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

namespace UVC.UIToolkit
{
    /// <summary>
    /// Dropdown 속성 View 클래스입니다.
    /// UTKDropdown을 사용하여 문자열 목록에서 선택합니다.
    /// </summary>
    [UxmlElement]
    public partial class UTKDropdownPropertyItemView : UTKPropertyItemViewBase, IUTKPropertyItemView<string>
    {
        #region Fields
        private UTKDropdown? _dropdown;

        private string _value = string.Empty;
        private List<string> _choices = new();

        private IUTKPropertyItem<string>? _boundData;
        #endregion

        #region Properties
        protected override string ViewTypeName => "UTKDropdownPropertyItemView";

        /// <summary>현재 값</summary>
        public string Value
        {
            get => _value;
            set
            {
                if (_value != value)
                {
                    _value = value ?? string.Empty;
                    UpdateValueUI();
                    OnValueChanged?.Invoke(_value);

                    if (_boundData != null && _boundData.Value != _value)
                    {
                        _boundData.Value = _value;
                    }
                }
            }
        }

        /// <summary>선택 가능한 항목 목록</summary>
        public List<string> Choices
        {
            get => _choices;
            set
            {
                _choices = value ?? new List<string>();
                if (_dropdown != null)
                {
                    _dropdown.SetOptions(_choices);
                }
            }
        }
        #endregion

        #region Events
        public event Action<string>? OnValueChanged;
        #endregion

        #region Constructor
        public UTKDropdownPropertyItemView() : base()
        {
            InitializeUI();
        }

        public UTKDropdownPropertyItemView(UTKDropdownPropertyItem data) : base()
        {
            _choices = data.Choices;
            _value = data.Value ?? (_choices.Count > 0 ? _choices[0] : string.Empty);
            Label = data.Name;
            _isReadOnly = data.IsReadOnly;

            InitializeUI();
            Bind(data);
        }

        public UTKDropdownPropertyItemView(string label, List<string> choices, string initialValue = "") : base()
        {
            _choices = choices ?? new List<string>();
            _value = initialValue ?? (_choices.Count > 0 ? _choices[0] : string.Empty);
            Label = label;
            InitializeUI();
        }

        public UTKDropdownPropertyItemView(string label, IEnumerable<string> choices, int selectedIndex = 0) : base()
        {
            _choices = choices?.ToList() ?? new List<string>();
            if (_choices.Count > 0 && selectedIndex >= 0 && selectedIndex < _choices.Count)
            {
                _value = _choices[selectedIndex];
            }
            Label = label;
            InitializeUI();
        }
        #endregion

        #region Initialization
        private void InitializeUI()
        {
            AddToClassList("utk-property-item-view");
            AddToClassList("utk-property-item-view--dropdown");

            if (!CreateUIFromUxml())
            {
                CreateUIFallback();
            }

            // UXML에서 요소 가져오기
            QueryUIElements();

            // 이벤트 등록
            RegisterEvents();

            UpdateValueUI();
            UpdateReadOnlyState();
        }

        private void QueryUIElements()
        {
            _dropdown = this.Q<UTKDropdown>("dropdown-field");

            // Fallback: UXML에서 못 찾으면 생성
            if (_valueContainer != null && _dropdown == null)
            {
                _dropdown = new UTKDropdown { name = "dropdown-field" };
                _dropdown.AddToClassList("utk-property-item-view__dropdown");
                _valueContainer.Add(_dropdown);
            }

            // 초기 값 설정
            if (_dropdown != null)
            {
                _dropdown.SetOptions(_choices);
                int selectedIndex = _choices.IndexOf(_value);
                _dropdown.SelectedIndex = Math.Max(0, selectedIndex);
                _dropdown.IsEnabled = !IsReadOnly;
            }
        }

        private void RegisterEvents()
        {
            if (_dropdown != null)
            {
                _dropdown.OnSelectionChanged += OnDropdownChanged;
            }
        }

        private void UnregisterEvents()
        {
            if (_dropdown != null)
            {
                _dropdown.OnSelectionChanged -= OnDropdownChanged;
            }
        }
        #endregion

        #region Override Methods
        protected override void CreateValueUI(VisualElement container)
        {
            // UXML/QueryUIElements 기반으로 생성하므로 여기서는 생성하지 않음
        }

        public override void RefreshUI()
        {
            UpdateValueUI();
        }

        protected override void OnReadOnlyStateChanged(bool isReadOnly)
        {
            if (_dropdown != null)
            {
                _dropdown.IsEnabled = !isReadOnly;
            }
        }
        #endregion

        #region Event Handling
        private void OnDropdownChanged(int index, string newValue)
        {
            if (_value != newValue)
            {
                _value = newValue;
                OnValueChanged?.Invoke(newValue);

                if (_boundData != null && _boundData.Value != newValue)
                {
                    _boundData.Value = newValue;
                }
            }
        }
        #endregion

        #region Value Update
        private void UpdateValueUI()
        {
            if (_dropdown != null && _dropdown.SelectedValue != _value)
            {
                _dropdown.SetSelectedValue(_value, notify: false);
            }
        }
        #endregion

        #region Public Methods
        /// <summary>선택 항목 추가</summary>
        public void AddChoice(string choice)
        {
            if (!_choices.Contains(choice))
            {
                _choices.Add(choice);
                if (_dropdown != null)
                {
                    _dropdown.AddOption(choice);
                }
            }
        }

        /// <summary>선택 항목 제거</summary>
        public bool RemoveChoice(string choice)
        {
            bool removed = _choices.Remove(choice);
            if (removed && _dropdown != null)
            {
                _dropdown.SetOptions(_choices);

                if (_value == choice && _choices.Count > 0)
                {
                    Value = _choices[0];
                }
            }
            return removed;
        }
        #endregion

        #region Data Binding
        public void Bind(IUTKPropertyItem data)
        {
            if (data is IUTKPropertyItem<string> stringData)
            {
                Bind(stringData);
            }
            else
            {
                Debug.LogWarning($"[UTKDropdownPropertyItemView] Cannot bind to non-string data: {data.GetType().Name}");
            }
        }

        public void Bind(IUTKPropertyItem<string> data)
        {
            Unbind();

            _boundData = data;

            Label = data.Name;
            _value = data.Value ?? string.Empty;
            IsReadOnly = data.IsReadOnly;
            IsVisible = data.IsVisible;
            TooltipText = data.Tooltip;

            if (data is UTKDropdownPropertyItem dropdownItem)
            {
                _choices = dropdownItem.Choices;
                if (_dropdown != null)
                {
                    _dropdown.SetOptions(_choices);
                }
            }

            data.OnTypedValueChanged += OnDataValueChanged;

            UpdateValueUI();
            UpdateReadOnlyState();
        }

        public void Unbind()
        {
            if (_boundData != null)
            {
                _boundData.OnTypedValueChanged -= OnDataValueChanged;
                _boundData = null;
            }
        }

        private void OnDataValueChanged(IUTKPropertyItem<string> item, string oldValue, string newValue)
        {
            if (_value != newValue)
            {
                _value = newValue ?? string.Empty;
                UpdateValueUI();
            }
        }
        #endregion

        #region Dispose
        protected override void Dispose(bool disposing)
        {
            if (_disposed) return;

            if (disposing)
            {
                UnregisterEvents();
                Unbind();

                OnValueChanged = null;
                _dropdown = null;
            }

            base.Dispose(disposing);
        }
        #endregion
    }
}