using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEngine;
using UnityEngine.UIElements;

namespace BITKit.UX
{
	[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property)]
	public class UXBindPathAttribute : Attribute
	{
		public string Path;
		public bool CanBeNull;

		public UXBindPathAttribute()
		{
		}

		public UXBindPathAttribute(string path)
		{
			Path = path;
		}

		public UXBindPathAttribute(string path, bool canBeNull)
		{
			Path = path;
			CanBeNull = canBeNull;
		}
	}

	public class UXUtils
	{
		public static void Inject(object self,VisualElement root=null)
		{
			UIDocument document = null;

			var field = self.GetType().GetField("document",
				BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);

			var rootVisualElementFieldInfo = self.GetType().GetField("RootVisualElement",
				BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
			var rootVisualElementPropertyInfo = self.GetType().GetProperty("RootVisualElement",
				BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);

			var rootVisualElement = (rootVisualElementFieldInfo, rootVisualElementPropertyInfo) switch
			{
				{ } when rootVisualElementPropertyInfo?.GetValue(self) is VisualElement ve => ve,
				{ } when rootVisualElementFieldInfo?.GetValue(self) is VisualElement ve => ve,
				_ => root,
			};
			

			if (rootVisualElement is not null)
			{

			}
			else
			{
				switch (field)
				{
					case null when self is MonoBehaviour monoBehaviour &&
					               monoBehaviour.TryGetComponent<UIDocument>(out document):
						break;
					case not null when field.GetValue(self) is UIDocument _document:
						document = _document;
						break;
					default:
						BIT4Log.Warning<UXUtils>($"document 未赋值或未找到@{self.GetType().Name}");
						return;
				}
			}


			foreach (var fieldInfo in self.GetType()
				         .GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly)
				         .Where(x => x.GetCustomAttribute<UXBindPathAttribute>() is not null)
			        )
			{
				var bindPathAtt = fieldInfo.GetCustomAttribute<UXBindPathAttribute>();
				VisualElement ve = (document, rootVisualElement) switch
				{
					(_, not null) => rootVisualElement,
					(not null, _) => document.rootVisualElement,
					_ => throw new NotImplementedException(),
				};
				foreach (var path in bindPathAtt.Path.Split("."))
				{
					ve = ve.Q(path);
				}

				//ve = document.rootVisualElement.Q(bindPathAtt.Path);
				if (bindPathAtt.CanBeNull is false && ve is null)
					BIT4Log.LogException(new NullReferenceException($"{self.GetType().Name},{rootVisualElement.name}上未找到{bindPathAtt.Path}"));

				try
				{
					fieldInfo.SetValue(self, ve);
				}
				catch (Exception e)
				{
					BIT4Log.Warning<UXUtils>(fieldInfo!.Name);
				}
			}
		}
	}
}