EventHandlerRegistration

@Singleton
public class EventHandlerRegistration {

    private final MethodFinder methodSearcher;
    private final JavaPlugin javaPlugin;
    private final Injector injector;

    @Inject
    public EventHandlerRegistration(MethodFinder methodSearcher,
                                    JavaPlugin javaPlugin,
                                    Injector injector) {
        this.methodSearcher = methodSearcher;
        this.javaPlugin = javaPlugin;
        this.injector = injector;
    }

    public void initialize(String... packageNames) {
        Preconditions.checkNotNull(packageNames);
        this.methodSearcher
                .filter(packageNames, MethodCriterion.annotatedWith(EventHandler.class))
                .forEach(
                        method -> {
                            EventHandler handler = method.getAnnotation(EventHandler.class);

                            Bukkit.getPluginManager()
                                    .registerEvent(
                                            ((Class<? extends Event>) method.getParameterTypes()[0]),
                                            new Listener() {},
                                            handler.priority(),
                                            (listener, event) -> {
                                                try {
                                                    if (method.getParameterTypes()[0].isAssignableFrom(event.getClass())) {
                                                        method.invoke(injector.getInstance(method.getDeclaringClass()), event);
                                                    }
                                                } catch (IllegalAccessException | InvocationTargetException e) {
                                                    e.printStackTrace();
                                                }
                                            },
                                            javaPlugin,
                                            handler.ignoreCancelled());
                        });
    }

}