import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
//import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CountDownLatch;
//import java.util.concurrent.LinkedBlockingQueue;

public class GameOfLife implements AutoCloseable {
	public class GOLThread extends Thread {
		//private BlockingQueue<Point> workQueue = new LinkedBlockingQueue<Point>();
		private Queue<Point> workQueue = new LinkedList<Point>();
		private boolean exiting = false;
		private boolean pointsProcessed = false;
		private GameOfLife parent;
		private Object _lock = new Object();
		public GOLThread(GameOfLife gol)
		{
			parent = gol;
		}
		public void setExiting()
		{
			exiting = true;
		}
		public void setPointsProcessed()
		{
			pointsProcessed = true;
		}
		public void addPoint(Point p)
		{
			synchronized(_lock) {
				workQueue.add(p);
			}
		}
		@Override
		public void run()
		{
			while (!exiting) {
				if (workQueue.isEmpty()) {
					if (pointsProcessed) {
						parent.canStep.countDown();
						pointsProcessed = false;
					}
					try {
						sleep(100);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				} else {
					Point p;
					synchronized(_lock) {
						p = workQueue.poll();
					}
					parent.getEnv().increment(p);
				}
			}			
		}
	}

	private int numThreads;
	private List<GOLThread> threads = new ArrayList<GOLThread>();
	private Environment curEnv;
	GameOfLife(Environment env)
	{
		curEnv = env;
	}
	synchronized void setThreadCount(int nThread) throws InterruptedException {
		numThreads = nThread;
		for (int i = 0; i < threads.size(); i++) threads.get(i).exiting = true;
		for (int i = 0; i < threads.size(); i++) threads.get(i).join();
		threads.clear();
		for (int i = 0; i < numThreads; i++) {
			threads.add(new GOLThread(this));
			threads.get(threads.size() - 1).start();
		}
	}
	public Environment getEnv()
	{
		return curEnv;
	}
	public CountDownLatch canStep;
	public void step() throws InterruptedException
	{
		canStep = new CountDownLatch(numThreads);
		int i = 0;
		for (Point p : curEnv.livingCells) {
			threads.get(i % threads.size()).addPoint(p);
			i++;
		}
		for (i = 0; i < threads.size(); i++) threads.get(i).setPointsProcessed();
		canStep.await();
		curEnv = curEnv.next();
	}
	public void start()
	{
		numThreads = 1;
		threads.add(new GOLThread(this));
		threads.get(threads.size() - 1).run();
	}
	@Override
	public void close() throws Exception {
		for (int i = 0; i < threads.size(); i++) threads.get(i).exiting = true;
		for (int i = 0; i < threads.size(); i++) threads.get(i).join();
	}

}