import java.awt.*;
import java.util.*;

public class Region {

     // Default width and height (in pixels) of a square.
    private final int SQUARE_SIZE = 20;
    public static boolean DEBUGGING = false;

    /**
     * EFFECT: Initialize a region with the given position, dimensions,
     * and color.
     */
    public Region (int upperLeftX, int upperLeftY, 
      int width, int height, Color c) {
	myUpperLeftX = upperLeftX;
	myUpperLeftY = upperLeftY;
	myWidth = width;
	myHeight = height;
	myColor = c;
	myId = ourNextId;
	ourNextId++;
	mySquares = new SquareList ( );
    }
    
    /**
     * EFFECT: Return true if this region contains the point at 
     * coordinates (x,y).
     */
    public boolean contains (int x, int y) {
	boolean result = x >= myUpperLeftX
	    && x <= myUpperLeftX+myWidth
	    && y >= myUpperLeftY
	    && y <= myUpperLeftY+myHeight;
	if (DEBUGGING) {
	    System.out.print ("Region " + myId);
	    if (result) {
		System.out.println (" contains (" + x + "," + y + ")");
	    } else {
		System.out.println (" does not contain (" + x + "," + y + ")");
	    }
	}
	return result;
    }

    /**
     * REQUIRES: This region contains the point (x,y).
     * MODIFIES: this.
     * EFFECTS: Determine which of this region's squares cover the pixel 
     * coordinate (x,y).  If there are any, remove them.  If there were
     * none, add a square centered at (x,y) to this region's squares,
     * making sure it doesn't extend outside the region.
     */
    public void handleClick (int x, int y) {
	if (!mySquares.handleClick (x, y)) {
	    int leftDistance = min (SQUARE_SIZE/2, x-myUpperLeftX);
	    int rightDistance = min (SQUARE_SIZE/2, myUpperLeftX+myWidth-x);
	    int upDistance = min (SQUARE_SIZE/2, y-myUpperLeftY);
	    int downDistance = min (SQUARE_SIZE/2, myUpperLeftY+myHeight-y);
	    int xDistance = min (leftDistance, rightDistance);
	    int yDistance = min (upDistance, downDistance);
	    int size = 2 * min (xDistance, yDistance);
	    mySquares.add (new Square (x, y, size, myColor));
	}
    }

    /**
     * REQUIRES: g != null.
     * MODIFIES: the displayed window.
     * EFFECT: Draws the region by first drawing a white-filled rectangle,
     * then drawing the border, then telling all the squares in the region
     * to draw (paint) themselves.	
     */
    public void paint (Graphics g) {
	g.setColor (Color.white);
	g.fillRect (myUpperLeftX, myUpperLeftY, myWidth, myHeight);
	g.setColor (Color.black);
	g.drawRect (myUpperLeftX, myUpperLeftY, myWidth, myHeight);
	Iterator iter = mySquares.elements ( );
	while (iter.hasNext ( )) {
	    Square sq = (Square) iter.next ( );
	    sq.paint (g);
	}
    }

    /**
     * REQUIRES: o != null; o's type is a subclass of Region.
     * EFFECT: Returns true when this region has the same position
     * and dimensions as o.
     */
    public boolean equals (Object o) {
	Region r = (Region) o;
	return myUpperLeftX == r.myUpperLeftX
	  && myUpperLeftY == r.myUpperLeftY
	  && myWidth == r.myWidth
	  && myHeight == r.myHeight;
    }
    
    /**
     * EFFECT: Returns the larger of a and b.
     */
    public static int max (int a, int b) {
	return a>b? a: b;
    }
    
    /**
     * EFFECT: Returns the smaller of a and b.
     */
    public static int min (int a, int b) {
	return a<b? a: b;
    }
    
    private int myUpperLeftX;	// upper left corner of this region
    private int myUpperLeftY;
    private int myWidth;	// width and height of this region
    private int myHeight;
    private Color myColor;	 // color of all the squares in this region
    private static int ourNextId = 1;
    private int myId;	 // helps to tell regions apart when debugging.
    private SquareList mySquares;
}