.StateMachine;
using Cysharp.Threading.Tasks;
using UnityEngine;
using UnityEngine.Serialization;
using UnityEngine.InputSystem;
using UnityEngine.UIElements;
using Debug = UnityEngine.Debug;

// ReSharper disable MemberCanBeProtected.Global
// ReSharper disable ClassWithVirtualMembersNeverInherited.Global
// ReSharper disable UnusedMember.Global
// ReSharper disable MemberCanBePrivate.Global

namespace BITKit.UX
{
	public abstract class UIToolKitPanel :StateAsync, IUXPanel,IDisposable
	{
		public const string USSEntry = "transition_entry";
		public const string USSEntryAsync = "transition_entry_async";
		public const string USSEntered = "transition_entried";
		public const string USSExit = "transition_exit";
		public const string USSExitAsync = "transition_exit_async";
		public const string USSExited = "transition_exited";

		protected readonly IUXService UXService;
		protected abstract string DocumentPath { get; }
		public VisualElement RootVisualElement { get; set; }
		protected VisualTreeAsset VisualTreeAsset { get; private set; }
		private readonly ValidHandle _isBusy = new();
		public readonly UniTaskCompletionSource WaitUtilInitialized = new();
		protected UniTaskCompletionSource WaitUtilTransitionCompleted=new();
		protected UIToolKitPanel(IUXService uxService)
		{
			UXService = uxService;
			uxService.Register(this);
		}
		
		public override async UniTask InitializeAsync()
		{
			await _isBusy;
			using var b = _isBusy.GetHandle();
			if (RootVisualElement is null)
			{
				VisualTreeAsset = await ModService.LoadAsset<VisualTreeAsset>(DocumentPath);

				try
				{
					RootVisualElement = UXService.Root.As<VisualElement>().Create(VisualTreeAsset);
				}
				catch (Exception e)
				{
					Debug.LogWarning(GetType().Name+DocumentPath);
					throw;
				}
		

				RootVisualElement.name = DocumentPath;
				
				RootVisualElement.pickingMode = PickingMode.Ignore;
				RootVisualElement.style.position = Position.Absolute;
				RootVisualElement.style.left = 0;
				RootVisualElement.style.right = 0;
				RootVisualElement.style.top = 0;
				RootVisualElement.style.bottom = 0;

				foreach (var uss in InitialUssClasses)
				{
					RootVisualElement.AddToClassList(uss);
				}

				var invisible = RootVisualElement.Create<VisualElement>();
				invisible.name = "invisible_return_generate";
				invisible.AddToClassList("background_generate");
				invisible.style.position = Position.Absolute;
				invisible.pickingMode = PickingMode.Ignore;
				invisible.style.left = 0;
				invisible.style.right = 0;
				invisible.style.top = 0;
				invisible.style.bottom = 0;
				invisible.SendToBack();

				if (CloseWhenClickOutside)
				{
					invisible.RegisterCallback<MouseDownEvent>(x => { OnReturn(); });
					invisible.pickingMode = PickingMode.Position;
				}

				if (IsWindow)
				{
					invisible.style.backgroundColor = new Color(0, 0, 0, 0.9f);
				}
		        
				UXUtils.Inject(this,RootVisualElement);
				
				RootVisualElement.SetActive(false);
				
				await OnInitiatedAsync.UniTaskFunc();
				
				RootVisualElement.RegisterCallback<TransitionRunEvent>(OnTransitionRun);
				RootVisualElement.RegisterCallback<TransitionStartEvent>(OnTransitionStart);
				RootVisualElement.RegisterCallback<TransitionEndEvent>(OnTransitionEnd);
				RootVisualElement.RegisterCallback<TransitionCancelEvent>(OnTransitionEnd);

				WaitUtilTransitionCompleted.TrySetResult();
				
				WaitUtilInitialized.TrySetResult();
				
				OnInitiated?.Invoke();
			}
		}

		private void OnTransitionStart(TransitionStartEvent evt)
		{
			WaitUtilTransitionCompleted = new();
		}

		private void OnTransitionRun(TransitionRunEvent evt)
		{
			//WaitUtilTransitionCompleted = new();
		}

		protected readonly InputActionGroup InputActionGroup = new()
		{
			allowGlobalActivation = false,
			Source = nameof(UIToolKitPanel)
		};
		public virtual bool CloseWhenClickOutside { get;}
		public virtual bool IsWindow { get; }
		public virtual string Index => GetType().Name;
		public virtual bool AllowReload { get; }
		public virtual  bool AllowCursor { get; }
		public virtual bool AllowInput { get; }
		public object Root => RootVisualElement;
		public virtual string[] InitialUssClasses { get; } = Array.Empty<string>();
		public bool IsDisposed { get; private set; }

		public bool IsEntered { get; set; }
		protected virtual void OnReturn()
		{
			UXService.Return();
		}
		protected virtual void OnPanelEntry(){}
		protected virtual void OnPanelExit(){}
		public override void OnStateEntry(IState old)
		{
			InputActionGroup.allowInput.AddElement(this);
			OnEntry?.Invoke();
		}
		public override async UniTask OnStateEntryAsync(IState old)
		{
			await InitializeAsync();

			//WaitUtilTransitionCompleted = new();

	        RootVisualElement.SetActive(true);
	        
	        //await UniTask.NextFrame();

	        if (IsWindow)
	        {
		        RootVisualElement.BringToFront();
	        }
	        
	        RootVisualElement.AddToClassList(USSEntry);

	        await UniTask.NextFrame();
	        
	        RootVisualElement.AddToClassList(USSEntryAsync);
	        
	        await UniTask.NextFrame();

			await EntryAsync();

	        try
	        {
		        if (OnEntryAsync is not null)
		        {
			        await OnEntryAsync.UniTaskFunc();
		        }
	        }
	        catch (Exception e)
	        {
		        BIT4Log.LogException(e);
	        }
	        
	        try
	        {
		        var cts = new CancellationTokenSource();
		        cts.CancelAfter(1000);
		        await WaitUtilTransitionCompleted.Task.AttachExternalCancellation(cts.Token);
	        }
	        catch (OperationCanceledException)
	        {
	        }

	        await UniTask.SwitchToMainThread();

	        RootVisualElement.AddToClassList(USSEntered);
	        
	        OnPanelEntry();
	        OnEntryCompleted?.Invoke();
	        
	        RootVisualElement.RemoveFromClassList(USSEntry);
	        RootVisualElement.RemoveFromClassList(USSEntryAsync);
		}
		private void OnTransitionEnd<TChangeEvent>(TChangeEvent evt)
		{
			WaitUtilTransitionCompleted.TrySetResult();
		}

		public virtual UniTask EntryAsync()
        {
	        return UniTask.CompletedTask;
        }

		public override void OnStateExit(IState old, IState newState)
		{
			OnPanelExit();
			InputActionGroup.allowInput.RemoveElement(this);
			OnExit?.Invoke();
		}

		public override async UniTask OnStateExitAsync(IState old, IState newState)
		{
			RootVisualElement?.RemoveFromClassList(USSEntered);
			await UniTask.NextFrame();
			
			RootVisualElement?.AddToClassList(USSExit);
			
			
			await UniTask.NextFrame();
			
			RootVisualElement?.AddToClassList(USSExitAsync);
			
			await UniTask.NextFrame();
			
			await OnExitAsync.UniTaskFunc();
			
			try
			{
				var cts = new CancellationTokenSource();
				cts.CancelAfter(1000);
				await WaitUtilTransitionCompleted.Task.AttachExternalCancellation(cts.Token);
			}
			catch (OperationCanceledException)
			{
			}

			RootVisualElement?.RemoveFromClassList(USSExit);
			RootVisualElement?.RemoveFromClassList(USSExitAsync);
			RootVisualElement?.AddToClassList(USSExited);
			RootVisualElement?.SetActive(false);

			if (AllowReload)
			{
				RootVisualElement?.RemoveFromHierarchy();
				RootVisualElement = null;
			}
			
			OnExitCompleted?.Invoke();
		}
		public event Action OnEntry;
		public event Func<UniTask> OnEntryAsync;
		public event Action OnEntryCompleted;
		public event Action OnExit;
		public event Func<UniTask> OnExitAsync;
		public event Action OnExitCompleted;
		public event Action OnInitiated;
		public event Func<UniTask> OnInitiatedAsync; 

		public virtual void OnTick(float deltaTime)
		{
		}

		public virtual void Dispose()
		{
			InputActionGroup.Dispose();
			RootVisualElement?.RemoveFromHierarchy();
			IsDisposed = true;
		}
	}

}