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

public class InscribedAngles extends JApplet {     

    double r, a, rad;
    int clicks;
    int x1,y1, x2,y2, x3,y3;
    int endX, endY;  //so mouseListener has access
    int rLen;
    int midX, midY;
    DecimalFormat d2;
    
    public void init() {
	
	rLen = getHeight()/2-20;  //mouseListener needs
	midX = getWidth()/2;
	midY = getHeight()/2;
	d2 = new DecimalFormat ("0.00");
		
 	addMouseListener(
	    new MouseAdapter() {
		public void mouseClicked( MouseEvent event) {
		    int px, py;
		    px = event.getX();
		    py = event.getY();
		    double d = distanceFormula(px,py,midX,midY);
		    double dc;
		    if (d > rLen)
		    	dc = d - rLen;
		    else
		    	dc = rLen - d;  //within the circle
		    if (dc < 30) {
		    	double m = (double)(py-midY)/(px-midX);
			double dx = rLen / Math.sqrt(m*m+1);
			double dy = rLen*m / Math.sqrt(m*m+1);
			int cx, cy;
			if (px < midX)
			    cx = midX - (int)dx;
			else
			    cx = midX + (int)dx;
			if (m > 0)
			    if (py < midY)
			        cy = midY - (int)dy;
			    else
			        cy = midY + (int)dy;
		   	else
			    if (py < midY)
			        cy = midY + (int)dy;
			    else
			        cy = midY - (int)dy;
			
		        clicks++;
		        switch (clicks) {
		        case 1:
			    x1 = cx;
			    //y1 = getHeight() - event.getY();
			    y1 = cy;
	                    //sx1 = x1*scale;
	                    //sy1 = y1*scale;
		 	    break;
		        case 2:
			    x2 = cx;
			    //y2 c getHeight() - event.getY();
			    y2 = cy;
	                    //sx2 = x2*scale;
	                    //sy2 = y2*scale;
			    break;
		        case 3:
			    x3 = cx;
			    //y3 c getHeight() - event.getY();
			    y3 = cy;
                            //sx3 = x3*scale;
                            //sy3 = y3*scale;   
			    break;
		        default: 
		    	    clicks = 3;   //set it back to 3??
		            return;    //do not repaint
		        }
		        repaint();
		    }
                }
	    }
        );
	
	addMouseMotionListener(
	       new MouseMotionAdapter() {
		   public void mouseDragged( MouseEvent event) {
	               int px = event.getX();
	               int py = event.getY();
	               //double x=-999, y=-999;  //inits to fake out compiler for showStatus
	               
		       double mouseDistance1 = distanceFormula(px,py, x1,y1);
		       double mouseDistance2 = distanceFormula(px,py, x2,y2);
		       double mouseDistance3 = distanceFormula(px,py, x3,y3);
		       
		       if (mouseDistance1<30 || mouseDistance2<30 || mouseDistance3<30) { 

		    	   double m = (double)(py-midY)/(px-midX);
		    	   if (px == midX)   //crossing vertical line
		    	   	m = 1000000;   //instead of inf
			   double dx = rLen / Math.sqrt(m*m+1);
			   double dy = rLen*m / Math.sqrt(m*m+1);
			   int cx, cy;
			   if (px < midX)
			       cx = midX - (int)dx;
			   else
			       cx = midX + (int)dx;
			   if (m > 0)
			       if (py < midY)
			           cy = midY - (int)dy;
			       else
			           cy = midY + (int)dy;
		   	   else
			       if (py < midY)
			           cy = midY + (int)dy;
			       else
			           cy = midY - (int)dy;

		       	   switch (minDistance(mouseDistance1,mouseDistance2,mouseDistance3)) {
		       	   case 1: x1 = cx; y1 = cy;
		       	   	break;
		       	   case 2: x2 = cx; y2 = cy;
		       	   	break;
		       	   case 3: x3 = cx; y3 = cy;
		       	   	break;
		       	   }
			   repaint();    	   
		    	    //there's a problem at vertical???
		    	    
		    
		           /*if (a < 180) {  //left right: px change
	               	       x = (double)(px-midX)/rLen;
	               	       if (x <= r && x >= -r)   //avoid going under?? at 0
	               	       //if (a < 0)  // ?? nope
	               	       	 //  a = 0;
		           }
		           else if (a > 180) {  //left right: opp. of upper half circle
	               	       x = (double)(midX-px)/rLen;
	               	       if (x <= r && x >= -r)   //avoid going under?? at 360
		               
		           }
		           else { //a==180  ??
		               if (py != midY) {  //has to be at least one pixel above or below
		                   y = (double)(py-midY)/rLen;
		               }
		           }
	               	   //showStatus("("+px+","+(getHeight()-py)+")  x="+x+"  y="+y+"  a="+a);
	               */
		       }   	
		   } 
	       }
	 );    
   }

    public void start(){
	clicks = 0;
	JOptionPane.showMessageDialog( this, "Click 3 points on the circle."+
		                             "\n   THEN Drag them around",
	                              "TriangleApplet: what to do",
	                              JOptionPane.INFORMATION_MESSAGE );
    }

    
    public void paint (Graphics g) {
	super.paint( g );   //erase 
        g.setFont( new Font( "SansSerif", Font.BOLD, 12 ) );

	g.drawString("Drag points around circle",5,70);

	int w = getWidth();
	int h = getHeight();
	
	g.drawOval(midX-rLen,midY-rLen,2*rLen,2*rLen);
	
	g.setColor(Color.RED);
	
	if (clicks < 3) {    //still getting the vertices
	    switch (clicks) {
	    case 1:
		g.fillOval(x1-2,y1-2,4,4);
		break;
	    case 2:
		//g.fillOval(x1-2,h-y1-2,4,4);
		//g.fillOval(x2-2,h-y2-2,4,4);
		g.fillOval(x1-2,y1-2,4,4);
		g.fillOval(x2-2,y2-2,4,4);
		break;
	    }
        }
        else  {        //clicks == 3 or mouse dragged a vertex
	    //g.fillOval(x1-2,h-y1-2,4,4);
	    //g.fillOval(x2-2,h-y2-2,4,4);
	    //g.fillOval(x3-2,h-y3-2,4,4);
	    g.fillOval(x1-2,y1-2,4,4);
	    g.fillOval(x2-2,y2-2,4,4);
	    g.fillOval(x3-2,y3-2,4,4);

	    g.drawLine(midX,midY, x1,y1);
	    g.drawLine(midX,midY, x2,y2);
	    g.drawLine(x1,y1, x3,y3);
	    g.drawLine(x2,y2, x3,y3);

	    double alpha, d13, d23, d12;
	    d13 = distanceFormula(x1,y1, x3,y3);
	    d23 = distanceFormula(x2,y2, x3,y3);
	    d12 = distanceFormula(x1,y1, x2,y2);
	    alpha = Math.toDegrees(Math.acos((d13*d13+d23*d23-d12*d12) / (2*d13*d23)));
            g.setColor( Color.BLUE );
	    g.drawString(""+d2.format(alpha)+"\u00B0",x3,y3);              
	    double m13 = (double)(y1-y3)/(x1-x3);
	    if (x1 == x3)
	    	m13 = 1000000;
	    double m23 = (double)(y2-y3)/(x2-x3);
	    if (x2 == x3)
	    	m23 = 1000000;
	    double angle13 = Math.toDegrees(Math.atan(m13));  //angle of the line
	    double angle23 = Math.toDegrees(Math.atan(m23));
	    if (x3 < midX)  //leftside
	        if (angle13 < angle23)   //from the bigger to the smaller
	            g.drawArc(x3-20,y3-20,40,40, -(int)angle23,(int)alpha);	
	        else
	            g.drawArc(x3-20,y3-20,40,40, -(int)angle13,(int)alpha);	
	    else	        	
	        if (angle13 < angle23)   //from the bigger to the smaller
	            g.drawArc(x3-20,y3-20,40,40, 180-(int)angle23,(int)alpha);	
	        else
	            g.drawArc(x3-20,y3-20,40,40, 180-(int)angle13,(int)alpha);	
	    showStatus("m13="+m13+"  m23="+m23+"  angle13="+angle13+"  angle23="+angle23+"  alpha="+alpha);
	    
	    g.drawArc(50,50,20,20, 45,90);	
	    g.drawArc(50,80,20,20, -45,90);	
	    g.drawArc(50,110,20,20, 180,90);	

	    
	    double beta, d1mid, d2mid;
	    d1mid = distanceFormula(x1,y1, midX,midY);
	    d2mid = distanceFormula(x2,y2, midX,midY);
	    beta = Math.toDegrees(Math.acos((d1mid*d1mid+d2mid*d2mid-d12*d12) / (2*d1mid*d2mid)));
	    g.drawString(""+d2.format(beta)+"\u00B0",midX,midY);       
	    //g.drawArc(midX-10,midY-10,20,20, 0,(int)beta);	
	    //g.drawArc(midX-15,midY-15,30,30, 0,(int)beta);	

	    double a1 = Math.toDegrees(Math.acos((d1mid*d1mid+d13*d13-rLen*rLen) / (2*d1mid*d13)));
	    g.drawString(""+d2.format(a1)+"\u00B0",x1,y1);       

	    double a2 = Math.toDegrees(Math.acos((d2mid*d2mid+d23*d23-rLen*rLen) / (2*d2mid*d23)));
	    g.drawString(""+d2.format(a2)+"\u00B0",x2,y2);  
        }
    }
	

    public double distanceFormula (double x1, double y1, double x2, double y2){
    	return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
    }
    //indicate which of 3 parameters is the min
    public int minDistance (double d1, double d2, double d3){
	if (d1<=d2 && d1<=d3)    	
	    return 1;
	else if (d2<=d1 && d2<=d3)    	
	    return 2;
	else
	    return 3;
    }
    
}