using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Reflection;
using TMPro;
using UnityEngine;
using UnityEngine.UI;

namespace DDD
{
    /// <summary>
    /// 바인딩 컨텍스트 - ViewModel과 View 간의 데이터 바인딩을 관리
    /// </summary>
    public class BindingContext
    {
        private readonly Dictionary<string, List<IBindingTarget>> _bindings = new();
        private readonly Dictionary<string, IValueConverter> _converters = new();
        private INotifyPropertyChanged _dataContext;

        /// <summary>
        /// 데이터 컨텍스트 (ViewModel) 설정
        /// </summary>
        /// <param name="dataContext">바인딩할 ViewModel</param>
        public void SetDataContext(INotifyPropertyChanged dataContext)
        {
            if (_dataContext != null)
                _dataContext.PropertyChanged -= OnPropertyChanged;

            _dataContext = dataContext;

            if (_dataContext != null)
            {
                _dataContext.PropertyChanged += OnPropertyChanged;
                RefreshAllBindings();
            }
        }

        /// <summary>
        /// 속성 바인딩 추가
        /// </summary>
        /// <param name="propertyPath">바인딩할 속성 경로</param>
        /// <param name="target">바인딩 타겟</param>
        /// <param name="converter">값 변환기 (선택사항)</param>
        public void Bind(string propertyPath, IBindingTarget target, IValueConverter converter = null)
        {
            if (!_bindings.ContainsKey(propertyPath))
                _bindings[propertyPath] = new List<IBindingTarget>();

            _bindings[propertyPath].Add(target);

            if (converter != null)
                _converters[propertyPath] = converter;

            // 즉시 초기값 설정
            UpdateBinding(propertyPath);
        }

        /// <summary>
        /// 속성 변경 이벤트 핸들러
        /// </summary>
        private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            UpdateBinding(e.PropertyName);
        }

        /// <summary>
        /// 특정 속성의 바인딩 업데이트
        /// </summary>
        /// <param name="propertyPath">업데이트할 속성 경로</param>
        private void UpdateBinding(string propertyPath)
        {
            if (!_bindings.ContainsKey(propertyPath)) return;

            var value = GetPropertyValue(propertyPath);

            // 컨버터 적용
            if (_converters.TryGetValue(propertyPath, out var converter))
                value = converter.Convert(value);

            foreach (var target in _bindings[propertyPath])
            {
                target.UpdateValue(value);
            }
        }

        /// <summary>
        /// 속성 값 가져오기 (리플렉션 사용)
        /// </summary>
        /// <param name="propertyPath">속성 경로</param>
        /// <returns>속성 값</returns>
        private object GetPropertyValue(string propertyPath)
        {
            if (_dataContext == null) return null;

            // 중첩 속성 지원 (예: "ItemData.Name")
            var properties = propertyPath.Split('.');
            object current = _dataContext;

            foreach (var prop in properties)
            {
                if (current == null) return null;

                var property = current.GetType().GetProperty(prop);
                current = property?.GetValue(current);
            }

            return current;
        }

        /// <summary>
        /// 모든 바인딩 새로고침
        /// </summary>
        private void RefreshAllBindings()
        {
            foreach (var propertyPath in _bindings.Keys)
            {
                UpdateBinding(propertyPath);
            }
        }

        /// <summary>
        /// 리소스 정리
        /// </summary>
        public void Dispose()
        {
            if (_dataContext != null)
                _dataContext.PropertyChanged -= OnPropertyChanged;

            _bindings.Clear();
            _converters.Clear();
        }
    }

    /// <summary>
    /// 속성 경로 캐시 - 성능 최적화를 위한 리플렉션 결과 캐싱
    /// </summary>
    public static class PropertyPathCache
    {
        private static readonly Dictionary<Type, Dictionary<string, PropertyInfo>> _cache = new();

        /// <summary>
        /// 캐시된 PropertyInfo 가져오기
        /// </summary>
        /// <param name="type">타입</param>
        /// <param name="propertyName">속성 이름</param>
        /// <returns>PropertyInfo</returns>
        public static PropertyInfo GetProperty(Type type, string propertyName)
        {
            if (!_cache.ContainsKey(type))
                _cache[type] = new Dictionary<string, PropertyInfo>();

            if (!_cache[type].ContainsKey(propertyName))
                _cache[type][propertyName] = type.GetProperty(propertyName);

            return _cache[type][propertyName];
        }
    }
}