package javameanmedian;
import java.util.Scanner;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;

public class JavaMeanMedian {
    static final String FILEPATH = "C:\\Users\\cghue\\Desktop\\"; // path name where file is located

    public static void main(String[] args) {
        // variables to control the disk file
        Scanner infile;         // input file object
        String filename;        // name of the file
        int recordCount = 0;   // number of records (lines) in the file
        int recordsToSkip = 0; // used when computing the median
        // variables for fields of each record in the file
        String lineFromFile;    // used when reading a line at a time from file
        int acctNo = 0;      // account number from a record in the file
        String customer = "";   // customer name from a record in the file
        double acctBal = 0.0;   // account balance from a record in the file
        // variable used to determine the mean and median
        double total = 0;       // used when computing the mean
        double mean = 0;         // mean (average) of all account balances
        double median = 0.0;    // median value of account balances


        // create the Scanner objects for the keyboard and disk access
        Scanner stdin = new Scanner(System.in);

        // get just the name of the file from the keyboard
        // build the pathname and filename
        // identify the folder where the file is located
        // The User name is in the environment variable USER on MacOS and Linux
        //   but it is in the environment variable USERNAME on Windows
        System.out.printf("Enter the name of the data file: ");
        filename = stdin.nextLine();  // read the filename from standard in
        String loginID = System.getenv("USER");  // MacOS or Linux?
        if (loginID == null) loginID = System.getenv("USERNAME"); // Windows?
        String BalancesFileName = FILEPATH + filename;
        double medianBalance = 0.0;
        try {
            // ---- PART 1, Count the number of records in the file
            //      Determine the mean when you know the
            //          record count and the total of all balances
            infile = new Scanner(new File(BalancesFileName));

            while (infile.hasNextInt()) // while there is still data in the file
            {
                acctNo = infile.nextInt();      // read int for account number
                customer = infile.next();       // read string for customer name
                acctBal = infile.nextDouble();  // read double for acct balance
                total += acctBal;
                recordCount++;
            }
            infile.close();
            System.out.printf("%d Records in %s\n", recordCount, filename);
            mean = total / recordCount;

            // ---- PART 2, Determine the number of records to skip
            if (recordCount % 2 == 1)
                recordsToSkip = recordCount/2;      // Odd number of records
            else
                recordsToSkip = recordCount/2 - 1;  // Even number of records

            // --- PART 3, open the file, skip leading records, determine median
            infile = new Scanner(new File(BalancesFileName));

            // Use an ArrayList to store the account balances
            ArrayList<Double> balances = new ArrayList<>();

            for (int i = 0; i < recordsToSkip; i++) {
                acctNo = infile.nextInt();
                customer = infile.next();
                acctBal = infile.nextDouble();
                balances.add(acctBal);
            }

            // Read the remaining balances and add them to the ArrayList
            while (infile.hasNextDouble()) {
                acctBal = infile.nextDouble();
                balances.add(acctBal);
            }

            // Sort the ArrayList
            Collections.sort(balances);


            // Calculate the median
            int midIndex = (recordCount) / 2;
            double midValue;

            if (recordCount % 2 == 1) {
                midValue = balances.get(midIndex);
                median = midValue;
            }

            // end of try block
            System.out.printf("\nThe mean of %s is %.2f\n\n", filename, mean);
            System.out.printf("The median of %s is %.2f\n\n", filename, median);
            System.out.println("MidIndex: " + midIndex);
            System.out.println("Median Balance: " + medianBalance);

        } catch (IOException ioe) {
            System.out.println("Exception occurred opening or reading " + BalancesFileName);
        }
    }
}