// RecursiveSquares.java
// Robert Sedgewick and Kevin Wayne
// Slightly reformatted by Andrew Davison, Nov. 2022

// https://introcs.cs.princeton.edu/java/23recursion/RecursiveSquares.java

/* Plot an order n tree of overlapping gray squares.

   Usage:
     > compile RecursiveSquares.java
     > run RecursiveSquares n
   e.g.
     > run RecursiveSquares 6
*/


public class RecursiveSquares
{

  public static void main(String[] args)
  {
    if (args.length != 1) {
      System.out.println("Usage: java RecursiveSquares <levels>");
      return;
    }
    int n = Integer.parseInt(args[0]);

    double x = 0.5, y = 0.5;   // center of square
    double size = 0.5;    // side length of square
    draw(n, x, y, size);
  } // end of main()



  private static void draw(int n, double x, double y, double size)
  // plot an order n recursive squares pattern
  // centered on (x, y) of the given side length
  {
    if (n == 0)
      return;

    drawSquare(x, y, size);

    // 2.2 ratio looks good
    double ratio = 2.2;

    // recursively draw 4 smaller trees of order n-1
    draw(n-1, x - size/2, y - size/2, size/ratio);   // lower left
    draw(n-1, x - size/2, y + size/2, size/ratio);   // upper left
    draw(n-1, x + size/2, y - size/2, size/ratio);   // lower right
    draw(n-1, x + size/2, y + size/2, size/ratio);   // upper right
  } // end of draw()


  private static void drawSquare(double x, double y, double size)
  // plot a square, centered on (x, y) of the given side length
  // with a light gray background and black border
  {
    StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
    StdDraw.filledSquare(x, y, size/2);
    StdDraw.setPenColor(StdDraw.BLACK);
    StdDraw.square(x, y, size/2);
  } 

}  // end of RecursiveSquares class