package cz.cuni.amis.utils;
   
   public class StopWatch {
   	
   	private long start;
   	
   	private double time = -1;
   
   	public StopWatch() {
  		start();
  	}
  	
  	/**
  	 * Watches are start()ed during construction, this will just refresh the start time. 
  	 */
  	public void start() {
  		start = System.nanoTime();
  	}
  	
  	/**
  	 * In millis
  	 * @return
  	 */
  	public double stop() {
  		time = (((double)System.nanoTime()) - start)/1000000;
  		start = System.nanoTime();
  		return time;
  	}
  	
  	/**
  	 * In millis
  	 * @return
  	 */
  	public double check() {
  		time = (((double)System.nanoTime()) - start)/1000000;		
  		return time;
  	}
  	
  	/**
  	 * In millis... returns last stop()/check() time. (Use stopStr() and then obtain time with time().)
  	 * @return
  	 */
  	public double time() {
  		if (time == -1) {
  			return (((double)System.nanoTime()) - start)/1000000;
  		}
  		return time;
  	}
  	
  	public String stopStr() {
  		return String.format("%.3f", stop()) + " ms";
  	}
  	
  	public String checkStr() {
  		return String.format("%.3f", check()) + " ms";
  	}
  	
  	public String timeStr() {
  		return String.format("%.3f", time()) + " ms";
  	}
  
  }