/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  
  package org.hipparchus.clustering.evaluation;
  
  import org.hipparchus.clustering.Cluster;
  import org.hipparchus.clustering.DoublePoint;
  import org.hipparchus.clustering.distance.EuclideanDistance;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  class SumOfClusterVariancesTest {
  
      private ClusterEvaluator<DoublePoint> evaluator;
  
      @BeforeEach
      void setUp() {
          evaluator = new SumOfClusterVariances<DoublePoint>(new EuclideanDistance());
      }
  
      @Test
      void testScore() {
          final DoublePoint[] points1 = new DoublePoint[] {
                  new DoublePoint(new double[] { 1 }),
                  new DoublePoint(new double[] { 2 }),
                  new DoublePoint(new double[] { 3 })
          };
  
          final DoublePoint[] points2 = new DoublePoint[] {
                  new DoublePoint(new double[] { 1 }),
                  new DoublePoint(new double[] { 5 }),
                  new DoublePoint(new double[] { 10 })
          };
  
          final List<Cluster<DoublePoint>> clusters = new ArrayList<Cluster<DoublePoint>>();
  
          final Cluster<DoublePoint> cluster1 = new Cluster<DoublePoint>();
          for (DoublePoint p : points1) {
              cluster1.addPoint(p);
          }
          clusters.add(cluster1);
  
          assertEquals(1.0/3.0, evaluator.score(clusters), 1e-6);
  
          final Cluster<DoublePoint> cluster2 = new Cluster<DoublePoint>();
          for (DoublePoint p : points2) {
              cluster2.addPoint(p);
          }
          clusters.add(cluster2);
  
          assertEquals(6.148148148, evaluator.score(clusters), 1e-6);
      }
  
      @Test
      void testOrdering() {
          assertTrue(evaluator.isBetterScore(10, 20));
          assertFalse(evaluator.isBetterScore(20, 1));
      }
  }