/**
 * Program for drawing a square fractal.
 */
public class Squares
{
	
	/**
	 * @param args Contains the parameters for the drawing. The first
	 *             (mandatory) is the recursion level. The second (optional)
	 *             is the base length of the first square. The default value
	 *             for this length is 100 if it is not specified. Each
	 *             parameter must be positive.
	 */
	public static void main(String args[])
	{
		int level;
		int length = 100;
		switch (args.length)
		{
			case 2:
				length = Integer.parseInt(args[1]);
				// fall-through
			case 1:
				level = Integer.parseInt(args[0]);
				break;
			default:
				System.out.println(
						"Es muessen zwischen 1 und 2 Parameter angegeben werden "
								+ "(Level und eventuell Basislaenge)!"
				);
				return;
		}
		if (level < 1)
		{
			System.out.println("Das Rekursionslevel muss positiv sein!");
			return;
		}
		if (length < 1)
		{
			System.out.println("Die Basislaenge muss positiv sein!");
			return;
		}
		Canvas c = new Canvas();
		Squares.paintFractal(c, level, length);
		c.refresh();
	}
	
	/**
	 * Draws a square fractal with the specified recursion level and base length
	 * on the specified canvas.
	 *
	 * @param c      The canvas to draw the tree on.
	 * @param level  The current recursion level.
	 * @param length The current length.
	 */
	private static void paintFractal(Canvas c, int level, double length)
	{
		if (level <= 0)
			return;
		
		c.square(length);
		
		// oben links
		c.move(-length/2, -length/2);
		paintFractal(c, level-1, length/2);
		
		// oben rechts
		c.move(length, 0);
		paintFractal(c, level-1, length/2);
		
		// unten rechts
		c.move(0, length);
		paintFractal(c, level-1, length/2);
		
		// unten links
		c.move(-length, 0);
		paintFractal(c, level-1, length/2);
		
		// zurueck zum mittelpunkt
		c.move(length/2, -length/2);
	}
	
}