public string InsertClient(Client client)
{
if (_clientDataService.GetClientByUsername(client.Username) != null)
{
throw new ArgumentException("Username is already taken");
}
// Force client id to be empty
client.ID = Guid.NewGuid().ToString();
client.Password = FinanceAPICore.Utilities.PasswordHasher.Hash(client.Password);
return(_clientDataService.InsertClient(client) ? client.ID : null);
}