/*
    * 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;
  
  import org.hamcrest.CoreMatchers;
  import org.hipparchus.clustering.distance.CanberraDistance;
  import org.hipparchus.clustering.distance.DistanceMeasure;
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.exception.NullArgumentException;
  import org.hipparchus.random.JDKRandomGenerator;
  import org.hipparchus.random.RandomGenerator;
  import org.junit.jupiter.api.Test;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  /**
   * Test cases for FuzzyKMeansClusterer.
   *
   */
  class FuzzyKMeansClustererTest {
  
      @Test
      void testCluster() {
          final List<DoublePoint> points = new ArrayList<DoublePoint>();
  
          // create 10 data points: [1], ... [10]
          for (int i = 1; i <= 10; i++) {
              final DoublePoint p = new DoublePoint(new double[] { i } );
              points.add(p);
          }
  
          final FuzzyKMeansClusterer<DoublePoint> transformer =
                  new FuzzyKMeansClusterer<DoublePoint>(3, 2.0);
          final List<CentroidCluster<DoublePoint>> clusters = transformer.cluster(points);
  
          // we expect 3 clusters:
          //   [1], [2], [3]
          //   [4], [5], [6], [7]
          //   [8], [9], [10]
          final List<DoublePoint> clusterOne = Arrays.asList(points.get(0), points.get(1), points.get(2));
          final List<DoublePoint> clusterTwo = Arrays.asList(points.get(3), points.get(4), points.get(5), points.get(6));
          final List<DoublePoint> clusterThree = Arrays.asList(points.get(7), points.get(8), points.get(9));
  
          boolean cluster1Found = false;
          boolean cluster2Found = false;
          boolean cluster3Found = false;
          assertEquals(3, clusters.size());
          for (final Cluster<DoublePoint> cluster : clusters) {
              if (cluster.getPoints().containsAll(clusterOne)) {
                  cluster1Found = true;
              }
              if (cluster.getPoints().containsAll(clusterTwo)) {
                  cluster2Found = true;
              }
              if (cluster.getPoints().containsAll(clusterThree)) {
                  cluster3Found = true;
              }
          }
          assertTrue(cluster1Found);
          assertTrue(cluster2Found);
          assertTrue(cluster3Found);
      }
  
      @Test
      void testTooSmallFuzzynessFactor() {
          assertThrows(MathIllegalArgumentException.class, () -> {
              new FuzzyKMeansClusterer<DoublePoint>(3, 1.0);
          });
      }
  
      @Test
      void testNullDataset() {
          assertThrows(NullArgumentException.class, () -> {
             final FuzzyKMeansClusterer<DoublePoint> clusterer = new FuzzyKMeansClusterer<DoublePoint>(3, 2.0);
             clusterer.cluster(null);
         });
     }
 
     @Test
     void testGetters() {
         final DistanceMeasure measure = new CanberraDistance();
         final RandomGenerator random = new JDKRandomGenerator();
         final FuzzyKMeansClusterer<DoublePoint> clusterer =
                 new FuzzyKMeansClusterer<DoublePoint>(3, 2.0, 100, measure, 1e-6, random);
 
         assertEquals(3, clusterer.getK());
         assertEquals(2.0, clusterer.getFuzziness(), 1e-6);
         assertEquals(100, clusterer.getMaxIterations());
         assertEquals(1e-6, clusterer.getEpsilon(), 1e-12);
         assertThat(clusterer.getDistanceMeasure(), CoreMatchers.is(measure));
         assertThat(clusterer.getRandomGenerator(), CoreMatchers.is(random));
     }
 
     @Test
     void testSingleCluster() {
         final List<DoublePoint> points = new ArrayList<DoublePoint>();
         points.add(new DoublePoint(new double[] { 1, 1 }));
 
         final FuzzyKMeansClusterer<DoublePoint> transformer =
                 new FuzzyKMeansClusterer<DoublePoint>(1, 2.0);
         final List<CentroidCluster<DoublePoint>> clusters = transformer.cluster(points);
 
         assertEquals(1, clusters.size());
     }
 
     @Test
     void testClusterCenterEqualsPoints() {
         final List<DoublePoint> points = new ArrayList<DoublePoint>();
         points.add(new DoublePoint(new double[] { 1, 1 }));
         points.add(new DoublePoint(new double[] { 1.00001, 1.00001 }));
         points.add(new DoublePoint(new double[] { 2, 2 }));
         points.add(new DoublePoint(new double[] { 3, 3 }));
 
         final FuzzyKMeansClusterer<DoublePoint> transformer =
                 new FuzzyKMeansClusterer<DoublePoint>(3, 2.0);
         final List<CentroidCluster<DoublePoint>> clusters = transformer.cluster(points);
 
         assertEquals(3, clusters.size());
     }
 
 }