package org.audit4j.core;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.LinkedList;
import java.util.Queue;
public class MovingAverage {
private final Queue<BigDecimal> window = new LinkedList<BigDecimal>();
private final int period;
private BigDecimal sum = BigDecimal.ZERO;
public MovingAverage(int period) {
assert period > 0 : "Period must be a positive integer";
this.period = period;
}
public void add(BigDecimal num) {
sum = sum.add(num);
window.add(num);
if (window.size() > period) {
sum = sum.subtract(window.remove());
}
}
public BigDecimal getAverage() {
if (window.isEmpty()) {
return BigDecimal.ZERO; // technically the average is undefined
}
BigDecimal divisor = BigDecimal.valueOf(window.size());
return sum.divide(divisor, 2, RoundingMode.HALF_UP);
}
}