/*
   filename:         circle.java
   description:      given coordinates for two points on a cirlce, outputs attributes of circle
   author:           Kalin Ringkvist, k.rainquist@comcast.net
   version:          1.00 2004-02-18
*/

//import  Java classes
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;//to detect the click on the button
import java.text.*;     //to format our output


public class circle extends JFrame
{
    //create instance variables
      private JLabel lblX1 = new JLabel("Location of first point (center of circle) on X axis (X1):");
      private JLabel lblY1 = new JLabel("Location of first point (center of circle) on Y axis (Y1):");
      private JLabel lblX2 = new JLabel("Location of second point (edge of circle) on X axis (X2):");
      private JLabel lblY2 = new JLabel("Location of second point (edge of cirlce) on Y axis (Y2):");
      private JTextField txbX1 = new JTextField("");
      private JTextField txbY1 = new JTextField("");
      private JTextField txbX2 = new JTextField("");
      private JTextField txbY2 = new JTextField("");
      private JButton butCalc = new JButton("Calculate");

      private CalculateButtonHandler calcHandler;

      //create DecimalFormat to format final output (used in
      DecimalFormat num = new DecimalFormat("0.000");

    public circle()
      {
         //get reference to JFrame.
         Container frame = getContentPane();

         //create and apply layout to the frame
         frame.setLayout(new GridLayout(5,2));

         //set result box as uneditable
         //txbResult.setEditable(false);

         //set the default operation to exit when the user closes the application
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         //set the title of the frame
         setTitle("Calculate the attributes of a circle.");

         //show the frame
         show();

         //put the objects on the form & align text
         frame.add(lblX1);
         //lblX1.setHorizontalAlignment(JTextField.CENTER);
         frame.add(txbX1);
         frame.add(lblY1);
         //lblY1.setHorizontalAlignment(JTextField.CENTER);
         frame.add(txbY1);
         frame.add(lblX2);
         //lblX2.setHorizontalAlignment(JTextField.CENTER);
         frame.add(txbX2);
         frame.add(lblY2);
         //lblY2.setHorizontalAlignment(JTextField.CENTER);
         frame.add(txbY2);
         frame.add(butCalc);


         //add action listener to butCalc to detect the click
         calcHandler = new CalculateButtonHandler();
         butCalc.addActionListener(calcHandler);
      }

   public static void main(String[] args)
   {

      circle c = new circle(); //instantiate class
      c.pack(); //pack the frame around the objects

   }


   //private class handles the button click event
   private class CalculateButtonHandler implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         //get the user input
         double dblX1 = Double.parseDouble(txbX1.getText());
         double dblY1 = Double.parseDouble(txbY1.getText());
         double dblX2 = Double.parseDouble(txbX2.getText());
         double dblY2 = Double.parseDouble(txbY2.getText());

         //call methods to calculate attributes
         double dblRadius = (radius(dblX1, dblY1, dblX2, dblY2));
         double dblCircum = (circumference(dblRadius));
         double dblArea = (area(dblRadius));

         //format and combine attributes with labels and line feeds into a string variable
         String strResult = "Radius:  " + num.format(dblRadius) + " units. \n Diameter:  " +
            num.format(dblRadius * 2) + " units. \n Circumference:  " + num.format(dblCircum) +
               " units. \n Area:  " + num.format(dblArea) + " square units.";

         //Display that string variable in a message dialog
         JOptionPane.showMessageDialog(null, strResult, "Results", JOptionPane.INFORMATION_MESSAGE);


      }
   }

//here begins the four required methods

   //calculates distance between the two points
   public static double distance(double X1, double Y1, double X2, double Y2)
   {
      return Math.sqrt((X2 - X1) * (X2 - X1) + (Y2 - Y1) * (Y2 - Y1));

   }


   //This seems to be a pointless method, doing nothing but calling another method
   public static double radius(double X1, double Y1, double X2, double Y2)
   {
      return distance(X1, Y1, X2, Y2);

   }


   //calculates circumference of the circle that's represented by the two points
   public static double circumference(double radius)
   {

      //doubled pi and multiplied by the radius
      return 6.2832 * radius;

   }


   //calculates the area of the circle
   public static double area(double radius)
   {

      //radius squared multiplied by pi
      return radius * radius * 3.1416;

   }



}