public static IEnumerable<AmortizedInstallment> Amortization(Money amount, int annualCompoundings, decimal rate, decimal minPayRate, Money paymentFloor, PayoffMode payMode)
{
decimal ratePerPeriod = rate / annualCompoundings;
Money remaining = amount;
var baseAmortization = from p in Enumerable.Range (1, int.MaxValue)
let interest = remaining * ratePerPeriod
let subBalance = remaining + interest
let basePay = remaining * minPayRate
let minPay = payMode == PayoffMode.PercentPlusInterest ? basePay + interest : basePay
let adjustedPay = minPay < paymentFloor ? paymentFloor : minPay
let actualPay = adjustedPay > subBalance ? subBalance : adjustedPay
select new AmortizedInstallment {
Installment = p,
Interest = interest,
Payment = actualPay,
BeforePayment = remaining += interest,
Balance = remaining -= actualPay
};
return baseAmortization.TakeWhile (x => x.BeforePayment > 0);
}
public Money ConvertToLocal(Money amount)
{
if (amount.CurrencyCode == NSLocale.CurrentLocale.CurrencyCode)
return amount;
if (Rates.ContainsKey(NSLocale.CurrentLocale.CurrencyCode))
return Money.NewMoney(amount.Value * Rates[NSLocale.CurrentLocale.CurrencyCode],
NSLocale.CurrentLocale.CurrencyCode);
// In this app, we're going to fail-back to the current amount rather than raise an exception
return amount;
}
public Money ConvertToGiven(Money amount, string currencyCode)
{
if (amount.CurrencyCode.Equals(currencyCode, StringComparison.OrdinalIgnoreCase))
return amount;
if (!Rates.ContainsKey (currencyCode))
return amount;
Money asBase = ConvertToBase(amount);
return new Money (asBase.Value * Rates[currencyCode], currencyCode);
}
public Money ConvertToBase(Money amount)
{
if (amount.CurrencyCode == BaseCurrency)
return amount;
if (Rates.ContainsKey(amount.CurrencyCode))
return Money.NewMoney(amount.Value * (1 / Rates[amount.CurrencyCode]), BaseCurrency);
// Can't convert to base? We'll return the original amount, the upstream code will need to handle exception
return amount;
}
public ConsequenceRequest(Money amount, TriggerType mode)
{
this.InitialAmount = amount;
this.TriggerMode = mode;
}
public override ConsequenceResult Calculate(ConsequenceRequest request)
{
if (request.InitialAmount == 0 || request.InitialAmount < LowerThreshold || request.InitialAmount > UpperThreshold)
return null;
try {
Money localizedMinPayment = ExchangeRates.CurrentRates.ConvertToGiven(MinimumPayment, request.InitialAmount.CurrencyCode);
var amortization = Financials.Amortization (request.InitialAmount,
CompoundingsPerYear (Compounding),
PercentAsDecimal (Rate),
PercentAsDecimal (MinPayPercent),
localizedMinPayment,
PayoffMode);
int installments = 0;
Money totalInterest = new Money(0, request.InitialAmount.CurrencyCode);
foreach (var i in amortization) {
installments++;
totalInterest += i.Interest;
}
Money payoff = request.InitialAmount + totalInterest;
return new ConsequenceResult (this,
request,
payoff,
new TabularResult (
request.Summary,
String.Format ("Amortization of a {0} loan at {1}%", request.InitialAmount, Rate),
this),
FormatCaption (this.Caption, new Dictionary<string,string> {
{"Periods", installments.ToString()},
{"Interest", totalInterest.ToString()}
}
), this.Image,
(payoff >= LowerResultLimit && payoff <= UpperResultLimit));
} catch (Exception ex) {
Console.WriteLine("{0} thrown when computing loan payoff: {1}", ex.GetType().Name, ex.Message);
return new ConsequenceResult(this,
request,
null,
"Oops, something went wrong in this calculator",
this.Image,
false);
}
}
