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

namespace UVC.UIToolkit
{
    /// <summary>
    /// Double 실수(64비트 배정밀도) 입력 필드 컴포넌트.
    /// Unity DoubleField를 래핑하여 커스텀 스타일을 적용합니다.
    /// float보다 높은 정밀도의 소수점 숫자를 입력받습니다.
    /// </summary>
    /// <remarks>
    /// <para><b>double(배정밀도 실수)란?</b></para>
    /// <para>double은 64비트 배정밀도 부동소수점 타입으로, float보다 더 정밀한 소수를 저장합니다.</para>
    /// <list type="bullet">
    ///   <item><description>과학 계산, 금융 데이터, 정밀 측정값에 사용</description></item>
    ///   <item><description>float보다 약 2배 정밀도 (유효숫자 15-17자리)</description></item>
    ///   <item><description>일반 게임 로직에는 UTKFloatField로 충분</description></item>
    /// </list>
    /// <para><b>float vs double:</b></para>
    /// <list type="bullet">
    ///   <item><description>float: 32비트, 유효숫자 6-9자리, 게임 그래픽에 적합</description></item>
    ///   <item><description>double: 64비트, 유효숫자 15-17자리, 정밀 계산에 적합</description></item>
    /// </list>
    /// </remarks>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 Double 필드 생성
    /// var doubleField = new UTKDoubleField();
    /// doubleField.label = "정밀 좌표";
    /// doubleField.Value = 3.141592653589793;
    ///
    /// // 값 변경 이벤트
    /// doubleField.OnValueChanged += (value) => {
    ///     Debug.Log($"값: {value:F15}");  // 소수점 15자리 출력
    /// };
    ///
    /// // 라벨과 기본값을 지정하는 생성자
    /// var latitudeField = new UTKDoubleField("위도", 37.5665);
    ///
    /// // 현재 값 읽기/쓰기
    /// double currentValue = doubleField.Value;
    /// doubleField.Value = 127.9780;
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code><![CDATA[
    /// <!-- 기본 Double 필드 -->
    /// <utk:UTKDoubleField label="경도" value="127.9780" />
    ///
    /// <!-- 비활성화 상태 -->
    /// <utk:UTKDoubleField label="PI" value="3.141592653589793" is-enabled="false" />
    /// ]]></code>
    /// <para><b>실제 활용 예시 (GPS 좌표):</b></para>
    /// <code>
    /// // GPS 좌표 입력 (높은 정밀도 필요)
    /// var latField = new UTKDoubleField("위도 (Latitude)", gpsData.Latitude);
    /// var lonField = new UTKDoubleField("경도 (Longitude)", gpsData.Longitude);
    ///
    /// latField.OnValueChanged += (lat) => gpsData.Latitude = lat;
    /// lonField.OnValueChanged += (lon) => gpsData.Longitude = lon;
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKDoubleField : DoubleField, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Input/UTKDoubleField";
        #endregion

        #region Fields
        private bool _disposed;
        private bool _isEnabled = true;
        #endregion

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

        #region Properties
        /// <summary>현재 값</summary>
        public double 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-double-field--disabled", !value);
            }
        }
        #endregion

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

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

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

        public UTKDoubleField(string label, double defaultValue = 0) : this()
        {
            this.label = label;
            value = defaultValue;
        }
        #endregion

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

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

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

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

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

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

            UTKThemeManager.Instance.OnThemeChanged -= OnThemeChanged;
            OnValueChanged = null;
            UnregisterCallback<ChangeEvent<double>>(OnFieldValueChanged);
        }
        #endregion
    }
}