namespace decePubClient.Services;

public enum ToastSeverity
{
	Info,
	Success,
	Warning,
	Error
}

public sealed record ToastMessage(Guid Id, ToastSeverity Severity, string Text);

/// <summary>
/// The app's snackbar: components add messages (usually through the SUtility extensions AddResponseError,
/// AddResponseSuccess, AddWarning, AddException) and Components/ToastHost.razor, placed once in MainLayout, shows them.
/// A message already on screen isn't added twice, and at most MaxMessages stay, oldest dropped first.
/// </summary>
public class ToastService
{
	const int MaxMessages = 12;

	readonly List<ToastMessage> messages = [];

	public event Action Changed;

	public IReadOnlyList<ToastMessage> Messages => messages;

	/// <summary>Shows a message; with closeAfter it closes itself, otherwise it stays until the user closes it.</summary>
	public void Add(ToastSeverity severity, string text, TimeSpan? closeAfter = null)
	{
		if (string.IsNullOrWhiteSpace(text) || messages.Any(m => m.Severity == severity && m.Text == text))
			return;

		var message = new ToastMessage(Guid.NewGuid(), severity, text);
		messages.Add(message);
		if (messages.Count > MaxMessages)
			messages.RemoveAt(0);
		Changed?.Invoke();

		if (closeAfter is { } delay)
			_ = CloseLater(message.Id, delay);
	}

	public void Close(Guid id)
	{
		if (messages.RemoveAll(m => m.Id == id) > 0)
			Changed?.Invoke();
	}

	async Task CloseLater(Guid id, TimeSpan delay, CancellationToken cancellationToken = default)
	{
		await Task.Delay(delay, cancellationToken);
		Close(id);
	}
}