/******************************************************************************
 * This program computes a loan amortization table.
 * 
 * Copyright © 2020 Richard Lesh.  All rights reserved.
 *****************************************************************************/

#undef NDEBUG

#include "Utils.hpp"
#include <cmath>
#include <fmt/format.h>
#include <iostream>
#include <string>

using namespace Utils;
using namespace std;

int main(int argc, char **argv) {
    if (argc != 4) {
        cout << fmt::format("Syntax: {0:s} loan_amount rate_per_annum term_in_years", argv[0]) << endl;
        exit(1);
    }

    double balance = Utils::stodWithDefault(string(argv[1]), 0.0);
    double const INTEREST_RATE = Utils::stodWithDefault(string(argv[2]), 0.05) / 12.0;
    int const PERIODS = Utils::stoiWithDefault(string(argv[3]), 30) * 12;
    double const PAYMENT = INTEREST_RATE * balance / (1.0 - pow(1.0 + INTEREST_RATE, -PERIODS));

    cout << "Month\tPayment\tPrinciple\tInterest\tBalance" << endl;
    cout << fmt::format("0\t\t\t\t{0:.2f}", balance) << endl;
    for (int i = 0; i < PERIODS; ++i) {
        double const INTEREST = balance * INTEREST_RATE;
        double const PRINCIPLE = PAYMENT - INTEREST;
        balance -= PRINCIPLE;
        cout << fmt::format("{0:d}\t{1:.2f}\t{2:.2f}\t{3:.2f}\t{4:.2f}", i + 1, PAYMENT, PRINCIPLE, INTEREST, balance) << endl;
    }
    return 0;
}