package de.intevation.flys.artifacts.model;

import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;


public class MovingAverage
{

    public static double[][] simple(double[][] values, double radius) {
        TreeMap<Double, Double> map = toMap(values);
        double[][] result = new double[values.length][values[0].length];
        int ndx = 0;
        for (double x: map.keySet()) {
            SortedMap<Double, Double> range =
                map.subMap(x-radius, true, x+radius, true);
            double avg = 0d;
            for (Double v: range.values()) {
                avg += v;
            }
            avg /= range.size();
            result[0][ndx] = x;
            result[1][ndx] = avg;
            ndx++;
        }
        return result;
    }

    public static double[][] weighted(double[][] values, double radius) {
        TreeMap<Double, Double> map = toMap(values);
        double[][] result = new double[values.length][values[0].length];
        int ndx = 0;
        for (double x: map.keySet()) {
            double avg = 0d;
            double weights = 0d;
            for (Map.Entry<Double, Double> e:
                map.subMap(x-radius, false, x+radius, false).entrySet()
            ) {
                double weight = 1d - Math.abs(x - e.getKey())/radius;
                avg += weight*e.getValue();
                weights += weight;
            }
            avg /= weights;
            result[0][ndx] = x;
            result[1][ndx] = avg;
            ndx++;
        }
        return result;
    }

    private static TreeMap<Double, Double> toMap(double[][] values) {
        TreeMap<Double, Double> map = new TreeMap<Double, Double>();
        for(int i = 0; i < values[0].length; i++) {
            map.put(values[0][i], values[1][i]);
        }
        return map;
    }
}