import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.text.*;

public class Avg2DDistance extends JApplet {

    String type;
    int length, radius;
    double [][] avgDistance;
    double [] avgDistanceRadius;  //for circle
    double minAvgDist, maxAvgDist;  
    double minAvgDistCirc, maxAvgDistCirc;

    public  void init () {

	double sumDist;
        DecimalFormat d1, d2;
	d1 = new DecimalFormat ("0.0");
	d2 = new DecimalFormat ("0.00");
	int showData=JOptionPane.NO_OPTION;

	type = JOptionPane.showInputDialog("[s]quare, [b]ox, [d]isk, [c]ircle?","s");

	String input;
	if (type.equals("s") || type.equals("b")) {
	    input = JOptionPane.showInputDialog("Length?","100");
	    length = Integer.parseInt(input);
	    if (length%2 == 1)  //odd
	        length--;  //step down to even

	    if (length <= 20)   //don't even ask if more than 20
	        showData = JOptionPane.showConfirmDialog(null,"Show the average distances?",
						 "show the data?",
						 JOptionPane.YES_NO_OPTION);
	}
	else {
	    input = JOptionPane.showInputDialog("Radius?","100");
	    radius = Integer.parseInt(input);
	}

	if (type.equals("s")) {
    	    avgDistance = new double[length][length];
	    minAvgDist = 1000000;
	    maxAvgDist = 0;
            for (int i=0; i<length/2; i++)     //lower-left quadrant only
                for (int j=0; j<length/2; j++) {
		    sumDist = 0;
                    for (int m=0; m<length; m++)
                        for (int n=0; n<length; n++)    //O(N^4)   !!!
                    	    sumDist += distanceFormula(i,j, m,n);
                    	
	            avgDistance[i][j] = sumDist/(length*length);
	            avgDistance[length-1-i][j] = avgDistance[i][j];  //lower right quadrant
	            avgDistance[i][length-1-j] = avgDistance[i][j];  //upper left symmetric
	            avgDistance[length-1-j][length-1-i] = avgDistance[i][j];  //upper-right: diagonal symmetry
	            if (avgDistance[i][j] < minAvgDist)
	                minAvgDist = avgDistance[i][j];
	            if (avgDistance[i][j] > maxAvgDist)
	                maxAvgDist = avgDistance[i][j];
                }
	}
	else if (type.equals("b")) {
    	    avgDistance = new double[length][length];
	    minAvgDist = 1000000;
	    maxAvgDist = 0;
            for (int i=0; i<length; i++)     //loop over all indexes but only process border ones
                for (int j=0; j<length; j++) {
                    if (i==0 || i==length-1 || j==0 || j==length-1) {  
		        sumDist = 0;                 ///to others on border
                        for (int m=0; m<length; m++)   //bottom row
                    	    sumDist += distanceFormula(i,j, m,0);
                        for (int m=0; m<length; m++)   //top row
                    	    sumDist += distanceFormula(i,j, m,length-1);
                        for (int m=1; m<length-1; m++)   //left column
                    	    sumDist += distanceFormula(i,j, 0,m);
                        for (int m=1; m<length-1; m++)   //right column
                    	    sumDist += distanceFormula(i,j, length-1,m);
	                avgDistance[i][j] = sumDist/(4*length-4); //divided by # on border
	                if (avgDistance[i][j] < minAvgDist)
	                    minAvgDist = avgDistance[i][j];
	                if (avgDistance[i][j] > maxAvgDist)
	                    maxAvgDist = avgDistance[i][j];
                    }
                }
	}
	else if (type.equals("d")) {
    	    //circle. take advantage of circular symmetry.
    	    avgDistanceRadius = new double[radius];   //jsut the points on the radius line
    	    minAvgDistCirc = 1000000;
    	    maxAvgDistCirc = 0;
    	    double numCirclePoints=4*radius*radius*.785;  //circle is approx PI/4 area of bounding square
    	    int d;
            for (int i=0; i<radius; i++) {
                sumDist = 0;         //distance to every point in the circle
                for (int x=0; x<2*radius; x++)   //bounding square
                    for (int y=0; y<2*radius; y++) {  
            	        d = (int)distanceFormula(x,y, radius,radius);  //distance to center
            	        if (d < radius)  //within the circle. 
                	    sumDist += distanceFormula(i,radius, x,y);  //Radius line parallel X axis
                    }

                avgDistanceRadius[i] = sumDist/numCirclePoints;
                if (avgDistanceRadius[i] < minAvgDistCirc)
                    minAvgDistCirc = avgDistanceRadius[i];	
                if (avgDistanceRadius[i] > maxAvgDistCirc)
                    maxAvgDistCirc = avgDistanceRadius[i];	
            }
	}
	
	else if (type.equals("c")) {
	    double avgDistRoundCircle = 2*Math.PI*(radius) / 4;  //one-fourth of circumference
	    double avgDistLine = Math.sqrt(2)*(radius);  //to point 1/4 of C away
	    JOptionPane.showMessageDialog(null,"Avg distance on circle: " + d2.format(avgDistRoundCircle) +
	    	                               "\nAvg distance straight line: " + d2.format(avgDistLine));
	    	                               	//"\nCenter's avg distance: " + d2.format(avgDistanceRadius[radius-1]));
	    //System.exit(1);
	}
	


	if (showData == JOptionPane.YES_OPTION) {
 	    JTextArea textarea = new JTextArea(length+2,6*length); 
 	    textarea.setLineWrap( true );
 	    textarea.setFont( new Font("Courier",Font.BOLD,14) );
	    JScrollPane scrollpane = new JScrollPane(textarea);
            
            for (int i=0; i<length; i++) {
                for (int j=0; j<length; j++)
		    textarea.append(" "+d1.format(avgDistance[i][j]));
                textarea.append("\n");
            }
	    textarea.append(""+d1.format(minAvgDist)+" "+d1.format(maxAvgDist));
	    JOptionPane.showMessageDialog(null, scrollpane,
                             "Avg 2D distances",
			      JOptionPane.PLAIN_MESSAGE);
	}
    }
    	
    public void paint(Graphics g) {
    
	super.paint(g);
        DecimalFormat d2;
	d2 = new DecimalFormat ("0.00");
	int frame=2;
	double range;
        double sumAvgs;
        int count;
    	Color [] grays = new Color[256];
    	for (int i=0; i<256; i++)   //256 shades of gray
    	    //grays[i] = new Color(255-i,255-i,255-i);
    	    grays[i] = new Color(255-i,0,0);   //shades of red
    	    
/*	g.setColor(Color.GREEN);
	g.fillRect(0,0, length+2*frame,length+2*frame);
	g.setColor(Color.WHITE);
	g.fillRect(frame,frame, length,length);
*/		
	if (type.equals("s") || type.equals("b")) {

    	    range = maxAvgDist-minAvgDist;
	    sumAvgs = 0;    	
	    count = 0;	
            for (int i=0; i<length; i++) 
                for (int j=0; j<length; j++) 
                    if (type.equals("s") || (type.equals("b")&&(i==0||i==length-1||j==0||j==length-1))) {
		        g.setColor(grays[(int)((avgDistance[i][j]-minAvgDist)/range*255)]);
		        g.drawLine(i+frame,j+frame, i+frame,j+frame);
		        sumAvgs += avgDistance[i][j];
		        count++;
		    //g.drawLine(length-1-i+frame,j+frame, length-1-i+frame,j+frame);
		    //g.drawLine(i+frame,length-1-j+frame, i+frame,length-1-j+frame);
		    //g.drawLine(length-1-j+frame,length-1-i+frame, length-1-j+frame,length-1-i+frame);
                }
            g.drawString("Averages: avg= "+d2.format(sumAvgs/count)+
            	         "  min="+d2.format(minAvgDist)+
            	         "  max="+d2.format(maxAvgDist), 2,length+20);
	}
    	
	else if (type.equals("d")) {
    	
	    //CIRCLE (disk)
            range = maxAvgDistCirc-minAvgDistCirc;
            int xOffset = 2, yOffset=2;
            int d;
	    sumAvgs = 0;    	
	    count = 0;	
            for (int x=0; x<2*radius; x++)   //bounding square
                for (int y=0; y<2*radius; y++) {  
            	    d = (int)distanceFormula(x,y, radius,radius);  //distance to center
            	    if (d < radius) { //within the circle.  is some i
	    	        g.setColor(grays[(int)((avgDistanceRadius[radius-1-d]-minAvgDistCirc)/range*255)]);
		        g.drawLine(x+xOffset,y+yOffset, x+xOffset,y+yOffset);
		        sumAvgs += avgDistanceRadius[d];
		        count++;
            	    }
                }
            g.drawString("Averages: avg= "+d2.format(sumAvgs/count)+
            	         "  min="+d2.format(minAvgDistCirc)+
            	         "  max="+d2.format(maxAvgDistCirc), 2,2*radius+20);
            g.drawString("Center's avg distance: " + d2.format(avgDistanceRadius[radius-1]),
            	         2,2*radius+40);
	}

    }
    

    public double distanceFormula (double x1, double y1, double x2, double y2){
    	return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
    }

}