import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;

import static javax.swing.SwingConstants.CENTER;

/**
 * File Week4Discussion.java
 * Simple area calculator.
 *
 * @author Lance Gundersen
 * @version 1.0
 * @since 2018-11-13
 */
class AreaCalculator {

    private JButton calculateButton;
    private JTextField sideOneText, sideTwoText, resultsText;

    private AreaCalculator() {
        this.CreateGui();
        // No validation at this time.
        this.calculateButton.addActionListener(e -> calculateArea(sideOneText.getText(), sideTwoText.getText()));
    }

    public static void main(String[] args) {
        new AreaCalculator();
    }

    // Calculate area and set results text to results. No error checking.
    private void calculateArea(String sideA, String sideB) {
        String results = String.valueOf(Double.parseDouble(sideA) * Double.parseDouble(sideB));
        this.resultsText.setText(results);
    }

    private void CreateGui() {
        // Used border of 10 more than once, DRY
        final EmptyBorder borderSizeTen = new EmptyBorder(10, 10, 10, 10);

        // Create frame
        JFrame frame = new JFrame("Area Calc");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setPreferredSize(new Dimension(350, 300));

        // Create panel layouts
        JPanel panel = new JPanel(new BorderLayout());
        panel.setBorder(borderSizeTen);
        JPanel panelTop = new JPanel(new GridLayout(6, 5, 5, 5));
        panelTop.setBorder(borderSizeTen);
        JPanel panelBottom = new JPanel(new GridLayout(2, 5, 5, 5));
        panelBottom.setBorder(borderSizeTen);

        // Side A input text field
        JLabel sideOneLabel = new JLabel("Length of Side A:", CENTER);
        this.sideOneText = new JTextField();
        this.sideOneText = new JTextField("", 10);

        // Side B input text field
        JLabel sideTwoLabel = new JLabel("Length of Side B:", CENTER);
        this.sideTwoText = new JTextField();
        this.sideTwoText = new JTextField("", 10);

        // Side A input text field
        JLabel resultsLabel = new JLabel("Area:", CENTER);
        this.resultsText = new JTextField();
        this.resultsText = new JTextField("", 10);

        // Results text field
        calculateButton = new JButton("Calculate Area");

        // Add all elements to the top panel
        panelTop.add(sideOneLabel);
        panelTop.add(this.sideOneText);
        panelTop.add(sideTwoLabel);
        panelTop.add(this.sideTwoText);
        panelTop.add(calculateButton);

        // Add all elements to the bottom panel
        panelBottom.add(resultsLabel);
        panelBottom.add(this.resultsText);

        // Add all elements to the main panel
        panel.add(panelTop, BorderLayout.NORTH);
        panel.add(panelBottom, BorderLayout.SOUTH);

        // Add all elements to the frame
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
    }

}