import java.util.HashMap;

import java.util.Map;

public class EventTracker implements Tracker {

private static EventTracker INSTANCE = new EventTracker();

private Map<String, Integer> tracker;

private EventTracker() {

this.tracker = new HashMap<>();

}

synchronized public Map<String, Integer> tracker() {

return tracker;

}

synchronized public static EventTracker getInstance() {

return INSTANCE;

}

public EventTracker(Map<String, Integer> tracker) {

this.tracker = tracker;

}

synchronized public void push(String message) {

tracker.put(message, tracker.getOrDefault(message, 0) + 1);

}

synchronized public boolean has(String message) {

return tracker.getOrDefault(message, 0) != 0;

}

synchronized public void handle(String message, EventHandler e) {

tracker.put(message, tracker.getOrDefault(message, 1) - 1);

e.handle();

}

}