package com.cedarsoft.business.calc;
import com.cedarsoft.business.Money;
import com.cedarsoft.business.MutableMoney;
import com.cedarsoft.business.payment.Payment;
import org.jetbrains.annotations.NotNull;
import org.joda.time.LocalDate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Calculates interests and related numbers
*/
public class InterestCalculator {
private double interestRate;
@NotNull
private final List<Payment> payments = new ArrayList<Payment>();
@NotNull
private final InterestCalculationSystem calculationSystem;
@NotNull
private final TimeSystem timeSystem;
/**
* Creates a new interest calculator.
* It is necessary to set the interest rate ({@link #setInterestRate(double)})
*
* @param calculationSystem the calculation system
* @param timeSystem the time system
*/
@Deprecated
public InterestCalculator( @NotNull InterestCalculationSystem calculationSystem, @NotNull TimeSystem timeSystem ) {
this.calculationSystem = calculationSystem;
this.timeSystem = timeSystem;
}
/**
* Creates a new interest calculator
*
* @param calculationSystem the calculation system
* @param timeSystem the time system
* @param interestRate the interest rate
*/
public InterestCalculator( @NotNull InterestCalculationSystem calculationSystem, @NotNull TimeSystem timeSystem, double interestRate ) {
this.calculationSystem = calculationSystem;
this.timeSystem = timeSystem;
this.interestRate = interestRate;
}
/**
* Sets the interest rate
*
* @param interestRate the interest rate
*/
public void setInterestRate( double interestRate ) {
this.interestRate = interestRate;
}
/**
* Adds a payment
*
* @param payment the payment
*/
public void addPayment( @NotNull Payment payment ) {
payments.add( payment );
}
/**
* Returns the interest rate
*
* @return the rate
*/
public double getInterestRate() {
return interestRate;
}
/**
* Calculates the interest until the given date.
* This method requires that at least one payment {@link #addPayment(Payment)}
* and the interest rate {@link #setInterestRate(double)} are set
*
* @param until the end date
* @return the interest
*/
@NotNull
public Money calculateInterestUntil( @NotNull LocalDate until ) {
if ( payments.isEmpty() ) {
throw new IllegalStateException( "Need at least one payment" );
}
if ( interestRate == 0 ) {
throw new IllegalStateException( "Interest rate not set" );
}
MutableMoney sum = new MutableMoney();
for ( Payment payment : payments ) {
double years = timeSystem.calculateYears( payment.getDate(), until );
double days = timeSystem.calculateDays( payment.getDate(), until );
sum.plus( calculationSystem.calculateInterest( payment.getAmount(), years, days, interestRate ) );
}
return sum.immutable();
}
/**
* Returns the payments
*
* @return the payments
*/
@NotNull
public List<Payment> getPayments() {
return Collections.unmodifiableList( payments );
}
/**
* Returns the calculation system
*
* @return the calculation system
*/
@NotNull
public InterestCalculationSystem getCalculationSystem() {
return calculationSystem;
}
/**
* Returns the time system
*
* @return the time system
*/
@NotNull
public TimeSystem getTimeSystem() {
return timeSystem;
}
}