1 files changed, 64 insertions, 0 deletions
diff --git a/LibBeatmapDownload/DownloadTaskList.cs b/LibBeatmapDownload/DownloadTaskList.cs
new file mode 100644
index 0000000..a449e96
--- /dev/null
+++ b/LibBeatmapDownload/DownloadTaskList.cs
@@ -0,0 +1,64 @@
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+
+namespace LibBeatmapDownload;
+
+public class DownloadTaskList : INotifyPropertyChanged {
+	public DownloadTaskList() {
+		Tasks.CollectionChanged += (sender, args) => {
+			if (args.NewItems is { Count: > 0 })
+				foreach (var downloadTask in args.NewItems) {
+					if (downloadTask is not DownloadTask task) {
+						Debug.WriteLine($"[DownloadTaskList] New task is {downloadTask?.GetType().FullName ?? "null"}!");
+						continue;
+					}
+
+					task.PropertyChanged += (taskSender, taskArgs) => {
+						if (taskArgs.PropertyName == nameof(DownloadTask.Status)) {
+							if (task.Status == Status.Finished) {
+								Task.Run(async () => {
+									await Task.Delay(1000);
+									Tasks.Remove(task);
+								});
+							}
+
+							SetField(ref _tasks,
+								new ObservableCollection<DownloadTask>(
+									_tasks
+										.OrderByDescending(x => x.Progress)
+										.ThenByDescending(x => x.Status)
+								),
+								nameof(Tasks));
+							OnPropertyChanged(nameof(Tasks));
+						}
+					};
+				}
+
+			// OnPropertyChanged(nameof(Tasks));
+		};
+	}
+
+	public event PropertyChangedEventHandler? PropertyChanged;
+
+	private ObservableCollection<DownloadTask> _tasks = new();
+
+	public ObservableCollection<DownloadTask> Tasks {
+		get => _tasks;
+		set => SetField(ref _tasks, value);
+	}
+
+	protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null) {
+		PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+	}
+
+	protected bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null) {
+		//check ObservableCollection by order
+
+		if (EqualityComparer<T>.Default.Equals(field, value)) return false;
+		field = value;
+		OnPropertyChanged(propertyName);
+		return true;
+	}
+}