XRLib/Assets/Scripts/UVC/UIToolkit/Common/UTKFoldout.cs

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

namespace UVC.UIToolkit
{
    /// <summary>
    /// 접을 수 있는 섹션 컴포넌트.
    /// Unity Foldout을 래핑하여 커스텀 스타일을 적용합니다.
    /// 헤더 클릭으로 내용을 펼치거나 접을 수 있습니다.
    /// </summary>
    /// <remarks>
    /// <para><b>Foldout(폴드아웃)이란?</b></para>
    /// <para>
    /// Foldout은 헤더를 클릭하여 내용을 펼치거나 접을 수 있는 컨테이너입니다.
    /// 아코디언(Accordion)이라고도 불리며, 많은 내용을 정리할 때 유용합니다.
    /// Unity Inspector에서 컴포넌트 섹션을 접는 것과 같은 동작입니다.
    /// </para>
    ///
    /// <para><b>Foldout vs Panel 차이:</b></para>
    /// <list type="bullet">
    /// <item><description><c>Foldout</c> - 간단한 접기/펼치기, 토글 화살표 표시</description></item>
    /// <item><description><c>Panel</c> - 헤더/푸터/액션 등 풍부한 기능, 더 많은 커스터마이징</description></item>
    /// </list>
    ///
    /// <para><b>주요 속성:</b></para>
    /// <list type="bullet">
    /// <item><description><c>text</c> - 헤더에 표시되는 제목</description></item>
    /// <item><description><c>value</c> / <c>IsExpanded</c> - 펼침 상태 (true=펼침, false=접힘)</description></item>
    /// </list>
    ///
    /// <para><b>실제 활용 예시:</b></para>
    /// <list type="bullet">
    /// <item><description>설정 페이지 - 고급 설정 숨기기</description></item>
    /// <item><description>FAQ - 질문 클릭 시 답변 표시</description></item>
    /// <item><description>인스펙터 - 컴포넌트 섹션 접기</description></item>
    /// <item><description>필터 패널 - 상세 필터 옵션 숨기기</description></item>
    /// </list>
    /// </remarks>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 폴드아웃
    /// var foldout = new UTKFoldout("고급 설정", expanded: false);
    /// foldout.Add(new Label("옵션 1"));
    /// foldout.Add(new Label("옵션 2"));
    /// 
    /// // 상태 변경 이벤트
    /// foldout.OnValueChanged += (isExpanded) => {
    ///     Debug.Log(isExpanded ? "펼쳐짐" : "접힘");
    /// };
    /// 
    /// // 프로그래밍 방식으로 상태 제어
    /// foldout.IsExpanded = true;
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <ui:UXML xmlns:utk="UVC.UIToolkit">
    ///     <!-- 기본 폴드아웃 -->
    ///     <utk:UTKFoldout text="설정" value="true">
    ///         <ui:Label text="내용 1" />
    ///         <ui:Label text="내용 2" />
    ///     </utk:UTKFoldout>
    ///     
    ///     <!-- 접힌 상태 -->
    ///     <utk:UTKFoldout text="고급 옵션" value="false">
    ///         <ui:Label text="숨겨진 내용" />
    ///     </utk:UTKFoldout>
    /// </ui:UXML>
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKFoldout : Foldout, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Common/UTKFoldout";
        #endregion

        #region Fields
        private bool _disposed;
        #endregion

        #region Events
        /// <summary>펼침/접힘 상태 변경 이벤트</summary>
        public event Action<bool>? OnValueChanged;
        #endregion

        #region Properties
        /// <summary>펼침 상태</summary>
        public bool IsExpanded
        {
            get => value;
            set => this.value = value;
        }
        #endregion

        #region Constructor
        public UTKFoldout() : base()
        {
            UTKThemeManager.Instance.ApplyThemeToElement(this);

            var uss = Resources.Load<StyleSheet>(USS_PATH);
            if (uss != null)
            {
                styleSheets.Add(uss);
            }

            SetupStyles();
            SetupEvents();
            SubscribeToThemeChanges();
        }

        public UTKFoldout(string title, bool expanded = true) : this()
        {
            text = title;
            value = expanded;
        }
        #endregion

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

        private void SetupEvents()
        {
            RegisterCallback<ChangeEvent<bool>>(OnFoldoutValueChanged);
        }

        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 Event Handlers
        private void OnFoldoutValueChanged(ChangeEvent<bool> evt)
        {
            OnValueChanged?.Invoke(evt.newValue);
        }
        #endregion

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

            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            UnregisterCallback<AttachToPanelEvent>(OnAttachToPanelForTheme);
            UnregisterCallback<DetachFromPanelEvent>(OnDetachFromPanelForTheme);
            OnValueChanged = null;
            UnregisterCallback<ChangeEvent<bool>>(OnFoldoutValueChanged);
        }
        #endregion
    }
}