// GET: Amortization
public ActionResult Amortizer()
{
// Create a data model instance.
var amortizationModel = new AmortizationModel();
// Create a tuple to pass multiple data models.
var tuple = new Tuple <AmortizationModel, List <MonthlyPaymentDetail> >
(amortizationModel, amortizationModel.MonthlyPaymentDetails);
return(View(tuple));
}
public ActionResult Amortizer(AmortizationModel amortizationModel)
{
// If no validation errors, create the amortization model.
if (ModelState.IsValid)
{
amortizationModel =
AmortizationProcessor.Instance
.GetPaymentModel(amortizationModel.LoanAMount
, amortizationModel.LoanTermInMonths
, amortizationModel.InterestRate)
.Result;
ModelState.Clear();
}
//Tuple is used to pass multiple data models.
var tuple = new Tuple <AmortizationModel, List <MonthlyPaymentDetail> >
(amortizationModel, amortizationModel.MonthlyPaymentDetails);
return(View(tuple));
}
public AmortizationPresenter(IAmortizationView amortizationView)
{
_amortizationView = amortizationView;
_amortizationModel = new AmortizationModel();
}
// GeneratePaymentModel method creates the loan amortization models.
// loanAmount, loanTermInMonths, and interestRate parameters are required.
// The starting date parameter is optional.
// This method is called asynchronously for better performance.
public static Task <AmortizationModel> GeneratePaymentModel(double loanAmount, short loanTermInMonths, double interestRate, DateTime?startingDate = null)
{
try
{
if (loanAmount <= 0 || loanTermInMonths <= 0 || interestRate <= 0)
{
throw
new ArgumentException("Loan amount, loan term (months), and interest rate must be greater than zero.");
}
// declare local variables
double monthlyInterest = 0;
short amortizationTerm = 0;
double currentBalance;
double cummulativeInterest = 0;
double monthlyPrincipal = 0;
double cummulativePrincipal = 0;
AmortizationModel amortizationModel = new AmortizationModel()
{
LoanAMount = loanAmount, LoanTermInMonths = loanTermInMonths, InterestRate = interestRate
};
// If no starting data, assume it to be today's date.
DateTime payDate = DateTime.Today;
if (startingDate != null)
{
payDate = (DateTime)startingDate;
}
currentBalance = loanAmount;
interestRate = interestRate * 0.01;
amortizationTerm = loanTermInMonths;
// Calculate the monthly payment and round it to 2 decimal places.
var monthlyinterestRate = interestRate / 12;
var monthlyPayment = (monthlyinterestRate / (1 - (Math.Pow((1 + monthlyinterestRate), -(amortizationTerm))))) * loanAmount;
monthlyPayment = Math.Round(monthlyPayment, 2);
// Save the starting date and the monthly payment the result set.
amortizationModel.StartingDate = payDate;
amortizationModel.MonthlyPayment = monthlyPayment;
// Loop for amortization term (number of monthly payments).
for (int j = 0; j < amortizationTerm; j++)
{
// Calculate monthly cycle
monthlyInterest = currentBalance * interestRate / 12;
monthlyPrincipal = monthlyPayment - monthlyInterest;
currentBalance = currentBalance - monthlyPrincipal;
// Adjust the last payment to make sure the final balance is 0.
if (j == amortizationTerm - 1 && currentBalance != monthlyPayment)
{
monthlyPayment += currentBalance;
currentBalance = 0;
}
// Update the Due Date.
payDate = payDate.AddMonths(1);
// Add to cummulative totals.
cummulativeInterest += monthlyInterest;
cummulativePrincipal += monthlyPrincipal;
// Add a MonthlyPaymentDetail to the MonthlyPaymentDetails collection.
amortizationModel.MonthlyPaymentDetails.Add
(new MonthlyPaymentDetail
{
PaymentNumber = j + 1,
DueDate = payDate,
PaymentAmount = Math.Round(monthlyPayment, 2),
InterestAmount = Math.Round(monthlyInterest, 2),
PrincipleAmount = Math.Round(monthlyPayment - monthlyInterest, 2),
RemainingBalance = Math.Round(currentBalance, 2)
});
}
// Add cummulative total interest and total repayment to the result set.
amortizationModel.TotalInterest = cummulativeInterest;
amortizationModel.TotalRepayment = amortizationModel.LoanAMount + amortizationModel.TotalInterest;
return(Task.FromResult(amortizationModel));
}
catch (Exception ex)
{
return(Task.FromException <AmortizationModel>(ex));
}
}
