// Solution to Lab 9

import java.util.*;

public class Payment
{

  public static double payment(double amount, int years, double intRate)
  {
    int numMonths;     // Loan duration in months.
    double monthRate;  // Interest rate converted to monthly decimal rate
    double multiplier; // formula multipler = 1+monthrate raised to  the
                       // numMonths power

    numMonths = years * 12;
    monthRate = intRate / 1200;
    multiplier = Math.pow(1+monthRate,numMonths);

    return ((amount * monthRate * multiplier) /
            (multiplier - 1));
  }

  public static void printTotals(int years, double amount, double intRate, 
                              double payment)
  {
    double totPayments;  // Total amount of money paid on the loan

    totPayments = payment * years * 12;
    System.out.printf("\n** RESULTS **\n\n");
    System.out.printf("For a %d year loan of ",years);
    System.out.printf("$%.2f",amount);
    System.out.printf(" at %.2f%% interest ---\n\n",intRate);
    System.out.printf("Monthly payment =  $%.2f\n",payment);
    System.out.printf("Total interest =   $%.2f\n",totPayments-amount);
  }

  public static void main(String[] args)
  {
    Scanner keyboard = new Scanner(System.in);
    double amount;   // loan amount
    int duration;    // loan length in years
    double intRate;  // interest rate as a percentage
    double monthlyPayment;  // monthly payment

    System.out.print("Enter loan amount: ");
    amount = keyboard.nextDouble();

    System.out.print("Enter loan duration in years: ");
    duration = keyboard.nextInt();

    System.out.print("Enter interest rate as a percent: ");
    intRate = keyboard.nextDouble();

    monthlyPayment = payment(amount,duration,intRate);
    printTotals(duration,amount,intRate,monthlyPayment);
  }
}