using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using BITKit.Mod;
using Cysharp.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using UnityEngine;
using UnityEngine.UIElements;
using Object = UnityEngine.Object;

namespace BITKit.UX
{
	/// <summary>
	/// 适用于Unity的UX Service
	/// </summary>
	public class UXService : IUXService
	{
		private readonly IAfterTicker _ticker;
		private readonly IServiceProvider _serviceProvider;
		private readonly CancellationTokenSource _cancellationTokenSource;
		public UXService(IAfterTicker ticker, IServiceProvider serviceProvider, CancellationTokenSource cancellationTokenSource)
		{
			_ticker = ticker;
			_serviceProvider = serviceProvider;
			_cancellationTokenSource = cancellationTokenSource;
			_entryGroup.OnEntry += OnEntry;
			_ticker.Add(OnTick);
		}
		
		private readonly EntryGroup<IUXPanel> _entryGroup = new();
		private readonly EntryGroup<IUXPanel> _windowEntryGroup = new();
		/// <summary>
		/// 内部注册面板队列
		/// </summary>
		private readonly Queue<IUXPanel> _registryQueue = new();

		/// <summary>
		/// 内部注销面板队列
		/// </summary>
		private readonly Queue<IUXPanel> _unRegistryQueue = new();

		/// <summary>
		/// 已注册面板字典
		/// </summary>
		private readonly Dictionary<string, IUXPanel> _panels = new();

		/// <summary>
		/// 等待启用的面板队列
		/// </summary>
		private readonly Stack<IUXPanel> _entryQueue = new();
		private readonly List<string> _entryQueueByName = new();

		/// <summary>
		/// 返回面板缓冲区
		/// </summary>
		private readonly DoubleBuffer<IUXPanel> _returnBuffer = new();

		/// <summary>
		/// 已启用面板
		/// </summary>
		private IUXPanel _currentPanel;

		/// <summary>
		/// 历史面板
		/// </summary>
		private static readonly Stack<IUXPanel> History = new();
		
		/// <summary>
		/// 清空历史面板,通常用于关闭返回上一步
		/// </summary>
		public static void ClearHistory() => History.Clear();

		public object Root { get; private set; }
		public async UniTask InitializeAsync()
		{
			
			var gameObject = new GameObject("UXService");
			Object.DontDestroyOnLoad(gameObject);

			_cancellationTokenSource.Token.Register(() =>
			{
Object.Destroy(gameObject);
			});
			
			var document = gameObject.AddComponent<UIDocument>();
			try
			{
				var panelSettings =await ModService.LoadAsset<PanelSettings>("ux_panel_settings");
				document.panelSettings = panelSettings;
			}
			catch (Exception e)
			{
				BIT4Log.Warning<UXService>("未找到ux_panel_settings");
				throw;
			}
		
		
			Root = document.rootVisualElement;
		}

		public void Register(IUXPanel panel) => _registryQueue.Enqueue(panel);

		public void UnRegister(IUXPanel panel) => _unRegistryQueue.Enqueue(panel);

		public void Entry<T>() where T : IUXPanel
		{
			var panel = _serviceProvider.GetRequiredService<T>();
			Entry(panel);
			//Entry(typeof(T).Name);
		}

		public void Entry(IUXPanel panel) => _entryQueue.Push(panel);
		public void Entry(string panelName) => _entryQueueByName.TryAdd(panelName);
		public IUXPanel CurrentPanel => _currentPanel;
		public event Action<IUXPanel, IUXPanel> OnPanelChanged;

		public void Return()
		{
			if(_windowEntryGroup.TryGetEntried(out _))
			{
				_windowEntryGroup.Entry(-1);
				return;
			}
			if (History.TryPop(out var returnPanel))
			{
				_returnBuffer.Release(returnPanel);
			}
		}

		

		private bool _initialized;

	
		private void OnEntry(IUXPanel obj)
		{
			OnPanelChanged?.Invoke(_currentPanel,obj);
			_currentPanel = obj;
		}
		private void OnTick(float delta)
		{
			try
			{
				while (_registryQueue.TryDequeue(out var result))
				{
					if (result is null) continue;
					_entryGroup.list.Add(result);
					_panels.Set(result.Index, result);
				}
			
				while (_unRegistryQueue.TryDequeue(out var result))
				{
					if (result is null) continue;
					_entryGroup.list.Remove(result);
					_panels.Remove(result.Index);
				}

				if (_returnBuffer.TryGetRelease(out var returnPanel))
				{
					_entryGroup.Entry(x=>x.Index==returnPanel.Index);
					BITAppForUnity.AllowCursor.SetElements(this, returnPanel.AllowCursor);
					BITInputSystem.AllowInput.SetElements(this, returnPanel.AllowInput);
				}

				foreach (var panelName in _entryQueueByName)
				{
					if (!_panels.TryGetValue(panelName, out var panel))continue;
					_entryQueue.Push(panel);
					_entryQueueByName.TryRemove(panelName);
					break;
				}
				if (_entryQueue.TryPop(out var nextPanel))
				{
					if (nextPanel.IsWindow)
					{
						_windowEntryGroup.Entry(nextPanel);
						return;
					}
					_windowEntryGroup.Entry(-1);
					History.Push(_currentPanel);
					_entryGroup.Entry(x=>x.Index==nextPanel.Index);
					BITAppForUnity.AllowCursor.SetElements(this, nextPanel.AllowCursor);
					BITInputSystem.AllowInput.SetElements(this, nextPanel.AllowInput);
				}
				if (_entryGroup.TryGetEntried(out var currentPanel))
				{
					currentPanel.OnTick(Time.deltaTime);
				}
				if(_windowEntryGroup.TryGetEntried(out var windowPanel))
				{
					windowPanel.OnTick(Time.deltaTime);
				}
			}
			catch (Exception e)
			{
				BIT4Log.LogException(e);
			}
		}

		public async void Dispose()
		{
			_ticker.Remove(OnTick);
			await UniTask.SwitchToMainThread();
			if (_currentPanel is not null)
			{
				// ReSharper disable once MethodHasAsyncOverload
				_currentPanel.Exit();
				await _currentPanel.ExitAsync();
				_currentPanel.Exited();
			}
		}
	}
}