/// <summary>
/// Registers a device in Azure Notification Hub.
/// </summary>
/// <remarks>
/// This first unregisters all existing user registrations
/// for the specified <paramref name="userId"/>.
/// </remarks>
/// <param name="userId">The user to subscribe.</param>
/// <param name="platform">The push notification platform.</param>
/// <param name="handle">Device handle.</param>
public virtual async Task RegisterAsync(Guid userId, PushNotificationPlatform platform, string handle)
{
// First clear the existing registration if it exists
if (await _notificationRegistrationRepository.ExistsAsync(userId))
{
var currentRegistration = await _notificationRegistrationRepository.GetAsync(userId);
await _notificationClient.UnregisterAsync(currentRegistration);
await _notificationRegistrationRepository.DeleteAsync(currentRegistration.Id);
}
// Create new registration and assign external id
var registration = await _notificationClient.RegisterAsync(new NotificationRegistration
{
Handle = handle,
PushNotificationPlatform = platform,
Id = userId
});
await _notificationRegistrationRepository.CreateAsync(registration);
}