calculate future value of fixed term deposit on opening or creation of deposit account.2

mifosng-provider/src/main/java/org/mifosng/platform/saving/domain/DepositAccount.java

@@ -118,14 +118,19 @@ public class DepositAccount extends AbstractAuditableCustom<AppUser, Long> {
     
 	public static DepositAccount openNew(
 			final Client client, final DepositProduct product,
-			final String externalId, final Money deposit, final BigDecimal interestRate, final Integer termInMonths, 
+			final String externalId, final Money deposit, final BigDecimal maturityInterestRate, final Integer tenureInMonths, 
 			final Integer interestCompoundedEvery, 
 			final PeriodFrequencyType interestCompoundedFrequencyPeriodType, 
 			final LocalDate commencementDate, 
 			final boolean renewalAllowed, 
-			final boolean preClosureAllowed) {
+			final boolean preClosureAllowed, 
-		return new DepositAccount(client, product, externalId, deposit, interestRate, termInMonths, 
+			final FixedTermDepositInterestCalculator fixedTermDepositInterestCalculator) {
-				interestCompoundedEvery, interestCompoundedFrequencyPeriodType, commencementDate, renewalAllowed, preClosureAllowed);
+		
+		Money futureValueOnMaturity = fixedTermDepositInterestCalculator.calculateInterestOnMaturityFor(deposit, tenureInMonths, 
+				maturityInterestRate, interestCompoundedEvery, interestCompoundedFrequencyPeriodType);
+		
+		return new DepositAccount(client, product, externalId, deposit, maturityInterestRate, tenureInMonths, 
+				interestCompoundedEvery, interestCompoundedFrequencyPeriodType, commencementDate, renewalAllowed, preClosureAllowed, futureValueOnMaturity);
 	}
 	
 	protected DepositAccount() {
@@ -139,7 +144,8 @@ public class DepositAccount extends AbstractAuditableCustom<AppUser, Long> {
 			final PeriodFrequencyType interestCompoundedFrequencyPeriodType, 
 			final LocalDate commencementDate,
 			final boolean renewalAllowed, 
-			final boolean preClosureAllowed) {
+			final boolean preClosureAllowed, 
+			final Money futureValueOnMaturity) {
 		this.client = client;
 		this.product = product;
 		this.externalId = externalId;
@@ -163,8 +169,8 @@ public class DepositAccount extends AbstractAuditableCustom<AppUser, Long> {
 		this.preClosureInterestRate = BigDecimal.ZERO;
 		
 		// derived fields
-		this.projectedInterestAccruedOnMaturity = BigDecimal.ZERO;
+		this.projectedInterestAccruedOnMaturity = futureValueOnMaturity.minus(deposit).getAmount();
-		this.projectedTotalOnMaturity = BigDecimal.ZERO;
+		this.projectedTotalOnMaturity = futureValueOnMaturity.getAmount();
 	}
 	
 	public boolean isDeleted() {

mifosng-provider/src/main/java/org/mifosng/platform/saving/domain/FixedTermDepositInterestCalculator.java

@@ -0,0 +1,66 @@
+package org.mifosng.platform.saving.domain;
+
+import java.math.BigDecimal;
+import java.math.MathContext;
+import java.math.RoundingMode;
+
+import org.mifosng.platform.currency.domain.Money;
+import org.mifosng.platform.loan.domain.PeriodFrequencyType;
+import org.springframework.stereotype.Service;
+
+@Service
+public class FixedTermDepositInterestCalculator {
+
+	public Money calculateInterestOnMaturityFor(
+			final Money deposit,
+			final Integer tenureInMonths, 
+			final BigDecimal maturityInterestRate,
+			final Integer interestCompoundedEvery,
+			final PeriodFrequencyType interestCompoundedFrequencyPeriodType) {
+
+		// TODO - Can change 'interest compounding' fields into something simpler like interestCompoundedFrequency {None (Simple Interest), Monthly, Quarterly, Half-Yearly, Annually}
+		//      - the 'interestCompoundedEvery' would then be inferred form the selected type.
+		//      - the special case of 'simple interest' or 'no compounding' would use simple formula rather than 'future value' function.
+		
+		// FIXME - assuming only monthly compounding period for now
+		MathContext mc = new MathContext(8, RoundingMode.HALF_EVEN);
+		Integer monthsInYear = 12;
+		
+		BigDecimal interestRateAsFraction = maturityInterestRate.divide(BigDecimal.valueOf(100), mc);
+		BigDecimal interestRateForOneMonth = interestRateAsFraction.divide(BigDecimal.valueOf(monthsInYear.doubleValue()), mc);
+		
+		BigDecimal ratePerCompoundingPeriod = interestRateForOneMonth.multiply(BigDecimal.valueOf(interestCompoundedEvery.doubleValue()), mc);
+		
+		Integer numberOfPeriods = tenureInMonths / interestCompoundedEvery;
+		
+		return fv(ratePerCompoundingPeriod, numberOfPeriods, deposit);
+	}
+
+	private static Money fv(final BigDecimal ratePerCompoundingPeriod, final Integer numberOfPeriods, final Money presentValue) {
+		
+		double pmtPerPeriod = Double.valueOf("0.0");
+		double pv = presentValue.negated().getAmount().doubleValue();
+		
+		double futureValue = fv(ratePerCompoundingPeriod.doubleValue(), numberOfPeriods.doubleValue(), pmtPerPeriod, pv, false);
+		
+		return Money.of(presentValue.getCurrency(), BigDecimal.valueOf(futureValue));
+	}
+	
+	/**
+	 * Future value of an amount given the number of payments, rate, amount of
+	 * individual payment, present value and boolean value indicating whether
+	 * payments are due at the beginning of period (false => payments are due at
+	 * end of period)
+	 */
+	private static double fv(double ratePeriodCompoundingPeriod, double numberOfCompoundingPeriods, double pmtPerPeriod, double presentValue, boolean type) {
+		double retval = 0;
+		if (ratePeriodCompoundingPeriod == 0) {
+			retval = -1 * (presentValue + (numberOfCompoundingPeriods * pmtPerPeriod));
+		} else {
+			double r1 = ratePeriodCompoundingPeriod + 1;
+			retval = ((1 - Math.pow(r1, numberOfCompoundingPeriods)) * (type ? r1 : 1) * pmtPerPeriod) / ratePeriodCompoundingPeriod - presentValue
+					* Math.pow(r1, numberOfCompoundingPeriods);
+		}
+		return retval;
+	}
+}

mifosng-provider/src/main/java/org/mifosng/platform/saving/service/DepositAccountAssembler.java

@@ -10,6 +10,7 @@ import org.mifosng.platform.exceptions.ClientNotFoundException;
 import org.mifosng.platform.exceptions.DepositProductNotFoundException;
 import org.mifosng.platform.loan.domain.PeriodFrequencyType;
 import org.mifosng.platform.saving.domain.DepositAccount;
+import org.mifosng.platform.saving.domain.FixedTermDepositInterestCalculator;
 import org.mifosng.platform.savingproduct.domain.DepositProduct;
 import org.mifosng.platform.savingproduct.domain.DepositProductRepository;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -23,11 +24,14 @@ public class DepositAccountAssembler {
 
 	private final ClientRepository clientRepository;
 	private final DepositProductRepository depositProductRepository;
+	private final FixedTermDepositInterestCalculator fixedTermDepositInterestCalculator;
 
 	@Autowired
-	public DepositAccountAssembler(final ClientRepository clientRepository, final DepositProductRepository depositProductRepository) {
+	public DepositAccountAssembler(final ClientRepository clientRepository, final DepositProductRepository depositProductRepository,
+			final FixedTermDepositInterestCalculator fixedTermDepositInterestCalculator) {
 		this.clientRepository = clientRepository;
 		this.depositProductRepository = depositProductRepository;
+		this.fixedTermDepositInterestCalculator = fixedTermDepositInterestCalculator;
 	}
 
 	public DepositAccount assembleFrom(final DepositAccountCommand command) {
@@ -76,14 +80,12 @@ public class DepositAccountAssembler {
 		}
 		// end of details allowed to be overriden from product
 		
-		// fixed-term interest calculator
-		
 		DepositAccount account = DepositAccount.openNew(client, product, command.getExternalId(), 
 				deposit, 
 				maturityInterestRate, 
 				tenureInMonths, compoundingInterestEvery, compoundingInterestFrequency, 
 				command.getCommencementDate(), 
-				renewalAllowed, preClosureAllowed);
+				renewalAllowed, preClosureAllowed, this.fixedTermDepositInterestCalculator);
 		
 		return account;
 	}