using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Paca.Core.Config;

namespace Paca.App.ViewModels;

/// <summary>
/// 설정 화면의 Input SSOT (Single Source of Truth) 뷰모델.
/// 원본 AppConfig와의 비교를 통한 실시간 Dirty 추적, 유효성 검사, 라이브 프리뷰, 초기화/가져오기/내보내기 일원화 관리.
/// </summary>
public sealed class SettingsViewModel : INotifyPropertyChanged
{
    private readonly AppConfig _originalConfig;
    private readonly Dictionary<string, object?> _originalValues = new(StringComparer.Ordinal);
    private readonly Dictionary<string, string> _errors = new(StringComparer.Ordinal);

    public event PropertyChangedEventHandler? PropertyChanged;
    public event Action<string>? LivePreviewRequested;

    public SettingsViewModel(AppConfig config)
    {
        _originalConfig = config;
        LoadFromConfig(config, isOriginalSnapshot: true);
    }

    #region Input Properties (SSOT)

    // 1. 외관 & 테마
    private string _theme = "dark";
    public string Theme
    {
        get => _theme;
        set { if (Set(ref _theme, value)) OnSettingChanged(nameof(Theme), true); }
    }

    private string? _accentColor;
    public string? AccentColor
    {
        get => _accentColor;
        set { if (Set(ref _accentColor, value)) OnSettingChanged(nameof(AccentColor), true); }
    }

    private string? _customThemePath;
    public string? CustomThemePath
    {
        get => _customThemePath;
        set { if (Set(ref _customThemePath, value)) OnSettingChanged(nameof(CustomThemePath), true); }
    }

    private string _uiDensity = "normal";
    public string UiDensity
    {
        get => _uiDensity;
        set { if (Set(ref _uiDensity, value)) OnSettingChanged(nameof(UiDensity), true); }
    }

    private double _uiScale = 1.0;
    public double UiScale
    {
        get => _uiScale;
        set { if (Set(ref _uiScale, Math.Clamp(value, 1.0, 2.0))) OnSettingChanged(nameof(UiScale), true); }
    }

    private double _uiFontScale = 1.0;
    public double UiFontScale
    {
        get => _uiFontScale;
        set { if (Set(ref _uiFontScale, Math.Clamp(value, 1.0, 2.0))) OnSettingChanged(nameof(UiFontScale), true); }
    }

    private string _uiFontFamily = "";
    public string UiFontFamily
    {
        get => _uiFontFamily;
        set { if (Set(ref _uiFontFamily, value)) OnSettingChanged(nameof(UiFontFamily), true); }
    }

    private string _uiFontKoreanFallback = "Malgun Gothic";
    public string UiFontKoreanFallback
    {
        get => _uiFontKoreanFallback;
        set { if (Set(ref _uiFontKoreanFallback, value)) OnSettingChanged(nameof(UiFontKoreanFallback), true); }
    }

    private double _uiFontSize = 13.0;
    public double UiFontSize
    {
        get => _uiFontSize;
        set { if (Set(ref _uiFontSize, value)) OnSettingChanged(nameof(UiFontSize), true); }
    }

    // 2. 일반 & 내비게이션
    private string _outputFolder = "";
    public string OutputFolder
    {
        get => _outputFolder;
        set { if (Set(ref _outputFolder, value)) OnSettingChanged(nameof(OutputFolder)); }
    }

    private string _homeUrl = "https://www.google.com";
    public string HomeUrl
    {
        get => _homeUrl;
        set { if (Set(ref _homeUrl, value)) OnSettingChanged(nameof(HomeUrl)); }
    }

    private string _language = "ko";
    public string Language
    {
        get => _language;
        set { if (Set(ref _language, value)) OnSettingChanged(nameof(Language)); }
    }

    private string _searchEngine = "Google";
    public string SearchEngine
    {
        get => _searchEngine;
        set { if (Set(ref _searchEngine, value)) OnSettingChanged(nameof(SearchEngine)); }
    }

    private bool _autoStart;
    public bool AutoStart
    {
        get => _autoStart;
        set { if (Set(ref _autoStart, value)) OnSettingChanged(nameof(AutoStart)); }
    }

    private bool _minimizeToTray;
    public bool MinimizeToTray
    {
        get => _minimizeToTray;
        set { if (Set(ref _minimizeToTray, value)) OnSettingChanged(nameof(MinimizeToTray)); }
    }

    // 3. 도구 모음 단추
    private ObservableCollection<string> _toolbarButtons = new(AppConfig.DefaultToolbarButtons);
    public ObservableCollection<string> ToolbarButtons
    {
        get => _toolbarButtons;
        set { if (Set(ref _toolbarButtons, value)) OnSettingChanged(nameof(ToolbarButtons), true); }
    }

    public bool HasToolbarButton(string key) => _toolbarButtons.Contains(key, StringComparer.OrdinalIgnoreCase);

    public void ToggleToolbarButton(string key, bool isChecked)
    {
        var exists = HasToolbarButton(key);
        if (isChecked && !exists)
        {
            _toolbarButtons.Add(key.ToLowerInvariant());
            OnSettingChanged(nameof(ToolbarButtons), true);
        }
        else if (!isChecked && exists)
        {
            var item = _toolbarButtons.FirstOrDefault(k => string.Equals(k, key, StringComparison.OrdinalIgnoreCase));
            if (item != null)
            {
                _toolbarButtons.Remove(item);
                OnSettingChanged(nameof(ToolbarButtons), true);
            }
        }
    }

    public void SetToolbarButtons(IEnumerable<string> buttons)
    {
        _toolbarButtons.Clear();
        foreach (var b in buttons) _toolbarButtons.Add(b);
        OnSettingChanged(nameof(ToolbarButtons), true);
    }

    // 4. 다운로드 엔진
    private int _concurrency = 8;
    public int Concurrency
    {
        get => _concurrency;
        set { if (Set(ref _concurrency, value)) OnSettingChanged(nameof(Concurrency)); }
    }

    private int _maxConcurrentDownloads = 3;
    public int MaxConcurrentDownloads
    {
        get => _maxConcurrentDownloads;
        set { if (Set(ref _maxConcurrentDownloads, value)) OnSettingChanged(nameof(MaxConcurrentDownloads)); }
    }

    private int _retries = 3;
    public int Retries
    {
        get => _retries;
        set { if (Set(ref _retries, value)) OnSettingChanged(nameof(Retries)); }
    }

    private long _minSizeMB = 0;
    public long MinSizeMB
    {
        get => _minSizeMB;
        set { if (Set(ref _minSizeMB, value)) OnSettingChanged(nameof(MinSizeMB)); }
    }

    private int _maxDownloadSpeedKbps = 0;
    public int MaxDownloadSpeedKbps
    {
        get => _maxDownloadSpeedKbps;
        set { if (Set(ref _maxDownloadSpeedKbps, value)) OnSettingChanged(nameof(MaxDownloadSpeedKbps)); }
    }

    private bool _autoClearCompleted;
    public bool AutoClearCompleted
    {
        get => _autoClearCompleted;
        set { if (Set(ref _autoClearCompleted, value)) OnSettingChanged(nameof(AutoClearCompleted)); }
    }

    private bool _openFolderOnComplete;
    public bool OpenFolderOnComplete
    {
        get => _openFolderOnComplete;
        set { if (Set(ref _openFolderOnComplete, value)) OnSettingChanged(nameof(OpenFolderOnComplete)); }
    }

    private string _subtitleLanguage = "";
    public string SubtitleLanguage
    {
        get => _subtitleLanguage;
        set { if (Set(ref _subtitleLanguage, value)) OnSettingChanged(nameof(SubtitleLanguage)); }
    }

    private string? _downloadScheduleWindow;
    public string? DownloadScheduleWindow
    {
        get => _downloadScheduleWindow;
        set { if (Set(ref _downloadScheduleWindow, value)) OnSettingChanged(nameof(DownloadScheduleWindow)); }
    }

    // 5. 알림 & 접근성
    private bool _notifySound = true;
    public bool NotifySound
    {
        get => _notifySound;
        set { if (Set(ref _notifySound, value)) OnSettingChanged(nameof(NotifySound)); }
    }

    private bool _doNotDisturb;
    public bool DoNotDisturb
    {
        get => _doNotDisturb;
        set { if (Set(ref _doNotDisturb, value)) OnSettingChanged(nameof(DoNotDisturb)); }
    }

    private bool _pauseOnPowerSaver;
    public bool PauseOnPowerSaver
    {
        get => _pauseOnPowerSaver;
        set { if (Set(ref _pauseOnPowerSaver, value)) OnSettingChanged(nameof(PauseOnPowerSaver)); }
    }

    private int _toastDurationMs = 3000;
    public int ToastDurationMs
    {
        get => _toastDurationMs;
        set { if (Set(ref _toastDurationMs, value)) OnSettingChanged(nameof(ToastDurationMs)); }
    }

    private bool _reduceMotion;
    public bool ReduceMotion
    {
        get => _reduceMotion;
        set { if (Set(ref _reduceMotion, value)) OnSettingChanged(nameof(ReduceMotion), true); }
    }

    private bool _showCaptions;
    public bool ShowCaptions
    {
        get => _showCaptions;
        set { if (Set(ref _showCaptions, value)) OnSettingChanged(nameof(ShowCaptions)); }
    }

    private bool _focusSelectsAddress = true;
    public bool FocusSelectsAddress
    {
        get => _focusSelectsAddress;
        set { if (Set(ref _focusSelectsAddress, value)) OnSettingChanged(nameof(FocusSelectsAddress)); }
    }

    private bool _pasteAndGo;
    public bool PasteAndGo
    {
        get => _pasteAndGo;
        set { if (Set(ref _pasteAndGo, value)) OnSettingChanged(nameof(PasteAndGo)); }
    }

    // 6. 브라우저 & 개인정보
    private bool _tabWheelSwitch;
    public bool TabWheelSwitch
    {
        get => _tabWheelSwitch;
        set { if (Set(ref _tabWheelSwitch, value)) OnSettingChanged(nameof(TabWheelSwitch)); }
    }

    private string _tabStripPosition = "top";
    public string TabStripPosition
    {
        get => _tabStripPosition;
        set { if (Set(ref _tabStripPosition, value)) OnSettingChanged(nameof(TabStripPosition)); }
    }

    private bool _verticalTabsDefault;
    public bool VerticalTabsDefault
    {
        get => _verticalTabsDefault;
        set { if (Set(ref _verticalTabsDefault, value)) OnSettingChanged(nameof(VerticalTabsDefault)); }
    }

    private string _verticalTabsPosition = "Left";
    public string VerticalTabsPosition
    {
        get => _verticalTabsPosition;
        set { if (Set(ref _verticalTabsPosition, value)) OnSettingChanged(nameof(VerticalTabsPosition)); }
    }

    private bool _verticalTabsCollapsed;
    public bool VerticalTabsCollapsed
    {
        get => _verticalTabsCollapsed;
        set { if (Set(ref _verticalTabsCollapsed, value)) OnSettingChanged(nameof(VerticalTabsCollapsed)); }
    }

    private double _verticalTabsWidth = 220.0;
    public double VerticalTabsWidth
    {
        get => _verticalTabsWidth;
        set { if (Set(ref _verticalTabsWidth, value)) OnSettingChanged(nameof(VerticalTabsWidth)); }
    }

    private bool _verticalTabsAutoExpand = true;
    public bool VerticalTabsAutoExpand
    {
        get => _verticalTabsAutoExpand;
        set { if (Set(ref _verticalTabsAutoExpand, value)) OnSettingChanged(nameof(VerticalTabsAutoExpand)); }
    }

    private bool _confirmCloseMultipleTabs = true;
    public bool ConfirmCloseMultipleTabs
    {
        get => _confirmCloseMultipleTabs;
        set { if (Set(ref _confirmCloseMultipleTabs, value)) OnSettingChanged(nameof(ConfirmCloseMultipleTabs)); }
    }

    private bool _bookmarkBarVisible;
    public bool BookmarkBarVisible
    {
        get => _bookmarkBarVisible;
        set { if (Set(ref _bookmarkBarVisible, value)) OnSettingChanged(nameof(BookmarkBarVisible)); }
    }

    private bool _restoreTabsSuspended;
    public bool RestoreTabsSuspended
    {
        get => _restoreTabsSuspended;
        set { if (Set(ref _restoreTabsSuspended, value)) OnSettingChanged(nameof(RestoreTabsSuspended)); }
    }

    private bool _tabTitleMultiline;
    public bool TabTitleMultiline
    {
        get => _tabTitleMultiline;
        set { if (Set(ref _tabTitleMultiline, value)) OnSettingChanged(nameof(TabTitleMultiline)); }
    }

    private List<string> _enabledFormats = new() { "hls", "dash", "mp4", "webm", "mkv", "m4v", "mov", "avi", "audio" };
    public List<string> EnabledFormats
    {
        get => _enabledFormats;
        set { if (Set(ref _enabledFormats, value)) OnSettingChanged(nameof(EnabledFormats)); }
    }

    // 7. 고급 & 도구 연동
    private string? _ffmpegPath;
    public string? FfmpegPath
    {
        get => _ffmpegPath;
        set { if (Set(ref _ffmpegPath, value)) OnSettingChanged(nameof(FfmpegPath)); }
    }

    private string? _ytDlpPath;
    public string? YtDlpPath
    {
        get => _ytDlpPath;
        set { if (Set(ref _ytDlpPath, value)) OnSettingChanged(nameof(YtDlpPath)); }
    }

    private bool _useCookiesForSocial = true;
    public bool UseCookiesForSocial
    {
        get => _useCookiesForSocial;
        set { if (Set(ref _useCookiesForSocial, value)) OnSettingChanged(nameof(UseCookiesForSocial)); }
    }

    private bool _autoInstallYtDlp = true;
    public bool AutoInstallYtDlp
    {
        get => _autoInstallYtDlp;
        set { if (Set(ref _autoInstallYtDlp, value)) OnSettingChanged(nameof(AutoInstallYtDlp)); }
    }

    private bool _autoUpdateYtDlp = true;
    public bool AutoUpdateYtDlp
    {
        get => _autoUpdateYtDlp;
        set { if (Set(ref _autoUpdateYtDlp, value)) OnSettingChanged(nameof(AutoUpdateYtDlp)); }
    }

    private bool _autoInstallDeno = true;
    public bool AutoInstallDeno
    {
        get => _autoInstallDeno;
        set { if (Set(ref _autoInstallDeno, value)) OnSettingChanged(nameof(AutoInstallDeno)); }
    }

    private string _defaultSocialQuality = "best";
    public string DefaultSocialQuality
    {
        get => _defaultSocialQuality;
        set { if (Set(ref _defaultSocialQuality, value)) OnSettingChanged(nameof(DefaultSocialQuality)); }
    }

    private string? _youtubePlayerClients;
    public string? YoutubePlayerClients
    {
        get => _youtubePlayerClients;
        set { if (Set(ref _youtubePlayerClients, value)) OnSettingChanged(nameof(YoutubePlayerClients)); }
    }

    private string _userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36";
    public string UserAgent
    {
        get => _userAgent;
        set { if (Set(ref _userAgent, value)) OnSettingChanged(nameof(UserAgent)); }
    }

    private string _proxyServer = "";
    public string ProxyServer
    {
        get => _proxyServer;
        set { if (Set(ref _proxyServer, value)) OnSettingChanged(nameof(ProxyServer)); }
    }

    // 8. 업데이트 & 정보
    private string _updateRepo = "";
    public string UpdateRepo
    {
        get => _updateRepo;
        set { if (Set(ref _updateRepo, value)) OnSettingChanged(nameof(UpdateRepo)); }
    }

    // 9. 암호 관리자 & Windows Hello
    private bool _enableWindowsHelloVault = true;
    public bool EnableWindowsHelloVault
    {
        get => _enableWindowsHelloVault;
        set { if (Set(ref _enableWindowsHelloVault, value)) OnSettingChanged(nameof(EnableWindowsHelloVault)); }
    }

    private int _vaultAutoLockMinutes = 15;
    public int VaultAutoLockMinutes
    {
        get => _vaultAutoLockMinutes;
        set { if (Set(ref _vaultAutoLockMinutes, value)) OnSettingChanged(nameof(VaultAutoLockMinutes)); }
    }

    private bool _requireBiometricForAutofill = false;
    public bool RequireBiometricForAutofill
    {
        get => _requireBiometricForAutofill;
        set { if (Set(ref _requireBiometricForAutofill, value)) OnSettingChanged(nameof(RequireBiometricForAutofill)); }
    }

    private bool _requireBiometricForPasswordReveal = true;
    public bool RequireBiometricForPasswordReveal
    {
        get => _requireBiometricForPasswordReveal;
        set { if (Set(ref _requireBiometricForPasswordReveal, value)) OnSettingChanged(nameof(RequireBiometricForPasswordReveal)); }
    }

    #endregion

    #region SSOT State Tracking & Validation

    private bool _isDirty;
    public bool IsDirty
    {
        get => _isDirty;
        private set => Set(ref _isDirty, value);
    }

    private int _dirtyCount;
    public int DirtyCount
    {
        get => _dirtyCount;
        private set => Set(ref _dirtyCount, value);
    }

    private string _validationSummary = "";
    public string ValidationSummary
    {
        get => _validationSummary;
        private set => Set(ref _validationSummary, value);
    }

    private bool _hasErrors;
    public bool HasErrors
    {
        get => _hasErrors;
        private set => Set(ref _hasErrors, value);
    }

    private void OnSettingChanged(string propertyName, bool requestLivePreview = false)
    {
        RecalculateDirtyState();
        Validate();
        if (requestLivePreview) LivePreviewRequested?.Invoke(propertyName);
    }

    public void RecalculateDirtyState()
    {
        int changed = 0;
        if (!Equals(_theme, _originalValues.GetValueOrDefault(nameof(Theme)))) changed++;
        if (!Equals(_accentColor, _originalValues.GetValueOrDefault(nameof(AccentColor)))) changed++;
        if (!Equals(_customThemePath, _originalValues.GetValueOrDefault(nameof(CustomThemePath)))) changed++;
        if (!Equals(_uiDensity, _originalValues.GetValueOrDefault(nameof(UiDensity)))) changed++;
        if (Math.Abs(_uiScale - (double)(_originalValues.GetValueOrDefault(nameof(UiScale)) ?? 1.0)) > 0.001) changed++;
        if (Math.Abs(_uiFontScale - (double)(_originalValues.GetValueOrDefault(nameof(UiFontScale)) ?? 1.0)) > 0.001) changed++;
        if (!Equals(_uiFontFamily, _originalValues.GetValueOrDefault(nameof(UiFontFamily)))) changed++;
        if (!Equals(_uiFontKoreanFallback, _originalValues.GetValueOrDefault(nameof(UiFontKoreanFallback)))) changed++;
        if (Math.Abs(_uiFontSize - (double)(_originalValues.GetValueOrDefault(nameof(UiFontSize)) ?? 13.0)) > 0.001) changed++;
        if (!Equals(_outputFolder, _originalValues.GetValueOrDefault(nameof(OutputFolder)))) changed++;
        if (!Equals(_homeUrl, _originalValues.GetValueOrDefault(nameof(HomeUrl)))) changed++;
        if (!Equals(_language, _originalValues.GetValueOrDefault(nameof(Language)))) changed++;
        if (!Equals(_searchEngine, _originalValues.GetValueOrDefault(nameof(SearchEngine)))) changed++;
        if (!Equals(_autoStart, _originalValues.GetValueOrDefault(nameof(AutoStart)))) changed++;
        if (!Equals(_minimizeToTray, _originalValues.GetValueOrDefault(nameof(MinimizeToTray)))) changed++;
        if (!Equals(_concurrency, _originalValues.GetValueOrDefault(nameof(Concurrency)))) changed++;
        if (!Equals(_maxConcurrentDownloads, _originalValues.GetValueOrDefault(nameof(MaxConcurrentDownloads)))) changed++;
        if (!Equals(_retries, _originalValues.GetValueOrDefault(nameof(Retries)))) changed++;
        if (!Equals(_minSizeMB, _originalValues.GetValueOrDefault(nameof(MinSizeMB)))) changed++;
        if (!Equals(_maxDownloadSpeedKbps, _originalValues.GetValueOrDefault(nameof(MaxDownloadSpeedKbps)))) changed++;
        if (!Equals(_autoClearCompleted, _originalValues.GetValueOrDefault(nameof(AutoClearCompleted)))) changed++;
        if (!Equals(_openFolderOnComplete, _originalValues.GetValueOrDefault(nameof(OpenFolderOnComplete)))) changed++;
        if (!Equals(_subtitleLanguage, _originalValues.GetValueOrDefault(nameof(SubtitleLanguage)))) changed++;
        if (!Equals(_downloadScheduleWindow, _originalValues.GetValueOrDefault(nameof(DownloadScheduleWindow)))) changed++;
        if (!Equals(_notifySound, _originalValues.GetValueOrDefault(nameof(NotifySound)))) changed++;
        if (!Equals(_doNotDisturb, _originalValues.GetValueOrDefault(nameof(DoNotDisturb)))) changed++;
        if (!Equals(_pauseOnPowerSaver, _originalValues.GetValueOrDefault(nameof(PauseOnPowerSaver)))) changed++;
        if (!Equals(_toastDurationMs, _originalValues.GetValueOrDefault(nameof(ToastDurationMs)))) changed++;
        if (!Equals(_reduceMotion, _originalValues.GetValueOrDefault(nameof(ReduceMotion)))) changed++;
        if (!Equals(_showCaptions, _originalValues.GetValueOrDefault(nameof(ShowCaptions)))) changed++;
        if (!Equals(_focusSelectsAddress, _originalValues.GetValueOrDefault(nameof(FocusSelectsAddress)))) changed++;
        if (!Equals(_pasteAndGo, _originalValues.GetValueOrDefault(nameof(PasteAndGo)))) changed++;
        if (!Equals(_tabWheelSwitch, _originalValues.GetValueOrDefault(nameof(TabWheelSwitch)))) changed++;
        if (!Equals(_tabStripPosition, _originalValues.GetValueOrDefault(nameof(TabStripPosition)))) changed++;
        if (!Equals(_verticalTabsDefault, _originalValues.GetValueOrDefault(nameof(VerticalTabsDefault)))) changed++;
        if (!Equals(_verticalTabsPosition, _originalValues.GetValueOrDefault(nameof(VerticalTabsPosition)))) changed++;
        if (!Equals(_verticalTabsCollapsed, _originalValues.GetValueOrDefault(nameof(VerticalTabsCollapsed)))) changed++;
        if (Math.Abs(_verticalTabsWidth - (double)(_originalValues.GetValueOrDefault(nameof(VerticalTabsWidth)) ?? 220.0)) > 0.001) changed++;
        if (!Equals(_verticalTabsAutoExpand, _originalValues.GetValueOrDefault(nameof(VerticalTabsAutoExpand)))) changed++;
        if (!Equals(_confirmCloseMultipleTabs, _originalValues.GetValueOrDefault(nameof(ConfirmCloseMultipleTabs)))) changed++;
        if (!Equals(_bookmarkBarVisible, _originalValues.GetValueOrDefault(nameof(BookmarkBarVisible)))) changed++;
        if (!Equals(_restoreTabsSuspended, _originalValues.GetValueOrDefault(nameof(RestoreTabsSuspended)))) changed++;
        if (!Equals(_tabTitleMultiline, _originalValues.GetValueOrDefault(nameof(TabTitleMultiline)))) changed++;
        if (!Equals(_ffmpegPath, _originalValues.GetValueOrDefault(nameof(FfmpegPath)))) changed++;
        if (!Equals(_ytDlpPath, _originalValues.GetValueOrDefault(nameof(YtDlpPath)))) changed++;
        if (!Equals(_useCookiesForSocial, _originalValues.GetValueOrDefault(nameof(UseCookiesForSocial)))) changed++;
        if (!Equals(_autoInstallYtDlp, _originalValues.GetValueOrDefault(nameof(AutoInstallYtDlp)))) changed++;
        if (!Equals(_autoUpdateYtDlp, _originalValues.GetValueOrDefault(nameof(AutoUpdateYtDlp)))) changed++;
        if (!Equals(_autoInstallDeno, _originalValues.GetValueOrDefault(nameof(AutoInstallDeno)))) changed++;
        if (!Equals(_defaultSocialQuality, _originalValues.GetValueOrDefault(nameof(DefaultSocialQuality)))) changed++;
        if (!Equals(_youtubePlayerClients, _originalValues.GetValueOrDefault(nameof(YoutubePlayerClients)))) changed++;
        if (!Equals(_userAgent, _originalValues.GetValueOrDefault(nameof(UserAgent)))) changed++;
        if (!Equals(_proxyServer, _originalValues.GetValueOrDefault(nameof(ProxyServer)))) changed++;
        if (!Equals(_updateRepo, _originalValues.GetValueOrDefault(nameof(UpdateRepo)))) changed++;
        if (!Equals(_enableWindowsHelloVault, _originalValues.GetValueOrDefault(nameof(EnableWindowsHelloVault)))) changed++;
        if (!Equals(_vaultAutoLockMinutes, _originalValues.GetValueOrDefault(nameof(VaultAutoLockMinutes)))) changed++;
        if (!Equals(_requireBiometricForAutofill, _originalValues.GetValueOrDefault(nameof(RequireBiometricForAutofill)))) changed++;
        if (!Equals(_requireBiometricForPasswordReveal, _originalValues.GetValueOrDefault(nameof(RequireBiometricForPasswordReveal)))) changed++;

        DirtyCount = changed;
        IsDirty = changed > 0;
    }

    public bool Validate()
    {
        _errors.Clear();

        if (Concurrency < 1) _errors[nameof(Concurrency)] = "세그먼트 동시 수는 1 이상의 숫자여야 합니다.";
        if (MaxConcurrentDownloads < 1) _errors[nameof(MaxConcurrentDownloads)] = "최대 동시 다운로드 수는 1 이상의 숫자여야 합니다.";
        if (Retries < 1) _errors[nameof(Retries)] = "재시도 횟수는 1 이상의 숫자여야 합니다.";
        if (MinSizeMB < 0) _errors[nameof(MinSizeMB)] = "최소 크기는 0 이상의 숫자여야 합니다.";
        if (MaxDownloadSpeedKbps < 0) _errors[nameof(MaxDownloadSpeedKbps)] = "속도 상한은 0 이상의 숫자여야 합니다.";
        if (ToastDurationMs < 500) _errors[nameof(ToastDurationMs)] = "토스트 표시 시간은 0.5초(500ms) 이상이어야 합니다.";

        if (!string.IsNullOrWhiteSpace(DownloadScheduleWindow) &&
            !Services.DownloadScheduler.TryParse(DownloadScheduleWindow.Trim(), out _, out _))
        {
            _errors[nameof(DownloadScheduleWindow)] = "예약 시간대는 HH:mm-HH:mm 형식이어야 합니다 (예: 02:00-08:00).";
        }

        if (!string.IsNullOrEmpty(AccentColor))
        {
            var acc = AccentColor.Trim();
            if (!(acc.Length == 7 && acc.StartsWith('#') && acc[1..].All(Uri.IsHexDigit)))
            {
                _errors[nameof(AccentColor)] = "강조색은 #RRGGBB 형식이어야 합니다.";
            }
        }

        HasErrors = _errors.Count > 0;
        ValidationSummary = HasErrors ? _errors.Values.First() : "";
        return !HasErrors;
    }

    public void LoadFromConfig(AppConfig config, bool isOriginalSnapshot = false)
    {
        _theme = config.Theme ?? "dark";
        _accentColor = config.AccentColor;
        _customThemePath = config.CustomThemePath;
        _uiDensity = config.UiDensity ?? "normal";
        _uiScale = Math.Clamp(config.UiScale, 1.0, 2.0);
        _uiFontScale = Math.Clamp(config.UiFontScale <= 0 ? 1.0 : config.UiFontScale, 1.0, 2.0);
        _uiFontFamily = config.UiFontFamily ?? "";
        _uiFontKoreanFallback = string.IsNullOrWhiteSpace(config.UiFontKoreanFallback) ? "Malgun Gothic" : config.UiFontKoreanFallback;
        _uiFontSize = config.UiFontSize > 0 ? config.UiFontSize : 13.0;

        _outputFolder = config.OutputFolder ?? "";
        _homeUrl = string.IsNullOrWhiteSpace(config.HomeUrl) ? "https://www.google.com" : config.HomeUrl;
        _language = config.Language ?? "ko";
        _searchEngine = config.SearchEngine ?? "Google";
        _autoStart = config.AutoStart;
        _minimizeToTray = config.MinimizeToTray;

        _toolbarButtons = new ObservableCollection<string>(config.ToolbarButtons ?? AppConfig.DefaultToolbarButtons);

        _concurrency = Math.Max(1, config.Concurrency);
        _maxConcurrentDownloads = Math.Max(1, config.MaxConcurrentDownloads);
        _retries = Math.Max(1, config.Retries);
        _minSizeMB = Math.Max(0, config.MinSizeMB);
        _maxDownloadSpeedKbps = Math.Max(0, config.MaxDownloadSpeedKbps);
        _autoClearCompleted = config.AutoClearCompleted;
        _openFolderOnComplete = config.OpenFolderOnComplete;
        _subtitleLanguage = config.SubtitleLanguage ?? "";
        _downloadScheduleWindow = config.DownloadScheduleWindow;

        _notifySound = config.NotifySound;
        _doNotDisturb = config.DoNotDisturb;
        _pauseOnPowerSaver = config.PauseOnPowerSaver;
        _toastDurationMs = config.ToastDurationMs > 0 ? config.ToastDurationMs : 3000;

        _reduceMotion = config.ReduceMotion;
        _showCaptions = config.ShowCaptions;
        _focusSelectsAddress = config.FocusSelectsAddress;
        _pasteAndGo = config.PasteAndGo;

        _tabWheelSwitch = config.TabWheelSwitch;
        _tabStripPosition = config.TabStripPosition ?? "top";
        _verticalTabsDefault = config.VerticalTabsDefault;
        _verticalTabsPosition = config.VerticalTabsPosition ?? "Left";
        _verticalTabsCollapsed = config.VerticalTabsCollapsed;
        _verticalTabsWidth = config.VerticalTabsWidth > 0 ? config.VerticalTabsWidth : 220.0;
        _verticalTabsAutoExpand = config.VerticalTabsAutoExpand;
        _confirmCloseMultipleTabs = config.ConfirmCloseMultipleTabs;
        _bookmarkBarVisible = config.BookmarkBarVisible;
        _restoreTabsSuspended = config.RestoreTabsSuspended;
        _tabTitleMultiline = config.TabTitleMultiline;
        _enabledFormats = config.EnabledFormats?.ToList() ?? new List<string> { "hls", "dash", "mp4" };

        _ffmpegPath = config.FfmpegPath;
        _ytDlpPath = config.YtDlpPath;
        _useCookiesForSocial = config.UseCookiesForSocial;
        _autoInstallYtDlp = config.AutoInstallYtDlp;
        _autoUpdateYtDlp = config.AutoUpdateYtDlp;
        _autoInstallDeno = config.AutoInstallDeno;
        _defaultSocialQuality = config.DefaultSocialQuality ?? "best";
        _youtubePlayerClients = config.YoutubePlayerClients;
        _userAgent = string.IsNullOrWhiteSpace(config.UserAgent)
            ? "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36"
            : config.UserAgent;
        _proxyServer = config.ProxyServer ?? "";

        _updateRepo = config.UpdateRepo ?? "";

        _enableWindowsHelloVault = config.EnableWindowsHelloVault;
        _vaultAutoLockMinutes = config.VaultAutoLockMinutes;
        _requireBiometricForAutofill = config.RequireBiometricForAutofill;
        _requireBiometricForPasswordReveal = config.RequireBiometricForPasswordReveal;

        if (isOriginalSnapshot)
        {
            _originalValues.Clear();
            _originalValues[nameof(Theme)] = _theme;
            _originalValues[nameof(AccentColor)] = _accentColor;
            _originalValues[nameof(CustomThemePath)] = _customThemePath;
            _originalValues[nameof(UiDensity)] = _uiDensity;
            _originalValues[nameof(UiScale)] = _uiScale;
            _originalValues[nameof(UiFontScale)] = _uiFontScale;
            _originalValues[nameof(UiFontFamily)] = _uiFontFamily;
            _originalValues[nameof(UiFontKoreanFallback)] = _uiFontKoreanFallback;
            _originalValues[nameof(UiFontSize)] = _uiFontSize;
            _originalValues[nameof(OutputFolder)] = _outputFolder;
            _originalValues[nameof(HomeUrl)] = _homeUrl;
            _originalValues[nameof(Language)] = _language;
            _originalValues[nameof(SearchEngine)] = _searchEngine;
            _originalValues[nameof(AutoStart)] = _autoStart;
            _originalValues[nameof(MinimizeToTray)] = _minimizeToTray;
            _originalValues[nameof(Concurrency)] = _concurrency;
            _originalValues[nameof(MaxConcurrentDownloads)] = _maxConcurrentDownloads;
            _originalValues[nameof(Retries)] = _retries;
            _originalValues[nameof(MinSizeMB)] = _minSizeMB;
            _originalValues[nameof(MaxDownloadSpeedKbps)] = _maxDownloadSpeedKbps;
            _originalValues[nameof(AutoClearCompleted)] = _autoClearCompleted;
            _originalValues[nameof(OpenFolderOnComplete)] = _openFolderOnComplete;
            _originalValues[nameof(SubtitleLanguage)] = _subtitleLanguage;
            _originalValues[nameof(DownloadScheduleWindow)] = _downloadScheduleWindow;
            _originalValues[nameof(NotifySound)] = _notifySound;
            _originalValues[nameof(DoNotDisturb)] = _doNotDisturb;
            _originalValues[nameof(PauseOnPowerSaver)] = _pauseOnPowerSaver;
            _originalValues[nameof(ToastDurationMs)] = _toastDurationMs;
            _originalValues[nameof(ReduceMotion)] = _reduceMotion;
            _originalValues[nameof(ShowCaptions)] = _showCaptions;
            _originalValues[nameof(FocusSelectsAddress)] = _focusSelectsAddress;
            _originalValues[nameof(PasteAndGo)] = _pasteAndGo;
            _originalValues[nameof(TabWheelSwitch)] = _tabWheelSwitch;
            _originalValues[nameof(TabStripPosition)] = _tabStripPosition;
            _originalValues[nameof(VerticalTabsDefault)] = _verticalTabsDefault;
            _originalValues[nameof(VerticalTabsPosition)] = _verticalTabsPosition;
            _originalValues[nameof(VerticalTabsCollapsed)] = _verticalTabsCollapsed;
            _originalValues[nameof(VerticalTabsWidth)] = _verticalTabsWidth;
            _originalValues[nameof(VerticalTabsAutoExpand)] = _verticalTabsAutoExpand;
            _originalValues[nameof(ConfirmCloseMultipleTabs)] = _confirmCloseMultipleTabs;
            _originalValues[nameof(BookmarkBarVisible)] = _bookmarkBarVisible;
            _originalValues[nameof(RestoreTabsSuspended)] = _restoreTabsSuspended;
            _originalValues[nameof(TabTitleMultiline)] = _tabTitleMultiline;
            _originalValues[nameof(FfmpegPath)] = _ffmpegPath;
            _originalValues[nameof(YtDlpPath)] = _ytDlpPath;
            _originalValues[nameof(UseCookiesForSocial)] = _useCookiesForSocial;
            _originalValues[nameof(AutoInstallYtDlp)] = _autoInstallYtDlp;
            _originalValues[nameof(AutoUpdateYtDlp)] = _autoUpdateYtDlp;
            _originalValues[nameof(AutoInstallDeno)] = _autoInstallDeno;
            _originalValues[nameof(DefaultSocialQuality)] = _defaultSocialQuality;
            _originalValues[nameof(YoutubePlayerClients)] = _youtubePlayerClients;
            _originalValues[nameof(UserAgent)] = _userAgent;
            _originalValues[nameof(ProxyServer)] = _proxyServer;
            _originalValues[nameof(UpdateRepo)] = _updateRepo;
            _originalValues[nameof(EnableWindowsHelloVault)] = _enableWindowsHelloVault;
            _originalValues[nameof(VaultAutoLockMinutes)] = _vaultAutoLockMinutes;
            _originalValues[nameof(RequireBiometricForAutofill)] = _requireBiometricForAutofill;
            _originalValues[nameof(RequireBiometricForPasswordReveal)] = _requireBiometricForPasswordReveal;
        }

        RecalculateDirtyState();
        Validate();
        OnPropertyChanged(""); // 전체 프로퍼티 리프레시
    }

    public void CommitToConfig(AppConfig target)
    {
        target.Theme = _theme;
        target.AccentColor = string.IsNullOrWhiteSpace(_accentColor) ? null : _accentColor.Trim();
        target.CustomThemePath = string.IsNullOrWhiteSpace(_customThemePath) ? null : _customThemePath.Trim();
        target.UiDensity = _uiDensity;
        target.UiScale = _uiScale;
        target.UiFontScale = _uiFontScale;
        target.UiFontFamily = _uiFontFamily.Trim();
        target.UiFontKoreanFallback = string.IsNullOrWhiteSpace(_uiFontKoreanFallback) ? "Malgun Gothic" : _uiFontKoreanFallback.Trim();
        target.UiFontSize = _uiFontSize;

        target.OutputFolder = _outputFolder.Trim();
        target.HomeUrl = string.IsNullOrWhiteSpace(_homeUrl) ? "https://www.google.com" : _homeUrl.Trim();
        target.Language = _language;
        target.SearchEngine = _searchEngine;
        target.AutoStart = _autoStart;
        target.MinimizeToTray = _minimizeToTray;

        target.ToolbarButtons = _toolbarButtons.ToList();

        target.Concurrency = Math.Max(1, _concurrency);
        target.MaxConcurrentDownloads = Math.Max(1, _maxConcurrentDownloads);
        target.Retries = Math.Max(1, _retries);
        target.MinSizeMB = Math.Max(0, _minSizeMB);
        target.MaxDownloadSpeedKbps = Math.Max(0, _maxDownloadSpeedKbps);
        target.AutoClearCompleted = _autoClearCompleted;
        target.OpenFolderOnComplete = _openFolderOnComplete;
        target.SubtitleLanguage = _subtitleLanguage ?? "";
        target.DownloadScheduleWindow = string.IsNullOrWhiteSpace(_downloadScheduleWindow) ? null : _downloadScheduleWindow.Trim();

        target.NotifySound = _notifySound;
        target.DoNotDisturb = _doNotDisturb;
        target.PauseOnPowerSaver = _pauseOnPowerSaver;
        target.ToastDurationMs = Math.Max(500, _toastDurationMs);

        target.ReduceMotion = _reduceMotion;
        target.ShowCaptions = _showCaptions;
        target.FocusSelectsAddress = _focusSelectsAddress;
        target.PasteAndGo = _pasteAndGo;

        target.TabWheelSwitch = _tabWheelSwitch;
        target.TabStripPosition = _tabStripPosition;
        target.VerticalTabsDefault = _verticalTabsDefault;
        target.VerticalTabsPosition = _verticalTabsPosition;
        target.VerticalTabsCollapsed = _verticalTabsCollapsed;
        target.VerticalTabsWidth = _verticalTabsWidth;
        target.VerticalTabsAutoExpand = _verticalTabsAutoExpand;
        target.ConfirmCloseMultipleTabs = _confirmCloseMultipleTabs;
        target.BookmarkBarVisible = _bookmarkBarVisible;
        target.RestoreTabsSuspended = _restoreTabsSuspended;
        target.TabTitleMultiline = _tabTitleMultiline;
        target.EnabledFormats = _enabledFormats.ToList();

        target.FfmpegPath = string.IsNullOrWhiteSpace(_ffmpegPath) ? null : _ffmpegPath.Trim();
        target.YtDlpPath = string.IsNullOrWhiteSpace(_ytDlpPath) ? null : _ytDlpPath.Trim();
        target.UseCookiesForSocial = _useCookiesForSocial;
        target.AutoInstallYtDlp = _autoInstallYtDlp;
        target.AutoUpdateYtDlp = _autoUpdateYtDlp;
        target.AutoInstallDeno = _autoInstallDeno;
        target.DefaultSocialQuality = _defaultSocialQuality;
        target.YoutubePlayerClients = string.IsNullOrWhiteSpace(_youtubePlayerClients) ? null : _youtubePlayerClients.Trim();
        target.UserAgent = string.IsNullOrWhiteSpace(_userAgent)
            ? "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36"
            : _userAgent.Trim();
        target.ProxyServer = _proxyServer.Trim();

        target.UpdateRepo = _updateRepo.Trim();

        target.EnableWindowsHelloVault = _enableWindowsHelloVault;
        target.VaultAutoLockMinutes = _vaultAutoLockMinutes;
        target.RequireBiometricForAutofill = _requireBiometricForAutofill;
        target.RequireBiometricForPasswordReveal = _requireBiometricForPasswordReveal;
    }

    public void ResetToDefaults()
    {
        var temp = new AppConfig();
        temp.ResetToDefaults();
        LoadFromConfig(temp, isOriginalSnapshot: false);
    }

    public void ResetToOriginal()
    {
        LoadFromConfig(_originalConfig, isOriginalSnapshot: true);
    }

    #endregion

    private bool Set<T>(ref T field, T value, [CallerMemberName] string? name = null)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(name);
        return true;
    }

    private void OnPropertyChanged([CallerMemberName] string? name = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }
}