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

namespace BITKit.UX
{
	public class TabContainer : VisualElement
	{
		public new class UxmlTraits:VisualElement.UxmlTraits
		{
			private readonly UxmlStringAttributeDescription _mTabPath = new ()
			{
				name = "TabPath",
			};
			public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
			{
				base.Init(ve, bag, cc);
				var container = (TabContainer)ve;
				container.TabPath = _mTabPath.GetValueFromBag(bag, cc);
			}
		}
		public new class UxmlFactory : UxmlFactory<TabContainer, UxmlTraits> { }
		public TabContainer()
		{
			RegisterCallback<AttachToPanelEvent>(RebuildOnEvent);
			RegisterCallback<DetachFromPanelEvent>(RebuildOnEvent);
			RegisterCallback<GeometryChangedEvent>(RebuildOnEvent);
			RegisterCallback<BlurEvent>(RebuildOnEvent);
			RegisterCallback<FocusEvent>(RebuildOnEvent);
		}
		public string TabPath
		{
			get=>_tabPath;
			set
			{
				_tabPath = value;
				Rebuild();
			}
		}
		private string _tabPath;
		private TabBar _tabBar;
		private int _index;
		private void RebuildOnEvent<T>(T evt)
		{
			Rebuild();
		}
		private void Rebuild()
		{
			if (_tabBar is not null)
			{
				_tabBar.OnTabChanged -= OnTabChanged;
			}
			var p = parent;
			while (p is not null)
			{
				_tabBar = p.Q<TabBar>(TabPath);
				if (_tabBar is not null)
				{
					break;
				}
				p = p.parent;
			}
			if (_tabBar is not null)
			{
				_tabBar.OnTabChanged += OnTabChanged;
				_index = _tabBar.CurrentTab;
			}
			OnTabChanged(_index);
		}

		private void OnTabChanged(int obj)
		{
			_index = obj;
			if (childCount < 0) return;
			for (var i = 0; i < childCount; i++)
			{
				var visualElement = this[i];
				visualElement.SetActive(i == _index);
			}
		}
	}
}