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

namespace UVC.UIToolkit
{
    /// <summary>
    /// Vector4(4D 벡터) 입력 필드 컴포넌트.
    /// Unity Vector4Field를 래핑하여 커스텀 스타일을 적용합니다.
    /// X, Y, Z, W 네 개의 float 값을 입력받습니다.
    /// </summary>
    /// <remarks>
    /// <para><b>Vector4란?</b></para>
    /// <para>Vector4는 4개의 float 값을 저장하는 구조체입니다.</para>
    /// <para>주로 다음 용도로 사용됩니다:</para>
    /// <para>- 동차 좌표(Homogeneous coordinates): 3D 변환에서 이동을 포함한 행렬 연산</para>
    /// <para>- 색상(RGBA): Red, Green, Blue, Alpha 값 (0~1 범위)</para>
    /// <para>- 쉐이더 파라미터: 커스텀 쉐이더에 전달하는 4개의 값</para>
    /// <para>- 사원수(Quaternion)와 유사한 구조로 회전 데이터 저장</para>
    /// </remarks>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 Vector4 필드 생성
    /// var vec4Field = new UTKVector4Field();
    /// vec4Field.label = "쉐이더 파라미터";
    ///
    /// // 초기값 설정
    /// vec4Field.Value = new Vector4(1, 0.5f, 0.5f, 1);
    ///
    /// // 값 변경 이벤트 처리
    /// vec4Field.OnValueChanged += (vec) => {
    ///     Debug.Log($"파라미터: X={vec.x}, Y={vec.y}, Z={vec.z}, W={vec.w}");
    /// };
    ///
    /// // 라벨 커스터마이징 (RGBA 색상용)
    /// vec4Field.XLabel = "R";
    /// vec4Field.YLabel = "G";
    /// vec4Field.ZLabel = "B";
    /// vec4Field.WLabel = "A";
    ///
    /// // 비활성화
    /// vec4Field.IsEnabled = false;
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <!-- 네임스페이스 선언 -->
    /// <UXML xmlns:utk="UVC.UIToolkit">
    ///     <!-- 기본 Vector4 필드 -->
    ///     <utk:UTKVector4Field label="값" />
    ///
    ///     <!-- RGBA 색상용 커스텀 라벨 -->
    ///     <utk:UTKVector4Field label="색상"
    ///         x-label="R" y-label="G" z-label="B" w-label="A" />
    ///
    ///     <!-- 비활성화 -->
    ///     <utk:UTKVector4Field label="고정값" is-enabled="false" />
    /// </UXML>
    /// </code>
    /// <para><b>실제 활용 예시:</b></para>
    /// <code>
    /// // 머티리얼 쉐이더 파라미터 설정
    /// var shaderParam = new UTKVector4Field("_MainTex_ST");
    /// shaderParam.XLabel = "Tile X";
    /// shaderParam.YLabel = "Tile Y";
    /// shaderParam.ZLabel = "Offset X";
    /// shaderParam.WLabel = "Offset Y";
    /// shaderParam.Value = new Vector4(1, 1, 0, 0);  // 기본 타일링
    /// shaderParam.OnValueChanged += (vec) => {
    ///     material.SetVector("_MainTex_ST", vec);
    /// };
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKVector4Field : Vector4Field, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Input/UTKVector4Field";
        #endregion

        #region Fields
        private bool _disposed;
        private bool _isEnabled = true;
        private string _xLabel = "X";
        private string _yLabel = "Y";
        private string _zLabel = "Z";
        private string _wLabel = "W";
        #endregion

        #region Events
        /// <summary>값 변경 이벤트</summary>
        public event Action<Vector4>? OnValueChanged;
        #endregion

        #region Properties
        /// <summary>활성화 상태</summary>
        [UxmlAttribute]
        public bool IsEnabled
        {
            get => _isEnabled;
            set
            {
                _isEnabled = value;
                SetEnabled(value);
                EnableInClassList("utk-vector4field--disabled", !value);
            }
        }

        /// <summary>현재 값</summary>
        public Vector4 Value
        {
            get => value;
            set => this.value = value;
        }

        /// <summary>X축 라벨</summary>
        [UxmlAttribute]
        public string XLabel
        {
            get => _xLabel;
            set
            {
                _xLabel = value;
                UpdateAxisLabels();
            }
        }

        /// <summary>Y축 라벨</summary>
        [UxmlAttribute]
        public string YLabel
        {
            get => _yLabel;
            set
            {
                _yLabel = value;
                UpdateAxisLabels();
            }
        }

        /// <summary>Z축 라벨</summary>
        [UxmlAttribute]
        public string ZLabel
        {
            get => _zLabel;
            set
            {
                _zLabel = value;
                UpdateAxisLabels();
            }
        }

        /// <summary>W축 라벨</summary>
        [UxmlAttribute]
        public string WLabel
        {
            get => _wLabel;
            set
            {
                _wLabel = value;
                UpdateAxisLabels();
            }
        }
        #endregion

        #region Constructor
        public UTKVector4Field() : base()
        {
            UTKThemeManager.Instance.ApplyThemeToElement(this);

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

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

        public UTKVector4Field(string label) : this()
        {
            this.label = label;
        }
        #endregion

        #region Setup
        private void SetupStyles()
        {
            AddToClassList("utk-vector4field");

            // 초기 라벨 설정
            schedule.Execute(() => UpdateAxisLabels());
        }

        private void SetupEvents()
        {
            this.RegisterValueChangedCallback(OnFieldValueChanged);
        }

        private void SubscribeToThemeChanges()
        {
            UTKThemeManager.Instance.OnThemeChanged += OnThemeChanged;
            RegisterCallback<DetachFromPanelEvent>(_ =>
            {
                UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            });
        }

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

        private void UpdateAxisLabels()
        {
            // Vector4Field의 내부 FloatField들을 찾아서 라벨 변경
            var floatFields = this.Query<FloatField>().ToList();
            if (floatFields.Count >= 4)
            {
                floatFields[0].label = _xLabel;
                floatFields[1].label = _yLabel;
                floatFields[2].label = _zLabel;
                floatFields[3].label = _wLabel;
            }
        }
        #endregion

        #region Event Handlers
        private void OnFieldValueChanged(ChangeEvent<Vector4> evt)
        {
            OnValueChanged?.Invoke(evt.newValue);
        }
        #endregion

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

            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            OnValueChanged = null;
        }
        #endregion
    }
}