//Mandelbrot.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Mandelbrot extends JApplet implements ActionListener {
    
    private JLabel startRealLabel;
    private JTextField startRealField;
    private JLabel endRealLabel;
    private JTextField endRealField;

    private JLabel startImagLabel;
    private JTextField startImagField;
    private JLabel endImagLabel;
    private JTextField endImagField;

    private JLabel stepsLabel;
    private JTextField stepsField;

    private JLabel maxItsLabel;
    private JTextField maxItsField;

    private JButton doitButton;

    private JLabel zoomLabel;
    private JTextField zoomField;

    private JPanel infoPanel;

    private MandelbrotPanel drawPanel;

    double scale;
    double originalZoom;
    double firstRealPress;   //set by mousePressed
    double firstImagPress;


    public void init() {

      Container container = getContentPane();  
      container.setLayout( new BorderLayout(2,2) ); 

      infoPanel = new JPanel();
      infoPanel.setLayout( new GridLayout(3,6));

      startRealLabel = new JLabel( "     Start real" );
      //      startRealLabel.setHorizontalTextPosition( SwingConstants.RIGHT );
      startRealField = new JTextField( 6 );
      startRealField.setText("-2.0");
      startRealField.setToolTipText( "Min x axis");
      infoPanel.add( startRealLabel );
      infoPanel.add( startRealField );

      endRealLabel = new JLabel( "     End real" );
      endRealField = new JTextField( 6 );
      endRealField.setText("1.0");
      endRealField.setToolTipText( "Max x axis");
      infoPanel.add( endRealLabel );
      infoPanel.add( endRealField );

      startImagLabel = new JLabel( "     Start imaginary" );
      startImagField = new JTextField( 6 );
      startImagField.setText("-1.0");
      startImagField.setToolTipText( "Min y axis");
      infoPanel.add( startImagLabel );
      infoPanel.add( startImagField );

      endImagLabel = new JLabel( "     End imaginary" );
      endImagField = new JTextField( 6 );
      endImagField.setText("1.0");
      endImagField.setToolTipText( "Max y axis");
      infoPanel.add( endImagLabel );
      infoPanel.add( endImagField );

      stepsLabel = new JLabel( "     Increments" );
      stepsField = new JTextField( 6 );
      stepsField.setText("1000");
      stepsField.setToolTipText( "x and y steps" );
      infoPanel.add( stepsLabel );
      infoPanel.add( stepsField );

      maxItsLabel = new JLabel( "     Max iterations" );
      maxItsField = new JTextField( 6 );
      maxItsField.setText("100");
      maxItsField.setToolTipText( "loop inside the snowman" );
      infoPanel.add( maxItsLabel );
      infoPanel.add( maxItsField );

      zoomLabel = new JLabel( "     Zoom factor" );
      zoomField = new JTextField( 6 );
      zoomField.setEditable( false );
      zoomField.setText("1");
      infoPanel.add( zoomLabel );
      infoPanel.add( zoomField );

      originalZoom = Double.parseDouble(endRealField.getText()) -
	  Double.parseDouble(startRealField.getText());

      doitButton = new JButton( "Do it" );
      doitButton.setToolTipText( "Display the set based on current parameters" );
      infoPanel.add( doitButton );

      doitButton.addActionListener( this );

      JLabel dummyLabel = new JLabel( "" );
      infoPanel.add( dummyLabel );
      infoPanel.add( dummyLabel );
      infoPanel.add( dummyLabel );

      container.add( infoPanel, BorderLayout.SOUTH);

      drawPanel = new MandelbrotPanel();
      container.add( drawPanel, BorderLayout.CENTER);

      addMouseMotionListener(
	  //anonymous inner class overrides mouseMoved
	  new MouseMotionAdapter() {

	      public void mouseMoved( MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );
		  double start_real = Double.parseDouble(startRealField.getText());
		  double end_real = Double.parseDouble(endRealField.getText());
		  double start_imag = Double.parseDouble(startImagField.getText());
		  double end_imag = Double.parseDouble(endImagField.getText());

		  if (r>=start_real && r<=end_real && 
		      imag>=start_imag && imag<=end_imag)

		      showStatus("(" + r + "," + imag + ")");
		  else
		      showStatus( "Change the parameters or drag mouse for close-up" );

	      }

	      public void mouseDragged( MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  showStatus("(" + r + "," + imag + ")");
	      }
	  }
      );

      addMouseListener (
          new MouseAdapter() {
	      public void mousePressed (MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  //dead bug: setText of textfields changed the coordinates
		  firstRealPress = r;
		  firstImagPress = imag;

	      }

	      public void mouseReleased (MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  if (r > firstRealPress) {
		      startRealField.setText ("" + firstRealPress);
		      endRealField.setText ("" + r);
		  }
		  else {
		      startRealField.setText ("" + r);
		      endRealField.setText ("" + firstRealPress);
		  }

		  if (imag > firstImagPress) {
		      startImagField.setText ("" + firstImagPress);
		      endImagField.setText ("" + imag);
		  }
		  else {
		      startImagField.setText ("" + imag);
		      endImagField.setText ("" + firstImagPress);
		  }


		  drawMandelbrot();
	      }
	  }
       );
    }


    public void start(){
	drawMandelbrot();
    }


    public void actionPerformed( ActionEvent event ) {
	if ( event.getSource() == doitButton ) {
	    drawMandelbrot();
	}
    }


    private double getR (int x ) {
	double start_real = Double.parseDouble(startRealField.getText());

	return x / scale + start_real;
    }

    private double getImag (int y ) {
	double start_imag = Double.parseDouble(startImagField.getText());
	double end_imag = Double.parseDouble(endImagField.getText());

	return -y / scale + end_imag;   //y axis is flipped
    }

    public void drawMandelbrot() {
	showStatus( "Calculating..." );//only the last showStatus is effective?
	 drawPanel.draw(
			Double.parseDouble(startRealField.getText()),
			Double.parseDouble(endRealField.getText()),
			Double.parseDouble(startImagField.getText()),
			Double.parseDouble(endImagField.getText()),
			Integer.parseInt(stepsField.getText()),
			Integer.parseInt(maxItsField.getText()));

	 //	 showStatus( "Change the parameters or drag mouse for close-up" );

	 double start_real, end_real, start_imag, end_imag;

	 start_real = Double.parseDouble(startRealField.getText());
	 end_real =   Double.parseDouble(endRealField.getText());
	 start_imag = Double.parseDouble(startImagField.getText());
	 end_imag =   Double.parseDouble(endImagField.getText());
	 
	 double dist_real = Math.abs(end_real - start_real);
	 double dist_imag = Math.abs(end_imag - start_imag);
	 
	 zoomField.setText("" + originalZoom/dist_real);
	 
	 double xScale = drawPanel.getWidth() / dist_real;
	 double yScale = drawPanel.getHeight() / dist_imag;
	 scale = Math.min(yScale,xScale);
    }

}


class MandelbrotPanel extends JPanel {

    private double start_real,
	end_real,
	start_imag,
	end_imag, 
	scale;
    private int max_its, steps;


    public void draw(double sReal,
		     double eReal,
		     double sImag,
		     double eImag, 
		     int stps, 
		     int its)
    {
	start_real = sReal;
	end_real = eReal;
	start_imag = sImag;
	end_imag = eImag;
	steps = stps;
	max_its = its;

	repaint();
    }


    public void paintComponent ( Graphics g )
    {
       super.paintComponent( g );

       int   its;
       int x1, y1;
       double inc_real, inc_imag;
       double zr, zi, t;


       double dist_real = Math.abs(end_real - start_real);
       double dist_imag = Math.abs(end_imag - start_imag);
       inc_real = dist_real / steps;
       inc_imag = dist_imag / steps;
       //       double mid_real = start_real + dist_real/2;
       //double mid_imag = start_imag + dist_imag/2;

       //       zoomField.setText("" + originalZoom/dist_real);

       double xScale = getWidth() / dist_real;
       double yScale = getHeight() / dist_imag;
       scale = Math.min(yScale,xScale);

       for (double r=start_real; r<end_real; r+=inc_real)
	   for (double imag=start_imag; imag<end_imag; imag+=inc_imag) {
	       zr = 0;
	       zi = 0;
	       its = 0;
	       while (its<max_its && zr*zr+zi*zi<4) {
		   t = zr*zr - zi*zi + r;
		   zi = 2*zr*zi + imag;
		   zr = t;
		   its++;
	       }

	       x1 = (int)(Math.abs(r -  start_real) * scale);
	       y1 = (int)(Math.abs(imag-end_imag) * scale); //y axis is flipped
	       
	       if (its == max_its)
		   g.setColor( Color.BLACK );
	       else
		   g.setColor( new Color( 128+(int)((double)its/max_its*128),0,0));

	       g.drawLine(x1,y1,x1,y1);  //point
	   }
    }
}