FINERACT-2114: Fix EMI adjustment when Interest Rate change has with Early Repayment Adjust Last case

fineract-core/src/main/java/org/apache/fineract/organisation/monetary/domain/Money.java

@@ -198,6 +198,14 @@ public class Money implements Comparable<Money> {
         return new Money(this.currencyCode, this.currencyDigitsAfterDecimal, this.amount.stripTrailingZeros(), this.inMultiplesOf, this.mc);
     }
 
+    public Money copy(final BigDecimal amount) {
+        return new Money(this.currencyCode, this.currencyDigitsAfterDecimal, amount.stripTrailingZeros(), this.inMultiplesOf, this.mc);
+    }
+
+    public Money copy(final double amount) {
+        return copy(BigDecimal.valueOf(amount));
+    }
+
     public Money plus(final Iterable<? extends Money> moniesToAdd) {
         BigDecimal total = this.amount;
         for (final Money moneyProvider : moniesToAdd) {
@@ -313,6 +321,14 @@ public class Money implements Comparable<Money> {
         return Money.of(monetaryCurrency(), newAmount, mc);
     }
 
+    public Money dividedBy(final long valueToDivideBy) {
+        if (valueToDivideBy == 1) {
+            return this;
+        }
+        final BigDecimal newAmount = this.amount.divide(BigDecimal.valueOf(valueToDivideBy), getMc());
+        return Money.of(monetaryCurrency(), newAmount, getMc());
+    }
+
     public Money multipliedBy(final BigDecimal valueToMultiplyBy) {
         return multipliedBy(valueToMultiplyBy, getMc());
     }

fineract-progressive-loan/src/main/java/org/apache/fineract/portfolio/loanaccount/loanschedule/data/EmiAdjustment.java

@@ -0,0 +1,57 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.fineract.portfolio.loanaccount.loanschedule.data;
+
+import java.util.List;
+import org.apache.fineract.organisation.monetary.domain.Money;
+
+public record EmiAdjustment(//
+        Money originalEmi, //
+        Money emiDifference, //
+        List<RepaymentPeriod> relatedRepaymentPeriods, //
+        long uncountablePeriods//
+) {
+
+    public boolean shouldBeAdjusted() {
+        double lowerHalfOfRelatedPeriods = Math.floor(numberOfRelatedPeriods() / 2.0);
+        return lowerHalfOfRelatedPeriods > 0.0 && !emiDifference.isZero() && emiDifference.abs() //
+                .multipliedBy(100) //
+                .isGreaterThan(originalEmi.copy(lowerHalfOfRelatedPeriods)); //
+    }
+
+    public Money adjustment() {
+        return emiDifference.dividedBy(Math.max(1, numberOfRelatedPeriods() - uncountablePeriods));
+    }
+
+    public Money adjustedEmi() {
+        return originalEmi.plus(adjustment());
+    }
+
+    public boolean hasLessEmiDifference(EmiAdjustment previousAdjustment) {
+        return emiDifference.abs().isLessThan(previousAdjustment.emiDifference.abs());
+    }
+
+    public boolean hasUncountablePeriods() {
+        return uncountablePeriods > 0;
+    }
+
+    private int numberOfRelatedPeriods() {
+        return relatedRepaymentPeriods.size();
+    }
+}

fineract-progressive-loan/src/main/java/org/apache/fineract/portfolio/loanproduct/calc/ProgressiveEMICalculator.java

@@ -34,6 +34,7 @@ import org.apache.fineract.portfolio.common.domain.DaysInMonthType;
 import org.apache.fineract.portfolio.common.domain.DaysInYearType;
 import org.apache.fineract.portfolio.common.domain.PeriodFrequencyType;
 import org.apache.fineract.portfolio.loanaccount.domain.LoanRepaymentScheduleInstallment;
+import org.apache.fineract.portfolio.loanaccount.loanschedule.data.EmiAdjustment;
 import org.apache.fineract.portfolio.loanaccount.loanschedule.data.InterestPeriod;
 import org.apache.fineract.portfolio.loanaccount.loanschedule.data.OutstandingDetails;
 import org.apache.fineract.portfolio.loanaccount.loanschedule.data.PeriodDueDetails;
@@ -287,33 +288,16 @@ public final class ProgressiveEMICalculator implements EMICalculator {
             final List<RepaymentPeriod> relatedRepaymentPeriods) {
         MathContext mc = scheduleModel.mc();
         ProgressiveLoanInterestScheduleModel newScheduleModel = null;
-
-        final int numberOfRelatedPeriods = relatedRepaymentPeriods.size();
-        double lowerHalfOfRelatedPeriods = Math.floor(numberOfRelatedPeriods / 2.0);
-        if (lowerHalfOfRelatedPeriods == 0.0) {
-            return;
-        }
-
-        long uncountablePeriods;
         int adjustCounter = 0;
+        EmiAdjustment emiAdjustment;
 
         do {
-            final Money emiDifference = getDifferenceBetweenLastTwoPeriod(relatedRepaymentPeriods, scheduleModel);
+            emiAdjustment = getEmiAdjustment(relatedRepaymentPeriods);
-            if (emiDifference.isZero(mc)) {
+            if (!emiAdjustment.shouldBeAdjusted()) {
                 break;
             }
-            final Money originalEmi = relatedRepaymentPeriods.get(numberOfRelatedPeriods - 2).getEmi();
+            Money adjustedEqualMonthlyInstallmentValue = applyInstallmentAmountInMultiplesOf(scheduleModel, emiAdjustment.adjustedEmi());
-            boolean shouldBeAdjusted = emiDifference.abs(mc).multipliedBy(100, mc)
+            if (adjustedEqualMonthlyInstallmentValue.isEqualTo(emiAdjustment.originalEmi())) {
-                    .isGreaterThan(Money.of(originalEmi.getCurrency(), BigDecimal.valueOf(lowerHalfOfRelatedPeriods), mc));
-            if (!shouldBeAdjusted) {
-                break;
-            }
-
-            uncountablePeriods = relatedRepaymentPeriods.stream().filter(rp -> originalEmi.isLessThan(rp.getTotalPaidAmount())).count();
-            Money adjustment = emiDifference.dividedBy(Math.max(1, numberOfRelatedPeriods - uncountablePeriods), mc);
-            Money adjustedEqualMonthlyInstallmentValue = applyInstallmentAmountInMultiplesOf(scheduleModel,
-                    originalEmi.plus(adjustment, mc));
-            if (adjustedEqualMonthlyInstallmentValue.isEqualTo(originalEmi)) {
                 break;
             }
             if (newScheduleModel == null) {
@@ -329,9 +313,7 @@ public final class ProgressiveEMICalculator implements EMICalculator {
             });
             calculateOutstandingBalance(newScheduleModel);
             calculateLastUnpaidRepaymentPeriodEMI(newScheduleModel);
-            final Money newEmiDifference = getDifferenceBetweenLastTwoPeriod(newScheduleModel.repaymentPeriods(), scheduleModel);
+            if (!getEmiAdjustment(newScheduleModel.repaymentPeriods()).hasLessEmiDifference(emiAdjustment)) {
-            final boolean newEmiHasLessDifference = newEmiDifference.abs(mc).isLessThan(emiDifference.abs(mc));
-            if (!newEmiHasLessDifference) {
                 break;
             }
 
@@ -349,7 +331,7 @@ public final class ProgressiveEMICalculator implements EMICalculator {
             });
             calculateOutstandingBalance(scheduleModel);
             adjustCounter++;
-        } while (uncountablePeriods > 0 && adjustCounter < 3);
+        } while (emiAdjustment.hasUncountablePeriods() && adjustCounter < 3);
     }
 
     /**
@@ -500,16 +482,17 @@ public final class ProgressiveEMICalculator implements EMICalculator {
                 : equalMonthlyInstallment;
     }
 
-    Money getDifferenceBetweenLastTwoPeriod(final List<RepaymentPeriod> repaymentPeriods,
+    public EmiAdjustment getEmiAdjustment(final List<RepaymentPeriod> repaymentPeriods) {
-            final ProgressiveLoanInterestScheduleModel scheduleModel) {
+        for (int idx = repaymentPeriods.size() - 1; idx > 0; --idx) {
-        MathContext mc = scheduleModel.mc();
+            RepaymentPeriod lastPeriod = repaymentPeriods.get(idx);
-        int numberOfUpcomingPeriods = repaymentPeriods.size();
+            RepaymentPeriod penultimatePeriod = repaymentPeriods.get(idx - 1);
-        if (numberOfUpcomingPeriods < 2) {
+            if (!lastPeriod.isFullyPaid() && !penultimatePeriod.isFullyPaid()) {
-            return Money.zero(scheduleModel.loanProductRelatedDetail().getCurrency(), mc);
+                Money emiDifference = lastPeriod.getEmi().minus(penultimatePeriod.getEmi());
+                return new EmiAdjustment(penultimatePeriod.getEmi(), emiDifference, repaymentPeriods,
+                        getUncountablePeriods(repaymentPeriods, penultimatePeriod.getEmi()));
+            }
         }
-        final RepaymentPeriod lastPeriod = repaymentPeriods.get(numberOfUpcomingPeriods - 1);
+        return new EmiAdjustment(repaymentPeriods.get(0).getEmi(), repaymentPeriods.get(0).getEmi().copy(0.0), repaymentPeriods, 0);
-        final RepaymentPeriod penultimatePeriod = repaymentPeriods.get(numberOfUpcomingPeriods - 2);
-        return lastPeriod.getEmi().minus(penultimatePeriod.getEmi(), mc);
     }
 
     /**
@@ -734,4 +717,9 @@ public final class ProgressiveEMICalculator implements EMICalculator {
                 .reduce(scheduleModel.getZero(), Money::add); //
     }
 
+    private long getUncountablePeriods(final List<RepaymentPeriod> relatedRepaymentPeriods, final Money originalEmi) {
+        return relatedRepaymentPeriods.stream() //
+                .filter(repaymentPeriod -> originalEmi.isLessThan(repaymentPeriod.getTotalPaidAmount())) //
+                .count(); //
+    }
 }

fineract-progressive-loan/src/test/java/org/apache/fineract/portfolio/loanproduct/calc/ProgressiveEMICalculatorTest.java

@@ -480,6 +480,53 @@ class ProgressiveEMICalculatorTest {
         checkPeriod(interestModel, 5, 0, 16.85, 0.003333333333, 0.06, 16.79, 0.0);
     }
 
+    @Test
+    public void test_reschedule_interest_on0120_adjsLst_dsbAmt100_dayInYears360_daysInMonth30_rpEvery1M() {
+
+        final List<LoanScheduleModelRepaymentPeriod> expectedRepaymentPeriods = new ArrayList<>();
+
+        expectedRepaymentPeriods.add(repayment(1, LocalDate.of(2024, 1, 1), LocalDate.of(2024, 2, 1)));
+        expectedRepaymentPeriods.add(repayment(2, LocalDate.of(2024, 2, 1), LocalDate.of(2024, 3, 1)));
+        expectedRepaymentPeriods.add(repayment(3, LocalDate.of(2024, 3, 1), LocalDate.of(2024, 4, 1)));
+        expectedRepaymentPeriods.add(repayment(4, LocalDate.of(2024, 4, 1), LocalDate.of(2024, 5, 1)));
+        expectedRepaymentPeriods.add(repayment(5, LocalDate.of(2024, 5, 1), LocalDate.of(2024, 6, 1)));
+        expectedRepaymentPeriods.add(repayment(6, LocalDate.of(2024, 6, 1), LocalDate.of(2024, 7, 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);
+
+        threadLocalContextUtil.when(ThreadLocalContextUtil::getBusinessDate).thenReturn(LocalDate.of(2024, 2, 14));
+
+        final ProgressiveLoanInterestScheduleModel interestModel = emiCalculator.generateInterestScheduleModel(expectedRepaymentPeriods,
+                loanProductRelatedDetail, installmentAmountInMultiplesOf, mc);
+
+        final Money disbursedAmount = toMoney(100.0);
+        emiCalculator.addDisbursement(interestModel, LocalDate.of(2024, 1, 1), disbursedAmount);
+
+        emiCalculator.payPrincipal(interestModel, LocalDate.of(2024, 7, 1), LocalDate.of(2024, 1, 15), toMoney(17.01));
+
+        final BigDecimal interestRateNewValue = BigDecimal.valueOf(4.0);
+        final LocalDate interestChangeDate = LocalDate.of(2024, 1, 20);
+        emiCalculator.changeInterestRate(interestModel, interestChangeDate, interestRateNewValue);
+
+        checkPeriod(interestModel, 0, 0, 16.80, 0.0, 0.0, 0.44, 16.36, 66.63);
+        checkPeriod(interestModel, 0, 1, 16.80, 0.002634408602, 0.26, 0.44, 16.36, 66.63);
+        checkPeriod(interestModel, 0, 2, 16.80, 0.000752688172, 0.06, 0.44, 16.36, 66.63);
+        checkPeriod(interestModel, 0, 3, 16.80, 0.001397849462, 0.12, 0.44, 16.36, 66.63);
+        checkPeriod(interestModel, 1, 0, 16.80, 0.003333333333, 0.22, 16.58, 50.05);
+        checkPeriod(interestModel, 2, 0, 16.80, 0.003333333333, 0.17, 16.63, 33.42);
+        checkPeriod(interestModel, 3, 0, 16.80, 0.003333333333, 0.11, 16.69, 16.73);
+        checkPeriod(interestModel, 4, 0, 16.79, 0.003333333333, 0.06, 16.73, 0.0);
+        checkPeriod(interestModel, 5, 0, 17.01, 0.003333333333, 0.0, 17.01, 0.0);
+    }
+
     @Test
     public void test_reschedule_interest_on0215_4per_disbursedAmt100_dayInYears360_daysInMonth30_repayEvery1Month() {