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;
	}
}