#nullable enable
using System;
using UnityEngine;
using UnityEngine.UIElements;

namespace UVC.UIToolkit
{
    /// <summary>
    /// 탭 컴포넌트.
    /// Unity Tab을 래핑하여 커스텀 스타일을 적용합니다.
    /// </summary>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // UTKTabView와 함께 사용
    /// var tabView = new UTKTabView();
    /// 
    /// var tab1 = new UTKTab();
    /// tab1.Text = "일반";
    /// tab1.Add(new Label("일반 탭 내용"));
    /// tabView.Add(tab1);
    /// 
    /// var tab2 = new UTKTab();
    /// tab2.Text = "고급";
    /// tab2.IsEnabled = false; // 비활성화
    /// tabView.Add(tab2);
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <ui:UXML xmlns:utk="UVC.UIToolkit">
    ///     <utk:UTKTabView>
    ///         <utk:UTKTab label="일반">
    ///             <ui:Label text="일반 내용" />
    ///         </utk:UTKTab>
    ///         <utk:UTKTab label="고급">
    ///             <ui:Label text="고급 내용" />
    ///         </utk:UTKTab>
    ///     </utk:UTKTabView>
    /// </ui:UXML>
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKTab : Tab, IDisposable
    {
        #region Fields
        private bool _disposed;
        private bool _isEnabled = true;
        #endregion

        #region Properties
        /// <summary>탭 텍스트</summary>
        public string Text
        {
            get => label;
            set => label = value;
        }

        /// <summary>선택 상태</summary>
        public bool IsSelected
        {
            get => ClassListContains("utk-tab--selected");
            set => EnableInClassList("utk-tab--selected", value);
        }

        /// <summary>활성화 상태</summary>
        [UxmlAttribute("is-enabled")]
        public bool IsEnabled
        {
            get => _isEnabled;
            set
            {
                _isEnabled = value;
                SetEnabled(value);
                EnableInClassList("utk-tab--disabled", !value);
            }
        }
        #endregion

        #region Constructor
        public UTKTab() : base()
        {
            UTKThemeManager.Instance.ApplyThemeToElement(this);
            SetupStyles();
            SubscribeToThemeChanges();
        }

        public UTKTab(string text) : this()
        {
            label = text;
        }
        #endregion

        #region Setup
        private void SetupStyles()
        {
            AddToClassList("utk-tab");
        }

        private void SubscribeToThemeChanges()
        {
            UTKThemeManager.Instance.OnThemeChanged += OnThemeChanged;
            RegisterCallback<AttachToPanelEvent>(OnAttachToPanelForTheme);
            RegisterCallback<DetachFromPanelEvent>(OnDetachFromPanelForTheme);
        }

        private void OnAttachToPanelForTheme(AttachToPanelEvent evt)
        {
            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            UTKThemeManager.Instance.OnThemeChanged += OnThemeChanged;
            UTKThemeManager.Instance.ApplyThemeToElement(this);
        }

        private void OnDetachFromPanelForTheme(DetachFromPanelEvent evt)
        {
            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
        }

        private void OnThemeChanged(UTKTheme theme)
        {
            UTKThemeManager.Instance.ApplyThemeToElement(this);
        }
        #endregion

        #region IDisposable
        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;

            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            UnregisterCallback<AttachToPanelEvent>(OnAttachToPanelForTheme);
            UnregisterCallback<DetachFromPanelEvent>(OnDetachFromPanelForTheme);
        }
        #endregion
    }
}