// by Nobukuni Kino
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import bprolog.plc.Plc;

public 
class Queens extends Applet implements Runnable {
	static int nqueens = 8;
	/* Run as an application */
    public static void main(String args[]) {
        Frame f = new Frame("Queens");

	f.addWindowListener(new WindowAdapter(){
	  public void windowClosing(WindowEvent e){
	    System.exit(0);
	  }});

	Queens qb = new Queens();
        qb.init();
        f.add("Center",qb);
        f.setSize(321,321);
        f.show();
	qb.run1();
	System.exit(0);
    }

	int w,h;
	Color pieceColor = new Color(255,150,150);
	Thread runner;

	public void start() {
		if (runner == null) {
			runner = new Thread(this);
			System.out.println("Start");
			runner.start();
		} else {
			runner.resume();
		}
	}

	public void stop() {
		if (runner != null) {
			runner.suspend();
		}
	}

	public void run(){}

	public void run1() {
		Plc.startPlc(new String []{});
		Integer[] queens = new Integer[nqueens];
		for (int i=0; i<nqueens; i++) queens[i] = new Integer(i+1);
		Plc goal = new Plc("callQueens", new Object[] {queens,this});
                Plc.exec("load('queens')");
		goal.call();
	}
				 
	public void paint(Graphics g) {
		board(g);
	}
	public void update(Graphics g) {
	}

	public void board(Graphics g) {
		w = (getSize().width-1)/nqueens;
		h = (getSize().height-1)/nqueens;
		g.setColor(Color.black);
		g.drawRect(0, 0, nqueens*w+1, nqueens*h+1);

		for (int i = 1; i <= nqueens; i++) {
			for (int j = 1; j <= nqueens; j++) {
				clearSquare(i,j);
			}
		}
	}
	public void putSquare(Integer row, Integer col) {
		putSquare(row.intValue(), col.intValue());
	}
	public void putSquare(int row, int col) {
		Graphics g = getGraphics();
		g.setColor(pieceColor);
		g.fillRect(w*(row-1)+1, h*(col-1)+1, w, h);
		Thread.yield();
	}
	
	public void clearSquare(Integer row, Integer col) {
		clearSquare(row.intValue(), col.intValue());
	}
	public void clearSquare(int row, int col) {
		Graphics g = getGraphics();
		if ((row+col)%2 == 1) {
			g.setColor(Color.black);
		}
		else {
			g.setColor(Color.white);
		}
		g.fillRect(w*(row-1)+1, h*(col-1)+1, w, h);
		Thread.yield();
	}
	public void sleep(Integer mill) {
		try {
			Thread.sleep(mill.intValue(),0);
		} catch(InterruptedException e) {}
	}
}