/// <inheritdoc />
/// <summary>
/// Finds the most appropriate type or subtype of
/// <typeparamref name="TProvider" /> whose type name is <paramref name="providerName" />
/// or which has been decorated with a <see cref="T:Platibus.Config.Extensibility.ProviderAttribute" /> with the
/// specified <paramref name="providerName" />.
/// </summary>
/// <typeparam name="TProvider">The provider type or at type from which the provider
/// must inherit</typeparam>
/// <param name="providerName">The provider name associated with the type</param>
/// <returns>Returns a new provider instance with the specified
/// <paramref name="providerName" /> and type.</returns>
/// <exception cref="T:System.NullReferenceException">Thrown if <paramref name="providerName" />
/// is <c>null</c> or whitespace.</exception>
/// <exception cref="T:Platibus.Config.Extensibility.ProviderNotFoundException">Thrown if no suitable providers are
/// found in the application domain.</exception>
/// <exception cref="T:Platibus.Config.Extensibility.MultipleProvidersFoundException">Thrown if there are multiple
/// providers found with the same priority.</exception>
/// <seealso cref="T:Platibus.Config.Extensibility.ProviderAttribute" />
public TProvider GetProvider <TProvider>(string providerName)
{
var providerType = Type.GetType(providerName);
if (providerType == null)
{
var prioritizedProviders = _reflectionService
.FindConcreteSubtypes <TProvider>()
.Where(t => !t.IsGenericTypeDefinition)
.WithProviderName(providerName)
.GroupByPriorityDescending()
.ToList();
var highestPriority = prioritizedProviders.FirstOrDefault();
if (highestPriority == null)
{
throw new ProviderNotFoundException(providerName);
}
var providers = highestPriority.ToList();
if (providers.Count > 1)
{
throw new MultipleProvidersFoundException(providerName, providers);
}
providerType = providers.First();
}
return((TProvider)Activator.CreateInstance(providerType));
}