using Android.Gms.Tasks;

namespace Massenger.Client;

internal static class AndroidTaskExtensions
{
    public static Task<string?> AsStringAsync(this Android.Gms.Tasks.Task task, System.Threading.CancellationToken cancellationToken = default)
    {
        var taskCompletionSource = new TaskCompletionSource<string?>(TaskCreationOptions.RunContinuationsAsynchronously);
        if (cancellationToken.CanBeCanceled)
        {
            cancellationToken.Register(() => taskCompletionSource.TrySetCanceled(cancellationToken));
        }

        task.AddOnCompleteListener(new TaskCompletionListener(taskCompletionSource));
        return taskCompletionSource.Task;
    }

    private sealed class TaskCompletionListener(TaskCompletionSource<string?> taskCompletionSource)
        : Java.Lang.Object,
          IOnCompleteListener
    {
        public void OnComplete(Android.Gms.Tasks.Task task)
        {
            if (task.IsCanceled)
            {
                taskCompletionSource.TrySetCanceled();
                return;
            }

            if (!task.IsSuccessful)
            {
                taskCompletionSource.TrySetException(new InvalidOperationException(task.Exception?.Message ?? "Android task failed."));
                return;
            }

            taskCompletionSource.TrySetResult(task.Result?.ToString());
        }
    }
}