Added application session services, along with initial restore and tracker implementations.

Harmonia.Core/Playlists/IPlaylistManager.cs

@@ -9,6 +9,7 @@ public interface IPlaylistManager
     Task<Playlist> AddPlaylistAsync();
     void RemovePlaylist(Playlist playlist);
     Playlist? FindPlaylistContaining(PlaylistSong playlistSong);
+    Playlist? FindPlaylistContaining(string playlistSongUID);
 
     event EventHandler? CurrentPlaylistChanged;
     event EventHandler<PlaylistAddedEventArgs> PlaylistAdded;

Harmonia.Core/Playlists/PlaylistManager.cs

@@ -88,6 +88,11 @@ public class PlaylistManager : IPlaylistManager
         return _playlistsBySongUid.GetValueOrDefault(playlistSong.UID);
     }
 
+    public Playlist? FindPlaylistContaining(string playlistSongUID)
+    {
+        return _playlistsBySongUid.GetValueOrDefault(playlistSongUID);
+    }
+
     private async void OnPlaylistUpdated(object? sender, PlaylistUpdatedEventArgs e)
     {
         if (sender is not Playlist playlist)

Harmonia.WinUI/App.xaml.cs

@@ -1,6 +1,7 @@
 using Harmonia.Core.Extensions;
 using Harmonia.WinUI.Caching;
 using Harmonia.WinUI.Messaging;
+using Harmonia.WinUI.Session;
 using Harmonia.WinUI.Storage;
 using Harmonia.WinUI.ViewModels;
 using Microsoft.Extensions.DependencyInjection;
@@ -31,6 +32,14 @@ public partial class App : Application
         services.AddSingleton<IStorageProvider, WindowsStorageProvider>();
         services.AddSingleton<IMessageService, WindowsMessageService>();
 
+        services.AddSingleton<ISessionService, JsonSessionService>();
+        services.AddSingleton(sp => sp.GetRequiredService<ISessionService>().Session.Window);
+        services.AddSingleton(sp => sp.GetRequiredService<ISessionService>().Session.Player);
+        services.AddSingleton(sp => sp.GetRequiredService<ISessionService>().Session.Playlist);
+
+        services.AddSingleton<ISessionRestorer, SessionRestorer>();
+        services.AddSingleton<ISessionTracker, SessionTracker>();
+
         services.AddHarmonia();
 
         ServiceProvider = services.BuildServiceProvider();
@@ -45,6 +54,15 @@ public partial class App : Application
     {
         await ServiceProvider.InitializeHarmoniaAsync();
 
+        ISessionService sessionService = ServiceProvider.GetRequiredService<ISessionService>();
+        await sessionService.LoadAsync();
+
+        ISessionRestorer sessionRestorer = ServiceProvider.GetRequiredService<ISessionRestorer>();
+        sessionRestorer.Restore();
+
+        ISessionTracker sessionTracker = ServiceProvider.GetRequiredService<ISessionTracker>();
+        sessionTracker.Start();
+
         _mainWindow = ServiceProvider.GetRequiredService<MainWindow>();
         _mainWindow.Activate();
     }

Harmonia.WinUI/MainWindow.xaml

@@ -9,7 +9,8 @@
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     mc:Ignorable="d"
-    Title="Harmonia.WinUI">
+    Title="Harmonia.WinUI"
+    Closed="OnMainWindowClosed">
 
     <Window.SystemBackdrop>
         <MicaBackdrop />

Harmonia.WinUI/MainWindow.xaml.cs

@@ -1,3 +1,5 @@
+using Harmonia.WinUI.Session;
+using Microsoft.UI.Windowing;
 using Microsoft.UI.Xaml;
 
 namespace Harmonia.WinUI;
@@ -6,10 +8,17 @@ public sealed partial class MainWindow : Window
 {
     private const string ApplicationTitle = "Harmonia";
 
-    public MainWindow()
+    private readonly ISessionService _sessionService;
+
+    private bool _isSaved;
+
+    public MainWindow(ISessionService sessionService)
     {
+        _sessionService = sessionService;
+
         InitializeComponent();
         InitializeTitleBar();
+        InitializeWindowState();
     }
 
     private void InitializeTitleBar()
@@ -18,4 +27,39 @@ public sealed partial class MainWindow : Window
         ExtendsContentIntoTitleBar = true;
         SetTitleBar(AppTitleBar);
     }
+
+    private void InitializeWindowState()
+    {
+        if (AppWindow.Presenter is OverlappedPresenter presenter && _sessionService.Session.Window.IsMaximized)
+        {
+            presenter.Maximize();
+        }
+
+        AppWindow.Changed += OnAppWindowChanged;
+    }
+
+    private void OnAppWindowChanged(AppWindow sender, AppWindowChangedEventArgs args)
+    {
+        if (sender.Presenter is not OverlappedPresenter presenter)
+            return;
+
+        // Ignore the minimized state so a minimize-then-close doesn't lose the maximized flag.
+        if (presenter.State is OverlappedPresenterState.Minimized)
+            return;
+
+        _sessionService.Session.Window.IsMaximized = presenter.State == OverlappedPresenterState.Maximized;
+    }
+
+    private async void OnMainWindowClosed(object sender, WindowEventArgs args)
+    {
+        if (_isSaved)
+            return;
+
+        args.Handled = true;
+
+        await _sessionService.SaveAsync();
+
+        _isSaved = true;
+        Close();
+    }
 }

Harmonia.WinUI/Session/ISessionRestorer.cs

@@ -0,0 +1,6 @@
+namespace Harmonia.WinUI.Session;
+
+public interface ISessionRestorer
+{
+    void Restore();
+}

Harmonia.WinUI/Session/ISessionService.cs

@@ -0,0 +1,10 @@
+using System.Threading.Tasks;
+
+namespace Harmonia.WinUI.Session;
+
+public interface ISessionService
+{
+    ApplicationSession Session { get; }
+    Task LoadAsync();
+    Task SaveAsync();
+}

Harmonia.WinUI/Session/ISessionTracker.cs

@@ -0,0 +1,6 @@
+namespace Harmonia.WinUI.Session;
+
+public interface ISessionTracker
+{
+    void Start();
+}

Harmonia.WinUI/Session/JsonSessionService.cs

@@ -0,0 +1,47 @@
+using System;
+using System.IO;
+using System.Text.Json;
+using System.Threading.Tasks;
+
+namespace Harmonia.WinUI.Session;
+
+public sealed class JsonSessionService : ISessionService
+{
+    private static readonly JsonSerializerOptions Options = new()
+    {
+        WriteIndented = true
+    };
+
+    private readonly string _filePath = Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+        "Harmonia",
+        "session.json"
+    );
+
+    public ApplicationSession Session { get; private set; } = new();
+
+    public async Task LoadAsync()
+    {
+        try
+        {
+            if (File.Exists(_filePath))
+            {
+                await using var stream = File.OpenRead(_filePath);
+                Session = await JsonSerializer.DeserializeAsync<ApplicationSession>(stream) ?? new();
+            }
+        }
+        catch
+        {
+            Session = new();
+        }
+    }
+
+    public async Task SaveAsync()
+    {
+        string directoryName = Path.GetDirectoryName(_filePath)!;
+        Directory.CreateDirectory(directoryName);
+
+        await using var stream = File.Create(_filePath);
+        await JsonSerializer.SerializeAsync(stream, Session, Options);
+    }
+}

Harmonia.WinUI/Session/SessionRestorer.cs

@@ -0,0 +1,55 @@
+using Harmonia.Core.Player;
+using Harmonia.Core.Playlists;
+using System;
+using System.Linq;
+
+namespace Harmonia.WinUI.Session;
+
+public class SessionRestorer(
+    ISessionService sessionService,
+    IPlaylistManager playlistManager,
+    IAudioPlayer audioPlayer) : ISessionRestorer
+{
+    public void Restore()
+    {
+        RestorePlaylist();
+        RestoreAudioPlayer();
+    }
+
+    private void RestorePlaylist()
+    {
+        PlaylistState playlistState = sessionService.Session.Playlist;
+
+        if (string.IsNullOrWhiteSpace(playlistState.OpenPlaylistUID))
+            return;
+
+        Playlist? playlist = playlistManager.Playlists.FirstOrDefault(p => p.UID == playlistState.OpenPlaylistUID);
+
+        if (playlist is null)
+            return;
+
+        playlistManager.CurrentPlaylist = playlist;
+    }
+
+    private void RestoreAudioPlayer()
+    {
+        AudioPlayerState audioPlayerState = sessionService.Session.Player;
+
+        if (string.IsNullOrWhiteSpace(audioPlayerState.PlaylistSongUID))
+            return;
+
+        Playlist? playlist = playlistManager.FindPlaylistContaining(audioPlayerState.PlaylistSongUID);
+
+        if (playlist is null)
+            return;
+
+        PlaylistSong? song = playlist.Songs.FirstOrDefault(s => s.UID == audioPlayerState.PlaylistSongUID);
+
+        if (song is null)
+            return;
+
+        //PlaybackMode playbackMode = audioPlayerState.PlaybackState
+
+        audioPlayer.LoadAsync(song, PlaybackMode.LoadOnly);
+    }
+}

Harmonia.WinUI/Session/SessionTracker.cs

@@ -0,0 +1,29 @@
+using Harmonia.Core.Player;
+using Harmonia.Core.Playlists;
+using System;
+
+namespace Harmonia.WinUI.Session;
+
+public class SessionTracker(
+    ISessionService sessionService,
+    IPlaylistManager playlistManager,
+    IAudioPlayer audioPlayer) : ISessionTracker
+{
+    public void Start()
+    {
+        playlistManager.CurrentPlaylistChanged += OnCurrentPlaylistChanged;
+        audioPlayer.PlayingSongChanged += OnPlayingSongChanged;
+    }
+
+    private void OnCurrentPlaylistChanged(object? sender, EventArgs e)
+    {
+        PlaylistState playlistState = sessionService.Session.Playlist;
+        playlistState.OpenPlaylistUID = playlistManager.CurrentPlaylist?.UID;
+    }
+
+    private void OnPlayingSongChanged(object? sender, PlayingSongChangedEventArgs e)
+    {
+        AudioPlayerState audioPlayerState = sessionService.Session.Player;
+        audioPlayerState.PlaylistSongUID = e.NewSong?.UID;
+    }
+}

Harmonia.WinUI/ViewModels/PlaylistsViewModel.cs

@@ -69,6 +69,7 @@ public partial class PlaylistsViewModel : ViewModelBase
 
         _playlists = new ObservableCollection<PlaylistItemViewModel>(_playlistManager.Playlists.Select(p => new PlaylistItemViewModel(p)));
         _selectedPlaylist = _playlists.FirstOrDefault(pv => pv.Playlist == _playlistManager.CurrentPlaylist);
+        _activePlaylist = _playlists.FirstOrDefault(pv => pv.Playlist == _audioPlayer.Playlist);
     }
 
     private void OnCurrentPlaylistChanged(object? sender, EventArgs e)

Harmonia.WinUI/Views/PlaylistsView.xaml.cs

@@ -17,6 +17,20 @@ public sealed partial class PlaylistsView : UserControl
         _viewModel = (PlaylistsViewModel)DataContext;
         _viewModel.PropertyChanging += OnViewModelPropertyChanging;
         _viewModel.PropertyChanged += OnViewModelPropertyChanged;
+
+        PlaylistsListView.ContainerContentChanging += OnContainerContentChanging;
+    }
+
+    private void OnContainerContentChanging(ListViewBase sender, ContainerContentChangingEventArgs args)
+    {
+        if (args.InRecycleQueue || args.ItemContainer is not ListViewItem listViewItem)
+            return;
+
+        PlaylistItemStyle style = ReferenceEquals(args.Item, _viewModel.ActivePlaylist)
+            ? PlaylistItemStyle.Selected
+            : PlaylistItemStyle.Normal;
+
+        UpdateListViewItemStyle(listViewItem, style);
     }
 
     private void OnViewModelPropertyChanging(object? sender, PropertyChangingEventArgs e)
@@ -41,11 +55,14 @@ public sealed partial class PlaylistsView : UserControl
 
     private void UpdateListViewItemStyle(PlaylistItemStyle style)
     {
-        ListViewItem listViewItem = (ListViewItem)PlaylistsListView.ContainerFromItem(_viewModel.ActivePlaylist);
-
-        if (listViewItem is null)
+        if (PlaylistsListView.ContainerFromItem(_viewModel.ActivePlaylist) is not ListViewItem listViewItem)
             return;
 
+        UpdateListViewItemStyle(listViewItem, style);
+    }
+
+    private void UpdateListViewItemStyle(ListViewItem listViewItem, PlaylistItemStyle style)
+    {
         FrameworkElement? frameworkElement = TryGetFrameworkElement(listViewItem, "PlaylistListViewItem");
 
         if (frameworkElement == null)