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

namespace UVC.UIToolkit
{
    /// <summary>
    /// Vector2(2D 벡터) 입력 필드 컴포넌트.
    /// Unity Vector2Field를 래핑하여 커스텀 스타일을 적용합니다.
    /// X, Y 두 개의 float 값을 입력받아 2D 좌표나 크기를 표현합니다.
    /// </summary>
    /// <remarks>
    /// <para><b>Vector2란?</b></para>
    /// <para>Vector2는 2차원 공간의 점이나 방향을 나타내는 구조체입니다.</para>
    /// <para>- X: 수평(가로) 방향의 값</para>
    /// <para>- Y: 수직(세로) 방향의 값</para>
    /// <para>주로 2D 게임의 위치, UI 크기, 텍스처 좌표(UV) 등에 사용됩니다.</para>
    /// </remarks>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 Vector2 필드 생성
    /// var vec2Field = new UTKVector2Field();
    /// vec2Field.label = "UI 크기";
    ///
    /// // 초기값 설정
    /// vec2Field.Value = new Vector2(100, 50);  // 가로 100, 세로 50
    ///
    /// // 값 변경 이벤트 처리
    /// vec2Field.OnValueChanged += (vec) => {
    ///     Debug.Log($"크기 변경: 가로={vec.x}, 세로={vec.y}");
    /// };
    ///
    /// // 라벨 커스터마이징
    /// vec2Field.XLabel = "가로";
    /// vec2Field.YLabel = "세로";
    ///
    /// // 비활성화
    /// vec2Field.IsEnabled = false;
    ///
    /// // 읽기 전용 (사용자가 수정할 수 없음)
    /// var readOnlyField = new UTKVector2Field("고정 크기");
    /// readOnlyField.Value = new Vector2(100, 50);
    /// readOnlyField.IsReadOnly = true;
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <!-- 네임스페이스 선언 -->
    /// <UXML xmlns:utk="UVC.UIToolkit">
    ///     <!-- 기본 Vector2 필드 -->
    ///     <utk:UTKVector2Field label="위치" />
    ///
    ///     <!-- 커스텀 라벨 -->
    ///     <utk:UTKVector2Field label="크기" x-label="Width" y-label="Height" />
    ///
    ///     <!-- 비활성화 -->
    ///     <utk:UTKVector2Field label="비활성화" is-enabled="false" />
    ///
    ///     <!-- 읽기 전용 -->
    ///     <utk:UTKVector2Field label="고정 크기" is-readonly="true" />
    /// </UXML>
    /// </code>
    /// <para><b>실제 활용 예시:</b></para>
    /// <code>
    /// // RectTransform 크기 조절
    /// var sizeField = new UTKVector2Field("UI 크기");
    /// sizeField.Value = rectTransform.sizeDelta;
    /// sizeField.OnValueChanged += (size) => {
    ///     rectTransform.sizeDelta = size;
    /// };
    ///
    /// // 스프라이트 피벗 설정
    /// var pivotField = new UTKVector2Field("피벗");
    /// pivotField.XLabel = "X (0~1)";
    /// pivotField.YLabel = "Y (0~1)";
    /// pivotField.Value = new Vector2(0.5f, 0.5f);  // 중앙
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKVector2Field : Vector2Field, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Input/UTKVector2Field";
        #endregion

        #region Fields
        private bool _disposed;
        private bool _isEnabled = true;
        private bool _isReadOnly = false;
        private string _xLabel = "X";
        private string _yLabel = "Y";
        #endregion

        #region Events
        /// <summary>값 변경 이벤트</summary>
        public event Action<Vector2>? OnValueChanged;
        #endregion

        #region Properties
        /// <summary>현재 값</summary>
        public Vector2 Value
        {
            get => value;
            set => this.value = value;
        }

        /// <summary>활성화 상태</summary>
        [UxmlAttribute("is-enabled")]
        public bool IsEnabled
        {
            get => _isEnabled;
            set
            {
                _isEnabled = value;
                SetEnabled(value);
                EnableInClassList("utk-vector2-field--disabled", !value);
            }
        }

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

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

        /// <summary>읽기 전용 상태</summary>
        [UxmlAttribute("is-readonly")]
        public bool IsReadOnly
        {
            get => _isReadOnly;
            set
            {
                _isReadOnly = value;
                UpdateReadOnlyState();
                EnableInClassList("utk-vector2-field--readonly", value);
            }
        }
        #endregion

        #region Constructor
        public UTKVector2Field() : base()
        {
            UTKThemeManager.Instance.ApplyThemeToElement(this);

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

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

        public UTKVector2Field(bool isReadOnly) : this()
        {
            _isReadOnly = isReadOnly;
            UpdateReadOnlyState();
        }

        public UTKVector2Field(string label, bool isReadOnly = false) : this()
        {
            this.label = label;
            _isReadOnly = isReadOnly;
            UpdateReadOnlyState();
        }
        #endregion

        #region Setup
        private void SetupStyles()
        {
            AddToClassList("utk-vector2-field");

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

        private void SetupEvents()
        {
            RegisterCallback<ChangeEvent<Vector2>>(OnFieldValueChanged);
        }

        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);
        }

        private void UpdateAxisLabels()
        {
            // Vector2Field의 내부 FloatField들을 찾아서 라벨 변경
            var floatFields = this.Query<FloatField>().ToList();
            if (floatFields.Count >= 2)
            {
                floatFields[0].label = _xLabel;
                floatFields[1].label = _yLabel;
            }
        }

        private void UpdateReadOnlyState()
        {
            // 내부 FloatField들의 TextInput을 찾아서 읽기 전용 설정
            var textInputs = this.Query<TextInputBaseField<float>>().ToList();
            foreach (var textInput in textInputs)
            {
                textInput.isReadOnly = _isReadOnly;
            }
        }
        #endregion

        #region Event Handlers
        private void OnFieldValueChanged(ChangeEvent<Vector2> 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<Vector2>>(OnFieldValueChanged);
        }
        #endregion
    }
}