using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;
using UnityEngine.UIElements;


namespace BITKit.IData
{
	public sealed class UXDataBindingHandler:IDisposable
	{
		internal unsafe UXDataBindingHandler(void* ptr, object value)
		{
			ValueObject = ptr;
			SafeValueObject = value;

			visualElement = value switch
			{
				Vector3 => new Vector3Field(),
				float => new FloatField(),
				int => new IntegerField(),
				_ => throw new InvalidCastException("未支持的数据类型"),
			};
			switch (visualElement)
			{
				case INotifyValueChanged<int> intField:
					intField.RegisterValueChangedCallback(evt =>
					{
						//UnsafeUtility.AsRef<int>(ValueObject) = evt.newValue;
						//Unsafe.Write(ValueObject,evt.newValue);
						UnsafeUtility.AsRef<int>(ValueObject) = evt.newValue;
					});
					break;
				case INotifyValueChanged<float> floatField:
					floatField.RegisterValueChangedCallback(evt =>
					{
						//Unsafe.Write(ValueObject,evt.newValue);
						UnsafeUtility.AsRef<float>(ValueObject) = evt.newValue;
					});
					break;
				case INotifyValueChanged<Vector3> vector3Field:
					vector3Field.RegisterValueChangedCallback(evt =>
					{
						//Unsafe.Write(ValueObject,evt.newValue);
						UnsafeUtility.AsRef<Vector3>(ValueObject) = evt.newValue;
					});
					
					break;
			}
		}
		internal readonly unsafe void* ValueObject;
		internal object SafeValueObject;
		public VisualElement visualElement { get; }
		public void Dispose()
		{
			visualElement.RemoveFromHierarchy();
		}
		public unsafe void OnValueChanged()
		{
			SafeValueObject = SafeValueObject switch
			{
				int => UnsafeUtility.AsRef<int>(ValueObject),
				float => UnsafeUtility.AsRef<float>(ValueObject),
				Vector3 => UnsafeUtility.AsRef<Vector3>(ValueObject),
				_ => null
			};
			switch (visualElement)
			{
				case INotifyValueChanged<int> intField:
					intField.SetValueWithoutNotify((int)SafeValueObject);
					break;
				case INotifyValueChanged<float> floatField:
					floatField.SetValueWithoutNotify((float)SafeValueObject);
					break;
				case INotifyValueChanged<Vector3> vector3Field:
					vector3Field.SetValueWithoutNotify((Vector3)SafeValueObject);
					break;
			}
		}
	}

	public class UXDataBindingService : MonoBehaviour
	{
		private static readonly List<UXDataBindingHandler> Handlers = new();

		public static unsafe UXDataBindingHandler CreateBinding(void* ptr, object value)
		{
			var handler = new UXDataBindingHandler(ptr, value);
			Handlers.Add(handler);
			return handler;
		}
		public static unsafe UXDataBindingHandler CreateBinding(TypedReference typedReference)
		{
			UXDataBindingHandler handler = null;
			var value = TypedReference.ToObject(typedReference);
			switch (value)
			{
				case int:
				{
					ref var rawValue = ref __refvalue(typedReference, int);
					handler = new UXDataBindingHandler(UnsafeUtility.AddressOf(ref rawValue), value);
				}
					break;
				case float:
				{
					ref var rawValue = ref __refvalue(typedReference, float);
					handler = new UXDataBindingHandler(UnsafeUtility.AddressOf(ref rawValue), value);
				}
					break;
				case Vector3:
				{
					ref var rawValue = ref __refvalue(typedReference, Vector3);
					handler = new UXDataBindingHandler(UnsafeUtility.AddressOf(ref rawValue), value);
				}
					break;
			}

// 			var handler = (value) switch
// 			{
// case int=> new UXDataBindingHandler(UnsafeUtility.AddressOf(ref value), value),
// 				_ => throw new InvalidCastException("未支持的数据类型"),
// 			};
			
			//var handler = new UXDataBindingHandler(&value, __refvalue(typedReference, object));
			Handlers.Add(handler);
			return handler;
		}
		

		[SerializeReference,SubclassSelector] private ITicker ticker;
		
		[SerializeField,ReadOnly] private int bindingCount;
		private void Start()
		{
			ticker.Add(OnTick);
			destroyCancellationToken.Register(() => { ticker.Remove(OnTick); });
		}
		

		private void OnTick(float obj)
		{
			foreach (var handler in Handlers.ToArray())
			{
				unsafe
				{
					if (handler.visualElement.parent is null)
					{
						Handlers.Remove(handler);
						continue;
					}
					
					object value = handler.SafeValueObject switch
					{
						int => UnsafeUtility.AsRef<int>(handler.ValueObject),
						float => UnsafeUtility.AsRef<float>(handler.ValueObject),
						Vector3 => UnsafeUtility.AsRef<Vector3>(handler.ValueObject),
						_ => null
					};

					if (value != handler.SafeValueObject)
					{
						handler.OnValueChanged();
					}
				}
			}
			bindingCount = Handlers.Count;
		}
	}
}