/// <summary>
/// Get all the event listeners for the given event type.
/// </summary>
/// <param name="services">Current service provider.</param>
/// <param name="modules">Active modules for the current guild..</param>
/// <returns>The event listeners.</returns>
private static IEnumerable <EventHandler> GetHandlers <TEvent>(
IServiceProvider services,
IReadOnlyCollection <string> modules = null)
where TEvent : IEvent
{
var checkEnabledModule = modules != null;
foreach (var handler in services.GetServices <IEventListener>())
{
var events = RegisteredEventListener.FromType(handler.GetType());
foreach (var eventHandler in events)
{
if (eventHandler.EventType != typeof(TEvent) ||
checkEnabledModule &&
eventHandler.Module != null &&
!modules.Contains(eventHandler.Module))
{
continue;
}
yield return(new EventHandler(handler, eventHandler));
}
}
}
public static IEnumerable <IRegisteredEventListener> FromMethod(Type listenerType, MethodInfo methodType)
{
// Get the return type.
var returnType = methodType.ReturnType;
if (returnType != typeof(void) && !returnType.IsTask())
{
throw new InvalidOperationException($"The method {methodType.GetFriendlyName()} does not return void or Task.");
}
// Register the event.
var attribute = methodType.GetCustomAttribute <EventListenerAttribute>(false);
Type[] eventTypes;
if (attribute.Events.Length == 0)
{
if (methodType.GetParameters().Length == 0 || !typeof(IEvent).IsAssignableFrom(methodType.GetParameters()[0].ParameterType))
{
throw new InvalidOperationException($"The first parameter of the method {methodType.GetFriendlyName()} should be the type {nameof(IEvent)}.");
}
eventTypes = new[] { methodType.GetParameters()[0].ParameterType };
}
else
{
eventTypes = attribute.Events;
}
// Get the module.
var module = attribute.Module;
foreach (var eventType in eventTypes)
{
var listener = new RegisteredEventListener(eventType, methodType, attribute, module, listenerType);
yield return(listener);
}
}
