package exceptionhandling;

import java.io.*;               // For File class and FileNotFoundException
import java.util.*;             // For Scanner and InputMismatchException
import java.text.DecimalFormat; // For the DecimalFormat class
import javax.swing.JOptionPane; // For the JOptionPane class

/**
 * This program demonstrates how exception handlers can be used to recover from
 * errors.
 */
public class SalesReport2
{

    public static void main(String[] args)
    {
        // change this to a file path in your computer
        String filename = "/Users/Mayelin/Documents/Teaching/COP3804/Input_Output_Files/SalesData.txt";
        int months = 0;                    // Month counter
        double oneMonth;                   // One month's sales
        double totalSales = 0.0;           // Total sales
        double averageSales;               // Average sales

        // Create a DecimalFormat object.
        DecimalFormat dollar = new DecimalFormat("#,##0.00");

        // Attempt to open the file by calling the openfile method.
        Scanner inputFile = openFile(filename);

        // If the openFile method returned null, then the file was not found. 
        // Get a new file name.
        while (inputFile == null)
        {
            filename = JOptionPane.showInputDialog(
                    "ERROR: " + filename
                    + " does not exist.\n"
                    + "Enter another file name: ");
            inputFile = openFile(filename);
        }

        // Process the contents of the file.
        while (inputFile.hasNext())
        {
            try
            {
                // Get a month's sales amount.
                oneMonth = inputFile.nextDouble();

                // Accumulate the amount.
                totalSales += oneMonth;

                // Increment the month counter.
                months++;
            } 
            catch (InputMismatchException e)
            {
                // Display an error message.
                JOptionPane.showMessageDialog(null,
                        "Non-numeric data found in the file.\n"
                        + "The invalid record will be skipped.");

                // Skip past the invalid data.
                inputFile.nextLine();
            }
        }

        // Close the file.
        inputFile.close();

        // Calculate the average.
        averageSales = totalSales / months;

        // Display the results.
        JOptionPane.showMessageDialog(null,
                "Number of months: " + months
                + "\nTotal Sales: $"
                + dollar.format(totalSales)
                + "\nAverage Sales: $"
                + dollar.format(averageSales));
        System.exit(0);
    }

    /**
     * The opeFile method opens the specified file and returns a reference to a
     * Scanner object.
     *
     * @param filename The name of the file to open.
     * @return A Scanner reference, if the file exists Otherwise, null is
     * returned.
     */
    public static Scanner openFile(String filename)
    {
        Scanner scan;

        // Attempt to open the file.
        try
        {
            File file = new File(filename);
            scan = new Scanner(file);
        } 
        catch (FileNotFoundException e)
        {
            scan = null;
        }

        return scan;
    }
}