import java.awt.*;
import java.awt.image.*;
import java.applet.*;
import java.net.*;

public class Direct extends java.applet.Applet
{
  final int x_dim = 200;
  final int y_dim = 200;

  int scaled = 0;
  DirectCanvas graph;
  Image arrayImage[] = new Image[3];
  Choice element_type;
  Label plot;
  Label element_label;
  Label d_number;
  Label d_scale;
  Label d_phase;
  Label v_number;
  Label v_scale;
  Label v_phase;
  Label x_axis[] = new Label[6];
  Label y_axis[] = new Label[6];
  Scrollbar sb_number;
  Scrollbar sb_scale;
  Scrollbar sb_phase;
  Scrollbar sb_range;

  public void init()
  {

      setLayout( null);

	graph = new DirectCanvas( this );
	graph.reshape( 20, 20, x_dim+21, y_dim+21 );
	add( graph );

      arrayImage[0] = getImage(getCodeBase(),"images/iso.gif");
      arrayImage[1] = getImage(getCodeBase(),"images/col.gif");
      arrayImage[2] = getImage(getCodeBase(),"images/par.gif");

      for(int i=0; i<6 ; i++){
        y_axis[i] = new Label(String.valueOf(40*i));
        y_axis[i].reshape(4,232-40*i,30,15);
        add(y_axis[i]);
        x_axis[i] = new Label(String.valueOf((40.0*i)/100.0));
        x_axis[i].reshape(33+40*i,243,20,15);
        add(x_axis[i]);
      }


      plot = new Label(" Directivity (D) vs. d/wavelength ",Label.CENTER);
      plot.setForeground(Color.blue);
      plot.reshape(0,0,x_dim,30);
      add( plot );

	d_number = new Label( "number of elements:" );
	d_number.reshape( x_dim + 60, 0, 200, 14 );
	add( d_number );

	d_scale = new Label( "scale factor:" );
	d_scale.reshape( x_dim + 60, 80, 200, 14 );
	add( d_scale );

	d_phase = new Label( "phase difference:" );
	d_phase.reshape( x_dim + 60, 40, 200, 14 );
	add( d_phase );

	sb_number = new Scrollbar( Scrollbar.HORIZONTAL, 2, 1, 2, 10 );
	sb_number.setPageIncrement( 2 );
	sb_number.reshape( x_dim + 60, 15, 200, 14 );
	add( sb_number );

	sb_scale = new Scrollbar( Scrollbar.HORIZONTAL, 1, 1, 1, 100 );
	sb_scale.setPageIncrement( 5 );
	sb_scale.reshape( x_dim + 60, 95, 200, 14 );
	add( sb_scale );

	sb_phase = new Scrollbar( Scrollbar.HORIZONTAL, 0, 1, 0, 359 );
	sb_phase.setPageIncrement( 20 );
	sb_phase.reshape( x_dim + 60, 55, 200, 14 );
	add( sb_phase );

      element_label = new Label("Element Type");
      element_label.reshape(x_dim+60,120,150,20);
      add(element_label);
 
      element_type = new Choice();
      element_type.addItem("Isotropic Element");
      element_type.addItem("Collinear short dipoles");
      element_type.addItem("Parallel short dipoles");
      element_type.reshape(x_dim + 60,145,200,30);
      add(element_type);

	v_number = new Label( String.valueOf( sb_number.getValue() ) );
	v_number.reshape( x_dim + 260, 15, 35, 14 );
	add( v_number );

	v_scale = new Label( String.valueOf( sb_scale.getValue() ) );
	v_scale.reshape( x_dim + 260, 95, 35, 14 );
	add( v_scale );

	v_phase = new Label( String.valueOf( sb_phase.getValue() ) );
	v_phase.reshape( x_dim + 260, 55, 35, 14 );
	add( v_phase );

	repaint();
  }

  public boolean handleEvent( Event event )
  {
    if ( event.id == Event.SCROLL_LINE_DOWN ||
	   event.id == Event.SCROLL_LINE_UP ||
	   event.id == Event.SCROLL_PAGE_DOWN ||
	   event.id == Event.SCROLL_PAGE_UP ||
	   event.id == Event.MOUSE_UP){
      v_number.setText(String.valueOf(sb_number.getValue()));
      v_phase.setText(String.valueOf(sb_phase.getValue()));
      if((v_scale.getText()).compareTo(String.valueOf(sb_scale.getValue()))!=0){
         v_scale.setText(String.valueOf(sb_scale.getValue()));
         for(int i = 0; i<6 ; i++)
           y_axis[i].setText(String.valueOf(40.0*i/sb_scale.getValue()));
         scaled = 1;
      } 
       else{
         scaled = 0;
       }
	graph.repaint();
      return true;
    }
    if(event.id == Event.SCROLL_ABSOLUTE){
	v_number.setText(String.valueOf(sb_number.getValue()));
      v_phase.setText(String.valueOf(sb_phase.getValue()));
      if((v_scale.getText()).compareTo(String.valueOf(sb_scale.getValue()))!=0){
         v_scale.setText(String.valueOf(sb_scale.getValue()));
         for(int i = 0; i<6 ; i++)

           y_axis[i].setText(String.valueOf(40.0*i/sb_scale.getValue()));
         scaled = 1;
	   graph.repaint();
       } 
       else{
         scaled = 0;
       }
    }
    if(event.id == Event.ACTION_EVENT){
	repaint();
	graph.repaint();
    }

    return super.handleEvent( event );
  }

  public void paint( Graphics g )
  {
	graph.paint( g );
  }
}


class DirectCanvas extends Canvas
{
  Direct parent;
 
  double r[] = new double[ 201 ];

  DirectCanvas( Direct applet )
  {
	parent = applet;
  }

  private double arfac( double n, double x )
  {
    double result,sinthing;
    try
    {
      sinthing = Math.abs(Math.sin(x/2));
      if(sinthing<.000001){
         result = 1.0;
      }
      else{
       result = Math.abs(Math.sin(n*x/2)/(n*sinthing));
      }
    }
    catch ( ArithmeticException ae )
    {
      result = 0.0;
    }

    return result;
  }

  private double raxi(double bd,double a,double n)
  {
    int diff,n1,n2,nholder,nindex,i;
    double ArfacList[];
    double result=0.0,ndouble;

    n1=(int)Math.ceil((a-bd)/(Math.PI/n));
    n2=(int)Math.floor((a+bd)/(Math.PI/n));
    diff = Math.abs(n2-n1);
    ArfacList= new double[diff+2];
    for(nindex=n1,i=1;nindex<=n2;nindex++,i++){
      ndouble = (double)nindex; 
      ArfacList[i] = arfac(n,ndouble*(Math.PI/n));
    }
    ArfacList[0] = arfac(n,(double)(a-bd));
    ArfacList[diff+1] = arfac(n,(double)(a+bd));
    for(i=0;i<=(diff+1);i++){
      result = Math.max(result,ArfacList[i]);
    }
    parent.showStatus("raxi is: " + Double.toString(result)+"n1 is: "+
                      Integer.toString(n1)+"n2 is: "+Integer.toString(n2));
    return result;
  }

  private double f( int distance )
  {
    double result=0.0,sumtot=0.0,m=0.0;
    int i=0;
    double scale = (double) parent.sb_scale.getValue();
    double bd = (distance/100.0)*Math.PI*2, a0=1.0;
    int pha = parent.sb_phase.getValue();
    double a = (Math.PI*pha/180.0);
    double n = (double) parent.sb_number.getValue();

    try 
    { 

    if(parent.element_type.getSelectedIndex()==0){
      a0=1.0;
      for(i=1;i<(int)n;i++){
         m=(double)i;
         sumtot += ((n-m)/(m*bd))*Math.sin(m*bd)*Math.cos(m*a);
      }

    }
    else if(parent.element_type.getSelectedIndex()==1){
        a0=2.0/3.0;
        for(i=1;i<(int)n;i++){
          m=(double)i;
          sumtot += ((n-m)/(m*bd))*(
                              (2.0/(m*m*bd*bd))*Math.sin(m*bd)+
                              (-2.0/(m*bd))*Math.cos(m*bd))*
                             Math.cos(m*a);
        }
     }
    
    else if(parent.element_type.getSelectedIndex()==2){
        a0=2.0/3.0;
        for(i=1;i<(int)n;i++){
          m=(double)i;
          sumtot += ((n-m)/(m*bd))*(
                              (1.0-1.0/(m*m*bd*bd))*Math.sin(m*bd)+
                              (1.0/(m*bd))*Math.cos(m*bd))*
                             Math.cos(m*a);        
        }
     }
    
      if(pha<14){
        result = 1/((a0/n)+(2/(n*n))*sumtot);
      }
      else{
        result = (raxi(bd,a,n)*raxi(bd,a,n))/((a0/n)+(2/(n*n))*sumtot);
      }

    }//end of try
    catch ( ArithmeticException ae )
    {
    result = 0.0;
    }
    return result;
 }


  public void paint( Graphics g)
  {
	int i,scale;
      scale = parent.sb_scale.getValue();

	g.setColor( Color.white);
      
      g.drawImage(parent.arrayImage[parent.element_type.getSelectedIndex()],
                   parent.x_dim+60,180,200,100,Color.white,parent);
      
	g.fillRect( 20, 20, parent.x_dim, parent.y_dim );
	g.setColor( Color.gray );

      for (i = 20; i <= parent.x_dim+40; i=i+(int)(parent.x_dim/10))
        g.drawLine(20,i,parent.x_dim+20,i);

      for (i = 20; i <= parent.y_dim+40; i=i+(int)(parent.y_dim/10))
        g.drawLine(i,20,i,parent.y_dim+20);

	g.setColor( Color.blue );

      if(parent.scaled==1){
        for ( i = 1; i < 200; i++){
          if((220-scale*r[i-1])>19 && (220-scale*r[i])>19 && (220-scale*r[i-1])<221 && (220-scale*r[i])<221)
            g.drawLine(i+20,(int)(220-scale*r[i-1]),i+21,(int)(220-scale*r[i]));
        }
      }
      else{
        r[0] = f(1);
        for ( i = 1; i < 200; i++){
	    r[i] = f(i);
          if((220-scale*r[i-1])>19 && (220-scale*r[i])>19 && (220-scale*r[i-1])<221 && (220-scale*r[i])<221)
            g.drawLine(i+20,(int)(220-scale*r[i-1]),i+21,(int)(220-scale*r[i]));
        }
     }
  }
}