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

namespace UVC.UIToolkit
{
    /// <summary>
    /// 최소-최대 범위 슬라이더 컴포넌트.
    /// Unity MinMaxSlider를 래핑하여 커스텀 스타일을 적용합니다.
    /// </summary>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 범위 슬라이더
    /// var slider = new UTKMinMaxSlider();
    /// slider.label = "가격 범위";
    /// slider.lowLimit = 0;
    /// slider.highLimit = 1000;
    /// slider.MinValue = 100;
    /// slider.MaxValue = 500;
    /// 
    /// // 값 변경 이벤트
    /// slider.OnValueChanged += (range) => {
    ///     Debug.Log($"범위: {range.x} ~ {range.y}");
    /// };
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <ui:UXML xmlns:utk="UVC.UIToolkit">
    ///     <utk:UTKMinMaxSlider label="범위" low-limit="0" high-limit="100" min-value="20" max-value="80" />
    /// </ui:UXML>
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKMinMaxSlider : MinMaxSlider, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Slider/UTKMinMaxSlider";
        #endregion

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

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

        #region Properties
        /// <summary>최소값</summary>
        public float MinValue
        {
            get => minValue;
            set => minValue = value;
        }

        /// <summary>최대값</summary>
        public float MaxValue
        {
            get => maxValue;
            set => maxValue = value;
        }

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

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

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

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

        public UTKMinMaxSlider(string label, float minLimit = 0f, float maxLimit = 100f, float minValue = 0f, float maxValue = 100f) : this()
        {
            this.label = label;
            this.lowLimit = minLimit;
            this.highLimit = maxLimit;
            this.minValue = minValue;
            this.maxValue = maxValue;
        }
        #endregion

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

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

        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 OnSliderValueChanged(ChangeEvent<Vector2> evt)
        {
            OnValueChanged?.Invoke(evt.newValue);
        }
        #endregion

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

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