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

namespace UVC.UIToolkit
{
    /// <summary>
    /// 입력 필드 컴포넌트.
    /// Unity TextField를 래핑하여 커스텀 스타일을 적용합니다.
    /// </summary>
    /// <example>
    /// <para><b>C# 코드에서 사용:</b></para>
    /// <code>
    /// // 기본 입력 필드
    /// var input = new UTKInputField();
    /// input.Label = "이름";
    /// input.Placeholder = "이름을 입력하세요";
    /// input.OnValueChanged += (value) => Debug.Log($"입력값: {value}");
    /// 
    /// // 비밀번호 입력 필드
    /// var password = new UTKInputField();
    /// password.Label = "비밀번호";
    /// password.isPasswordField = true;
    /// 
    /// // 검증 오류 표시
    /// input.SetError("이름은 필수입니다.");
    /// input.ClearError();
    /// 
    /// // 변형 스타일
    /// input.Variant = UTKInputField.InputFieldVariant.Outlined;
    /// </code>
    /// <para><b>UXML에서 사용:</b></para>
    /// <code>
    /// <ui:UXML xmlns:utk="UVC.UIToolkit">
    ///     <!-- 기본 입력 필드 -->
    ///     <utk:UTKInputField label="이름" />
    ///     
    ///     <!-- 플레이스홀더 -->
    ///     <utk:UTKInputField label="이메일" Placeholder="example@email.com" />
    ///     
    ///     <!-- 비밀번호 필드 -->
    ///     <utk:UTKInputField label="비밀번호" is-password-field="true" />
    ///     
    ///     <!-- 여러 줄 입력 -->
    ///     <utk:UTKInputField label="설명" multiline="true" />
    ///     
    ///     <!-- 비활성화 -->
    ///     <utk:UTKInputField label="읽기전용" IsEnabled="false" value="수정 불가" />
    /// </ui:UXML>
    /// </code>
    /// </example>
    [UxmlElement]
    public partial class UTKInputField : TextField, IDisposable
    {
        #region Constants
        private const string USS_PATH = "UIToolkit/Input/UTKInputField";
        #endregion

        #region Fields
        private bool _disposed;
        private bool _isEnabled = true;
        private string _errorMessage = "";
        private InputFieldVariant _variant = InputFieldVariant.Default;
        #endregion

        #region Events
        /// <summary>값 변경 이벤트</summary>
        public event Action<string>? OnValueChanged;
        /// <summary>포커스 이벤트</summary>
        public event Action? OnFocused;
        /// <summary>포커스 해제 이벤트</summary>
        public event Action? OnBlurred;
        /// <summary>엔터 키 이벤트</summary>
        public event Action<string>? OnSubmit;
        #endregion

        #region Properties
        /// <summary>입력 값</summary>
        public string Value
        {
            get => value;
            set => SetValue(value, true);
        }

        /// <summary>플레이스홀더 텍스트</summary>
        [UxmlAttribute("placeholder")]
        public string Placeholder
        {
            get => textEdition.placeholder;
            set => textEdition.placeholder = value;
        }

        /// <summary>에러 메시지</summary>
        [UxmlAttribute("error-message")]
        public string ErrorMessage
        {
            get => _errorMessage;
            set
            {
                _errorMessage = value;
                EnableInClassList("utk-input--error", !string.IsNullOrEmpty(value));
            }
        }

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

        /// <summary>읽기 전용</summary>
        public new bool isReadOnly
        {
            get => base.isReadOnly;
            set
            {
                base.isReadOnly = value;
                EnableInClassList("utk-input--readonly", value);
            }
        }

        /// <summary>멀티라인 모드</summary>
        public new bool multiline
        {
            get => base.multiline;
            set
            {
                base.multiline = value;
                EnableInClassList("utk-input--multiline", value);
            }
        }

        /// <summary>스타일 변형</summary>
        [UxmlAttribute("variant")]
        public InputFieldVariant Variant
        {
            get => _variant;
            set
            {
                _variant = value;
                UpdateVariant();
            }
        }
        #endregion

        #region Enums
        public enum InputFieldVariant
        {
            Default,
            Filled,
            Outlined
        }
        #endregion

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

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

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

            // UXML에서 로드될 때 속성이 설정된 후 UI 갱신
            // Unity 6의 소스 생성기는 Deserialize에서 필드에 직접 값을 할당하므로
            // AttachToPanelEvent를 사용하여 패널에 연결된 후 UI를 갱신
            RegisterCallback<AttachToPanelEvent>(OnAttachToPanel);
        }

        public UTKInputField(string label, string placeholder = "") : this()
        {
            this.label = label;
            Placeholder = placeholder;
        }
        #endregion

        #region Setup
        private void SetupStyles()
        {
            AddToClassList("utk-input");
            UpdateVariant();
        }

        private void SetupEvents()
        {
            this.RegisterValueChangedCallback(OnTextValueChanged);

            RegisterCallback<FocusInEvent>(_ =>
            {
                EnableInClassList("utk-input--focused", true);
                OnFocused?.Invoke();
            });

            RegisterCallback<FocusOutEvent>(_ =>
            {
                EnableInClassList("utk-input--focused", false);
                OnBlurred?.Invoke();
            });

            RegisterCallback<KeyDownEvent>(evt =>
            {
                if (evt.keyCode == KeyCode.Return && !multiline)
                {
                    OnSubmit?.Invoke(value);
                }
            });
        }

        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 OnAttachToPanel(AttachToPanelEvent evt)
        {
            // UXML 속성이 설정된 후 한 번만 UI 갱신
            UnregisterCallback<AttachToPanelEvent>(OnAttachToPanel);
            UpdateVariant();

            // IsEnabled 상태 적용
            SetEnabled(_isEnabled);
            EnableInClassList("utk-input--disabled", !_isEnabled);
        }

        private void OnTextValueChanged(ChangeEvent<string> evt)
        {
            OnValueChanged?.Invoke(evt.newValue);
        }
        #endregion

        #region Methods
        /// <summary>
        /// 값 설정
        /// </summary>
        public void SetValue(string newValue, bool notify)
        {
            if (value == newValue) return;

            if (notify)
            {
                value = newValue ?? "";
            }
            else
            {
                SetValueWithoutNotify(newValue ?? "");
            }
        }

        /// <summary>
        /// 선택 영역 설정
        /// </summary>
        public void SelectAll()
        {
            textSelection.SelectAll();
        }

        private void UpdateVariant()
        {
            RemoveFromClassList("utk-input--default");
            RemoveFromClassList("utk-input--filled");
            RemoveFromClassList("utk-input--outlined");

            var variantClass = _variant switch
            {
                InputFieldVariant.Filled => "utk-input--filled",
                InputFieldVariant.Outlined => "utk-input--outlined",
                _ => "utk-input--default"
            };
            AddToClassList(variantClass);
        }

        #endregion

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

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