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/**
 * @file mortgage.cpp
 * @brief Computes the annual after-tax cost of a new house
 * @author syb0rg
 * @date 10/9/14
 */

#include <cctype>
#include <iostream>
#include <limits>

/**
 * Makes sure data isn't malicious, and signals user to re-enter proper data if invalid
 */
long double getSanitizedDouble()
{
    long double input = 0.0L;
    while(!(std::cin >> input) || input < 0)
    {
        // clear the error flag that was set so that future I/O operations will work correctly
        std::cin.clear();
        // skips to the next newline
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
        std::cout << "Invalid input.  Please enter a positive number: ";
    }
    return input;
}

/**
 * Safetly grabs and returns a lowercase version of the character (if the lowercase exists)
 */
char32_t getSanitizedChar()
{
    // absorb newline character (if existant) from previous input
    if(std::cin.peek() == '\n') std::cin.ignore();
    return std::tolower(std::cin.get());
}

int main()
{
    do
    {
        long double housePrice = 0.0L;
        long double downPayment = 0.0L;

        // get input for house price, re-read input if not a positive number
        std::cout << "Enter the price of the house: $";
        housePrice = getSanitizedDouble();

        // get input for down payment, re-read input if not a positive number
        std::cout << "Enter the down-payment: $";
        downPayment = getSanitizedDouble();

        long double loanBalance = housePrice - downPayment;
        long double interest = .06 * loanBalance;
        long double annualMortgage = (.03 * loanBalance) + interest;
        long double savings = .35 * interest;
        long double totalCost = annualMortgage - savings;

        std::cout << "The annual after-tax cost of the house is $" << totalCost << std::endl;

        std::cout << "Run the program again (y/N): ";  // signify n as default with capital letter
    } while ('y' == getSanitizedChar());
}

constexpr long double ANNUAL_MORTGAGE_COST = 0.03; 
constexpr long double LOAN_PRINCIPAL_PLUS = 0.06;
constexpr long double MARGINAL_TAX_RATE = 0.35;

long double totalPayment(long double housePrice, long double downPayment){

    long double loanBalance = housePrice - downPayment;
    long double interest = LOAN_PRINCIPAL_PLUS * loanBalance;
    long double annualMortgage = (ANNUAL_MORTGAGE_COST * loanBalance) + interest;
    long double savings = MARGINAL_TAX_RATE * interest;
    long double totalCost = annualMortgage - savings;

    return totalCost;
}

double total_cost(double balance);