// ------------------------------------------------
private void OnCalculate(object sender, RoutedEventArgs e)
{
double reader;
if (!string.IsNullOrEmpty(tbLoanAmount.Text) && double.TryParse(tbLoanAmount.Text, out reader) && reader > 0)
{
var svc = new AmortSvc();
var req = new CalculateAmortizationRequest();
// ----------------------------------------------------------------------
// Reader got the Loan Amount value in order to get into this code block.
req.LoanAmount = reader;
if (double.TryParse(tbTax.Text, out reader))
{
req.AnnualTax = reader;
}
if (double.TryParse(tbAPR.Text, out reader))
{
req.InterestRate = reader;
}
if (double.TryParse(tbPeriod.Text, out reader))
{
req.NumberOfPayments = reader;
}
if (double.TryParse(tbDownPayment.Text, out reader))
{
req.DownPayment = reader;
}
if (double.TryParse(tbAltPmt.Text, out reader))
{
req.AlternatePaymentAmt = reader;
}
if (double.TryParse(tbInsurance.Text, out reader))
{
req.AnnualInsurancePmt = reader;
}
int intReader;
if (int.TryParse(tbAltStart.Text, out intReader))
{
req.AlternatePaymentNo = intReader;
}
response = svc.CalculateAmortization(req);
var totalPayments = 0d;
var totalInterest = 0d;
var totalInsurance = 0d;
var totalTax = 0d;
var totalPrinciple = 0d;
foreach (var detail in response.PaymentDetails)
{
totalPayments += detail.Payment;
totalInterest += detail.Interest;
totalInsurance += detail.Insurance;
totalTax += detail.Tax;
totalPrinciple += detail.Principle;
}
dgOut.ItemsSource = response.PaymentDetails;
tbTotalTax.Text = totalTax.ToString("c");
tbTotalPayments.Text = totalPayments.ToString("c");
tbTotalInterest.Text = totalInterest.ToString("c");
tbTotalInsurance.Text = totalInsurance.ToString("c");
tbNumberOfPayments.Text = response.PaymentDetails.Count.ToString();
btnPrint.IsEnabled = true;
}
}
// ------------------------------------------------
public CalculateAmortizationResponse CalculateAmortization(CalculateAmortizationRequest req)
{
var retVal = new CalculateAmortizationResponse();
var rate = req.InterestRate;
var loanAmount = req.LoanAmount - req.DownPayment;
// ---------------------------------------------------------
// Tax and Insurance are constant, and are simply the Annual
// amount spread over twelve months.
var tax = (req.AnnualTax / 12);
var insurance = (req.AnnualInsurancePmt / 12);
var balance = req.LoanAmount;
var payment = (double)CalculatePayment(new CalculatePaymentRequest(req)).PaymentAmount;
var paymentNo = 0;
while (balance != 0 && balance > 0)
{
if (req.AlternatePaymentAmt > 0)
{
if (paymentNo >= req.AlternatePaymentNo)
{
payment = req.AlternatePaymentAmt;
}
}
// ------------------------------------------------------
// calculate interest rate based on remaining loan amount
var interest = (loanAmount * rate) / 12;
if (loanAmount < payment)
{
payment = loanAmount + interest + tax + insurance;
}
// -------------------------------------------------------------------
// calculate principle by subtracting the interest, tax, and insurance
var principle = payment - interest - tax - insurance;
// -----------------------------------------------------------------------
// The new loan amount is the old loan amount minus the principal payment.
loanAmount -= principle;
balance = (int)loanAmount;
// -----------------------------------------------
// prevent a negative number once loan is paid off
if (balance <= 0)
{
loanAmount = 0;
}
var detail = new PaymentDetail();
detail.PaymentNo = ++paymentNo;
detail.Tax = Math.Round(tax, 2);
detail.Payment = Math.Round(payment, 2);
detail.Interest = Math.Round(interest, 2);
detail.Balance = Math.Round(loanAmount, 2);
detail.Principle = Math.Round(principle, 2);
detail.Insurance = Math.Round(insurance, 2);
retVal.PaymentDetails.Add(detail);
}
return(retVal);
}