import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import java.util.Scanner;
import javax.swing.*;

public class mortgageCalculatorGui2 {

    public static void main(String[] args) {
        //------------------------
        //Use GUI to calculate mortgages
        mcFrame mc = new mcFrame();
        mc.createWindow();
    }
}

class MortgageCalculator {

    private int years; //number of years on the loan
    private double loan;  // amount of loan
    private double interest;// percentage of interest
    private double monthlyPayment;// amount ofmonthly payment 
    private double totalPayment; // this is the loan amount plus interest
    private double interestPaid;//monthly interst payment
    private double balanceLoan;// loan balance
    private double balancePrinciple;// principle balance
    //display variables
    private String str;// header, 
    private int displayCount;//display counter
    private int scroll;//scroll counter
    private Scanner input;
    //display for gui
    private StringBuffer strForGui; //string buffer for gui display

    public MortgageCalculator(int years, double loan, double interest) {
        this.years = years;
        this.loan = loan;
        this.interest = interest;
        input = new Scanner(System.in);
        //get monthly payment
        //interest is in percentage, so for monthly interest, interest = (interset/100)/12=interest/1200..
        monthlyPayment = loan * (interest / 1200) * (1 + 1 / (Math.pow(1 + interest / 1200, years * 12) - 1));
        totalPayment = monthlyPayment * years * 12;//the total payment is the sum of loan amount and the 
        //total of the interest paid over the course of the loan
        balanceLoan = totalPayment;
        balancePrinciple = this.loan;
    }
    //use to display schedule on console

    public void displaySchedule() {
        //display schedule
        while (displayCount < years * 12) {
            //prepare the heading
            str = (String.format("%10s %10s %10s %10s", "month", "payment", "interest", "balance"));// returns the next element in the literation, 10s means reserve 10 spaces for a string variable
            System.out.println(str);
            while ((scroll + 1 < 13) && (displayCount < years * 12)) {
                interestPaid = balancePrinciple * interest / 1200; //monthly interest paid
                balanceLoan = balanceLoan - monthlyPayment; //calculated monthly loan balance
                balancePrinciple = balancePrinciple - (monthlyPayment - interestPaid);//calculated monthly principle
                str = (String.format("%10d %10.2f %10.2f %10.2f", displayCount + 1, monthlyPayment, interestPaid, balanceLoan));
                System.out.println(str);
                scroll++;
                displayCount++;
            }
            scroll = 0;
            System.out.println("Press enter to continue");
            input.nextLine();
        }
    }
    //use to display schedule on GUI

    public String displayScheduleForGui() {
        strForGui = new StringBuffer();
        DecimalFormat formatter = new DecimalFormat("$###,##0.00");
        strForGui.append(String.format("%15s %15s %15s %15s\n", "month", "payment", "interest", "balance"));
        while (displayCount < years * 12) {
            interestPaid = balancePrinciple * interest / 1200; //monthly interest paid
            balanceLoan = balanceLoan - monthlyPayment; //calculated monthly loan balance
            balancePrinciple = balancePrinciple - (monthlyPayment - interestPaid);//calculated monthly principle
            strForGui.append(String.format("%15d %20s %20s %20s\n", displayCount + 1,
                    formatter.format(monthlyPayment),
                    formatter.format(interestPaid),
                    formatter.format(balanceLoan)));
            displayCount++;
        }
        return strForGui.toString();
    }
}
//use this class to display schedule on GUI
class mcFrame extends JFrame {
    //private fields

    private JFrame f;
    private JPanel inputPanel;
    private JPanel yearInputPanel, rateInputPanel, amountInputPanel,
            calculateButtonPanel, outputPanel;
    private JLabel yearLabel, rateLabel, amountLabel;
    private JTextField year, rate, loanAmount;
    private JButton calculate;
    private JTextArea output;
    private JScrollPane scrollPane;
    //create GUI window

    public void createWindow() {
        f = new JFrame("Mortgage Calculator");
        f.setSize(400, 450);
        Container c = f.getContentPane();
        c.setLayout(new BorderLayout());
        //input panel
        inputPanel = new JPanel();
        inputPanel.setPreferredSize(new Dimension(400, 80));
        inputPanel.setLayout(new FlowLayout());
        //year input panel
        yearInputPanel = new JPanel();
        yearInputPanel.setPreferredSize(new Dimension(90, 50));
        yearInputPanel.setLayout(new GridLayout(2, 1));
        yearLabel = new JLabel("Enter year:");
        year = new JTextField(10); //year input
        yearInputPanel.add(yearLabel);
        yearInputPanel.add(year);
        //rate input panel
        rateInputPanel = new JPanel();
        rateInputPanel.setPreferredSize(new Dimension(90, 50));
        rateInputPanel.setLayout(new GridLayout(2, 1));
        rateLabel = new JLabel("Enter rate:");
        rate = new JTextField(10); //interest rate input
        rateInputPanel.add(rateLabel);
        rateInputPanel.add(rate);
        //amount input panel
        amountInputPanel = new JPanel();
        amountInputPanel.setPreferredSize(new Dimension(90, 50));
        amountInputPanel.setLayout(new GridLayout(2, 1));
        amountLabel = new JLabel("Enter amount:");
        loanAmount = new JTextField(10); //loan amount input
        amountInputPanel.add(amountLabel);
        amountInputPanel.add(loanAmount);
        //button to start calculation
        calculateButtonPanel = new JPanel();
        calculateButtonPanel.setPreferredSize(new Dimension(90, 50));
        calculateButtonPanel.setLayout(new BorderLayout());
        calculate = new JButton("Calculate");
        calculate.addActionListener(new ActionListener() { //handles button click event

            @Override
            public void actionPerformed(ActionEvent e) {
                int numYear;
                float numRate;
                double numAmount;
                if (year.getText().equals("") || rate.getText().equals("") || loanAmount.getText().equals("")) {
                    JOptionPane.showMessageDialog(null, "Input cannot be empty!!");
                } else {
                    try {
                        numYear = Integer.parseInt(year.getText());
                        numRate = Float.parseFloat(rate.getText());
                        numAmount = Double.parseDouble(loanAmount.getText());
                        MortgageCalculator mortgage = new MortgageCalculator(numYear, numAmount, numRate);
                        output.setText("");
                        output.append(mortgage.displayScheduleForGui());
                    } catch (NumberFormatException excp) {
                        JOptionPane.showMessageDialog(null, excp.toString());
                    }
                }
            }
        });
        calculateButtonPanel.add(calculate, BorderLayout.CENTER);
        inputPanel.add(yearInputPanel);
        inputPanel.add(rateInputPanel);
        inputPanel.add(amountInputPanel);
        inputPanel.add(calculateButtonPanel);
        c.add(inputPanel, BorderLayout.NORTH);

        //output panel
        outputPanel = new JPanel();
        outputPanel.setLayout(new BorderLayout());
        output = new JTextArea(); //display for output
        scrollPane = new JScrollPane(output);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        output.setEditable(false);
        outputPanel.add(scrollPane, BorderLayout.CENTER);
        c.add(outputPanel, BorderLayout.CENTER);

        //add main menubar
        f.setJMenuBar(createJMenuBar());
        
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }
    //method to add main menu bar
    public JMenuBar createJMenuBar() {
        
        //array for the available loans
        final double[][] loans ={{7,5.35},{15,5.5},{30,5.75}};
        //variables for manu bar
        JMenuBar menuBar;
        JMenu availableMortgage;
        JMenuItem menuItem1, menuItem2, menuItem3;
        //main menu bar
        menuBar = new JMenuBar();
        //menu for available mortgages
        availableMortgage = new JMenu("Available Mortgages");
        menuBar.add(availableMortgage);
        //menu item for 7years 5.35% interest
        menuItem1 = new JMenuItem("7 years 5.35%");
        menuItem1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                year.setText(Integer.toString((int)loans[0][0]));
                rate.setText(Double.toString(loans[0][1]));
            }
        });
        //menu item for 15years 5.5% interest
        menuItem2 = new JMenuItem("15 years 5.5%");
        menuItem2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                year.setText(Integer.toString((int)loans[1][0]));
                rate.setText(Double.toString(loans[1][1]));
            }
        });
        //menu item for 30years 5.75% interest
        menuItem3 = new JMenuItem("30 years 5.75%");
        menuItem3.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                year.setText(Integer.toString((int)loans[2][0]));
                rate.setText(Double.toString(loans[2][1]));
            }
        });
        availableMortgage.add(menuItem1);
        availableMortgage.add(menuItem2);
        availableMortgage.add(menuItem3);

        return menuBar;
    }
}