FINERACT-1981: Enhance EMI Calculator Daily Interest calculation

2024-11-06 09:46:36 +01:00
parent 0bc14ab7f3
commit 51b6dfa08e
7 changed files with 214 additions and 49 deletions
@@ -27,6 +27,7 @@ import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.Setter;
 import lombok.ToString;
+import org.apache.fineract.infrastructure.core.service.DateUtils;
 import org.apache.fineract.infrastructure.core.service.MathUtil;
 import org.apache.fineract.organisation.monetary.domain.Money;

@@ -42,27 +43,31 @@ public class InterestPeriod implements Comparable<InterestPeriod> {
    private LocalDate dueDate;
    @Setter
    private BigDecimal rateFactor;
+    @Setter
+    private BigDecimal rateFactorTillPeriodDueDate;
    private Money disbursementAmount;
    private Money balanceCorrectionAmount;
    private Money outstandingLoanBalance;
    private final MathContext mc;

    public InterestPeriod(RepaymentPeriod repaymentPeriod, LocalDate fromDate, LocalDate dueDate, BigDecimal rateFactor,
-            Money disbursementAmount, Money balanceCorrectionAmount, Money outstandingLoanBalance, MathContext mc) {
+            BigDecimal rateFactorTillPeriodDueDate, Money disbursementAmount, Money balanceCorrectionAmount, Money outstandingLoanBalance,
+            MathContext mc) {
        this.repaymentPeriod = repaymentPeriod;
        this.fromDate = fromDate;
        this.dueDate = dueDate;
        this.rateFactor = rateFactor;
+        this.rateFactorTillPeriodDueDate = rateFactorTillPeriodDueDate;
        this.disbursementAmount = disbursementAmount;
        this.balanceCorrectionAmount = balanceCorrectionAmount;
        this.outstandingLoanBalance = outstandingLoanBalance;
        this.mc = mc;
    }

-    public InterestPeriod(RepaymentPeriod repaymentPeriod, InterestPeriod interestPeriod, MathContext mc) {
+    public InterestPeriod(RepaymentPeriod repaymentPeriod, InterestPeriod interestPeriod) {
        this(repaymentPeriod, interestPeriod.getFromDate(), interestPeriod.getDueDate(), interestPeriod.getRateFactor(),
-                interestPeriod.getDisbursementAmount(), interestPeriod.getBalanceCorrectionAmount(),
-                interestPeriod.getOutstandingLoanBalance(), mc);
+                interestPeriod.getRateFactorTillPeriodDueDate(), interestPeriod.getDisbursementAmount(),
+                interestPeriod.getBalanceCorrectionAmount(), interestPeriod.getOutstandingLoanBalance(), interestPeriod.getMc());
    }

    @Override
@@ -79,7 +84,19 @@ public class InterestPeriod implements Comparable<InterestPeriod> {
    }

    public Money getCalculatedDueInterest() {
-        return getOutstandingLoanBalance().multipliedBy(getRateFactor(), mc);
+        final BigDecimal interestDueTillRepaymentDueDate = getOutstandingLoanBalance()//
+                .multipliedBy(getRateFactorTillPeriodDueDate(), mc).getAmount() //
+                .divide(BigDecimal.valueOf(getLengthTillPeriodDueDate()), mc) //
+                .multiply(BigDecimal.valueOf(getLength()), mc); //
+        return Money.of(outstandingLoanBalance.getCurrency(), interestDueTillRepaymentDueDate, mc);
+    }
+
+    public long getLength() {
+        return DateUtils.getDifferenceInDays(fromDate, dueDate);
+    }
+
+    public long getLengthTillPeriodDueDate() {
+        return DateUtils.getDifferenceInDays(fromDate, repaymentPeriod.getDueDate());
    }

    public void updateOutstandingLoanBalance() {
@@ -189,7 +189,7 @@ public class ProgressiveLoanInterestScheduleModel {
        previousInterestPeriod.addDisbursementAmount(disbursedAmount);
        previousInterestPeriod.addBalanceCorrectionAmount(correctionAmount);
        final InterestPeriod interestPeriod = new InterestPeriod(repaymentPeriod, previousInterestPeriod.getDueDate(), originalDueDate,
-                BigDecimal.ZERO, getZero(), getZero(), getZero(), mc);
+                BigDecimal.ZERO, BigDecimal.ZERO, getZero(), getZero(), getZero(), mc);
        repaymentPeriod.getInterestPeriods().add(interestPeriod);
    }

@@ -69,8 +69,8 @@ public class RepaymentPeriod {
        this.mc = mc;
        this.interestPeriods = new ArrayList<>();
        // There is always at least 1 interest period, by default with same from-due date as repayment period
-        getInterestPeriods()
-                .add(new InterestPeriod(this, getFromDate(), getDueDate(), BigDecimal.ZERO, getZero(mc), getZero(mc), getZero(mc), mc));
+        getInterestPeriods().add(new InterestPeriod(this, getFromDate(), getDueDate(), BigDecimal.ZERO, BigDecimal.ZERO, getZero(mc),
+                getZero(mc), getZero(mc), mc));
        this.paidInterest = getZero(mc);
        this.paidPrincipal = getZero(mc);
    }
@@ -87,7 +87,7 @@ public class RepaymentPeriod {
        this.mc = mc;
        // There is always at least 1 interest period, by default with same from-due date as repayment period
        for (InterestPeriod interestPeriod : repaymentPeriod.interestPeriods) {
-            interestPeriods.add(new InterestPeriod(this, interestPeriod, mc));
+            interestPeriods.add(new InterestPeriod(this, interestPeriod));
        }
    }

@@ -314,38 +314,42 @@ public final class ProgressiveEMICalculator implements EMICalculator {

    void calculateRateFactorForRepaymentPeriod(final RepaymentPeriod repaymentPeriod,
            final ProgressiveLoanInterestScheduleModel scheduleModel) {
-        repaymentPeriod.getInterestPeriods().forEach(interestPeriod -> interestPeriod
-                .setRateFactor(calculateRateFactorPerPeriod(repaymentPeriod, interestPeriod, scheduleModel)));
+        repaymentPeriod.getInterestPeriods().forEach(interestPeriod -> {
+            interestPeriod.setRateFactor(calculateRateFactorPerPeriod(scheduleModel, repaymentPeriod, interestPeriod.getFromDate(),
+                    interestPeriod.getDueDate()));
+            interestPeriod.setRateFactorTillPeriodDueDate(calculateRateFactorPerPeriod(scheduleModel, repaymentPeriod,
+                    interestPeriod.getFromDate(), repaymentPeriod.getDueDate()));
+        });
    }

    /**
     * Calculate Rate Factor for an exact Period
     */
-    BigDecimal calculateRateFactorPerPeriod(final RepaymentPeriod repaymentPeriod, final InterestPeriod interestPeriod,
-            final ProgressiveLoanInterestScheduleModel scheduleModel) {
+    BigDecimal calculateRateFactorPerPeriod(final ProgressiveLoanInterestScheduleModel scheduleModel, final RepaymentPeriod repaymentPeriod,
+            final LocalDate interestPeriodFromDate, final LocalDate interestPeriodDueDate) {
        final MathContext mc = scheduleModel.mc();
        final LoanProductRelatedDetail loanProductRelatedDetail = scheduleModel.loanProductRelatedDetail();
-        final BigDecimal interestRate = calcNominalInterestRatePercentage(scheduleModel.getInterestRate(interestPeriod.getFromDate()),
+        final BigDecimal interestRate = calcNominalInterestRatePercentage(scheduleModel.getInterestRate(interestPeriodFromDate),
                scheduleModel.mc());
        final DaysInYearType daysInYearType = DaysInYearType.fromInt(loanProductRelatedDetail.getDaysInYearType());
        final DaysInMonthType daysInMonthType = DaysInMonthType.fromInt(loanProductRelatedDetail.getDaysInMonthType());
        final PeriodFrequencyType repaymentFrequency = loanProductRelatedDetail.getRepaymentPeriodFrequencyType();
        final BigDecimal repaymentEvery = BigDecimal.valueOf(loanProductRelatedDetail.getRepayEvery());

-        final BigDecimal daysInMonth = BigDecimal.valueOf(daysInMonthType.getNumberOfDays(interestPeriod.getFromDate()));
-        final BigDecimal daysInYear = BigDecimal.valueOf(daysInYearType.getNumberOfDays(interestPeriod.getFromDate()));
+        final BigDecimal daysInMonth = BigDecimal.valueOf(daysInMonthType.getNumberOfDays(interestPeriodFromDate));
+        final BigDecimal daysInYear = BigDecimal.valueOf(daysInYearType.getNumberOfDays(interestPeriodFromDate));
        final BigDecimal actualDaysInPeriod = BigDecimal
-                .valueOf(DateUtils.getDifferenceInDays(interestPeriod.getFromDate(), interestPeriod.getDueDate()));
+                .valueOf(DateUtils.getDifferenceInDays(interestPeriodFromDate, interestPeriodDueDate));
        final BigDecimal calculatedDaysInPeriod = BigDecimal
                .valueOf(DateUtils.getDifferenceInDays(repaymentPeriod.getFromDate(), repaymentPeriod.getDueDate()));
-        final int numberOfYearsDifferenceInPeriod = interestPeriod.getDueDate().getYear() - interestPeriod.getFromDate().getYear();
+        final int numberOfYearsDifferenceInPeriod = interestPeriodDueDate.getYear() - interestPeriodFromDate.getYear();
        final boolean partialPeriodCalculationNeeded = daysInYearType == DaysInYearType.ACTUAL && numberOfYearsDifferenceInPeriod > 0;

        // TODO check: loanApplicationTerms.calculatePeriodsBetweenDates(startDate, endDate); // calculate period data
        // TODO review: (repayment frequency: days, weeks, years; validation day is month fix 30)
        // TODO refactor this logic to represent in interest period
        if (partialPeriodCalculationNeeded) {
-            final BigDecimal cumulatedPeriodFractions = calculatePeriodFractions(interestPeriod, mc);
+            final BigDecimal cumulatedPeriodFractions = calculatePeriodFractions(interestPeriodFromDate, interestPeriodDueDate, mc);
            return rateFactorByRepaymentPartialPeriod(interestRate, repaymentEvery, cumulatedPeriodFractions, BigDecimal.ONE,
                    BigDecimal.ONE, mc);
        }
@@ -357,18 +361,19 @@ public final class ProgressiveEMICalculator implements EMICalculator {
    /**
     * Calculate Period fractions part based on how much year has in the period
     *
-     * @param interestPeriod
+     * @param interestPeriodFromDate
+     * @param interestPeriodDueDate
     * @return
     */
-    BigDecimal calculatePeriodFractions(InterestPeriod interestPeriod, MathContext mc) {
+    BigDecimal calculatePeriodFractions(final LocalDate interestPeriodFromDate, final LocalDate interestPeriodDueDate, MathContext mc) {
        BigDecimal cumulatedRateFactor = BigDecimal.ZERO;
-        int actualYear = interestPeriod.getFromDate().getYear();
-        int endYear = interestPeriod.getDueDate().getYear();
-        LocalDate actualDate = interestPeriod.getFromDate();
+        int actualYear = interestPeriodFromDate.getYear();
+        int endYear = interestPeriodDueDate.getYear();
+        LocalDate actualDate = interestPeriodFromDate;
        LocalDate endOfActualYear;

        while (actualYear <= endYear) {
-            endOfActualYear = actualYear == endYear ? interestPeriod.getDueDate() : LocalDate.of(actualYear, 12, 31);
+            endOfActualYear = actualYear == endYear ? interestPeriodDueDate : LocalDate.of(actualYear, 12, 31);
            BigDecimal numberOfDaysInYear = BigDecimal.valueOf(Year.of(actualYear).length());
            BigDecimal calculatedDaysInActualYear = BigDecimal.valueOf(DateUtils.getDifferenceInDays(actualDate, endOfActualYear));
            cumulatedRateFactor = cumulatedRateFactor.add(calculatedDaysInActualYear.divide(numberOfDaysInYear, mc), mc);
@@ -1110,6 +1110,138 @@ class ProgressiveEMICalculatorTest {
        checkPeriod(interestSchedule, 5, 0, 16.89, 0.003950916667, 0.07, 16.82, 0.0);
    }

+    @Test
+    public void test_dailyInterest_disbursedAmt1000_dayInYears360_daysInMonth30_repayIn1Month() {
+
+        final List<LoanScheduleModelRepaymentPeriod> expectedRepaymentPeriods = new ArrayList<>();
+
+        expectedRepaymentPeriods.add(repayment(1, LocalDate.of(2024, 1, 1), LocalDate.of(2024, 2, 1)));
+
+        final BigDecimal interestRate = BigDecimal.valueOf(7.0);
+        final Integer installmentAmountInMultiplesOf = null;
+
+        Mockito.when(loanProductRelatedDetail.getAnnualNominalInterestRate()).thenReturn(interestRate);
+        Mockito.when(loanProductRelatedDetail.getDaysInYearType()).thenReturn(DaysInYearType.DAYS_360.getValue());
+        Mockito.when(loanProductRelatedDetail.getDaysInMonthType()).thenReturn(DaysInMonthType.DAYS_30.getValue());
+        Mockito.when(loanProductRelatedDetail.getRepaymentPeriodFrequencyType()).thenReturn(PeriodFrequencyType.MONTHS);
+        Mockito.when(loanProductRelatedDetail.getRepayEvery()).thenReturn(1);
+        Mockito.when(loanProductRelatedDetail.getCurrency()).thenReturn(monetaryCurrency);
+
+        final ProgressiveLoanInterestScheduleModel interestModel = emiCalculator.generateInterestScheduleModel(expectedRepaymentPeriods,
+                loanProductRelatedDetail, installmentAmountInMultiplesOf, mc);
+
+        final Money disbursedAmount = toMoney(1000.0);
+        emiCalculator.addDisbursement(interestModel, LocalDate.of(2024, 1, 1), disbursedAmount);
+
+        checkPeriod(interestModel, 0, 0, 1005.83, 0.0, 0.0, 5.83, 1000.0, 0.0);
+        checkPeriod(interestModel, 0, 1, 1005.83, 0.005833333333, 5.83, 1000.0, 0.0);
+
+        final LocalDate dueDate = LocalDate.of(2024, 2, 1);
+        final LocalDate startDay = LocalDate.of(2024, 1, 1);
+
+        checkDailyInterest(interestModel, dueDate, startDay, 1, 0.19, 0.19);
+        checkDailyInterest(interestModel, dueDate, startDay, 2, 0.19, 0.38);
+        checkDailyInterest(interestModel, dueDate, startDay, 3, 0.18, 0.56);
+        checkDailyInterest(interestModel, dueDate, startDay, 4, 0.19, 0.75);
+        checkDailyInterest(interestModel, dueDate, startDay, 5, 0.19, 0.94);
+        checkDailyInterest(interestModel, dueDate, startDay, 6, 0.19, 1.13);
+        checkDailyInterest(interestModel, dueDate, startDay, 7, 0.19, 1.32);
+        checkDailyInterest(interestModel, dueDate, startDay, 8, 0.18, 1.50);
+        checkDailyInterest(interestModel, dueDate, startDay, 9, 0.19, 1.69);
+        checkDailyInterest(interestModel, dueDate, startDay, 10, 0.19, 1.88);
+        checkDailyInterest(interestModel, dueDate, startDay, 11, 0.19, 2.07);
+        checkDailyInterest(interestModel, dueDate, startDay, 12, 0.19, 2.26);
+        checkDailyInterest(interestModel, dueDate, startDay, 13, 0.18, 2.44);
+        checkDailyInterest(interestModel, dueDate, startDay, 14, 0.19, 2.63);
+        checkDailyInterest(interestModel, dueDate, startDay, 15, 0.19, 2.82);
+        checkDailyInterest(interestModel, dueDate, startDay, 16, 0.19, 3.01);
+        checkDailyInterest(interestModel, dueDate, startDay, 17, 0.19, 3.20);
+        checkDailyInterest(interestModel, dueDate, startDay, 18, 0.19, 3.39);
+        checkDailyInterest(interestModel, dueDate, startDay, 19, 0.18, 3.57);
+        checkDailyInterest(interestModel, dueDate, startDay, 20, 0.19, 3.76);
+        checkDailyInterest(interestModel, dueDate, startDay, 21, 0.19, 3.95);
+        checkDailyInterest(interestModel, dueDate, startDay, 22, 0.19, 4.14);
+        checkDailyInterest(interestModel, dueDate, startDay, 23, 0.19, 4.33);
+        checkDailyInterest(interestModel, dueDate, startDay, 24, 0.18, 4.51);
+        checkDailyInterest(interestModel, dueDate, startDay, 25, 0.19, 4.70);
+        checkDailyInterest(interestModel, dueDate, startDay, 26, 0.19, 4.89);
+        checkDailyInterest(interestModel, dueDate, startDay, 27, 0.19, 5.08);
+        checkDailyInterest(interestModel, dueDate, startDay, 28, 0.19, 5.27);
+        checkDailyInterest(interestModel, dueDate, startDay, 29, 0.18, 5.45);
+        checkDailyInterest(interestModel, dueDate, startDay, 30, 0.19, 5.64);
+        checkDailyInterest(interestModel, dueDate, startDay, 31, 0.19, 5.83);
+    }
+
+    @Test
+    public void test_dailyInterest_disbursedAmt2000_dayInYears360_daysInMonth30_repayIn2Month() {
+
+        final List<LoanScheduleModelRepaymentPeriod> expectedRepaymentPeriods = new ArrayList<>();
+
+        expectedRepaymentPeriods.add(repayment(1, LocalDate.of(2024, 1, 1), LocalDate.of(2024, 2, 1)));
+
+        final BigDecimal interestRate = BigDecimal.valueOf(7.0);
+        final Integer installmentAmountInMultiplesOf = null;
+
+        Mockito.when(loanProductRelatedDetail.getAnnualNominalInterestRate()).thenReturn(interestRate);
+        Mockito.when(loanProductRelatedDetail.getDaysInYearType()).thenReturn(DaysInYearType.DAYS_360.getValue());
+        Mockito.when(loanProductRelatedDetail.getDaysInMonthType()).thenReturn(DaysInMonthType.DAYS_30.getValue());
+        Mockito.when(loanProductRelatedDetail.getRepaymentPeriodFrequencyType()).thenReturn(PeriodFrequencyType.MONTHS);
+        Mockito.when(loanProductRelatedDetail.getRepayEvery()).thenReturn(1);
+        Mockito.when(loanProductRelatedDetail.getCurrency()).thenReturn(monetaryCurrency);
+
+        final ProgressiveLoanInterestScheduleModel interestModel = emiCalculator.generateInterestScheduleModel(expectedRepaymentPeriods,
+                loanProductRelatedDetail, installmentAmountInMultiplesOf, mc);
+
+        final Money disbursedAmount1st = toMoney(1000.0);
+        final Money disbursedAmount2nd = toMoney(1000.0);
+        emiCalculator.addDisbursement(interestModel, LocalDate.of(2024, 1, 1), disbursedAmount1st);
+        emiCalculator.addDisbursement(interestModel, LocalDate.of(2024, 1, 15), disbursedAmount2nd);
+
+        checkPeriod(interestModel, 0, 0, 2009.03, 0.0, 0.0, 9.03, 2000.0, 0.0);
+        checkPeriod(interestModel, 0, 1, 2009.03, 0.002634408602, 2.63, 9.03, 2000.0, 0.0);
+        checkPeriod(interestModel, 0, 2, 2009.03, 0.003198924731, 6.40, 9.03, 2000.0, 0.0);
+
+        final LocalDate dueDate = LocalDate.of(2024, 2, 1);
+        final LocalDate startDay = LocalDate.of(2024, 1, 1);
+
+        // 1st 1000 disbursement accruals
+        // Total Interest: 5.83 (31 days), 2.63 (14 days)
+        checkDailyInterest(interestModel, dueDate, startDay, 1, 0.19, 0.19);
+        checkDailyInterest(interestModel, dueDate, startDay, 2, 0.19, 0.38);
+        checkDailyInterest(interestModel, dueDate, startDay, 3, 0.18, 0.56);
+        checkDailyInterest(interestModel, dueDate, startDay, 4, 0.19, 0.75);
+        checkDailyInterest(interestModel, dueDate, startDay, 5, 0.19, 0.94);
+        checkDailyInterest(interestModel, dueDate, startDay, 6, 0.19, 1.13);
+        checkDailyInterest(interestModel, dueDate, startDay, 7, 0.19, 1.32);
+        checkDailyInterest(interestModel, dueDate, startDay, 8, 0.18, 1.50);
+        checkDailyInterest(interestModel, dueDate, startDay, 9, 0.19, 1.69);
+        checkDailyInterest(interestModel, dueDate, startDay, 10, 0.19, 1.88);
+        checkDailyInterest(interestModel, dueDate, startDay, 11, 0.19, 2.07);
+        checkDailyInterest(interestModel, dueDate, startDay, 12, 0.19, 2.26);
+        checkDailyInterest(interestModel, dueDate, startDay, 13, 0.18, 2.44);
+        checkDailyInterest(interestModel, dueDate, startDay, 14, 0.19, 2.63);
+
+        // 2nd 1000 disbursement accruals
+        // Total Interest: 6.40 (17 days)
+        checkDailyInterest(interestModel, dueDate, startDay, 15, 0.38, 3.01);
+        checkDailyInterest(interestModel, dueDate, startDay, 16, 0.37, 3.38);
+        checkDailyInterest(interestModel, dueDate, startDay, 17, 0.38, 3.76);
+        checkDailyInterest(interestModel, dueDate, startDay, 18, 0.38, 4.14);
+        checkDailyInterest(interestModel, dueDate, startDay, 19, 0.37, 4.51);
+        checkDailyInterest(interestModel, dueDate, startDay, 20, 0.38, 4.89);
+        checkDailyInterest(interestModel, dueDate, startDay, 21, 0.38, 5.27);
+        checkDailyInterest(interestModel, dueDate, startDay, 22, 0.37, 5.64);
+        checkDailyInterest(interestModel, dueDate, startDay, 23, 0.38, 6.02);
+        checkDailyInterest(interestModel, dueDate, startDay, 24, 0.37, 6.39);
+        checkDailyInterest(interestModel, dueDate, startDay, 25, 0.38, 6.77);
+        checkDailyInterest(interestModel, dueDate, startDay, 26, 0.38, 7.15);
+        checkDailyInterest(interestModel, dueDate, startDay, 27, 0.37, 7.52);
+        checkDailyInterest(interestModel, dueDate, startDay, 28, 0.38, 7.90);
+        checkDailyInterest(interestModel, dueDate, startDay, 29, 0.38, 8.28);
+        checkDailyInterest(interestModel, dueDate, startDay, 30, 0.37, 8.65);
+        checkDailyInterest(interestModel, dueDate, startDay, 31, 0.38, 9.03);
+    }
+
    private static LoanScheduleModelRepaymentPeriod repayment(int periodNumber, LocalDate fromDate, LocalDate dueDate) {
        final Money zeroAmount = Money.zero(monetaryCurrency);
        return LoanScheduleModelRepaymentPeriod.repayment(periodNumber, fromDate, dueDate, zeroAmount, zeroAmount, zeroAmount, zeroAmount,
@@ -1126,6 +1258,17 @@ class ProgressiveEMICalculatorTest {
        return period;
    }

+    private static void checkDailyInterest(final ProgressiveLoanInterestScheduleModel interestModel, final LocalDate repaymentPeriodDueDate,
+            final LocalDate interestStartDay, final int dayOffset, final double dailyInterest, final double interest) {
+        Money previousInterest = emiCalculator
+                .getPayableDetails(interestModel, repaymentPeriodDueDate, interestStartDay.plusDays(dayOffset - 1)).getPayableInterest();
+        Money currentInterest = emiCalculator.getPayableDetails(interestModel, repaymentPeriodDueDate, interestStartDay.plusDays(dayOffset))
+                .getPayableInterest();
+
+        Assertions.assertEquals(dailyInterest, toDouble(currentInterest.minus(previousInterest)));
+        Assertions.assertEquals(interest, toDouble(currentInterest));
+    }
+
    private static void checkPeriod(final ProgressiveLoanInterestScheduleModel interestScheduleModel, final int repaymentIdx,
            final int interestIdx, final double emiValue, final double rateFactor, final double interestDue, final double principalDue,
            final double remaingBalance) {