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

namespace UVC.UIToolkit
{
    /// <summary>
    /// 모달 뒤의 배경을 차단하고 클릭 시 닫힘 처리를 담당하는 컴포넌트
    /// </summary>
    [UxmlElement]
    public partial class UTKModalBlocker : VisualElement, IDisposable
    {
        #region Constants
        private const string USS_CLASS = "utk-modal-blocker";
        private const float DEFAULT_OPACITY = 0.7f;
        private const int FADE_DURATION_MS = 200;
        #endregion

        #region Fields
        private bool _disposed;
        private bool _closeOnClick;
        private float _targetOpacity;
        #endregion

        #region Events
        /// <summary>
        /// 블로커가 클릭되었을 때 발생
        /// </summary>
        public event Action? OnBlockerClicked;
        #endregion

        #region Constructor
        /// <summary>
        /// UTKModalBlocker 생성자
        /// </summary>
        public UTKModalBlocker()
        {
            AddToClassList(USS_CLASS);

            // 기본 스타일 설정
            style.position = Position.Absolute;
            style.left = 0;
            style.top = 0;
            style.right = 0;
            style.bottom = 0;
            style.backgroundColor = new Color(0, 0, 0, 0);

            // 클릭 이벤트 등록
            RegisterCallback<ClickEvent>(OnClick);
        }
        #endregion

        #region Static Factory
        /// <summary>
        /// 모달 블로커를 생성하고 표시합니다.
        /// parent의 panel.visualTree에 블로커를 추가합니다.
        /// </summary>
        /// <param name="parent">panel 접근용 부모 요소</param>
        /// <param name="opacity">배경 투명도 (0~1)</param>
        /// <param name="closeOnClick">클릭 시 자동 닫힘 여부</param>
        /// <returns>생성된 UTKModalBlocker 인스턴스</returns>
        public static UTKModalBlocker Show(VisualElement parent, float opacity = DEFAULT_OPACITY, bool closeOnClick = false)
        {
            var blocker = new UTKModalBlocker
            {
                _closeOnClick = closeOnClick,
                _targetOpacity = Mathf.Clamp01(opacity)
            };

            var root = parent.panel?.visualTree ?? parent;
            root.Add(blocker);
            blocker.FadeIn();

            return blocker;
        }
        #endregion

        #region Public Methods
        /// <summary>
        /// 블로커를 숨기고 제거합니다.
        /// </summary>
        public void Hide()
        {
            FadeOut(() =>
            {
                style.display = DisplayStyle.None;
                RemoveFromHierarchy();
                Dispose();
            });
        }

        /// <summary>
        /// 모달 콘텐츠를 블로커 앞에 추가합니다.
        /// </summary>
        /// <param name="modalContent">모달 콘텐츠 요소</param>
        public void ShowModal(VisualElement modalContent)
        {
            if (modalContent == null)
                return;

            // 모달 콘텐츠를 블로커 다음에 추가
            var parent = this.parent;
            if (parent != null)
            {
                int blockerIndex = parent.IndexOf(this);
                parent.Insert(blockerIndex + 1, modalContent);
            }
        }

        /// <summary>
        /// 블로커를 맨 위로 가져옵니다.
        /// </summary>
        public void BringToFront()
        {
            this.BringToFront();
        }
        #endregion

        #region Private Methods
        private void OnClick(ClickEvent evt)
        {
            // 블로커 자체가 클릭된 경우에만 처리 (버블링된 이벤트 무시)
            if (evt.target != this)
                return;

            OnBlockerClicked?.Invoke();

            if (_closeOnClick)
            {
                Hide();
            }

            evt.StopPropagation();
        }

        private void FadeIn()
        {
            // 시작 투명도
            style.backgroundColor = new Color(0, 0, 0, 0);

            // 애니메이션
            schedule.Execute(() =>
            {
                style.transitionDuration = new StyleList<TimeValue>(new List<TimeValue> { new TimeValue(FADE_DURATION_MS, TimeUnit.Millisecond) });
                style.transitionProperty = new StyleList<StylePropertyName>(new List<StylePropertyName> { new StylePropertyName("background-color") });
                style.backgroundColor = new Color(0, 0, 0, _targetOpacity);
            });
        }

        private void FadeOut(Action? onComplete = null)
        {
            style.transitionDuration = new StyleList<TimeValue>(new List<TimeValue> { new TimeValue(FADE_DURATION_MS, TimeUnit.Millisecond) });
            style.transitionProperty = new StyleList<StylePropertyName>(new List<StylePropertyName> { new StylePropertyName("background-color") });
            style.backgroundColor = new Color(0, 0, 0, 0);

            // 페이드 아웃 완료 후 콜백
            schedule.Execute(() => onComplete?.Invoke()).ExecuteLater(FADE_DURATION_MS);
        }
        #endregion

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

            _disposed = true;

            UnregisterCallback<ClickEvent>(OnClick);
            OnBlockerClicked = null;
        }
        #endregion
    }
}