import java.util.*;
import edu.ucdavis.jr.*;

public class Clock {

  /*
    @return   The current simulation time.
  */
  public op MyTime getTime();

  /*
    Sets a timer such that the capability ch will be called after
    the time t has elapsed from the time the timer was set.
    This means that if the simulation time was 18:32:12 when the
    timer is set and the timeout is 00:01:20 then the alarm will be
    set off at simulation time 18:33:32.  This timer can be used to
    make sure that certain things happen at specific times during the
    simulation.
  */
  public op void setAlarm(cap void() ch, MyTime t);

  /*
    Stops the clock.
  */
  public op void shutdown();

  /*
    The method returns after the given number of simulation seconds has passed.
  */
  public void delay(int seconds) {
    cap void () alarm = new op void ();
    setAlarm(alarm, new MyTime(seconds));
    receive alarm();
  }

  private op void tick();

  private MyTime currentTime;
  private int ms;
  private Map<MyTime, Set<cap void()>> alarms = new HashMap<MyTime, Set<cap void()>>();

  private op void stopTicker();

  /*
    @param ms   Specifies how many milliseconds one second of simulation time
                should take in real time. If given the value 10, each second in
                the simulation will take 10 milliseconds.
  */
  public Clock(int ms) {
    currentTime = new MyTime(0, 0 ,0);
    this.ms = ms;
  }

  private process loop {
    boolean run = true;
    while (run) {
      inni void tick() {
	Set<cap void()> chs = alarms.remove(currentTime);
	if (chs!=null)
	  for(Object ch : chs)
	    send ((cap void())ch)();
	currentTime.increment();
      } [] MyTime getTime() {
	return (MyTime)currentTime.clone();
      } [] void setAlarm(cap void() ch, MyTime t) {
	MyTime at = ((MyTime)currentTime.clone()).add(t);
	Set<cap void()> chs = alarms.remove(at);
	if (chs == null) {
	  chs = new HashSet<cap void()>();
	}
	chs.add(ch);
	alarms.put(at, chs);
      } [] void shutdown() {
	run = false;
      }
    }
    send stopTicker();
    if (alarms.size() > 0)
      System.err.println("Some alarms left: "+alarms);
  }

  private process ticker {
    boolean run = true;
    long next = System.currentTimeMillis();
    long w;
    do {
      inni void stopTicker() {
	run = false;
      }
      else {
	next += ms;
	w = Math.max(0,next-System.currentTimeMillis());
	edu.ucdavis.jr.JR.nap(w);
	send tick();
      }
    } while (run);
  }
}