LlamaCasty/ViewModels/MainViewModel.Background.cs

using System.Collections.ObjectModel;
using System.IO;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    // Screen background: a permanent live capture (desktop/game) that every scene
    // shows at the bottom layer. One shared capture session per key — the
    // ScreenCaptureManager refcounts by key, mirroring CameraManager.
    private readonly IFullScreenDetector _fullScreenDetector;
    private readonly ScreenCaptureManager _screenCaptureManager;
    private readonly ScreenCaptureSourceFactory _screenCaptureFactory;
    private readonly IWindowEnumerator _windowEnumerator;

    /// <summary>Test seam (mirrors CameraEnumeratorOverride): a real-Win32 test
    /// swaps in a fake enumerator to drive the "window dies -> re-heal" flow.</summary>
    internal static IWindowEnumerator? WindowEnumeratorOverride { get; set; }

    private ImageSource? _activeBackgroundImage;
    private ImageSource? _backgroundImage;
    private bool _backgroundSizeMismatch;
    private string _backgroundSizeMismatchText = "";
    private HashSet<string> _liveCaptureKeys = new();

    public ObservableCollection<DisplayInfo> Displays { get; } = new();

    public ImageSource? ActiveBackgroundImage
    {
        get => _activeBackgroundImage;
        private set => SetProperty(ref _activeBackgroundImage, value);
    }

    /// <summary>The active scene's live-capture background frame (rendered below the
    /// static background). Set from the shared capture bitmap as it arrives.</summary>
    public ImageSource? BackgroundImage
    {
        get => _backgroundImage;
        private set
        {
            if (SetProperty(ref _backgroundImage, value))
            {
                OnPropertyChanged(nameof(ShowPreviewPlaceholder));
                OnPropertyChanged(nameof(BackgroundVisible));
            }
        }
    }

    public bool BackgroundVisible => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.IsVisible == true;

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

    public string BackgroundSizeMismatchText
    {
        get => _backgroundSizeMismatchText;
        private set => SetProperty(ref _backgroundSizeMismatchText, value);
    }

    public ICommand ChangeCaptureCommand { get; }
    public ICommand RefreshCaptureCommand { get; }
    public ICommand SetBackgroundDisplayCommand { get; }
    public ICommand ToggleShowDesktopCommand { get; }
    public ICommand BrowseBackgroundCommand { get; }

    private void UpdateActiveBackground()
    {
        // Static-art rows only. Capture-flavored rows (Live) must NEVER feed
        // ActiveBackgroundImage — it renders above BackgroundImage, so it would
        // permanently cover the desktop/game capture. Live's canvas shows
        // DisplaySource instead (capture, falling back to live-background.jpg).
        var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
        ActiveBackgroundImage = background != null && !string.IsNullOrWhiteSpace(background.AssetId)
            ? ImageCache.Get(background.AssetId)
            : null;
        OnPropertyChanged(nameof(ShowPreviewPlaceholder));
    }

    private void UpdateBackgroundImage()
    {
        var scene = StagedScene;
        var background = scene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
        BackgroundImage = background?.DisplaySource;

        if (background != null && !background.UseDefaultBackground
            && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)
            && System.IO.File.Exists(background.CustomBackgroundPath))
        {
            try
            {
                var bmi = new System.Windows.Media.Imaging.BitmapImage();
                bmi.BeginInit();
                bmi.UriSource = new System.Uri(background.CustomBackgroundPath);
                bmi.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
                bmi.EndInit();
                bmi.Freeze();

                double expectedRatio = 1920.0 / 1080.0;
                double imageRatio = (double)bmi.PixelWidth / bmi.PixelHeight;
                double ratioDiff = Math.Abs(imageRatio - expectedRatio) / expectedRatio;

                if (ratioDiff > 0.05)
                {
                    BackgroundSizeMismatch = true;
                    BackgroundSizeMismatchText =
                        $"Image is {bmi.PixelWidth}\u00d7{bmi.PixelHeight} \u2014 stream expects 1920\u00d71080 (16:9)";
                }
                else
                {
                    BackgroundSizeMismatch = false;
                    BackgroundSizeMismatchText = "";
                }
            }
            catch
            {
                BackgroundSizeMismatch = false;
                BackgroundSizeMismatchText = "";
            }
        }
        else
        {
            BackgroundSizeMismatch = false;
            BackgroundSizeMismatchText = "";
        }
    }

    private void RefreshSnapshotsAsync()
    {
        foreach (var scene in Scenes)
        {
            // Minis never render live captures. While the Live screen is staged
            // (being previewed) its mini shows the green placeholder; unstaged,
            // it shows the stored default art. Real-time surface = center only.
            var stagedLive = ReferenceEquals(scene, StagedScene)
                && SceneCatalog.Is(scene.Name, SceneCatalog.Live);
            var img = stagedLive ? null : LoadBackgroundImage(scene);
            if (img != null)
                scene.Snapshot = img;
            else if (scene.Snapshot == null || stagedLive)
                scene.Snapshot = CreatePlaceholderSnapshot(scene.Name);
        }
    }


    // Full-screen game on its monitor, else null (static bg fallback — no
    // infinity mirror). Called at launch (from ReacquireScreenCaptures, before
    // the window steals focus) and on focus regain (RefreshBackgroundAutoCapture).
    // When a background has ShowDesktop=true, returns the primary monitor instead
    // of null so the desktop is always visible.
    private string? ResolveAutoCaptureKey()
    {
        var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
        if (gameMonitor != null)
            return $"{MonitorKeyPrefix}{gameMonitor}";

        if (AllBackgrounds().Any(b => b.ShowDesktop))
            return $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
        return null;
    }

    // After a layout load / file open: make sure every background-enabled scene
    // has a background, give any background without a persisted key the auto-detected
    // one, then acquire one capture per unique background key. ScreenCaptureManager
    // refcounts by key, so every scene pointing at the same monitor shares one
    // session. Captures no longer referenced by any scene are released.
    private void ReacquireScreenCaptures()
    {
        HealBackgrounds();

        // Transient keys ("picker:" picks and "window:" pins) are session-scoped
        // (see ScreenCaptureSourceFactory): a persisted HWND can be recycled to an
        // unrelated window after restart, so a reload never resurrects them — the
        // background falls back to auto-detection instead.
        foreach (var transient in AllBackgrounds()
                     .Where(b => IsTransientCaptureKey(b.CaptureKey)))
            transient.CaptureKey = null;

        var auto = ResolveAutoCaptureKey();
        if (auto == null)
        {
            foreach (var background in AllBackgrounds())
                background.CaptureKey = null;
        }
        else
        {
            foreach (var background in AllBackgrounds())
                if (string.IsNullOrWhiteSpace(background.CaptureKey))
                    background.CaptureKey = auto;
        }

        var keys = AllBackgrounds()
            .Select(b => b.CaptureKey!)
            .Where(k => !string.IsNullOrWhiteSpace(k))
            .ToHashSet();

        // A layout reload replaces the scenes; stop captures that are no longer
        // referenced (mirrors ReacquireWebcam's device swap).
        foreach (var stale in _liveCaptureKeys.Except(keys))
            _ = _screenCaptureManager.ReleaseAllAsync(stale);
        _liveCaptureKeys = keys;

        foreach (var key in keys)
            _ = _screenCaptureManager.AcquireAsync(key);

        _fullScreenDetector.StartWatching();
    }

    // ScreenCaptureManager creates the shared WriteableBitmap on the UI thread;
    // every background pointing at that key picks it up.
    private void OnScreenPreviewBitmapChanged(string key, WriteableBitmap bitmap)
    {
        var activeBackground = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
        if (activeBackground?.CaptureKey == key)
            BackgroundImage = bitmap;

        foreach (var background in AllBackgrounds().Where(b => b.CaptureKey == key))
            background.VideoImageSource = bitmap;
    }

    // EVENT_SYSTEM_FOREGROUND fires whenever the foreground window changes.
    // When a full-screen game appears on a different monitor than the current
    // background, auto-redesignate. When ShowDesktop is enabled and no fullscreen
    // game is detected, fall back to the primary monitor (desktop view).
    private void OnFullscreenMonitorChanged(int? monitor)
    {
        // A live window pin outranks the fullscreen-game detector: while the
        // pinned window still enumerates, keep it as the backdrop (the creator's
        // explicit choice beats auto-detection). Only when the window is gone
        // does auto-fallback (game → desktop → static) reclaim the background.
        var current = AllBackgrounds().FirstOrDefault();
        if (current != null && IsAliveWindowPin(current.CaptureKey)) return;

        if (monitor != null)
        {
            var newKey = $"{MonitorKeyPrefix}{monitor}";
            if (current?.CaptureKey == newKey) return;
            _ = RedesignateBackgroundAsync(newKey);
        }
        else if (AllBackgrounds().Any(b => b.ShowDesktop))
        {
            var desktopKey = $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
            if (current?.CaptureKey == desktopKey) return;
            _ = RedesignateBackgroundAsync(desktopKey);
        }
    }

    // Manual refresh: the "Refresh Capture" context menu item. Reads the
    // current foreground directly (no caching needed — the hook handles
    // automatic detection).
    public void RefreshBackgroundAutoCapture()
    {
        var detected = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
        if (detected == null) return;
        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{detected}");
    }

    /// <summary>Whether the active background is in Show Desktop mode.
    /// Bindable IsChecked property for the context menu toggle.</summary>
    public bool BackgroundShowDesktop
    {
        get => StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground)?.ShowDesktop ?? false;
        set
        {
            var background = StagedScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
            if (background == null || background.ShowDesktop == value) return;
            background.ShowDesktop = value;
            OnPropertyChanged(nameof(BackgroundShowDesktop));
            ScheduleSave();
            if (value)
            {
                _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}");
            }
            else
            {
                var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
                if (gameMonitor != null)
                    _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{gameMonitor}");
                else
                    _ = ClearBackgroundCaptureAsync();
            }
        }
    }

    private void ToggleBackgroundShowDesktop() => BackgroundShowDesktop = !BackgroundShowDesktop;

    private void BrowseBackground()
    {
        var scene = StagedScene;
        if (scene == null) return;
        var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
        if (bg == null) return;

        var dlg = new Microsoft.Win32.OpenFileDialog
        {
            Title = "Select background image",
            Filter = "Image files (*.jpg;*.jpeg;*.png;*.bmp)|*.jpg;*.jpeg;*.png;*.bmp|All files (*.*)|*.*",
        };
        if (dlg.ShowDialog() != true) return;

        bg.CustomBackgroundPath = dlg.FileName;
        bg.UseDefaultBackground = false;
        try
        {
            using var fs = new System.IO.FileStream(dlg.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
            var bytes = new byte[fs.Length];
            fs.Read(bytes, 0, bytes.Length);
            var assetId = AddAsset(bytes);
            if (assetId != null)
                bg.AssetId = assetId;
        }
        catch { /* non-critical */ }

        UpdateActiveBackground();
        RefreshSnapshotsAsync();
        ScheduleSave();
    }

    /// <summary>Release the background capture so the static placeholder image shows.</summary>
    private async Task ClearBackgroundCaptureAsync()
    {
        var oldKeys = AllBackgrounds()
            .Select(b => b.CaptureKey!)
            .Where(k => !string.IsNullOrWhiteSpace(k))
            .ToHashSet();

        foreach (var background in AllBackgrounds())
        {
            background.CaptureKey = null;
            background.VideoImageSource = null;
        }

        foreach (var key in oldKeys)
            await _screenCaptureManager.ReleaseAllAsync(key);

        _liveCaptureKeys.Clear();
        UpdateBackgroundImage();
        ScheduleSave();
    }

    private async Task RedesignateBackgroundAsync(string newKey)
    {
        var oldKeys = AllBackgrounds()
            .Select(b => b.CaptureKey!)
            .Where(k => !string.IsNullOrWhiteSpace(k))
            .ToHashSet();

        foreach (var background in AllBackgrounds())
            background.CaptureKey = newKey;

        foreach (var oldKey in oldKeys.Where(k => k != newKey))
            await _screenCaptureManager.ReleaseAllAsync(oldKey);
        if (!oldKeys.Contains(newKey))
            await _screenCaptureManager.AcquireAsync(newKey);
        _liveCaptureKeys = new HashSet<string> { newKey };
        UpdateBackgroundImage();
        ScheduleSave();
    }

    // "Change Capture…": the OS GraphicsCapturePicker designates the target.
    // Picks are transient (see ScreenCaptureSourceFactory) — a reload falls
    // back to auto-detection.
    public async Task ChangeBackgroundCaptureAsync()
    {
        var key = await _screenCaptureFactory.PickAsync();
        if (key == null) return;
        await RedesignateBackgroundAsync(key);
    }

    // In-app display picker: point every background at a specific monitor.
    private void SetBackgroundCapture(DisplayInfo? display)
    {
        if (display == null) return;
        _ = RedesignateBackgroundAsync($"{MonitorKeyPrefix}{display.Index}");
    }

    // ─── Background model (TASK 25): exactly ONE Background per screen, index 0,
    // never removable or re-addable. Static default art on Starting/BRB/Chat/Ending;
    // on Live it's the capture-flavored row (Show Desktop / monitor switch /
    // fullscreen-game detect) falling back to live-background.jpg. ───

    private static string? DefaultBackgroundAsset(string sceneName) => sceneName switch
    {
        SceneCatalog.Starting => "starting-background.jpg",
        SceneCatalog.Brb => "brb-background.jpg",
        SceneCatalog.Chat => "chat-background.jpg",
        SceneCatalog.Ending => "ending-background.jpg",
        SceneCatalog.Live => "live-background.jpg",
        _ => null,
    };

    /// <summary>Heals every scene to the locked Background model after a layout
    /// load: keeps the correct flavor per scene at index 0 named "Background",
    /// drops duplicates/stale rows, re-seeds missing ones.</summary>
    private void HealBackgrounds()
    {
        NormalizeBackgrounds(Scenes);
        foreach (var scene in Scenes)
        {
            _sceneGraph.InvalidateBake(scene);
            var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
            if (background != null)
                StampDefaultBackgroundAsset(background, scene.Name);
        }
        OnPropertyChanged(nameof(ShowSourcesEmptyHint));
    }

    /// <summary>Points a background row at its scene's shipped default art when it
    /// carries none. A custom image (Browse…) always wins and is never overwritten.</summary>
    private void StampDefaultBackgroundAsset(Source background, string sceneName)
    {
        if (!string.IsNullOrWhiteSpace(background.AssetId)) return;
        if (!background.UseDefaultBackground && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)) return;
        var asset = DefaultBackgroundAsset(sceneName);
        if (asset == null) return;

        try
        {
            var uri = new Uri($"pack://application:,,,/Assets/{asset}", UriKind.Absolute);
            using var stream = Application.GetResourceStream(uri)?.Stream;
            if (stream == null) return;
            using var ms = new MemoryStream();
            stream.CopyTo(ms);
            background.AssetId = AddAsset(ms.ToArray());
        }
        catch { /* non-critical — the app works without default art */ }
    }
}