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A Lavaplayer fork maintained by Lavalink

There is a newer version: 2.2.2

package com.sedmelluq.discord.lavaplayer.tools;

import java.util.function.Function;

/**
 * Utility class for calculating averages on the last N values, with input and output transformers.
 */
public class RingBufferMath {
    private final double[] values;
    private final Function inputProcessor;
    private final Function outputProcessor;
    private double sum;
    private int position;
    private int size;

    /**
     * @param size            Maximum number of values to remember.
     * @param inputProcessor  Input transformer.
     * @param outputProcessor Output transformer.
     */
    public RingBufferMath(int size, Function inputProcessor, Function outputProcessor) {
        this.values = new double[size];
        this.inputProcessor = inputProcessor;
        this.outputProcessor = outputProcessor;
    }

    /**
     * @param value Original value to add (before transformation)
     */
    public void add(double value) {
        value = inputProcessor.apply(value);

        sum -= values[position];
        values[position] = value;
        sum += values[position];

        position = (position + 1) == values.length ? 0 : position + 1;
        size = Math.min(values.length, size + 1);
    }

    /**
     * @return Transformed mean of the internal values.
     */
    public double mean() {
        if (size == 0) {
            return outputProcessor.apply(0.0);
        } else {
            return outputProcessor.apply(sum / size);
        }
    }
}