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

namespace UVC.UIToolkit
{
    /// <summary>
    /// Long 정수(64비트) 입력 필드 컴포넌트.
    /// Unity LongField를 래핑하여 커스텀 스타일을 적용합니다.
    /// -9,223,372,036,854,775,808 ~ 9,223,372,036,854,775,807 범위의 정수를 입력받습니다.
    /// </summary>
    /// <remarks>
    /// <para><b>long(장정수)란?</b></para>
    /// <para>long은 64비트 부호 있는 정수 타입으로, int보다 훨씬 큰 범위의 정수를 저장합니다.</para>
    /// <list type="bullet">
    ///   <item><description>파일 크기(바이트), 타임스탬프, 고유 ID 등에 사용</description></item>
    ///   <item><description>int 범위(-21억~21억)를 초과하는 값에 적합</description></item>
    ///   <item><description>일반 정수는 UTKIntegerField 사용 권장 (메모리 효율)</description></item>
    /// </list>
    /// </remarks>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 Long 필드 생성
    /// var longField = new UTKLongField();
    /// longField.label = "파일 크기 (bytes)";
    /// longField.Value = 1024L * 1024L * 1024L;  // 1GB
    ///
    /// // 값 변경 이벤트
    /// longField.OnValueChanged += (value) => {
    ///     Debug.Log($"파일 크기: {value} bytes");
    /// };
    ///
    /// // 라벨과 기본값을 지정하는 생성자
    /// var timestampField = new UTKLongField("타임스탬프", DateTimeOffset.UtcNow.ToUnixTimeMilliseconds());
    ///
    /// // 현재 값 읽기/쓰기
    /// long currentValue = longField.Value;
    /// longField.Value = 5000000000L;  // 50억
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code><![CDATA[
    /// <!-- 기본 Long 필드 -->
    /// <utk:UTKLongField label="ID" value="9999999999" />
    ///
    /// <!-- 비활성화 상태 -->
    /// <utk:UTKLongField label="고정 ID" is-enabled="false" />
    /// ]]></code>
    /// <para><b>실제 활용 예시 (파일 정보):</b></para>
    /// <code>
    /// // 파일 크기 표시
    /// var fileSizeField = new UTKLongField("파일 크기", fileInfo.Length);
    /// fileSizeField.IsEnabled = false;  // 읽기 전용
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKLongField : LongField, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Input/UTKLongField";
        #endregion

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

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

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

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

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

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

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

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

        private void SetupEvents()
        {
            RegisterCallback<ChangeEvent<long>>(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);
        }
        #endregion

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