import java.util.Date;
import java.applet.*;
import java.awt.Graphics;
import java.awt.event.*;
import java.awt.*;
import Rectangle;
import Line;
import Potential;

public class magnetandloop extends Applet 
{
    double x1 = 50.0;
    double y1 = 250.;
    int go = 1;
    int lastx;

    double tim = 0;
    double dtim=0.01;

    static double qvalue = 10;
    static double betavalue = 200;

    double recentx[];
    long recentt[];
    double I_loop=0.;

    int max = 4;
    int j;
    int xcoord, ycoord;
    long lastt;

    int maxtim =1;
    int brectcx;
    int brectcy;

    double dist1;
    double dist2;
    double compx, compx1, compx2;
    double compy, compy1, compy2;
    double dummy = 0.;
    double rada = 100.;
    double ang=Math.PI/6.;

    int x2 = 325;
    int y2 = 240;

    int numline = 2;

    Rectangle rect;
    Line line;

/*
public void Reset()
    {
	x1 = 50.0;
	y1 = 250.;
	go = 1;
	tim = 0;
	repaint();
    }

public void Settvalue(String m)
    {
  	maxtim = new Integer(m).intValue();
    }

public void Setqvalue(String m)
    {
	qvalue = new Double(m).doubleValue();
    }

public void Setbvalue(String m)
    {
	betavalue = new Double(m).doubleValue();
    }

public void SetGo()
    {
	go = 1;
	repaint();
    }
*/
 
public void init()
    {
	setBackground(java.awt.Color.white);
	rect = new Rectangle(0,10,15,(int)x1,(int)y1);
	
 	recentx = new double[max+1];
	recentt = new long[max+1];
	line=new Line(0.0,0.0,0.0,0.0);

    }

public void paint(Graphics g)
    {
	//if(tim==0 && go==1)
//	if(go==1)
//	    {
		//while(tim<maxtim)
		  {    
		   	line.ang = ang;  //the angle of field line measured from horizontal
    			line.emag = 1;

			rect.cx = (int)x1;
			rect.cy = (int)y1;


/*			g.setColor(java.awt.Color.white);
    			g.drawLine(brectcx-rect.rw,brectcy-rect.rh,brectcx-rect.rw,brectcy+rect.rh);
    			g.drawLine(brectcx-rect.rw,brectcy-rect.rh,brectcx+rect.rw,brectcy-rect.rh);
    			g.drawLine(brectcx+rect.rw,brectcy-rect.rh,brectcx+rect.rw,brectcy+rect.rh);
    			g.drawLine(brectcx+rect.rw,brectcy+rect.rh,brectcx-rect.rw,brectcy+rect.rh);
*/
			g.setColor(java.awt.Color.black);

    			g.drawLine(rect.cx-rect.rw,rect.cy-rect.rh,rect.cx-rect.rw,rect.cy+rect.rh);
    			g.drawLine(rect.cx-rect.rw,rect.cy-rect.rh,rect.cx+rect.rw,rect.cy-rect.rh);
    			g.drawLine(rect.cx+rect.rw,rect.cy-rect.rh,rect.cx+rect.rw,rect.cy+rect.rh);
    			g.drawLine(rect.cx+rect.rw,rect.cy+rect.rh,rect.cx-rect.rw,rect.cy+rect.rh);

    	    while(line.ang >= -ang)
         	{
        	    line.sx = x1 + 30 * Math.cos(line.ang);
        	    line.sy = y1 + 30 * Math.sin(line.ang);
	
        	    dist1 = Math.sqrt(Math.pow(line.sx-x1, 2) + Math.pow(line.sy - y1, 2));

        	    double delarc = 9.;
                    double intarc;
                    intarc = delarc/3.;

             	    while(dist1 > 25.0 && line.sx < 450 && line.sx > 0 && line.sy < 500 && line.sy > 0 && line.emag > .00000001)
                	{

                	    dist1 = Math.sqrt(Math.pow(line.sx-x1, 2) + Math.pow(line.sy - y1, 2));

 			//compute components of dipole field 

                	    compy1 = (3.*(line.sx-x1)*(line.sy-y1)/4.*Math.PI)/Math.pow(Math.pow(line.sx-x1,2)+Math.pow(line.sy-y1,2),2.5) ;
                	    compx1 = ((2.*Math.pow(line.sx-x1,2)-Math.pow(line.sy-y1,2))/4.*Math.PI)/Math.pow(Math.pow(line.sx-x1,2) + Math.pow(line.sy-y1,2),2.5);

 			//compute components of field due to ring, respectively
                        //note we are dividing by lambda beta where lambda is set to 2

	                    Potential pinto=new Potential(dummy,rada, line.sy-250., line.sx-225.);
	                    Potential pintx=new Potential(dummy,rada, line.sy-250., line.sx + intarc-225.);
	                    Potential pinty=new Potential(dummy,rada, line.sy + intarc-250.,line.sx-225.);

              	    compx2 = -0.01*I_loop*(pinty.Pota-pinto.Pota)/ intarc;
              	    compy2 =0.01*I_loop*(pintx.Pota-pinto.Pota)/ intarc;

                       //note we are dividing comp2 by "a*a" to scale properly
                            compx=compx1+compx2/rada;
                            compy=compy1+compy2/rada;

                	    line.emag = Math.sqrt(Math.pow(compx,2) + Math.pow(compy,2));

                	    line.ex = line.sx + delarc * (compx/line.emag);
                	    line.ey = line.sy + delarc * (compy/line.emag);

			    g.drawLine((int)line.sx, (int)line.sy, (int)line.ex, (int)line.ey);

                	    line.sx = line.ex;
                	    line.sy = line.ey;

                	}
	    	    line.ang = line.ang - 2.*ang;
        	}
  	    brectcx = rect.cx;
	    brectcy = rect.cy;

	    tim+=dtim;
	    System.out.println("tim=" +tim);

	    //g.setColor(java.awt.Color.white);
	    //g.fillRect(0,0,450,500);
	    g.setColor(java.awt.Color.black);
	    g.drawOval(225,150,20,(2*(int)rada));
    	 	    }  	   
 //   	    }
}

/*
public boolean mouseMove(Event e, int x, int y)
    {
 
    xcoord = x;
    ycoord = y;
    return true;
    }
*/
 
public boolean mouseDown(Event e, int x, int y)
    {
    xcoord = x;
    ycoord = y;

    if(xcoord < (int)x1 + rect.rw && xcoord > (int)x1-rect.rw && ycoord < (int)y1+rect.rh && ycoord > (int)y1-rect.rh)
   	{
	rect.hit = 1;
	}
	return true;
    }  
 
public boolean mouseUp(Event e, int x, int y)
    {
    rect.hit = 0;
    return true;
    }
 
public boolean mouseDrag(Event e, int x, int y)
    {
    xcoord = x;
    ycoord = y;
    if (rect.hit == 1)
        {
        lastx = rect.cx;
        lastt = new Date().getTime();
 
        if(j <= max)
            {
            recentx[j] = lastx;
            recentt[j] = lastt;
            rect.cx = x;
	    x1 = rect.cx;
            }
        else if(j > max)
            {
            j = 0;
            while(j < max)
                {
                recentx[j] = recentx[(j+1)];
                recentt[j] = recentt[(j+1)];
                j++;
                }
                recentx[j] = lastx;
                recentt[j] = lastt;
                rect.cx = x;
		x1 = rect.cx;
            }
        j++;
        System.out.println("Recentx[0] = " + recentx[0] + " Recentx[1] = " + recentx[1] + " Recentx[2] = " + recentx[2]);
        System.out.println("Recentt[0] = " + recentt[0] + " Recentt[1] = " + recentt[1] + " Recentt[2] = " + recentt[2]);
	System.out.println("x=" + x + " y = " + y+ "I_loop  " + I_loop);
         I_loop=recentx[max]-recentx[max-1];
         
        repaint();
        }
    return true;
    }  
}