//QuadraticApplet.java

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

public class QuadraticApplet extends JApplet implements ActionListener {
                            
    JLabel formulaLabel, aLabel, bLabel, cLabel, equationLabel, x1Label, x2Label, numSolutionsLabel, 
    	vertexHLabel, discriminantLabel, focusLabel, directrixLabel, distanceLabel, latusRectumLabel,
	xLowLabel, xHighLabel, yLowLabel, yHighLabel, tickIntervalLabel;
    JTextField aField, bField, cField, x1Field, x2Field, numSolutionsField, 
    	vertexHField, vertexKField, discriminantField, focusXField, focusYField, directrixField, 
    		distanceField, latusRectumField,
	xLowField, xHighField, yLowField, yHighField, tickIntervalField;
    JButton zoomInButton, zoomOutButton;
    PlotPanel quadPlotPanel;

    public void init() {  

	int westpanelwidth=200;
	
	Container container = getContentPane();  
	container.setLayout(null);   //** no Layout Manager	
	
	quadPlotPanel = new PlotPanel();
	quadPlotPanel.setBounds(westpanelwidth,0,getWidth()-westpanelwidth,getHeight());
	container.add(quadPlotPanel);
	//dummy blank plot...   NOT needed anymore
	//quadPlotPanel.newPlot(null,null,0,0,0,0,0,0,0,1,2,1,2,10);   //??have it paint, else nothing displays?!?!?

	JPanel westPanel = new JPanel();
	westPanel.setLayout( new GridLayout(14,1) ); 
	westPanel.setBackground(Color.LIGHT_GRAY);
	westPanel.setBounds(0,0, westpanelwidth,450);
	//westPanel.setLayout(null); 
	container.add(westPanel);
	
	JPanel formulaPanel = new JPanel();
	formulaPanel.setLayout(new FlowLayout());
	westPanel.add(formulaPanel);
	JPanel coeffsPanel = new JPanel();
	coeffsPanel.setLayout(new FlowLayout());
	//topPanel.setBounds(0,0, 200,50);
	westPanel.add(coeffsPanel);
	JPanel equationPanel = new JPanel();
	equationPanel.setLayout(new FlowLayout());
	westPanel.add(equationPanel);
	JPanel discriminantPanel = new JPanel();
	discriminantPanel.setLayout(new FlowLayout());
	westPanel.add(discriminantPanel);
	JPanel numSolutionsPanel = new JPanel();
	numSolutionsPanel.setLayout(new FlowLayout());
	westPanel.add(numSolutionsPanel);
	JPanel midPanel = new JPanel();
	midPanel.setLayout(new FlowLayout());
	westPanel.add(midPanel);

	JPanel vertexPanel = new JPanel();
	vertexPanel.setLayout(new FlowLayout());
	westPanel.add(vertexPanel);
	JPanel focusPanel = new JPanel();
	focusPanel.setLayout(new FlowLayout());
	westPanel.add(focusPanel);
	JPanel directrixPanel = new JPanel();
	directrixPanel.setLayout(new FlowLayout());
	westPanel.add(directrixPanel);
	JPanel distancePanel = new JPanel();
	distancePanel.setLayout(new FlowLayout());
	westPanel.add(distancePanel);
	JPanel latusRectumPanel = new JPanel();
	latusRectumPanel.setLayout(new FlowLayout());
	westPanel.add(latusRectumPanel);
	
	JPanel plotXPanel = new JPanel();
	plotXPanel.setLayout(new FlowLayout());
	westPanel.add(plotXPanel);
	JPanel plotYPanel = new JPanel();
	plotYPanel.setLayout(new FlowLayout());
	westPanel.add(plotYPanel);
	JPanel plotTickPanel = new JPanel();
	plotTickPanel.setLayout(new FlowLayout());
	westPanel.add(plotTickPanel);


	JPanel zoomPanel = new JPanel();
	zoomPanel.setBackground(Color.BLACK);
	zoomPanel.setBounds(0,getHeight()-200, westpanelwidth,40);
	container.add(zoomPanel);

	
	formulaLabel = new JLabel( "y=ax\u00B2+bx+c" );
	formulaPanel.add(formulaLabel);

	aLabel = new JLabel( "a" );
	coeffsPanel.add( aLabel );
	aField = new JTextField("1",3 );
	aField.setHorizontalAlignment(JTextField.RIGHT);
	aField.addActionListener( this );
	coeffsPanel.add( aField );
	
	bLabel = new JLabel( "b" );
	coeffsPanel.add( bLabel );
	bField = new JTextField("0",3 );
	bField.setHorizontalAlignment(JTextField.RIGHT);
	bField.addActionListener( this );
	coeffsPanel.add( bField );
	
	cLabel = new JLabel( "c" );
	coeffsPanel.add( cLabel );
	cField = new JTextField("0",3 );
	cField.setHorizontalAlignment(JTextField.RIGHT);
	cField.addActionListener( this );
	coeffsPanel.add( cField );

	equationLabel = new JLabel( quadraticEquation(Double.parseDouble(aField.getText()),
		                                      Double.parseDouble(bField.getText()),
		                                      Double.parseDouble(cField.getText())));
	equationPanel.add(equationLabel);

	numSolutionsLabel = new JLabel( "# real solutions" );
	numSolutionsPanel.add( numSolutionsLabel );
	numSolutionsField = new JTextField( 1 );
	numSolutionsField.setEditable(false);
	numSolutionsPanel.add( numSolutionsField );
	
	x1Label = new JLabel( "x=" );
	midPanel.add( x1Label );
	x1Field = new JTextField( 4 );
	x1Field.setBackground(Color.CYAN);
	x1Field.setHorizontalAlignment(JTextField.RIGHT);
	x1Field.setEditable(false);
	midPanel.add( x1Field );
	
	x2Label = new JLabel( "x=" );
	midPanel.add( x2Label );
	x2Field = new JTextField( 4 );
	x2Field.setBackground(Color.CYAN);
	x2Field.setHorizontalAlignment(JTextField.RIGHT);
	x2Field.setEditable(false);
	midPanel.add( x2Field );

	discriminantLabel = new JLabel( "Discriminant b\u00B2-4ac" );
	discriminantPanel.add( discriminantLabel );
	discriminantField = new JTextField( 4 );
	discriminantField.setHorizontalAlignment(JTextField.RIGHT);
	discriminantField.setEditable(false);
	discriminantPanel.add( discriminantField );

	vertexHLabel = new JLabel( "Vertex (h,k)" );
	vertexPanel.add( vertexHLabel );
	vertexHField = new JTextField( 4 );
	vertexHField.setBackground(Color.MAGENTA);
	vertexHField.setHorizontalAlignment(JTextField.RIGHT);
	vertexHField.setEditable(false);
	vertexPanel.add( vertexHField );

	vertexKField = new JTextField( 4 );
	vertexKField.setBackground(Color.MAGENTA);
	vertexKField.setEditable(false);
	vertexKField.setHorizontalAlignment(JTextField.RIGHT);
	vertexPanel.add( vertexKField );

	focusLabel = new JLabel( "Focus (x,y)" );
	focusPanel.add( focusLabel );
	focusXField = new JTextField( 4 );
	focusXField.setBackground(Color.GREEN);
	focusXField.setHorizontalAlignment(JTextField.RIGHT);
	focusXField.setEditable(false);
	focusPanel.add( focusXField );

	focusYField = new JTextField( 4 );
	focusYField.setBackground(Color.GREEN);
	focusYField.setEditable(false);
	focusYField.setHorizontalAlignment(JTextField.RIGHT);
	focusPanel.add( focusYField );

	directrixLabel = new JLabel( "Directrix y=" );
	directrixPanel.add( directrixLabel );
	directrixField = new JTextField( 4 );
	directrixField.setBackground(Color.YELLOW);
	directrixField.setHorizontalAlignment(JTextField.RIGHT);
	directrixField.setEditable(false);
	directrixPanel.add( directrixField );

	distanceLabel = new JLabel( "|F-V|=|V-D|=" );
	distancePanel.add( distanceLabel );
	distanceField = new JTextField( 4 );
	//distanceField.setBackground(Color.YELLOW);
	distanceField.setHorizontalAlignment(JTextField.RIGHT);
	distanceField.setEditable(false);
	distancePanel.add( distanceField );

	latusRectumLabel = new JLabel( "|latus rectum|" );
	latusRectumPanel.add( latusRectumLabel );
	latusRectumField = new JTextField( 4 );
	latusRectumField.setBackground(Color.PINK);
	latusRectumField.setHorizontalAlignment(JTextField.RIGHT);
	latusRectumField.setEditable(false);
	latusRectumPanel.add( latusRectumField );

	xLowLabel = new JLabel( "X low" );
	plotXPanel.add( xLowLabel );
	xLowField = new JTextField( "-5",3 );
	xLowField.setHorizontalAlignment(JTextField.RIGHT);
	xLowField.addActionListener( this );
	plotXPanel.add( xLowField );
	
	xHighLabel = new JLabel( "X high" );
	plotXPanel.add( xHighLabel );
	xHighField = new JTextField( "5",3 );
	xHighField.setHorizontalAlignment(JTextField.RIGHT);
	xHighField.addActionListener( this );
	plotXPanel.add( xHighField );
	
	yLowLabel = new JLabel( "Y low" );
	plotYPanel.add( yLowLabel );
	yLowField = new JTextField( "-3",3 );
	yLowField.setHorizontalAlignment(JTextField.RIGHT);
	yLowField.addActionListener( this );
	plotYPanel.add( yLowField );
	
	yHighLabel = new JLabel( "Y high" );
	plotYPanel.add( yHighLabel );
	yHighField = new JTextField( "3",3 );
	yHighField.setHorizontalAlignment(JTextField.RIGHT);
	yHighField.addActionListener( this );
	plotYPanel.add( yHighField );
	
	tickIntervalLabel = new JLabel( "Tick interval" );
	plotTickPanel.add( tickIntervalLabel );
	tickIntervalField = new JTextField( "1",2 );
	tickIntervalField.setHorizontalAlignment(JTextField.RIGHT);
	tickIntervalField.addActionListener( this );
	plotTickPanel.add( tickIntervalField );

	zoomInButton = new JButton( "Zoom IN" );
	zoomPanel.add( zoomInButton );
	zoomInButton.addActionListener( this );
	
	zoomOutButton = new JButton( "Zoom OUT" );
	zoomPanel.add( zoomOutButton );
	zoomOutButton.addActionListener( this );
	
	aField.postActionEvent();  
    }


    public void actionPerformed( ActionEvent event ) {

	double a, b, c, discriminant,  h, k, focusX, focusY, directrix;
	double x1=Double.POSITIVE_INFINITY, x2=Double.POSITIVE_INFINITY;
	
        DecimalFormat d2, d3;
	d2 = new DecimalFormat ("0.00");
	d3 = new DecimalFormat ("0.000");

	try {
	    a = Double.parseDouble(aField.getText());
	    b = Double.parseDouble(bField.getText());
	    c = Double.parseDouble(cField.getText());
	}
	catch (NumberFormatException e) {
	    JOptionPane.showMessageDialog(null,
					  "a, b, and c must be numbers",
					  "Quadratic: Invalid input",
					  JOptionPane.ERROR_MESSAGE);
	    return;
	}

        discriminant = b*b - 4*a*c;
	h = -b / (2 * a);
	k = -(b*b-4*a*c) / (4*a);
	focusX = h;       //oh...
	focusY = k + 1/(4*a);  
	directrix = k - 1/(4*a);
	
        if (a == 0) {
	/*    x1Field.setText("");
	    x2Field.setText("");
	    numSolutionsField.setText("");
	    discriminantField.setText("");
	    vertexHField.setText("");
	    vertexKField.setText("");
	    focusXField.setText("");
	    focusYField.setText("");
	    directrixField.setText("");
          */
            JOptionPane.showMessageDialog(null,
					  "a can not be 0",
					  "Quadratic: Invalid input",
					  JOptionPane.ERROR_MESSAGE);
	    return;
	}
        else if (discriminant > 0) {
            // calculate the two possible real values for x.
            x1 = (-b + Math.sqrt(discriminant)) / (2 * a);
            x2 = (-b - Math.sqrt(discriminant)) / (2 * a);
	    numSolutionsField.setText("2");
 	    x1Field.setText(""+d2.format(x1));
	    x2Field.setText(""+d2.format(x2));
       }
        else if (discriminant == 0) {
            //one real root
            x1 = -b / (2*a);
	    numSolutionsField.setText("1");
	    x1Field.setText(""+d2.format(x1));
	    x2Field.setText("");
        }
        else {
            //no real roots
	    numSolutionsField.setText("0");
	    x1Field.setText("");
	    x2Field.setText("");
	}

	discriminantField.setText(""+d2.format(discriminant));
	vertexHField.setText(""+d2.format(h));
	vertexKField.setText(""+d2.format(k));
        focusXField.setText(""+d2.format(focusX));
        focusYField.setText(""+d2.format(focusY));
        directrixField.setText(""+d2.format(directrix));
	equationLabel.setText( quadraticEquation(a,b,c));
	distanceField.setText(""+d3.format(Math.abs(k-focusY)));
	latusRectumField.setText(""+d3.format(4*Math.abs(k-focusY)));
	
	double xLo, xHi, yLo, yHi, tickInt;
	try {
	    xLo = Double.parseDouble(xLowField.getText());
	    xHi = Double.parseDouble(xHighField.getText());
	    yLo = Double.parseDouble(yLowField.getText());
	    yHi = Double.parseDouble(yHighField.getText());
	    tickInt = Double.parseDouble(tickIntervalField.getText());
	}
	catch (NumberFormatException e) {
	    JOptionPane.showMessageDialog(null,
					  "Plotting coordinates must be numbers",
					  "Quadratic plotting: Invalid input",
					  JOptionPane.ERROR_MESSAGE);
	    return;
	}

	if (xLo>xHi || yLo>yHi || tickInt<=0) {
	    JOptionPane.showMessageDialog(null,
					  "Bad plotting coordinates",
					  "Quadratic plotting: Invalid input",
					  JOptionPane.ERROR_MESSAGE);
	    return;
	}

	if ( event.getSource() == zoomInButton ) {
	    double scale = .9;   //shrink the grid by 10%
	    xLo *= scale;
	    xHi *= scale;
	    yLo *= scale;
	    yHi *= scale;
	    xLowField.setText(""+d2.format(xLo));
	    xHighField.setText(""+d2.format(xHi));
	    yLowField.setText(""+d2.format(yLo));
	    yHighField.setText(""+d2.format(yHi));
	    //repaint();    
	}
	else if ( event.getSource() == zoomOutButton ) {
	    double scale = 1.1;   //grow the grid by 10%
	    xLo *= scale;
	    xHi *= scale;
	    yLo *= scale;
	    yHi *= scale;
	    xLowField.setText(""+d2.format(xLo));
	    xHighField.setText(""+d2.format(xHi));
	    yLowField.setText(""+d2.format(yLo));
	    yHighField.setText(""+d2.format(yHi));
	    //repaint();    
	}

	double [] X = new double[2000];
        double [] Y = new double[2000];
        double xDiff = (xHi - xLo) / X.length;
        X[0] = xLo;
        Y[0] = a*X[0]*X[0] + b*X[0] + c;
        for (int i=1; i<X.length; i++) {
            X[i] = X[i-1] + xDiff;
            Y[i] = a*X[i]*X[i] + b*X[i] + c;
        }
        quadPlotPanel.newPlot(X,Y, a,b,c, x1,x2, h, k, focusX, focusY,directrix,xLo,xHi,yLo,yHi,tickInt);

    }

    public String quadraticEquation(double a, double b, double c) {
	String eq="y=";
	if (a < 0)
	    eq += "-";
	if (a!=-1 && a!=1)
	    eq +=  Math.abs(a);
	eq += "x\u00B2 ";
	if (b != 0) {
	    if (b < 0)
	    	eq += "- ";
	    else
	    	eq += "+ ";
	    if (b!=-1 && b!=1)
	    	eq += Math.abs(b);
	    eq += "x ";
	}
	if (c != 0) {
	    if (c < 0)
	    	eq += "- ";
	    else
	    	eq += "+ ";
	    	eq += Math.abs(c);
	}
	return eq;
    }
}