annotations/Windows/Azaion.Annotator/PlayerControlHandler.cs

using System.IO;
using System.Windows;
using System.Windows.Input;
using Azaion.Annotator.DTO;
using LibVLCSharp.Shared;
using MediatR;

namespace Azaion.Annotator;

public class PlayerControlHandler(LibVLC libVLC, MediaPlayer mediaPlayer, MainWindow mainWindow, FormState formState, Config config) :
        INotificationHandler<KeyEvent>,
        INotificationHandler<AnnClassSelectedEvent>,
        INotificationHandler<PlaybackControlEvent>,
        INotificationHandler<VolumeChangedEvent>
{
    private const int STEP = 20;
    private const int LARGE_STEP = 5000;
    private const int RESULT_WIDTH = 1280;
    
    private static readonly string[] CatchSenders = ["ForegroundWindow", "ScrollViewer", "VideoView"];

    private readonly Dictionary<Key, PlaybackControlEnum> KeysControlEnumDict = new()
    {
        { Key.Space, PlaybackControlEnum.Pause },
        { Key.Left,  PlaybackControlEnum.PreviousFrame },
        { Key.Right, PlaybackControlEnum.NextFrame },
        { Key.Enter, PlaybackControlEnum.SaveAnnotations },
        { Key.Delete, PlaybackControlEnum.RemoveSelectedAnns },
        { Key.X, PlaybackControlEnum.RemoveAllAnns }
    };

    public async Task Handle(AnnClassSelectedEvent notification, CancellationToken cancellationToken)
    {
        SelectClass(notification.AnnotationClass);
        await Task.CompletedTask;
    } 
        

    private void SelectClass(AnnotationClass annClass)
    {
        mainWindow.Editor.CurrentAnnClass = annClass;
        foreach (var ann in mainWindow.Editor.CurrentAnns.Where(x => x.IsSelected)) 
            ann.AnnotationClass = annClass;
        mainWindow.LvClasses.SelectedIndex = annClass.Id;
    }

    public async Task Handle(KeyEvent notification, CancellationToken cancellationToken)
    {
        if (!CatchSenders.Contains(notification.Sender.GetType().Name))
            return;
        
        var key = notification.Args.Key;
        var keyNumber = (int?)null;
        
        if ((int)key >= (int)Key.D1 && (int)key <= (int)Key.D9) 
            keyNumber = key - Key.D1;
        if ((int)key >= (int)Key.NumPad1 && (int)key <= (int)Key.NumPad9) 
            keyNumber = key - Key.NumPad1;
        if (keyNumber.HasValue)
            SelectClass(mainWindow.AnnotationClasses[keyNumber.Value]);
        
        if (KeysControlEnumDict.TryGetValue(key, out var value)) 
            await ControlPlayback(value);

        await VolumeControl(key);
    }

    private async Task VolumeControl(Key key)
    {
        switch (key)
        {
            case Key.VolumeMute when mediaPlayer.Volume == 0:
                await ControlPlayback(PlaybackControlEnum.TurnOnVolume);
                break;
            case Key.VolumeMute:
                await ControlPlayback(PlaybackControlEnum.TurnOffVolume);
                break;
            case Key.Up:
            case Key.VolumeUp:
                var vUp = Math.Min(100, mediaPlayer.Volume + 5);
                ChangeVolume(vUp);
                mainWindow.Volume.Value = vUp; 
                break;
            case Key.Down:
            case Key.VolumeDown:
                var vDown = Math.Max(0, mediaPlayer.Volume - 5);
                ChangeVolume(vDown);
                mainWindow.Volume.Value = vDown;
                break;
        }
    }

    public async Task Handle(PlaybackControlEvent notification, CancellationToken cancellationToken)
    {
        await ControlPlayback(notification.PlaybackControl);
        mainWindow.VideoView.Focus();
    }

    private async Task ControlPlayback(PlaybackControlEnum controlEnum)
    {
        var isCtrlPressed = Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl);
        var step = isCtrlPressed ? LARGE_STEP : STEP;

        switch (controlEnum)
        {
            case PlaybackControlEnum.Play:
                Play();
                break;
            case PlaybackControlEnum.Pause:
                mediaPlayer.Pause();
                if (!mediaPlayer.IsPlaying) 
                    mainWindow.BlinkHelp(HelpTexts.HelpTextsDict[HelpTextEnum.AnnotationHelp]);
                break;
            case PlaybackControlEnum.Stop:
                mediaPlayer.Stop();
                break;
            case PlaybackControlEnum.PreviousFrame:
                mediaPlayer.SetPause(true);
                mediaPlayer.Time -= step;
                mainWindow.VideoSlider.Value = mediaPlayer.Position * 100;
                break;
            case PlaybackControlEnum.NextFrame:
                mediaPlayer.SetPause(true);
                mediaPlayer.Time += step;
                mainWindow.VideoSlider.Value = mediaPlayer.Position * 100;
                break;
            case PlaybackControlEnum.SaveAnnotations:
                await SaveAnnotations();
                break;
            case PlaybackControlEnum.RemoveSelectedAnns:
                mainWindow.Editor.RemoveSelectedAnns();
                break;
            case PlaybackControlEnum.RemoveAllAnns:
                mainWindow.Editor.RemoveAllAnns();
                break;
            case PlaybackControlEnum.TurnOnVolume:
                mainWindow.TurnOnVolumeBtn.Visibility = Visibility.Collapsed;
                mainWindow.TurnOffVolumeBtn.Visibility = Visibility.Visible;
                mediaPlayer.Volume = formState.CurrentVolume;
                break;
            case PlaybackControlEnum.TurnOffVolume:
                mainWindow.TurnOffVolumeBtn.Visibility = Visibility.Collapsed;
                mainWindow.TurnOnVolumeBtn.Visibility = Visibility.Visible;
                formState.CurrentVolume = mediaPlayer.Volume;
                mediaPlayer.Volume = 0;
                break;
            case PlaybackControlEnum.None:
                break;
            default:
                throw new ArgumentOutOfRangeException(nameof(controlEnum), controlEnum, null);
        }
    }

    public async Task Handle(VolumeChangedEvent notification, CancellationToken cancellationToken)
    {
        ChangeVolume(notification.Volume);
        await Task.CompletedTask;
    }

    private void ChangeVolume(int volume)
    {
        formState.CurrentVolume = volume;
        mediaPlayer.Volume = volume;
    }
    
    private void Play()
    {
        if (mainWindow.LvFiles.SelectedItem == null)
            return;
        var fileInfo = (VideoFileInfo)mainWindow.LvFiles.SelectedItem;

        formState.CurrentFile = fileInfo.Name;
        mainWindow.LoadExistingAnnotations();
        
        mediaPlayer.Stop();
        mediaPlayer.Play(new Media(libVLC, fileInfo.Path));
        mainWindow.BlinkHelp(HelpTexts.HelpTextsDict[HelpTextEnum.PauseForAnnotations]);
    }
    
    private async Task SaveAnnotations()
    {
        if (string.IsNullOrEmpty(formState.CurrentFile))
            return;

        var fName = formState.GetTimeName(TimeSpan.FromMilliseconds(mediaPlayer.Time));
        var currentAnns = mainWindow.Editor.CurrentAnns
            .Select(x => x.Info.ToLabelCoordinates(mainWindow.Editor.RenderSize, formState.CurrentVideoSize))
            .ToList();
        var labels = string.Join(Environment.NewLine, currentAnns.Select(x => x.ToString()));

        if (!Directory.Exists(config.LabelsDirectory))
            Directory.CreateDirectory(config.LabelsDirectory);
        if (!Directory.Exists(config.ImagesDirectory))
            Directory.CreateDirectory(config.ImagesDirectory);
                
        await File.WriteAllTextAsync($"{config.LabelsDirectory}/{fName}.txt", labels);

        var resultHeight = (uint)Math.Round(RESULT_WIDTH / formState.CurrentVideoSize.Width * formState.CurrentVideoSize.Height); 
            
        mediaPlayer.TakeSnapshot(0, $"{config.ImagesDirectory}/{fName}.jpg", RESULT_WIDTH, resultHeight);
                
        mainWindow.Annotations[fName] = currentAnns;
        mainWindow.Editor.RemoveAllAnns();
        mediaPlayer.Play();
    }
}