package de.mrbesen.telegram.event;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.function.Consumer;

public class EventManager {

	private HashMap<Class<? extends Event>, ArrayList<Consumer<? extends Event>>> listeners = new HashMap<>();

	public EventManager() {}

	public <T extends Event> void registerEvent(Class<T> eventtype, Consumer<T> handler) {
		if (handler == null) {
			throw new NullPointerException();
		}

		//get list
		ArrayList<Consumer<? extends Event>> list = listeners.get(eventtype);
		if (list == null) {
			//create and add list
			list = new ArrayList<>();
			listeners.put(eventtype, list);
		} else if(list.contains(handler)) {
			throw new IllegalArgumentException("listener allready registered");
		}

		list.add(handler); // ad to list
	}

	public Event callEvent(Event e) {
		if(e == null) return null;

		ArrayList<Consumer<? extends Event>> listner = listeners.get(e.getClass());
		if(listner != null) {
			for (Consumer listn : listner) {
				try {
					listn.accept(e);
				} catch (Throwable t) {
					System.err.println("Error occurred on Handling Event: " + e.getClass().getSimpleName());
					t.printStackTrace();
				}
			}
		}
		return e;
	}
}