feat: Implement lyrics download feature.

src/ZonyLrcTools.Desktop/App.axaml

@@ -5,6 +5,7 @@
 
     <Application.Styles>
         <FluentTheme />
+        <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Fluent.xaml"/>
     </Application.Styles>
 
     <Application.Resources>

src/ZonyLrcTools.Desktop/Resources/UIStrings.en-US.resx

@@ -242,4 +242,8 @@
   <data name="Common_Info" xml:space="preserve">
     <value>Info</value>
   </data>
+  <!-- Error Messages -->
+  <data name="Error_NoMusicFiles" xml:space="preserve">
+    <value>No music files found in the selected folder.</value>
+  </data>
 </root>

src/ZonyLrcTools.Desktop/Resources/UIStrings.resx

@@ -242,4 +242,8 @@
   <data name="Common_Info" xml:space="preserve">
     <value>提示</value>
   </data>
+  <!-- Error Messages -->
+  <data name="Error_NoMusicFiles" xml:space="preserve">
+    <value>在所选文件夹中没有找到任何音乐文件。</value>
+  </data>
 </root>

src/ZonyLrcTools.Desktop/Services/DialogService.cs

@@ -2,6 +2,7 @@ using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Platform.Storage;
+using ZonyLrcTools.Desktop.Views.Dialogs;
 
 namespace ZonyLrcTools.Desktop.Services;
 
@@ -47,14 +48,18 @@ public class DialogService : IDialogService
 
     public async Task<bool> ShowConfirmDialogAsync(string title, string message)
     {
-        // TODO: Implement custom confirm dialog
-        await Task.CompletedTask;
-        return true;
+        if (MainWindow == null) return false;
+
+        var dialog = new ConfirmDialog(title, message);
+        var result = await dialog.ShowDialog<bool>(MainWindow);
+        return result;
     }
 
     public async Task ShowMessageAsync(string title, string message)
     {
-        // TODO: Implement custom message dialog
-        await Task.CompletedTask;
+        if (MainWindow == null) return;
+
+        var dialog = new MessageDialog(title, message);
+        await dialog.ShowDialog(MainWindow);
     }
 }

src/ZonyLrcTools.Desktop/ViewModels/LyricsDownloadViewModel.cs

@@ -1,7 +1,14 @@
 using System.Collections.ObjectModel;
+using Avalonia.Threading;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using Microsoft.Extensions.Options;
+using ZonyLrcTools.Common;
+using ZonyLrcTools.Common.Configuration;
+using ZonyLrcTools.Common.Infrastructure.IO;
+using ZonyLrcTools.Common.Infrastructure.Threading;
 using ZonyLrcTools.Common.Lyrics;
+using ZonyLrcTools.Common.TagInfo;
 using ZonyLrcTools.Desktop.Infrastructure.Localization;
 using ZonyLrcTools.Desktop.Services;
 
@@ -11,9 +18,14 @@ public partial class LyricsDownloadViewModel : ViewModelBase
 {
     private readonly ILyricsDownloader _lyricsDownloader;
     private readonly IDialogService _dialogService;
+    private readonly IFileScanner _fileScanner;
+    private readonly ITagLoader _tagLoader;
+    private readonly GlobalOptions _options;
     private readonly IUILocalizationService? _localization;
 
     private CancellationTokenSource? _downloadCts;
+    private Dictionary<string, MusicFileViewModel> _musicFileMap = new();
+    private List<MusicInfo> _scannedMusicInfos = new();
 
     [ObservableProperty]
     private string? _selectedFolderPath;
@@ -38,6 +50,21 @@ public partial class LyricsDownloadViewModel : ViewModelBase
     [NotifyPropertyChangedFor(nameof(CanStartDownload))]
     private bool _isDownloading;
 
+    [ObservableProperty]
+    [NotifyCanExecuteChangedFor(nameof(StartDownloadCommand))]
+    [NotifyCanExecuteChangedFor(nameof(SelectFolderCommand))]
+    [NotifyPropertyChangedFor(nameof(CanStartDownload))]
+    private bool _isScanning;
+
+    [ObservableProperty]
+    private int _scanProgressCount;
+
+    [ObservableProperty]
+    private int _scanTotalCount;
+
+    [ObservableProperty]
+    private double _scanProgressPercentage;
+
     [ObservableProperty]
     private string? _currentProcessingFile;
 
@@ -49,6 +76,7 @@ public partial class LyricsDownloadViewModel : ViewModelBase
     public string LyricsParallel => _localization?["Lyrics_Parallel"] ?? "Parallel:";
     public string LyricsStartDownload => _localization?["Lyrics_StartDownload"] ?? "Start Download";
     public string LyricsStopDownload => _localization?["Lyrics_StopDownload"] ?? "Stop Download";
+    public string LyricsScanning => _localization?["Lyrics_Status_Scanning"] ?? "Scanning files...";
     public string CommonTotal => _localization?["Common_Total"] ?? "Total:";
     public string CommonFiles => _localization?["Common_Files"] ?? "files";
     public string CommonSuccess => _localization?["Common_Success"] ?? "Success:";
@@ -58,17 +86,23 @@ public partial class LyricsDownloadViewModel : ViewModelBase
     public string ColumnFilePath => _localization?["Column_FilePath"] ?? "File Path";
     public string ColumnStatus => _localization?["Column_Status"] ?? "Status";
 
-    public bool CanStartDownload => !IsDownloading && !string.IsNullOrEmpty(SelectedFolderPath);
+    public bool CanStartDownload => !IsDownloading && !IsScanning && MusicFiles.Count > 0;
 
     public ObservableCollection<MusicFileViewModel> MusicFiles { get; } = new();
 
     public LyricsDownloadViewModel(
         ILyricsDownloader lyricsDownloader,
         IDialogService dialogService,
+        IFileScanner fileScanner,
+        ITagLoader tagLoader,
+        IOptions<GlobalOptions> options,
         IUILocalizationService? localization = null)
     {
         _lyricsDownloader = lyricsDownloader;
         _dialogService = dialogService;
+        _fileScanner = fileScanner;
+        _tagLoader = tagLoader;
+        _options = options.Value;
         _localization = localization;
 
         if (_localization != null)
@@ -86,6 +120,7 @@ public partial class LyricsDownloadViewModel : ViewModelBase
         OnPropertyChanged(nameof(LyricsParallel));
         OnPropertyChanged(nameof(LyricsStartDownload));
         OnPropertyChanged(nameof(LyricsStopDownload));
+        OnPropertyChanged(nameof(LyricsScanning));
         OnPropertyChanged(nameof(CommonTotal));
         OnPropertyChanged(nameof(CommonFiles));
         OnPropertyChanged(nameof(CommonSuccess));
@@ -96,32 +131,155 @@ public partial class LyricsDownloadViewModel : ViewModelBase
         OnPropertyChanged(nameof(ColumnStatus));
     }
 
-    [RelayCommand]
+    [RelayCommand(CanExecute = nameof(CanSelectFolder))]
     private async Task SelectFolderAsync()
     {
-        var folder = await _dialogService.ShowFolderPickerAsync("Select Music Folder");
+        var folder = await _dialogService.ShowFolderPickerAsync(
+            _localization?["Lyrics_SelectFolder"] ?? "Select Music Folder");
         if (string.IsNullOrEmpty(folder)) return;
 
         SelectedFolderPath = folder;
-        OnPropertyChanged(nameof(CanStartDownload));
+        await ScanFilesAsync();
+    }
+
+    private bool CanSelectFolder => !IsScanning && !IsDownloading;
+
+    private async Task ScanFilesAsync()
+    {
+        if (string.IsNullOrEmpty(SelectedFolderPath)) return;
+
+        IsScanning = true;
+        MusicFiles.Clear();
+        _musicFileMap.Clear();
+        _scannedMusicInfos.Clear();
+        ScanProgressCount = 0;
+        ScanTotalCount = 0;
+        ScanProgressPercentage = 0;
+        TotalCount = 0;
+        CompletedCount = 0;
+        FailedCount = 0;
+        ProgressPercentage = 0;
+
+        try
+        {
+            var files = (await _fileScanner.ScanMusicFilesAsync(SelectedFolderPath, _options.SupportFileExtensions))
+                .ToList();
+
+            if (files.Count == 0)
+            {
+                await _dialogService.ShowMessageAsync(
+                    _localization?["Common_Info"] ?? "Info",
+                    _localization?["Error_NoMusicFiles"] ?? "No music files found in the selected folder.");
+                IsScanning = false;
+                OnPropertyChanged(nameof(CanStartDownload));
+                return;
+            }
+
+            ScanTotalCount = files.Count;
+
+            using var warpTask = new WarpTask(ParallelCount);
+            var scanTasks = files.Select(file =>
+                warpTask.RunAsync(async () =>
+                {
+                    var musicInfo = await _tagLoader.LoadTagAsync(file);
+
+                    await Dispatcher.UIThread.InvokeAsync(() =>
+                    {
+                        if (musicInfo != null &&
+                            (!string.IsNullOrEmpty(musicInfo.Name) || !string.IsNullOrEmpty(musicInfo.Artist)))
+                        {
+                            var vm = new MusicFileViewModel
+                            {
+                                FilePath = musicInfo.FilePath,
+                                Name = musicInfo.Name,
+                                Artist = musicInfo.Artist,
+                                StatusMessage = _localization?["Status_Pending"] ?? "Pending"
+                            };
+                            MusicFiles.Add(vm);
+                            _musicFileMap[musicInfo.FilePath] = vm;
+                            _scannedMusicInfos.Add(musicInfo);
+                        }
+
+                        ScanProgressCount++;
+                        ScanProgressPercentage = ScanProgressCount * 100.0 / ScanTotalCount;
+                    });
+                }));
+
+            await Task.WhenAll(scanTasks);
+
+            TotalCount = MusicFiles.Count;
+        }
+        catch (Exception ex)
+        {
+            await _dialogService.ShowMessageAsync(
+                _localization?["Common_Error"] ?? "Error",
+                ex.Message);
+        }
+        finally
+        {
+            IsScanning = false;
+            OnPropertyChanged(nameof(CanStartDownload));
+        }
     }
 
     [RelayCommand(CanExecute = nameof(CanStartDownload))]
     private async Task StartDownloadAsync()
     {
-        if (string.IsNullOrEmpty(SelectedFolderPath)) return;
+        if (_scannedMusicInfos.Count == 0) return;
 
         IsDownloading = true;
         CompletedCount = 0;
         FailedCount = 0;
         ProgressPercentage = 0;
+        TotalCount = _scannedMusicInfos.Count;
+
+        // Reset all row statuses
+        foreach (var vm in MusicFiles)
+        {
+            vm.IsProcessed = false;
+            vm.IsSuccessful = false;
+            vm.StatusMessage = _localization?["Status_Pending"] ?? "Pending";
+        }
 
         _downloadCts = new CancellationTokenSource();
 
         try
         {
-            // TODO: Implement actual download logic using _lyricsDownloader
-            await Task.Delay(1000, _downloadCts.Token); // Placeholder
+            await _lyricsDownloader.DownloadAsync(
+                _scannedMusicInfos,
+                ParallelCount,
+                async musicInfo =>
+                {
+                    await Dispatcher.UIThread.InvokeAsync(() =>
+                    {
+                        if (_musicFileMap.TryGetValue(musicInfo.FilePath, out var vm))
+                        {
+                            vm.IsProcessed = true;
+                            vm.IsSuccessful = musicInfo.IsSuccessful;
+
+                            if (musicInfo.IsPruneMusic)
+                            {
+                                vm.StatusMessage = _localization?["Status_Skipped"] ?? "Skipped";
+                            }
+                            else if (musicInfo.IsSuccessful)
+                            {
+                                vm.StatusMessage = _localization?["Status_Success"] ?? "Success";
+                            }
+                            else
+                            {
+                                vm.StatusMessage = _localization?["Status_Failed"] ?? "Failed";
+                            }
+                        }
+
+                        if (musicInfo.IsSuccessful)
+                            CompletedCount++;
+                        else
+                            FailedCount++;
+
+                        ProgressPercentage = (CompletedCount + FailedCount) * 100.0 / TotalCount;
+                    });
+                },
+                _downloadCts.Token);
         }
         catch (OperationCanceledException)
         {

src/ZonyLrcTools.Desktop/Views/Dialogs/ConfirmDialog.axaml

@@ -0,0 +1,39 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="ZonyLrcTools.Desktop.Views.Dialogs.ConfirmDialog"
+        Title=""
+        Width="400"
+        Height="200"
+        CanResize="False"
+        WindowStartupLocation="CenterOwner"
+        SizeToContent="Height">
+
+    <Grid Margin="24" RowDefinitions="Auto,*,Auto">
+        <!-- Title -->
+        <TextBlock Grid.Row="0"
+                   x:Name="TitleText"
+                   FontSize="16"
+                   FontWeight="SemiBold"
+                   Margin="0,0,0,12" />
+
+        <!-- Message -->
+        <TextBlock Grid.Row="1"
+                   x:Name="MessageText"
+                   TextWrapping="Wrap"
+                   Margin="0,0,0,20" />
+
+        <!-- Buttons -->
+        <StackPanel Grid.Row="2"
+                    Orientation="Horizontal"
+                    HorizontalAlignment="Right"
+                    Spacing="8">
+            <Button x:Name="CancelButton"
+                    MinWidth="80"
+                    Click="OnCancelClick" />
+            <Button x:Name="ConfirmButton"
+                    MinWidth="80"
+                    Classes="accent"
+                    Click="OnConfirmClick" />
+        </StackPanel>
+    </Grid>
+</Window>

src/ZonyLrcTools.Desktop/Views/Dialogs/ConfirmDialog.axaml.cs

@@ -0,0 +1,35 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Microsoft.Extensions.DependencyInjection;
+using ZonyLrcTools.Desktop.Infrastructure.Localization;
+
+namespace ZonyLrcTools.Desktop.Views.Dialogs;
+
+public partial class ConfirmDialog : Window
+{
+    public ConfirmDialog()
+    {
+        InitializeComponent();
+    }
+
+    public ConfirmDialog(string title, string message) : this()
+    {
+        TitleText.Text = title;
+        MessageText.Text = message;
+        Title = title;
+
+        var localization = App.Services?.GetService<IUILocalizationService>();
+        ConfirmButton.Content = localization?["Common_OK"] ?? "OK";
+        CancelButton.Content = localization?["Common_Cancel"] ?? "Cancel";
+    }
+
+    private void OnConfirmClick(object? sender, RoutedEventArgs e)
+    {
+        Close(true);
+    }
+
+    private void OnCancelClick(object? sender, RoutedEventArgs e)
+    {
+        Close(false);
+    }
+}

src/ZonyLrcTools.Desktop/Views/Dialogs/MessageDialog.axaml

@@ -0,0 +1,32 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="ZonyLrcTools.Desktop.Views.Dialogs.MessageDialog"
+        Title=""
+        Width="400"
+        Height="200"
+        CanResize="False"
+        WindowStartupLocation="CenterOwner"
+        SizeToContent="Height">
+
+    <Grid Margin="24" RowDefinitions="Auto,*,Auto">
+        <!-- Title -->
+        <TextBlock Grid.Row="0"
+                   x:Name="TitleText"
+                   FontSize="16"
+                   FontWeight="SemiBold"
+                   Margin="0,0,0,12" />
+
+        <!-- Message -->
+        <TextBlock Grid.Row="1"
+                   x:Name="MessageText"
+                   TextWrapping="Wrap"
+                   Margin="0,0,0,20" />
+
+        <!-- OK Button -->
+        <Button Grid.Row="2"
+                x:Name="OkButton"
+                HorizontalAlignment="Right"
+                MinWidth="80"
+                Click="OnOkClick" />
+    </Grid>
+</Window>

src/ZonyLrcTools.Desktop/Views/Dialogs/MessageDialog.axaml.cs

@@ -0,0 +1,29 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Microsoft.Extensions.DependencyInjection;
+using ZonyLrcTools.Desktop.Infrastructure.Localization;
+
+namespace ZonyLrcTools.Desktop.Views.Dialogs;
+
+public partial class MessageDialog : Window
+{
+    public MessageDialog()
+    {
+        InitializeComponent();
+    }
+
+    public MessageDialog(string title, string message) : this()
+    {
+        TitleText.Text = title;
+        MessageText.Text = message;
+        Title = title;
+
+        var localization = App.Services?.GetService<IUILocalizationService>();
+        OkButton.Content = localization?["Common_OK"] ?? "OK";
+    }
+
+    private void OnOkClick(object? sender, RoutedEventArgs e)
+    {
+        Close();
+    }
+}

src/ZonyLrcTools.Desktop/Views/Pages/LyricsDownloadPage.axaml

@@ -1,6 +1,7 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="using:ZonyLrcTools.Desktop.ViewModels"
+             xmlns:loc="using:ZonyLrcTools.Desktop.Infrastructure.Localization"
              x:Class="ZonyLrcTools.Desktop.Views.Pages.LyricsDownloadPage"
              x:DataType="vm:LyricsDownloadViewModel">
 
@@ -56,6 +57,7 @@
                         <Button Command="{Binding StartDownloadCommand}"
                                 Content="{Binding LyricsStartDownload}"
                                 IsVisible="{Binding !IsDownloading}"
+                                IsEnabled="{Binding CanStartDownload}"
                                 Classes="accent"
                                 MinWidth="100" />
                         <Button Command="{Binding CancelDownloadCommand}"
@@ -65,7 +67,21 @@
                     </StackPanel>
                 </Grid>
 
-                <!-- Progress Bar (visible during download) -->
+                <!-- Progress Bar: Scanning phase -->
+                <StackPanel IsVisible="{Binding IsScanning}" Spacing="8">
+                    <ProgressBar Value="{Binding ScanProgressPercentage}"
+                                 Maximum="100"
+                                 Height="6" />
+                    <TextBlock HorizontalAlignment="Center" FontSize="12" Opacity="0.8">
+                        <Run Text="{Binding LyricsScanning}" />
+                        <Run Text=" " />
+                        <Run Text="{Binding ScanProgressCount}" />
+                        <Run Text=" / " />
+                        <Run Text="{Binding ScanTotalCount}" />
+                    </TextBlock>
+                </StackPanel>
+
+                <!-- Progress Bar: Download phase -->
                 <StackPanel IsVisible="{Binding IsDownloading}" Spacing="8">
                     <ProgressBar Value="{Binding ProgressPercentage}"
                                  Maximum="100"
@@ -90,20 +106,25 @@
                       GridLinesVisibility="Horizontal"
                       BorderThickness="0">
                 <DataGrid.Columns>
-                    <DataGridTextColumn Header="{Binding ColumnSongName}"
+                    <DataGridTextColumn x:DataType="vm:MusicFileViewModel"
+                                        Header="{loc:Localize Column_SongName}"
                                         Binding="{Binding Name}"
                                         Width="*" />
-                    <DataGridTextColumn Header="{Binding ColumnArtist}"
+                    <DataGridTextColumn x:DataType="vm:MusicFileViewModel"
+                                        Header="{loc:Localize Column_Artist}"
                                         Binding="{Binding Artist}"
                                         Width="150" />
-                    <DataGridTextColumn Header="{Binding ColumnFilePath}"
+                    <DataGridTextColumn x:DataType="vm:MusicFileViewModel"
+                                        Header="{loc:Localize Column_FilePath}"
                                         Binding="{Binding FilePath}"
                                         Width="250" />
-                    <DataGridTextColumn Header="{Binding ColumnStatus}"
+                    <DataGridTextColumn x:DataType="vm:MusicFileViewModel"
+                                        Header="{loc:Localize Column_Status}"
                                         Binding="{Binding StatusMessage}"
                                         Width="100" />
                 </DataGrid.Columns>
             </DataGrid>
+
         </Border>
 
         <!-- Status Bar -->