namespace decePubClient.Services
{
	/// <summary>
	/// Asks before what can't be undone (deleting a post, blocking, leaving a group, signing out): Ask shows the question
	/// in ConfirmHost (MainLayout) and returns whether the reader confirmed it. One question at a time; a second one asked
	/// while the first is open answers the first no.
	/// </summary>
	public class ConfirmService
	{
		TaskCompletionSource<bool> pending;

		public event Action Changed;

		public bool IsAsking => pending is not null;
		public string Heading { get; private set; }
		public string Text { get; private set; }
		public string ConfirmText { get; private set; }
		/// <summary>The confirm button shows as a danger (it deletes or cuts something off).</summary>
		public bool Danger { get; private set; }

		public async Task<bool> Ask(string heading, string text, string confirmText, bool danger, CancellationToken cancellationToken = default)
		{
			pending?.TrySetResult(false);
			var asking = new TaskCompletionSource<bool>();
			pending = asking;
			(Heading, Text, ConfirmText, Danger) = (heading, text, confirmText, danger);
			Changed?.Invoke();
			await using var cancel = cancellationToken.Register(() => asking.TrySetResult(false));
			var confirmed = await asking.Task;
			if (pending == asking)
			{
				pending = null;
				Changed?.Invoke();
			}
			return confirmed;
		}

		public void Answer(bool confirmed) => pending?.TrySetResult(confirmed);
	}
}