/**
* Copyright (C) cedarsoft GmbH.
*
* Licensed under the GNU General Public License version 3 (the "License")
* with Classpath Exception; you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.cedarsoft.org/gpl3ce
* (GPL 3 with Classpath Exception)
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 only, as
* published by the Free Software Foundation. cedarsoft GmbH designates this
* particular file as subject to the "Classpath" exception as provided
* by cedarsoft GmbH in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 3 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 3 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
* or visit www.cedarsoft.com if you need additional information or
* have any questions.
*/
package com.cedarsoft.business.calc;
import com.cedarsoft.business.Money;
import com.cedarsoft.business.MutableMoney;
import javax.annotation.Nonnull;
import org.joda.time.LocalDate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Calculates the interests for a given {@link InterestRateProvider}.
*/
public class VariableInterestCalculationSystem {
@Nonnull
private final InterestRateProvider interestRateProvider;
@Nonnull
private final InterestCalculationSystem backingCalculationSystem;
@Nonnull
private final TimeSystem timeSystem;
/**
* Creates a new calculation system
*
* @param interestRateProvider the interest rate provider
* @param backingCalculationSystem the backing calculation system
* @param timeSystem the time system
*/
public VariableInterestCalculationSystem( @Nonnull InterestRateProvider interestRateProvider, @Nonnull InterestCalculationSystem backingCalculationSystem, @Nonnull TimeSystem timeSystem ) {
this.interestRateProvider = interestRateProvider;
this.backingCalculationSystem = backingCalculationSystem;
this.timeSystem = timeSystem;
}
/**
* Calculates the interest for the given amount and dates.
*
* @param amount the amount the interest is calculated for
* @param begin the begin of the period
* @param end the end of the period
* @return the payment rent
*/
@Nonnull
public Rent calculateInterest( @Nonnull Money amount, @Nonnull LocalDate begin, @Nonnull LocalDate end ) {
//Switch over the validity period
switch ( getInterestRateProvider().getValidityPeriod() ) {
case CONSTANT:
return calculateInterestConstantRate( amount, begin, end );
case MONTHLY:
return calculateInterestMonthlyPeriod( amount, begin, end );
default:
throw new UnsupportedOperationException( "not yet implemented for " + getInterestRateProvider().getValidityPeriod() );
}
}
/**
* Calculates the interest for a interest rate provider with monthly changing interest rates.
*
* @param amount the amount
* @param begin the begin
* @param end the end
* @return the interest
*/
@Nonnull
public Rent calculateInterestMonthlyPeriod( @Nonnull Money amount, @Nonnull LocalDate begin, @Nonnull LocalDate end ) {
List<InterestDetails> interestDetails = new ArrayList<InterestDetails>();
//Create a runner that represents the begin of the actual month
//For the first month this may be another day of month than 1
LocalDate actualMonthBegin = begin;
//Now iterate over all months
MutableMoney rentSummer = new MutableMoney();
while ( actualMonthBegin.isBefore( end ) ) {
LocalDate actualMonthEnd = actualMonthBegin.plusMonths( 1 );
//Check if this month is complete --> else only add the rest
if ( actualMonthEnd.isAfter( end ) ) {
actualMonthEnd = end;
}
double monthYears = getTimeSystem().calculateYears( actualMonthBegin, actualMonthEnd );
double monthDays = getTimeSystem().calculateDays( actualMonthBegin, actualMonthEnd );
double monthRate = getInterestRateProvider().getRate( actualMonthBegin );
//add the rent for the rent
Money baseForMonth = rentSummer.immutable();
Money compoundInterest;
if ( getBackingCalculationSystem().isCompoundSystem() && baseForMonth.getValue() != 0 ) {
compoundInterest = getBackingCalculationSystem().calculateInterest( baseForMonth, monthYears, monthDays, monthRate );
rentSummer.plus( compoundInterest );
} else {
compoundInterest = Money.ZERO;
}
//add the rent for the amount
Money interest = getBackingCalculationSystem().calculateInterest( amount, monthYears, monthDays, monthRate );
rentSummer.plus( interest );
//Build the information object (if expected)
interestDetails.add( new InterestDetails( actualMonthBegin, actualMonthEnd, monthRate, baseForMonth, interest.plus( compoundInterest ), monthDays ) );
//Next month --> now we really need the first day of the month
actualMonthBegin = actualMonthBegin.plusMonths( 1 ).withDayOfMonth( 1 );
}
return new Rent( amount, begin, end, interestDetails );
}
/**
* Calculates the interest for a interest rate provider with a constant rate
*
* @param amount the amount
* @param begin the begin
* @param end the end
* @return the interest
*/
@Nonnull
private Rent calculateInterestConstantRate( @Nonnull Money amount, @Nonnull LocalDate begin, @Nonnull LocalDate end ) {
double years = getTimeSystem().calculateYears( begin, end );
double days = getTimeSystem().calculateDays( begin, end );
double rate = getInterestRateProvider().getRate( begin );
Money interest = getBackingCalculationSystem().calculateInterest( amount, years, days, rate );
//We need just one interest details since the interest rate is constant
InterestDetails interestDetails = new InterestDetails( begin, begin.plusDays( 1 ), rate, amount, interest, days );//todo check end date
return new Rent( amount, begin, end, Collections.singletonList( interestDetails ) );
}
@Nonnull
public InterestRateProvider getInterestRateProvider() {
return interestRateProvider;
}
@Nonnull
public InterestCalculationSystem getBackingCalculationSystem() {
return backingCalculationSystem;
}
@Nonnull
public TimeSystem getTimeSystem() {
return timeSystem;
}
}