LlamaCasty/ViewModels/MainViewModel.Trax.cs

using System.IO;
using System.Windows.Media;
using Microsoft.Win32;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services.Audio;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    // TRAX (TASK 9): free background music at a fixed quiet volume, playing to
    // the default device so it rides the loopback into the stream. The dot is
    // red (no track) / yellow (loaded, stopped) / green (playing).
    private readonly MusicPlayer _musicPlayer = new();
    private Music? _music;
    private bool _musicPlaying;

    private static readonly SolidColorBrush TraxIdleBrush = CreateBrush("#555");
    /// <summary>True while the TRAX background track is playing.</summary>
    public bool IsMusicPlaying
    {
        get => _musicPlaying;
        private set
        {
            if (SetProperty(ref _musicPlaying, value))
            {
                OnPropertyChanged(nameof(TraxDotBrush));
                OnPropertyChanged(nameof(TraxToolTip));
            }
        }
    }

    private string? _traxError;

    /// <summary>Error message from the last TRAX load/playback failure; null = no error.</summary>
    public string? TraxError
    {
        get => _traxError;
        private set => SetProperty(ref _traxError, value);
    }

    /// <summary>TRAX status dot: green = playing, gray = idle or no track.</summary>
    public SolidColorBrush TraxDotBrush => _musicPlayer.IsPlaying
        ? BarOnBrush
        : TraxIdleBrush;

    public string TraxToolTip => _musicPlayer.TrackName != null
        ? $"TRAX: {_musicPlayer.TrackName} — left-click {(IsMusicPlaying ? "pauses" : "plays")}, right-click chooses a track"
        : "No track — left-click or right-click to choose background music";

    /// <summary>Left-click on TRAX: no track → pick one; otherwise toggle play/pause.</summary>
    public void TraxLeftClick()
    {
        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
            PickTraxTrack();
        else if (IsMusicPlaying)
            PauseTrax();
        else
            PlayTrax();
    }

    /// <summary>Right-click on TRAX: always open the track picker (never the OS viewer).</summary>
    public void TraxRightClick() => PickTraxTrack();

    private void PickTraxTrack()
    {
        var dialog = new OpenFileDialog
        {
            Title = "Choose background music",
            Filter = "Music (*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg)|*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg|All files (*.*)|*.*",
        };
        if (dialog.ShowDialog() != true)
            return;

        _music = new Music { TrackPath = dialog.FileName, IsEnabled = true };
        LoadTrax(play: true);
    }

    private void LoadTrax(bool play)
    {
        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
            return;

        try
        {
            _musicPlayer.Load(_music.TrackPath);
            UpdateTraxLocalGain();
            _music.IsEnabled = true;
            TraxError = null;
            if (play)
                _musicPlayer.Play();
        }
        catch (Exception ex)
        {
            AppLog.Write($"TRAX: failed to load '{_music.TrackPath}': {ex.Message}");
            TraxError = $"Failed to load: {Path.GetFileName(_music.TrackPath)} — {ex.Message}";
        }
        RefreshTraxUi();
        ScheduleSave();
    }

    private void PlayTrax() => _musicPlayer.Play();

    private void PauseTrax() => _musicPlayer.Pause();

    private void OnTraxPlaybackEnded(Exception? ex)
    {
        if (ex != null)
        {
            AppLog.Write($"TRAX: playback error: {ex.Message}");
            TraxError = $"Playback error: {ex.Message}";
        }
        RefreshTraxUi();
    }

    private void RefreshTraxUi()
    {
        IsMusicPlaying = _musicPlayer.IsPlaying;
        OnPropertyChanged(nameof(TraxDotBrush));
        OnPropertyChanged(nameof(TraxToolTip));
    }

    /// <summary>Mirrors the desktop/game audio bar's volume and mute onto the
    /// music so the creator hears the controls work in the headphones (the
    /// track rides the loopback channel, so it must duck the same way locally).
    /// Called whenever the game volume/mute change and on TRAX load.</summary>
    private void UpdateTraxLocalGain()
    {
        _musicPlayer.LocalGain = GameMuted ? 0f : 1f;
    }
}