//--------------------------------------------------------------------------
//  Assignment #1 - Monthly Payment of a Loan
//
//  Written by B M Massie
//  September 2008
//
//  Purpose:  To compute the monthly payment of an installment loan and 
//            the balance remaining after half of the installments have 
//            been made.
//--------------------------------------------------------------------------

// ----------- Preprocessor Section -----------

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

// --------------- Main Function ---------------

int main ()
{

// ----- Variables and Constants

   int
      k,                 // half the number of payments   
      NumPay;            // number of monthly payments		
   float
      AmtLoan,           // the amount of loan
      IntRate,           // the annual interest rate
      Payment,		 // the payment 
      MonPay,            // monthly payment
      Balance,           // total balance
      Tintpay,           // the total interest paid
      temp;		 // an equation 1 + (i / 12)      
        
// ----- Input Phase
   cout << "\n\n  Welcome to the Loan Analysis Program!" << endl;
   cout << "\n\n          Enter your loan amount --> ";
   cin >> AmtLoan;
   cout << "\n          Enter your annual interest rate --------> ";
   cin >> IntRate;
   cout << "\n          Enter your number of monthly payments ------> ";
   cin >> NumPay;

// ----- Processing Phase

   temp = (1 + (IntRate / 12));  
  
   Payment  = (pow (temp,NumPay)) / (pow (temp,NumPay) - 1) * AmtLoan * (IntRate / 12);

   k = (NumPay / 2); 

   Balance  = Payment  * (1 - pow (temp,k - NumPay)) / (IntRate / 12);

   Tintpay = Payment * NumPay - AmtLoan;
 
// ----- Output Phase

   cout << fixed << setprecision(2);    // force fixed point format for floats
 
   cout << "\n\n~~~~~~~~~~~~~~~Loan Summary~~~~~~~~~~~~~~~~"<< endl;
   cout << "\n     Annual Interest Rate:              " << IntRate * 100;
   cout << "\n     Number of Monthly Payments:        " << NumPay << endl;
   cout << "\n     Loan Amount:                     $ " << setw(10) << AmtLoan;
   cout << "\n     Monthly payment:                 $ " << setw(10) << Payment; 
   cout << "\n     Balance halfway through:         $ " << setw(10) << Balance;
   cout << "\n     Total interest paid:             $ " << setw(10) << Tintpay << endl;

   return 0;
}