/**
 * Assignment #4, Program 1
 * Program to print out a table giving total credit
 * card payments for various interest rates
 * and monthly payments.
 * Author: Mark Allen Weiss
 * SSN: 000-00-0000
 * Course: COP-2210 Section 8
 * Date: October 19, 1998
 *
 * CERTIFICATION OF SOLE AUTHORSHIP
 * I certify that this work is solely my own and
 * that none if it is the work of any other person.
 * I further certify that I have not provided any
 * assistance to other students enrolled in COP-2210 that
 * would render their CERTIFICATION OF SOLE AUTHORSHIP
 * invalid. I understand that violations of this pledge
 * may result in severe sanctions.
 *
 *
 *
 * -----------------------------------
 *   (Mark Allen Weiss)       <--- Put your name here, and sign above
 */

#include <iostream.h>
#include <iomanip.h>

void PrintTableLine( double LoanAmt, double Apr, double LowPay,
                     double HighPay, double PayInc );
double ComputeTotalPay( double InitialBalance, double Apr,
                        double MonthlyPayment );
void PrintHeader( double InitialBalance, double LowMonthlyPay,
                  double HighMonthlyPay, double MonthlyPayIncrement );
void PrintTable( double InitialBalance );
void PrintStars( int HowMany );

const double LOW_MONTH_PAYMENT =   100.00;
const double HIGH_MONTH_PAYMENT =  400.00;
const double MONTH_PAYMENT_INC =    50.00;
const double LOW_APR =               7.0;
const double HIGH_APR =             22.0;
const double APR_INC =               0.1;
const double WILL_NEVER_PAYOFF =   1e200;

const int DECIMAL_PLACES = 2;
const int MONEY_WIDTH = 8;

  // Because of roundoff errors, repeated additions of 0.1 are not exact.
  // So we use an extra FUDGE_FACTOR to make sure loops are correct.
const double FUDGE_FACTOR = 0.01;

int main( )
{
    double InitialBalance;

    cout << "Enter initial balance: " << endl;
    cin >> InitialBalance;

    cout.precision( DECIMAL_PLACES );
    cout.setf( ios::fixed );
    cout.setf( ios::showpoint );

    PrintTable( InitialBalance );
    return 0;
}

/**
 * Print out the table given an InitialBalance.
 */
void PrintTable( double InitialBalance )
{
    double Apr;

    PrintHeader( InitialBalance, LOW_MONTH_PAYMENT, HIGH_MONTH_PAYMENT,
                            MONTH_PAYMENT_INC );

    for( Apr = LOW_APR; Apr <= HIGH_APR + FUDGE_FACTOR; Apr += APR_INC )
        PrintTableLine( InitialBalance, Apr, LOW_MONTH_PAYMENT,
                    HIGH_MONTH_PAYMENT, MONTH_PAYMENT_INC );
}

/*
 * Print a line corresponding to some fixed interest rate.
 */

void PrintTableLine( double LoanAmt, double Apr, double LowPay,
                  double HighPay, double PayInc )
{
    double TotalPay, MonthPay;

    cout.precision( 1 );
    cout << setw( 4 ) << Apr << "%:";   // interest rate
    cout.precision( DECIMAL_PLACES );   // Restore the precision

    for( MonthPay = LowPay; MonthPay <= HighPay + FUDGE_FACTOR;
                                         MonthPay += PayInc )
    {
        TotalPay = ComputeTotalPay( LoanAmt, Apr, MonthPay );
        cout << " ";
        if( TotalPay == WILL_NEVER_PAYOFF )
            PrintStars( MONEY_WIDTH );
        else
            cout << setw( MONEY_WIDTH ) << TotalPay;
    }

    cout << endl;
}

/**
 * Function that computes the total payments given the three parameters.
 */
double ComputeTotalPay( double InitialBalance, double Apr, double MonthPayment )
{
    double Mpr;        // monthly interest rate
    double TotalPayment = 0.0;
    double CurrentBalance;

    CurrentBalance = InitialBalance;
    Mpr = Apr / 12.0 / 100.0;

    while( MonthPayment < CurrentBalance )
    {
        TotalPayment += MonthPayment;     // Monthly
        CurrentBalance -= MonthPayment;   //    payment
        CurrentBalance *= 1 + Mpr;        // Interest
    
        if( CurrentBalance >= InitialBalance )
            return WILL_NEVER_PAYOFF;
    }

    TotalPayment += CurrentBalance;

    return TotalPayment;
}

/**
 * Print the header for the table.
 */
void PrintHeader( double LoanAmount, double LowMonth,
                  double HighMonth, double MonthInc )
{
    double MonthPay;

    cout << "                  PAYING OFF A $" << LoanAmount << " LOAN" << endl; 
    cout << "  TOTAL PAYMENTS FOR GIVEN INTEREST RATE AND MONTHLY PAYMENT";
    cout << endl << "      ";

    for( MonthPay = LowMonth; MonthPay <= HighMonth + FUDGE_FACTOR;
                                                  MonthPay += MonthInc )
        cout << " " << setw( MONEY_WIDTH ) << MonthPay;
    cout << endl;
}

/**
 * Print a bunch of stars.
 */
void PrintStars( int HowMany )
{
    for( int i = 0; i < HowMany; i++ )
        cout << '*';
}