using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Threading;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services;
using ytLive.Services.Audio;
using ytLive.Services.Compositor;
using ytLive.Services.Encoder;

namespace ytLive.ViewModels;

public partial class MainViewModel : ViewModelBase
{
    private readonly YouTubeAuthService _youtubeAuth;
    private readonly YouTubeStreamService _youtubeStream;
    private readonly YouTubeChatService _youtubeChat;

    private SceneElement? _selectedElement;

    private LayoutStore _layoutStore;
    private string? _activeLayoutPath;
    private DispatcherTimer? _saveDebounce;
    private bool _isLoading;

    // Toasts (TASK 24): non-blocking user-facing messages. Parameterless ctor
    // news up the real service; the VM is built from XAML so no DI seam exists.
    private readonly INotificationService _notifications = new NotificationService();

    // Live frame pipeline (TASK 4 ship step 5): composites the active scene at the
    // tier's FPS and paces frames into the encoder. The RTMP URL seam stays null
    // until the live-stream create flow (TASK 5) supplies the reusable stream URL.
    private readonly Func<string?> _rtmpUrlProvider;
    private readonly TransitionService _transition = new();

    private WebView2Manager? _webView2Manager;

    // Branding flash (monetization): a full-frame "made with LlamaCasty!" shown
    // for ~1s every 300s on the live output, ~25% opacity. Paid unlock sets
    // BrandFlashEnabled = false. See ai.md "Monetization".
    private readonly DispatcherTimer _brandFlashTimer;
    private readonly DispatcherTimer _brandFlashOffTimer;
    private bool _brandFlashEnabled = true;
    private bool _brandFlashActive;

    public SceneElement? SelectedElement
    {
        get => _selectedElement;
        set
        {
            if (_selectedElement != null)
                _selectedElement.PropertyChanged -= OnSelectedElementPropertyChanged;
            if (SetProperty(ref _selectedElement, value))
            {
                OnPropertyChanged(nameof(IsWebcamSelected));
                OnPropertyChanged(nameof(IsElementsPanelEmpty));
                if (_selectedElement != null)
                    _selectedElement.PropertyChanged += OnSelectedElementPropertyChanged;
            }
        }
    }

    private void OnSelectedElementPropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        if (e.PropertyName == nameof(SceneElement.UseDefaultBackground))
        {
            UpdateBackgroundImage();
            RefreshSnapshotsAsync();
            ScheduleSave();
        }
    }

    private static readonly SolidColorBrush BarOnBrush = CreateBrush("#2ecc71");
    private static readonly SolidColorBrush BarOffBrush = CreateBrush("#e94560");
    private static SolidColorBrush CreateBrush(string hex)
        => (SolidColorBrush)new BrushConverter().ConvertFromString(hex)!;

    /// <summary>True when the Elements panel should show the "No configurable elements" hint.</summary>
    public bool IsElementsPanelEmpty => SelectedElement is { } el
        && !el.IsDraggable && !el.IsWebcam
        && el is not Source { Type: SourceType.Countdown or SourceType.WebSource or SourceType.ChatBox };

    public bool ShowPreviewPlaceholder => !ShowEmptySceneHint && ActiveBackgroundImage == null && BackgroundImage == null;

    // Paid unlock flips this off (see ai.md "Monetization"). When disabled the
    // cadence timer is stopped and any active flash is hidden immediately.
    public bool BrandFlashEnabled
    {
        get => _brandFlashEnabled;
        set
        {
            if (!SetProperty(ref _brandFlashEnabled, value)) return;
            if (value)
            {
                if (IsLive) StartBrandFlashTimer();
            }
            else
            {
                _brandFlashTimer.Stop();
                _brandFlashOffTimer.Stop();
                BrandFlashActive = false;
            }
        }
    }

    public bool BrandFlashActive
    {
        get => _brandFlashActive;
        private set => SetProperty(ref _brandFlashActive, value);
    }

    // Window geometry pass-through (code-behind owns the WPF specifics).
    public (double Left, double Top, double Width, double Height, string State)? RestoreWindowState()
        => _layoutStore.LoadWindowState();

    public void PersistWindowState(double left, double top, double width, double height, string state)
        => _layoutStore.SaveWindowState(left, top, width, height, state);

    // Commands
    public ICommand AddSceneCommand { get; }
    public ICommand AddSourceCommand { get; }
    public ICommand AddImageCommand { get; }
    public ICommand RemoveSourceCommand { get; }
    public ICommand EditElementCommand { get; }
    public ICommand ToggleElementVisibilityCommand { get; }
    public ICommand ActivateLicenseCommand { get; }
    public ICommand OpenLicenseEntryCommand { get; }
    public ICommand OpenHotkeyConfigCommand { get; }
    public ICommand ChangeAccountCommand { get; }
    public ICommand LogoutCommand { get; }

    public MainViewModel()
    {
        AppLog.Write("MainViewModel ctor begin");
        _youtubeAuth = new YouTubeAuthService(OAuthCredentials.ClientId, OAuthCredentials.ClientSecret,
            sessionChanged: ch => TokenStore.Save(ch));
        _youtubeStream = new YouTubeStreamService(_youtubeAuth);
        _youtubeChat = new YouTubeChatService(_youtubeAuth);
        AppLog.Write("MainViewModel ctor: services created");

        _selectedQuality = QualityOptions[0];
        ApplyStreamQuality(_selectedQuality);

        _youtubeChat.MessageReceived += OnChatMessageReceived;

        _liveTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(1) };
        _liveTimer.Tick += OnLiveTimerTick;
        _volumeFlashTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(300) };
        _volumeFlashTimer.Tick += (_, _) => EndVolumeFlash();

        _gameVolumeFlashTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(300) };
        _gameVolumeFlashTimer.Tick += (_, _) => EndGameVolumeFlash();

        _saveDebounce = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(1500) };
        _saveDebounce.Tick += (_, _) => SaveLayoutNow();

        _brandFlashTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(300) };
        _brandFlashTimer.Tick += OnBrandFlashTimerTick;
        _brandFlashOffTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(750) };
        _brandFlashOffTimer.Tick += (_, _) => { _brandFlashOffTimer.Stop(); BrandFlashActive = false; };

        _healthPollTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(30) };
        _healthPollTimer.Tick += OnHealthPollTick;

        Scenes.CollectionChanged += OnScenesChanged;

        AddSceneCommand = new RelayCommand(name => AddScene(name as string ?? string.Empty));
        AddSourceCommand = new RelayCommand(parameter => AddSource(parameter));
        AddWebcamCommand = new RelayCommand(_ => _ = AddWebcamToStagedSceneAsync());
        AddImageCommand = new RelayCommand(_ => AddImage());
        RemoveSourceCommand = new RelayCommand(element => RemoveElement(element as SceneElement));
        EditElementCommand = new RelayCommand(element => BeginEditElement(element as SceneElement));
        ToggleElementVisibilityCommand = new RelayCommand(element => ToggleElementVisibility(element as SceneElement));
        ChangeWebcamCommand = new RelayCommand(_ => _ = ChangeWebcamAsync(), _ => CanChangeWebcam);
        ShowWebcamCommand = new RelayCommand(_ => ShowWebcamInStagedScene(), _ => CanShowWebcamInStagedScene);
        OpenSocialDialogCommand = new RelayCommand(_ => OpenSocialDialog());
        ChangeCaptureCommand = new RelayCommand(_ => _ = ChangeBackgroundCaptureAsync());
        RefreshCaptureCommand = new RelayCommand(_ => RefreshBackgroundAutoCapture());
        SetBackgroundDisplayCommand = new RelayCommand(display => SetBackgroundCapture(display as DisplayInfo));
        ToggleShowDesktopCommand = new RelayCommand(_ => ToggleBackgroundShowDesktop());
        BrowseBackgroundCommand = new RelayCommand(_ => BrowseBackground());
        ToggleMicMuteCommand = new RelayCommand(_ => ToggleMicMute());
        ToggleGameMuteCommand = new RelayCommand(_ => ToggleGameMute());
        OpenMicPickerCommand = new RelayCommand(_ => PickMicrophone());
        OpenSettingsCommand = new RelayCommand(_ => ShowOverlay(nameof(IsSettingsOpen), "App Settings"));
        OpenBugCommand = new RelayCommand(_ => ShowOverlay(nameof(IsBugOpen), "Report Bug"));
        OpenFeatureCommand = new RelayCommand(_ => ShowOverlay(nameof(IsFeatureOpen), "Feature Request"));
        OpenAboutCommand = new RelayCommand(_ => ShowOverlay(nameof(IsAboutOpen), "About"));
        CloseOverlayCommand = new RelayCommand(_ => ShowOverlay());
        SubmitBugCommand = new RelayCommand(_ => SubmitBug());
        SubmitFeatureCommand = new RelayCommand(_ => SubmitFeature());
        OpenChannelCommand = new RelayCommand(_ => OpenUrl(ChannelUrl));
        OpenMastodonCommand = new RelayCommand(_ => OpenUrl(MastodonUrl));
        OpenCoffeeCommand = new RelayCommand(_ => OpenUrl(CoffeeUrl));
        OpenPremiumCommand = new RelayCommand(_ => OpenUrl(PremiumUrl), _ => IsPremiumAvailable);
        OpenLicensesCommand = new RelayCommand(_ => ShowLicenses());
        StartStreamCommand = new RelayCommand(_ => StartSession());
        EndStreamCommand = new RelayCommand(_ => StopStream(), _ => IsLive || IsRecording);
        ChooseRecordFolderCommand = new RelayCommand(_ => ChooseRecordFolder());
        ResetRecordFolderCommand = new RelayCommand(_ => ResetRecordFolder());
        ActivateLicenseCommand = new RelayCommand(_ => _ = ActivateLicenseAsync(), _ => !IsLicenseValidating);
        OpenLicenseEntryCommand = new RelayCommand(_ => IsLicenseEntryOpen = !IsLicenseEntryOpen);
        OpenHotkeyConfigCommand = new RelayCommand(_ => OpenHotkeyConfig());
        ChangeAccountCommand = new RelayCommand(_ => _ = ChangeAccountAsync());
        LogoutCommand = new RelayCommand(_ => _ = SignOutYouTubeAsync());

        _layoutStore = new LayoutStore(LayoutPathOverride ?? DefaultLayoutPath);
        _activeLayoutPath = _layoutStore.ActivePath;
        _recordFolder = _layoutStore.LoadRecordFolder();

        // Load saved hotkey bindings (filled with defaults for any unbound actions).
        _hotkeyBindings = _layoutStore.LoadHotkeyBindings();

        BroadcastForm = new Services.LiveBroadcastFormViewModel(
            () => _layoutStore,
            () => _youtubeStream,
            () => CurrentBroadcastId,
            () => IsLive);

        // Restore the last picked mic so the mixer's first capture attaches to
        // the same, already-vetted device (green dot) or reports it missing
        // (yellow) instead of silently falling back to the default.
        MicSourceName = _layoutStore.LoadMicSourceName();

        _cameraEnumerator = new MediaCaptureCameraEnumerator();
        _cameraManager = new CameraManager(
            _cameraEnumerator,
            id => new MediaCaptureFrameSource(id),
            System.Windows.Application.Current?.Dispatcher);
        _cameraManager.PreviewBitmapChanged += OnCameraPreviewBitmapChanged;
        _cameraManager.CameraFailed += OnCameraFailed;

        _microphoneEnumerator = new WinRtMicrophoneEnumerator();

        // The mixer consumes these Func seams live each mix tick, so the volume
        // sliders and mute buttons are stream-honest (they also update the
        // meters' display). Before this wiring the gains defaulted to unity and
        // the controls were decorative.
        _gainProvider = new AudioGainProvider(
            () => MicMuted,
            () => MicVolume,
            () => GameMuted,
            () => GameAudioVolume);
        _audioMixer = new AudioMixer(
            new WasapiMicAudioSource(() => MicSourceName),
            new WasapiLoopbackAudioSource(),
            message => AppLog.Write(message),
            micGain: _gainProvider.MicGain,
            loopbackGain: _gainProvider.LoopbackGain);
        _audioMixer.MicLevelChanged += OnMicLevelChanged;
        _audioMixer.LoopbackLevelChanged += OnLoopbackLevelChanged;
        _audioMixer.MicConnected += OnMicConnected;
        _audioMixer.MicFailed += OnMicFailed;
        _musicPlayer.PlaybackEnded += OnTraxPlaybackEnded;
        _ = StartMicCaptureAsync();

        _fullScreenDetector = new Win32FullScreenDetector();
        _fullScreenDetector.FullscreenMonitorChanged += OnFullscreenMonitorChanged;
        foreach (var display in _fullScreenDetector.GetDisplays())
            Displays.Add(display);

        _screenCaptureFactory = new ScreenCaptureSourceFactory(
            () => new WindowInteropHelper(System.Windows.Application.Current?.MainWindow).Handle);
        _screenCaptureManager = new ScreenCaptureManager(
            _screenCaptureFactory.Resolve,
            System.Windows.Application.Current?.Dispatcher);
        _screenCaptureManager.PreviewBitmapChanged += OnScreenPreviewBitmapChanged;
        _screenCaptureManager.CaptureFailed += (key, message) =>
            AppLog.Write($"ScreenCaptureManager: capture '{key}' failed: {message}");

        _chatLayer = new ChatOverlayLayer(new ChatBoxRenderer());

        _rtmpUrlProvider = () => _reusableStreamUrl; // TASK 5: the reusable stream's ingest URL
        _framePump = new FramePump(
            sceneProvider: () => StagedScene,
            frameResolver: ResolveOutputFrame,
            compositorOptions: BuildCompositorOptions,
            encoderOptions: BuildEncoderOptions,
            encoderFactory: () => new FfmpegEncoder(new FfmpegLocator()),
            log: message => AppLog.Write(message),
            socialBar: () => (_socialBarFrame, _socials?.BarPosition ?? SocialBarPosition.Bottom),
            transition: _transition,
            fromSceneProvider: () => LiveScene);
        _framePump.Failed += OnFramePumpFailed;
        _framePump.HealthUpdated += OnFramePumpHealthUpdated;

        LoadLayout();
        // The cached reusable stream gives the pump its RTMP URL the moment go-live
        // starts (the pump reads the URL once at startup — no waiting on YouTube).
        _reusableStream = _layoutStore.LoadReusableStream();
        _reusableStreamUrl = _reusableStream?.RtmpUrl;
        _ = LoadSavedSessionAsync();
        _ = ValidateLicenseAtStartupAsync();
        AppLog.Write("MainViewModel ctor end");
    }

    private static string DefaultLayoutPath => Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
        "ytLlive",
        "ytLlive.db");

    // Test seam: a real MainWindow test must never read or write the user's
    // real layout DB (it would persist test sources over real ones). Tests set
    // this to a temp path before constructing MainWindow and reset it after.
    internal static string? LayoutPathOverride { get; set; }

    private void LoadLayout()
    {
        _isLoading = true;
        try
        {
            AppLog.Write("LoadLayout begin");
            var scenes = _layoutStore.Load();
            Scenes.Clear();
            foreach (var scene in scenes)
                Scenes.Add(scene);

            if (Scenes.Count == 0)
            {
                foreach (var name in SceneCatalog.All)
                    AddScene(name);
            }
            HealBackgrounds();
            RefreshHotkeyLabels();

            foreach (var scene in Scenes)
                foreach (var config in scene.Elements.OfType<WebcamSceneConfig>())
                {
                    ClampWebcamToBounds(config, scene.Name);
                    HealLegacySquareRect(config);
                }

            // One-time heal: ChatBox layers created before the "YouTube Chat"
            // default still carry the old "Chat" name — creator renames untouched.
            foreach (var scene in Scenes)
                foreach (var source in scene.Elements.OfType<Source>())
                    if (source.Type == SourceType.ChatBox
                        && string.Equals(source.Name, "Chat", StringComparison.OrdinalIgnoreCase))
                        source.Name = "YouTube Chat";

            AppLog.Write($"LoadLayout: {Scenes.Count} scenes loaded");
        }
        finally
        {
            _isLoading = false;
        }
        StagedScene = Scenes.FirstOrDefault();
        UpdateActiveBackground();
        UpdateActiveChatBoxPreviews();
        StartMockChatPreview();
        UpdateBackgroundImage();
        ReacquireWebcam();
        ReacquireScreenCaptures();
        RegisterLoadedWebSources();
        _socials = _layoutStore.Socials;
        RenderSocialBarFrame();
        HealFediverseSoftwareInBackground();
        OnPropertyChanged(nameof(HasSocials));
        OnPropertyChanged(nameof(SocialBarVisible));
        OnPropertyChanged(nameof(SocialBarDotBrush));
        _music = _layoutStore.Music;
        LoadTrax(play: false);

        var (transType, transDur) = _layoutStore.LoadTransitionSettings();
        if (Enum.TryParse<TransitionType>(transType, true, out var parsed))
            SelectedTransitionType = parsed;
        TransitionDurationMs = transDur;

        BroadcastForm.Load();

        ScheduleSave();
        AppLog.Write("LoadLayout end");
    }


    public void Shutdown()
    {
        _saveDebounce?.Stop();
        SaveLayoutNow();
        _audioMixer.Dispose();
        _framePump.Dispose();
        _cameraManager.Dispose();
        _screenCaptureManager.Dispose();
        _webView2Manager?.Dispose();
        _layoutStore.Dispose();
        _musicPlayer.Dispose();
        _youtubeChat.Dispose();
    }

    public void SaveLayoutNow()
    {
        _saveDebounce?.Stop();
        try
        {
            _layoutStore.Save(Scenes, _webcam, _socials, _music);
            _layoutStore.SaveTransitionSettings(
                SelectedTransitionType.ToString(), TransitionDurationMs);
        }
        catch (Exception ex)
        {
            Debug.WriteLine($"Layout save failed: {ex.Message}");
        }
    }

    private void ScheduleSave()
    {
        if (_isLoading || _saveDebounce == null) return;
        _saveDebounce.Stop();
        _saveDebounce.Start();
    }

    private void BeginEditElement(SceneElement? element)
    {
        if (element == null) return;
        element.IsEditing = true;
    }

    private void ToggleElementVisibility(SceneElement? element)
    {
        if (element == null) return;
        element.IsVisible = !element.IsVisible;
        if (element is Source { IsBackground: true })
            OnPropertyChanged(nameof(BackgroundVisible));
    }


    // Scene-element → latest frame, for the live compositor. The map mirrors the
    // preview: webcam by DeviceId, live captures (the background) by CaptureKey,
    // images/background by AssetId. A null frame leaves the element transparent.
    private VideoFrame? ResolveOutputFrame(SceneElement element)
    {
        return element switch
        {
            WebcamSceneConfig webcam => _cameraManager.GetLatestFrame(webcam.WebcamId),
            Source { IsLiveCapture: true, CaptureKey: not null } live => _screenCaptureManager.GetLatestFrame(live.CaptureKey),
            Source { Type: SourceType.ChatBox } chatBox => RenderChatBox(chatBox),
            Source { Type: SourceType.WebSource } web => _webView2Manager?.GetLatestFrame(web.Id),
            Source { AssetId: not null } image => StaticPixelCache.Get(image.AssetId),
            _ => null,
        };
    }

    // The tier's crop rect over the 1920x1080 master, integer-aligned (the VM's
    // OutputRect* are doubles — the vertical 607.5 half-pixel crop rounds to 608).
    private CompositorOptions BuildCompositorOptions()
    {
        var quality = SelectedQuality;
        return new CompositorOptions
        {
            SourceRectX = (int)Math.Round(OutputRectX),
            SourceRectY = (int)Math.Round(OutputRectY),
            SourceRectWidth = (int)Math.Round(OutputRectWidth),
            SourceRectHeight = (int)Math.Round(OutputRectHeight),
            OutputWidth = quality.Width,
            OutputHeight = quality.Height,
        };
    }

    // First flash shortly after go-live, then every 300s (the cadence resets on
    // the first tick so the interval is 5s only for that one shot).
    private void StartBrandFlashTimer()
    {
        _brandFlashTimer.Stop();
        _brandFlashTimer.Interval = TimeSpan.FromSeconds(5);
        _brandFlashTimer.Start();
    }

    private void OnBrandFlashTimerTick(object? sender, EventArgs e)
    {
        _brandFlashTimer.Stop();
        _brandFlashTimer.Interval = TimeSpan.FromSeconds(300);
        _brandFlashTimer.Start();
        ShowBrandFlash();
    }

    private void ShowBrandFlash()
    {
        if (!IsLive || !BrandFlashEnabled) return;
        BrandFlashActive = true;
        _brandFlashOffTimer.Stop();
        _brandFlashOffTimer.Start();
    }

    }