package de.mrbesen.telegram.event;

import java.lang.reflect.Method;
import java.util.ArrayList;

public class EventManager {
	
	private ArrayList<EventListener> listeners = new ArrayList<EventListener>();
	private ArrayList<EventMethod> handler = new ArrayList<EventMethod>();
	
	public EventManager() {
		
	}
	
	@SuppressWarnings("unchecked")
	public void registerEvent(EventListener listener) {
		if(listener == null) {
			throw new NullPointerException();
		}
		if(listeners.contains(listener)) {
			throw new RuntimeException("Listener is allready registered.");
		}
		listeners.add(listener);
		//scanning handler
		for(Method met : listener.getClass().getMethods()) {
			EventHandler h = met.getAnnotation(EventHandler.class);
			if(h != null) {//handler annotation vorhanden
				if(met.getParameterCount() == 1) {//only one parameter required
					Class<?> parameterclass = met.getParameters()[0].getClass();
					if(Event.class.isAssignableFrom(parameterclass) && !parameterclass.equals(Event.class)) {//the needed parameter is a Event-subclass)
						handler.add(new EventMethod((Class<? extends Event>) parameterclass, met, listener));
					} else {
						//warn / error?
					}
				} else {
					//warn?
				}
			}
		}
	}

	public Event callEvent(Event e) {
		for(EventMethod met : handler) {
			try {
				e = met.callEvent(e);
			} catch(Throwable t) {
				System.err.println("Error while calling Event " + e.getClass().getSimpleName() + " at " + met.listener.getClass().getSimpleName() + ":" + met.met.getName());
				t.printStackTrace();
			}
		}
		return e;
	}

	private class EventMethod {
		private EventListener listener;
		private Method met;
		private Class<? extends Event> eventtype;
		
		private EventMethod(Class<? extends Event> eventtype, Method m, EventListener list) {
			this.met = m;
			this.eventtype = eventtype;
			this.listener = list;
		}
		
		private Event callEvent(Event e) {
			if(eventtype.equals(e.getClass())) {
				try {
					met.invoke(listener, e);
				} catch(Throwable t) {
					t.printStackTrace();
				}
			}
			return e;
		}
	}
}