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

namespace BITKit.UX
{
	/// <summary>
	/// Tab容器,仅用于快速生成TabBar
	/// </summary>
	[UnityEngine.Scripting.Preserve]
	public class TabBar : VisualElement,INotifyValueChanged<int>
	{
		public new class UxmlTraits:VisualElement.UxmlTraits
		{
			private readonly UxmlIntAttributeDescription m_TabBarAttribute = new ()
			{
				name = "CurrentTab",
				defaultValue = -1
			};
			private readonly UxmlStringAttributeDescription m_TabsAttribute = new ()
			{
				name = "tabs"
			};
			private readonly UxmlBoolAttributeDescription m_allowFocus = new ()
			{
				name = "allowFocus",
				defaultValue = true
			};
			public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
			{
				base.Init(ve, bag, cc);
				var tabBar = (TabBar)ve;
				tabBar.CurrentTab = m_TabBarAttribute.GetValueFromBag(bag, cc);
				tabBar.Tabs = m_TabsAttribute.GetValueFromBag(bag, cc);
				tabBar.allowFocus = m_allowFocus.GetValueFromBag(bag, cc);
			}
		}
		public new class UxmlFactory : UxmlFactory<TabBar, UxmlTraits> { }
		// These are USS class names for the control overall and the label.

		public TabBar()
		{
			RegisterCallback<AttachToPanelEvent>(UpdateI);
			RegisterCallback<DetachFromPanelEvent>(UpdateI);
			RegisterCallback<GeometryChangedEvent>(UpdateI);
		}

		private void UpdateI(object _)
		{
			CurrentTab = _currentTab;
		}
		
		public event Action<int> OnTabChanged; 
		
		private Button[] _buttons = Array.Empty<Button>();
		private int _currentTab;
		public int CurrentTab
		{
			get=>_currentTab;
			set
			{
				if(_currentTab == value)return;
				_currentTab = value;
				SetTabs(value);
			}
		}
		
		private string tabs;
		public string Tabs
		{
			get => tabs;
			set
			{
				tabs = value;
				SetTabs(value);
			}
		}
		
		private bool allowFocus;
		public bool AllowFocus
		{
			get => allowFocus;
			set
			{
				allowFocus = value;
				foreach (var x in _buttons)
				{
					x.focusable = value;
				}
			}
		}
		
		
		private void SetTabs(string value)
		{
			var split = value.Split(",");
			foreach (var x in _buttons)
			{
				x.RemoveFromHierarchy();
			}
			_buttons = new Button[split.Length];
			for (var i = 0; i < split.Length; i++)
			{
				var tabName = split[i];
				var index = i;
				var button = _buttons[i] = this.Create<Button>();
				button.AddToClassList("v"+i);
				button.text = tabName;
				button.focusable = allowFocus;
				button.clicked += () => CurrentTab = index;
			}
		}

		private void SetTabs(int index)
		{
			SetValueWithoutNotify(index);
			OnTabChanged?.Invoke(index);
			MarkDirtyRepaint();
		}

		public void SetValueWithoutNotify(int newValue)
		{
			switch (newValue)
			{
				case var _ when newValue < 0 || newValue > _buttons.Length:
					return;
			}
			for (var i = 0; i < _buttons.Length; i++)
			{
				var button = _buttons[i];
				var entry = newValue == i;
				button.SetEnabled(!entry);
			}
		}
        int INotifyValueChanged<int>.value
		{
			get => CurrentTab;
			set=>CurrentTab = value;
		}
	}


}