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

namespace UVC.UIToolkit
{
    /// <summary>
    /// DateRange 속성 View 클래스입니다.
    /// 시작일, 종료일 두 개의 DatePicker를 사용하여 날짜 범위를 표시/편집합니다.
    /// </summary>
    [UxmlElement]
    public partial class UTKDateRangePropertyItemView : UTKPropertyItemViewBase, IUTKPropertyItemView<UTKDateRange>
    {
        #region Fields
        private UTKInputField? _startField;
        private UTKInputField? _endField;
        private UTKButton? _startPickerBtn;
        private UTKButton? _endPickerBtn;
        private UTKDatePicker? _currentPicker;
        private bool _isEditingStart;

        private UTKDateRange _value;
        private string _dateFormat = "yyyy-MM-dd";

        private IUTKPropertyItem<UTKDateRange>? _boundData;
        #endregion

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

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

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

        /// <summary>날짜 표시 형식</summary>
        [UxmlAttribute("date-format")]
        public string DateFormat
        {
            get => _dateFormat;
            set
            {
                _dateFormat = value ?? "yyyy-MM-dd";
                UpdateValueUI();
            }
        }
        #endregion

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

        #region Constructor
        public UTKDateRangePropertyItemView() : base()
        {
            _value = new UTKDateRange(DateTime.Today, DateTime.Today);
            InitializeUI();
        }

        public UTKDateRangePropertyItemView(string label, UTKDateRange value = default) : base()
        {
            _value = value.Start == default ? new UTKDateRange(DateTime.Today, DateTime.Today) : value;
            Label = label;
            InitializeUI();
        }

        public UTKDateRangePropertyItemView(string label, DateTime start, DateTime end) : base()
        {
            _value = new UTKDateRange(start, end);
            Label = label;
            InitializeUI();
        }
        #endregion

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

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

            // UXML에서 요소 가져오기
            QueryUIElements();

            // 이벤트 등록
            RegisterEvents();

            UpdateValueUI();
            UpdateReadOnlyState();
        }

        private void QueryUIElements()
        {
            _startField = this.Q<UTKInputField>("start-field");
            _startPickerBtn = this.Q<UTKButton>("start-picker-btn");
            _endField = this.Q<UTKInputField>("end-field");
            _endPickerBtn = this.Q<UTKButton>("end-picker-btn");

            // Fallback: UXML에서 못 찾으면 생성
            if (_valueContainer != null)
            {
                if (_startField == null)
                {
                    _startField = new UTKInputField { name = "start-field" };
                    _startField.style.flexGrow = 1;
                    _startField.AddToClassList("utk-property-item-view__field");
                    _valueContainer.Add(_startField);
                }

                if (_startPickerBtn == null)
                {
                    _startPickerBtn = new UTKButton("...", "", UTKButton.ButtonVariant.Secondary)
                    {
                        name = "start-picker-btn"
                    };
                    _startPickerBtn.AddToClassList("utk-property-item-view__picker-btn");
                    _valueContainer.Add(_startPickerBtn);
                }

                // Separator 확인 및 생성
                if (this.Q<UTKLabel>(className: "utk-property-item-view__range-separator") == null)
                {
                    var separator = new UTKLabel("~", UTKLabel.LabelSize.Body2);
                    separator.AddToClassList("utk-property-item-view__range-separator");
                    _valueContainer.Add(separator);
                }

                if (_endField == null)
                {
                    _endField = new UTKInputField { name = "end-field" };
                    _endField.style.flexGrow = 1;
                    _endField.AddToClassList("utk-property-item-view__field");
                    _valueContainer.Add(_endField);
                }

                if (_endPickerBtn == null)
                {
                    _endPickerBtn = new UTKButton("...", "", UTKButton.ButtonVariant.Secondary)
                    {
                        name = "end-picker-btn"
                    };
                    _endPickerBtn.AddToClassList("utk-property-item-view__picker-btn");
                    _valueContainer.Add(_endPickerBtn);
                }
            }

            // 초기 값 설정
            if (_startField != null)
            {
                _startField.SetValue(_value.Start.ToString(_dateFormat), false);
                _startField.isReadOnly = true;//IsReadOnly와 상관 없이 편집 불가
            }
            if (_endField != null)
            {
                _endField.SetValue(_value.End.ToString(_dateFormat), false);
                _endField.isReadOnly = true;//IsReadOnly와 상관 없이 편집 불가
            }
            if (_startPickerBtn != null)
            {
                _startPickerBtn.IsEnabled = !IsReadOnly;
            }
            if (_endPickerBtn != null)
            {
                _endPickerBtn.IsEnabled = !IsReadOnly;
            }
        }

        private void RegisterEvents()
        {
            if (_startField != null)
            {
                _startField.OnValueChanged += OnStartTextChanged;
            }
            if (_endField != null)
            {
                _endField.OnValueChanged += OnEndTextChanged;
            }
            if (_startPickerBtn != null)
            {
                _startPickerBtn.OnClicked += OnStartPickerClicked;
            }
            if (_endPickerBtn != null)
            {
                _endPickerBtn.OnClicked += OnEndPickerClicked;
            }
        }

        private void UnregisterEvents()
        {
            if (_startField != null)
            {
                _startField.OnValueChanged -= OnStartTextChanged;
            }
            if (_endField != null)
            {
                _endField.OnValueChanged -= OnEndTextChanged;
            }
            if (_startPickerBtn != null)
            {
                _startPickerBtn.OnClicked -= OnStartPickerClicked;
            }
            if (_endPickerBtn != null)
            {
                _endPickerBtn.OnClicked -= OnEndPickerClicked;
            }
        }
        #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 (_startField != null) _startField.isReadOnly = isReadOnly;
            if (_endField != null) _endField.isReadOnly = isReadOnly;
            if (_startPickerBtn != null) _startPickerBtn.style.display = isReadOnly ? DisplayStyle.None : DisplayStyle.Flex;
            if (_endPickerBtn != null) _endPickerBtn.style.display = isReadOnly ? DisplayStyle.None : DisplayStyle.Flex;
        }
        #endregion

        #region Event Handling
        private void OnStartPickerClicked()
        {
            _isEditingStart = true;
            OpenPicker(_value.Start);
        }

        private void OnEndPickerClicked()
        {
            _isEditingStart = false;
            OpenPicker(_value.End);
        }

        private void OnStartTextChanged(string newValue)
        {
            if (DateTime.TryParse(newValue, out DateTime date))
            {
                var range = new UTKDateRange(date.Date, _value.End);
                if (!_value.Equals(range))
                {
                    _value = range;
                    OnValueChanged?.Invoke(range);

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

        private void OnEndTextChanged(string newValue)
        {
            if (DateTime.TryParse(newValue, out DateTime date))
            {
                var range = new UTKDateRange(_value.Start, date.Date);
                if (!_value.Equals(range))
                {
                    _value = range;
                    OnValueChanged?.Invoke(range);

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

        private void OpenPicker(DateTime initialDate)
        {
            if (_currentPicker != null) return;

            var root = this as VisualElement;
            while (root.parent != null) root = root.parent;

            string title = _isEditingStart ? $"{Label} - 시작일" : $"{Label} - 종료일";
            _currentPicker = UTKDatePicker.Show(root, initialDate, UTKDatePicker.PickerMode.DateOnly, title);
            _currentPicker.OnDateSelected += OnPickerDateSelected;
            _currentPicker.OnClosed += OnPickerClosed;
        }

        private void ClosePicker()
        {
            if (_currentPicker != null)
            {
                _currentPicker.OnDateSelected -= OnPickerDateSelected;
                _currentPicker.OnClosed -= OnPickerClosed;
                _currentPicker.Close();
                _currentPicker = null;
            }
        }

        private void OnPickerDateSelected(DateTime date)
        {
            if (_isEditingStart)
            {
                Value = new UTKDateRange(date.Date, _value.End);
            }
            else
            {
                Value = new UTKDateRange(_value.Start, date.Date);
            }
            ClosePicker();
        }

        private void OnPickerClosed() => _currentPicker = null;
        #endregion

        #region Value Update
        private void UpdateValueUI()
        {
            if (_startField != null)
            {
                var formatted = _value.Start.ToString(_dateFormat);
                if (_startField.Value != formatted)
                {
                    _startField.SetValue(formatted, false);
                }
            }

            if (_endField != null)
            {
                var formatted = _value.End.ToString(_dateFormat);
                if (_endField.Value != formatted)
                {
                    _endField.SetValue(formatted, false);
                }
            }
        }
        #endregion

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

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

            _boundData = data;

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

            if (data is UTKDateRangePropertyItem dateRangeItem)
            {
                _dateFormat = dateRangeItem.DateFormat;
            }

            data.OnTypedValueChanged += OnDataValueChanged;

            UpdateValueUI();
            UpdateReadOnlyState();
        }

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

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

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

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

                OnValueChanged = null;
                _startField = null;
                _endField = null;
                _startPickerBtn = null;
                _endPickerBtn = null;
            }

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