Natour, O. 11/9/15 Csc-111-D01 Hw 5.31

/*
 * Name: Omar Natour
 * Date: 11/9/2015
 * Course Number: CSC-111 D01
 * Course Name: Introduction to Java Programming
 * Problem Number: 5.31
 * Email: Ojnatour0001@student.stcc.edu
 * Problem Description: Check if credit card number is valid
 */

import java.util.Scanner;

public class CreditCardV {

    public static void main(String args[]) {
        final String TITLE = "Credit Card Validator";
        final String CONTINUE_PROMPT = "Do this again? [y/N] ";

        System.out.println("Welcome to " + TITLE);
        Scanner sc = new Scanner(System.in);
        do {
            System.out.println();
            process(sc, args);
            System.out.println();
        } while (doThisAgain(sc, CONTINUE_PROMPT));
        sc.close();

        System.out.println();
        System.out.println("Thank you for using " + TITLE);
    }

    // ************************************************************************

    private static boolean doThisAgain(Scanner sc, String prompt) {
        System.out.print(prompt);
        String doOver = sc.nextLine();
        return doOver.equalsIgnoreCase("Y");
    }

    // ************************************************************************

    private static void process(Scanner sc, String args[]) {
        // Code here is merely a sample
        System.out.print("Enter Credit Card No: ");
        long ccn = sc.nextLong();
        sc.nextLine(); // IMPORTANT!! Reset Scanner after retrieving values for
                        // process

        if (isValid(ccn))
            System.out.println("Credit Card Number is Valid!");
        else
            System.out.println("Credit Card Number is NOT Valid!");
    }

    // ************************************************************************

    public static boolean isValid(long ccn) {
        if (ccn <= 0)
            return false;

        int size = getSize(ccn);
        if (size < 13 || size > 16)
            return false;

        if (!(prefixMatched(ccn)))
            return false;

        return (sumOfDoubleEvenPlace(ccn) + sumOfOddPlace(ccn)) % 10 == 0;
    }


    public static int sumOfDoubleEvenPlace(long number) {
        int sum = 0;
        while (number > 0) {
            int last2Digits = (int) (number % 100);
            int evenDigit = last2Digits / 10;

            sum = sum + getDigit(2 * evenDigit);
            number = number / 100;

        }
        return sum;
    }

    public static int getDigit(int number) {
        if (number <= 9)
            return number;
        else
            return number / 10 + number % 10;
    }

    public static int sumOfOddPlace(long number) {
        int sum = 0;
        while (number > 0) {
            int last2Digits = (int) (number % 10);

            sum = sum + getDigit(last2Digits);
            number = number / 100;

        }
        return sum;
    }

    public static boolean prefixMatched(long number) {
        if (getPrefix(number) == 4 || (getPrefix(number) == 5 || (getPrefix(number) == 37 || (getPrefix(number) == 6))))
            return true;
        else
            return false;
    }

    public static int getSize(long d) {
        int count = 0;
        while (d > 0) {
            d = d / 10;
            count++;
        }
        return count;
    }

    public static long getPrefix(long number) {
        while (number > 9) {
            number /= 10;
            if (number == 37)
                break;
        }

        return number;
    }

}