using System;
using System.Collections;
using System.Collections.Generic;
#if UNITY_EDITOR
using UnityEditor;
#endif
using UnityEngine;
using UnityEngine.UIElements;

namespace BITKit.UX
{
	/// <summary>
	/// 适用于Unity的UX Service
	/// </summary>
	public class UXService : MonoBehaviour, IUXService
	{
		[RuntimeInitializeOnLoadMethod]
		private static void Initialized()
		{
			RegistryQueue.Clear();
			UnRegistryQueue.Clear();
			Panels.Clear();
			EntryQueue.Clear();
			EntryCompletedPanels.Clear();
			History.Clear();
		}

		/// <summary>
		/// 内部注册面板队列
		/// </summary>
		private static readonly Queue<IUXPanel> RegistryQueue = new();

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

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

		/// <summary>
		/// 等待启用的面板队列
		/// </summary>
		private static readonly Stack<IUXPanel> EntryQueue = new();

		/// <summary>
		/// 已启用面板
		/// </summary>
		internal static readonly Stack<IUXPanel> EntryCompletedPanels = new();

		/// <summary>
		/// 历史面板
		/// </summary>
		private static readonly Stack<IUXPanel> History = new();

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

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

		public static void Entry<T>() where T : IUXPanel => EntryQueue.Push(Panels[typeof(T).Name]);

		public static void Return()
		{
			if (!History.TryPop(out _)) return;
			if (History.TryPop(out var returnPanel))
			{
				Entry(returnPanel);
			}
		}

		public static void Entry(IUXPanel panel) => EntryQueue.Push(panel);

		public static void Entry(string panelName) => EntryQueue.Push(Panels[panelName]);

		[SerializeReference, SubclassSelector] private IUXPanel initialPanel;

		private bool initialized;
		private void Awake()
		{
			DI.Register<IUXService>(this);
		}

		private void Update()
		{
			while (UnRegistryQueue.TryDequeue(out var result))
			{
				if (result is null) continue;
				Panels.Remove(result.Index);
			}

			while (RegistryQueue.TryDequeue(out var result))
			{
				if (result is null) continue;
				Panels.Set(result.Index, result);
				result.Exit();
			}

			if (initialized is false && initialPanel is not null)
			{
				initialized = true;
				Entry(initialPanel);
			}

			if (!EntryQueue.TryPop(out var next)) return;

			while (EntryCompletedPanels.TryPop(out var entryCompletedPanel))
			{
				entryCompletedPanel?.Exit();
			}

			next.Entry();
			
			BITAppForUnity.AllowCursor.SetElements(this, next.AllowCursor);
			BITInputSystem.AllowInput.SetElements(this, next.AllowInput);
			
			EntryCompletedPanels.Push(next);
			History.Push(next);
		}

		void IUXService.Register(IUXPanel panel) => Register(panel);

		void IUXService.UnRegister(IUXPanel panel) => UnRegister(panel);

		void IUXService.Entry<T>() => Entry<T>();

		void IUXService.Return() => Return();

		void IUXService.Entry(IUXPanel panel) => Entry(panel);

		void IUXService.Entry(string panelName) => Entry(panelName);
	}
	#if UNITY_EDITOR
	[CustomEditor(typeof(UXService))]
	public class UXServiceInspector:BITInspector<UXService>
	{
		private Label currentPanelLabel;
		private Label panelsLabel;
		public override VisualElement CreateInspectorGUI()
		{
			FillDefaultInspector();
			CreateSubTitle("States");
			currentPanelLabel = root.Create<Label>();
			CreateSubTitle("Panels");
			panelsLabel = root.Create<Label>();
			
			return root;
		}

		protected override void OnUpdate()
		{
			panelsLabel.text=string.Join("\n",UXService.Panels); 
			currentPanelLabel.text = string.Join("\n",UXService.EntryCompletedPanels); 
		}
	}
	#endif
}