private Money getTotalInterestOnLoan(
final MonetaryCurrency currency,
final List<LoanRepaymentScheduleInstallment> repaymentScheduleInstallments) {
Money cumulativeInterest = Money.zero(currency);
for (LoanRepaymentScheduleInstallment scheduledRepayment : repaymentScheduleInstallments) {
cumulativeInterest = cumulativeInterest.plus(scheduledRepayment.getInterest(currency));
}
return cumulativeInterest;
}
@Override
public Money calculate(
final LocalDate actualDisbursementDate,
final LocalDate paidInFullDate,
final Money loanPrincipal,
final BigDecimal interestRatePerAnnum,
final List<LoanRepaymentScheduleInstallment> repaymentScheduleInstallments,
final List<LoanTransaction> loanRepayments) {
MonetaryCurrency currency = loanPrincipal.getCurrency();
Money totalOriginalInterest = getTotalInterestOnLoan(currency, repaymentScheduleInstallments);
BigDecimal dailyEquivalentPeriodicInterestRate =
interestRatePerAnnum.divide(BigDecimal.valueOf(36500), 9, RoundingMode.HALF_EVEN);
Money totalRecalculatedPrincipalPaid = Money.zero(loanPrincipal.getCurrency());
Money totalRecalculatedInterestPaid = Money.zero(loanPrincipal.getCurrency());
LocalDate lastBalanceDate = actualDisbursementDate;
Money outstandingBalance = loanPrincipal;
for (LoanTransaction loanRepayment : loanRepayments) {
int daysAtBalance =
Days.daysBetween(lastBalanceDate, loanRepayment.getTransactionDate()).getDays();
BigDecimal periodInterestRateForPaymentPeriod =
dailyEquivalentPeriodicInterestRate.multiply(BigDecimal.valueOf(daysAtBalance));
BigDecimal interestDueOnPaymentDateAmount =
outstandingBalance.getAmount().multiply(periodInterestRateForPaymentPeriod);
Money interestDueOnPaymentDate =
Money.of(loanPrincipal.getCurrency(), interestDueOnPaymentDateAmount);
Money principalDueOnPaymentDate =
loanRepayment.getAmount(currency).minus(interestDueOnPaymentDate);
totalRecalculatedPrincipalPaid =
totalRecalculatedPrincipalPaid.plus(principalDueOnPaymentDate);
totalRecalculatedInterestPaid = totalRecalculatedInterestPaid.plus(interestDueOnPaymentDate);
logger.warn(
"Installment: "
+ lastBalanceDate
+ " - "
+ loanRepayment.getTransactionDate()
+ " principal: "
+ principalDueOnPaymentDate
+ "interest: "
+ interestDueOnPaymentDate
+ " total: "
+ loanRepayment.getAmount());
lastBalanceDate = loanRepayment.getTransactionDate();
outstandingBalance = outstandingBalance.minus(principalDueOnPaymentDate);
}
// finally
// add up total paid to date - work out interest due on that
int daysAtBalance = Days.daysBetween(lastBalanceDate, paidInFullDate).getDays();
BigDecimal periodInterestRateForPaymentPeriod =
dailyEquivalentPeriodicInterestRate.multiply(BigDecimal.valueOf(daysAtBalance));
BigDecimal interestDueOnPaymentDateAmount =
outstandingBalance.getAmount().multiply(periodInterestRateForPaymentPeriod);
Money interestDueOnPaymentDate =
Money.of(loanPrincipal.getCurrency(), interestDueOnPaymentDateAmount);
Money principalDueOnPaymentDate = outstandingBalance;
Money netOutstandingOnPaidInFullDate = principalDueOnPaymentDate.plus(interestDueOnPaymentDate);
totalRecalculatedPrincipalPaid = totalRecalculatedPrincipalPaid.plus(principalDueOnPaymentDate);
totalRecalculatedInterestPaid = totalRecalculatedInterestPaid.plus(interestDueOnPaymentDate);
logger.warn(
"Installment: "
+ lastBalanceDate
+ " - "
+ paidInFullDate
+ " principal: "
+ principalDueOnPaymentDate
+ "interest: "
+ interestDueOnPaymentDate
+ " total: "
+ netOutstandingOnPaidInFullDate);
lastBalanceDate = paidInFullDate;
outstandingBalance = outstandingBalance.minus(principalDueOnPaymentDate);
Money rebate = Money.zero(loanPrincipal.getCurrency());
// Interest can be greater for following reasons:
// 1. calculated interest may be slightly ahead based on daily
// equivalent
// method of calculating interest compared to original method.
// 2. payments were under expected amount or after expected date
// resulting in larger outstanding balance being used to calculate
// interest
// at each repayment point in time.
if (totalRecalculatedInterestPaid.isLessThan(totalOriginalInterest)
&& totalRecalculatedInterestPaid.isGreaterThanZero()) {
rebate = totalOriginalInterest.minus(totalRecalculatedInterestPaid);
}
return rebate;
}