import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;

public class LoanApplet extends JApplet {
  // Declare and create text fields for interest rate
  // year, loan amount, monthly payment, and total payment
  private JTextField jtfAnnualInterestRate = new JTextField();
  private JTextField jtfNumberOfYears = new JTextField();
  private JTextField jtfLoanAmount = new JTextField();
  private JTextField jtfMonthlyPayment = new JTextField();
  private JTextField jtfTotalPayment = new JTextField();

  // Declare and create a Compute Payment button
  private JButton jbtComputeLoan = new JButton("Compute Payment");

  /** Initialize user interface */
  public void init() {
    // Set properties on the text fields
    jtfMonthlyPayment.setEditable(false);
    jtfTotalPayment.setEditable(false);

    // Right align text fields
    jtfAnnualInterestRate.setHorizontalAlignment(JTextField.RIGHT);
    jtfNumberOfYears.setHorizontalAlignment(JTextField.RIGHT);
    jtfLoanAmount.setHorizontalAlignment(JTextField.RIGHT);
    jtfMonthlyPayment.setHorizontalAlignment(JTextField.RIGHT);
    jtfTotalPayment.setHorizontalAlignment(JTextField.RIGHT);

    // Panel p1 to hold labels and text fields
    JPanel p1 = new JPanel(new GridLayout(5, 2));
    p1.add(new JLabel("Annual Interest Rate"));
    p1.add(jtfAnnualInterestRate);
    p1.add(new JLabel("Number of Years"));
    p1.add(jtfNumberOfYears);
    p1.add(new JLabel("Loan Amount"));
    p1.add(jtfLoanAmount);
    p1.add(new JLabel("Monthly Payment"));
    p1.add(jtfMonthlyPayment);
    p1.add(new JLabel("Total Payment"));
    p1.add(jtfTotalPayment);
    p1.setBorder(new
      TitledBorder("Enter interest rate, year and loan amount"));

    // Panel p2 to hold the button
    JPanel p2 = new JPanel(new FlowLayout(FlowLayout.RIGHT));
    p2.add(jbtComputeLoan);

    // Add the components to the applet
    add(p1, BorderLayout.CENTER);
    add(p2, BorderLayout.SOUTH);

    // Register listener
    jbtComputeLoan.addActionListener(new ButtonListener());
  }

  /** Handle the Compute Payment button */
  private class ButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      // Get values from text fields
      double interest =
        Double.parseDouble(jtfAnnualInterestRate.getText());
      int year =
        Integer.parseInt(jtfNumberOfYears.getText());
      double loanAmount =
        Double.parseDouble(jtfLoanAmount.getText());

      // Create a loan object
      Loan loan = new Loan(interest, year, loanAmount);

      // Display monthly payment and total payment
      jtfMonthlyPayment.setText(String.format("%.2f",
        loan.getMonthlyPayment()));
      jtfTotalPayment.setText(String.format("%.2f",
        loan.getTotalPayment()));
    }
  }
}