harmonia/Harmonia.WinUI/ViewModels/PlaylistsViewModel.cs

using Harmonia.Core.Player;
using Harmonia.Core.Playlists;
using Microsoft.UI.Dispatching;
using System;
using System.Collections.ObjectModel;
using System.Linq;

namespace Harmonia.WinUI.ViewModels;

public partial class PlaylistsViewModel : ViewModelBase
{
    private readonly IPlaylistManager _playlistManager;
    private readonly IAudioPlayer _audioPlayer;
    private readonly DispatcherQueue _dispatcherQueue;

    private ObservableCollection<PlaylistItemViewModel> _playlists = [];
    public ObservableCollection<PlaylistItemViewModel> Playlists
    {
        get
        {
            return _playlists;
        }
        set
        {
            SetProperty(ref _playlists, value);
        }
    }

    private PlaylistItemViewModel? _selectedPlaylist = null;
    public PlaylistItemViewModel? SelectedPlaylist
    {
        get
        {
            return _selectedPlaylist;
        }
        set
        {
            if (SetProperty(ref _selectedPlaylist, value))
            {
                _playlistManager.CurrentPlaylist = value?.Playlist;
            }
        }
    }

    private PlaylistItemViewModel? _activePlaylist = null;
    public PlaylistItemViewModel? ActivePlaylist
    {
        get
        {
            return _activePlaylist;
        }
        set
        {
            SetProperty(ref _activePlaylist, value);
        }
    }

    public PlaylistsViewModel(IPlaylistManager playlistManager, IAudioPlayer audioPlayer)
    {
        _playlistManager = playlistManager;
        _playlistManager.PlaylistAdded += OnPlaylistAdded;
        _playlistManager.PlaylistRemoved += OnPlaylistRemoved;
        _playlistManager.CurrentPlaylistChanged += OnCurrentPlaylistChanged;

        _audioPlayer = audioPlayer;
        _audioPlayer.PlayingSongChanged += OnPlayingSongChanged;

        _dispatcherQueue = DispatcherQueue.GetForCurrentThread();

        _playlists = new ObservableCollection<PlaylistItemViewModel>(_playlistManager.Playlists.Select(p => new PlaylistItemViewModel(p)));
        _selectedPlaylist = _playlists.FirstOrDefault(pv => pv.Playlist == _playlistManager.CurrentPlaylist);
    }

    private void OnCurrentPlaylistChanged(object? sender, EventArgs e)
    {
        SelectedPlaylist = _playlists.FirstOrDefault(pv => pv.Playlist == _playlistManager.CurrentPlaylist);
    }

    private void OnPlaylistAdded(object? sender, PlaylistAddedEventArgs e)
    {
        Playlists.Add(new PlaylistItemViewModel(e.Playlist));
    }

    private void OnPlaylistRemoved(object? sender, PlaylistRemovedEventArgs e)
    {
        var playlistView = Playlists.FirstOrDefault(pv => pv.Playlist == e.Playlist);

        if (playlistView != null)
        {
            playlistView.Unsubscribe();
            Playlists.Remove(playlistView);
        }
    }

    private void OnPlayingSongChanged(object? sender, PlayingSongChangedEventArgs e)
    {
        _dispatcherQueue.TryEnqueue(UpdateActivePlaylist);
    }

    private void UpdateActivePlaylist()
    {
        ActivePlaylist = Playlists.FirstOrDefault(pv => pv.Playlist == _audioPlayer.Playlist);
    }
}