/******************************************************************************
 * This program masks all but the last four digits if a credit card number.
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

#undef NDEBUG

#include "Utils.hpp"
#include <iostream>
#include <regex>
#include <string>
#include <vector>

using namespace Utils;
using namespace std;

static const vector<string> TEST_CASES = {"1234 5678 9012 3456", "4893 8573 0203 1929", "6992 2839 4929 3902"};

string mask_credit_card(string card_number) noexcept {
    return std::regex_replace(card_number, regex("\\d{4,4} "), "XXXX ");
}

int main(int argc, char **argv) {
    for (auto s : TEST_CASES) {
        cout << mask_credit_card(s) << endl;
    }
    return 0;
}