package tr.gov.ulakbim.jDenetX.cluster;

import weka.core.Instance;

import java.util.Arrays;

public abstract class CFCluster extends SphereCluster {

    /**
     * Number of points in the cluster.
     */
    protected double N;
    /**
     * Linear sum of all the points added to the cluster.
     */
    protected double[] LS;
    /**
     * Squared sum of all the points added to the cluster.
     */
    protected double[] SS;

    /**
     * Instatiates an empty kernel with the given dimensionality.
     *
     * @param dimensions The number of dimensions of the points that can be in
     *                   this kernel.
     */
    public CFCluster(Instance instance, int dimensions) {
        this(instance.toDoubleArray(), dimensions);
    }

    protected CFCluster(int dimensions) {
        this.N = 0;
        this.LS = new double[dimensions];
        this.SS = new double[dimensions];
        Arrays.fill(this.LS, 0.0);
        Arrays.fill(this.SS, 0.0);
    }

    public CFCluster(double[] center, int dimensions) {
        this.N = 1;
        this.LS = center;
        this.SS = new double[dimensions];
        for (int i = 0; i < SS.length; i++) {
            SS[i] = Math.pow(center[i], 2);
        }
    }

    public CFCluster(CFCluster cluster) {
        this.N = cluster.N;
        this.LS = Arrays.copyOf(cluster.LS, cluster.LS.length);
        this.SS = Arrays.copyOf(cluster.SS, cluster.SS.length);
    }

    public void add(CFCluster cluster) {
        this.N += cluster.N;
        addVectors(this.LS, cluster.LS);
        addVectors(this.SS, cluster.SS);
    }


    /**
     * @return this kernels' center
     */
    @Override
    public double[] getCenter() {
        assert (this.N > 0);
        double res[] = new double[this.LS.length];
        for (int i = 0; i < res.length; i++) {
            res[i] = this.LS[i] / N;
        }
        return res;
    }


    @Override
    public abstract double getInclusionProbability(Instance instance);

    /**
     * See interface <code>Cluster</code>
     *
     * @return The radius of the cluster.
     */
    @Override
    public abstract double getRadius();

    /**
     * See interface <code>Cluster</code>
     *
     * @return The weight.
     * @see Cluster#getWeight()
     */
    @Override
    public double getWeight() {
        return N;
    }

    /**
     * Adds the second array to the first array element by element. The arrays
     * must have the same length.
     *
     * @param a1 Vector to which the second vector is added.
     * @param a2 Vector to be addded. This vector does not change.
     */
    public static void addVectors(double[] a1, double[] a2) {
        assert (a1 != null);
        assert (a2 != null);
        assert (a1.length == a2.length) : "Adding two arrays of different "
                + "length";

        for (int i = 0; i < a1.length; i++) {
            a1[i] += a2[i];
        }
    }


}