/*
    * 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
    *
    *      http://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.
   */
  package org.apache.commons.math4.legacy.random;
  
  import org.junit.Assert;
  
  import java.io.InputStream;
  
  import org.apache.commons.math4.legacy.exception.OutOfRangeException;
  import org.junit.Before;
  import org.junit.Test;
  
  public class SobolSequenceGeneratorTest {
      private static final String RESOURCE_NAME = "/assets/org/apache/commons/math4/legacy/random/new-joe-kuo-6.21201";
  
      private double[][] referenceValues = {
              { 0.0, 0.0, 0.0 },
              { 0.5, 0.5, 0.5 },
              { 0.75, 0.25, 0.25 },
              { 0.25, 0.75, 0.75 },
              { 0.375, 0.375, 0.625 },
              { 0.875, 0.875, 0.125 },
              { 0.625, 0.125, 0.875 },
              { 0.125, 0.625, 0.375 },
              { 0.1875, 0.3125, 0.9375 },
              { 0.6875, 0.8125, 0.4375 }
      };
  
      private SobolSequenceGenerator generator;
  
      @Before
      public void setUp() {
          generator = new SobolSequenceGenerator(3);
      }
  
      @Test
      public void test3DReference() {
          for (int i = 0; i < referenceValues.length; i++) {
              double[] result = generator.get();
              Assert.assertArrayEquals(referenceValues[i], result, 1e-6);
              Assert.assertEquals(i + 1, generator.getNextIndex());
          }
      }
  
      @Test
      public void testConstructor() {
          try {
              new SobolSequenceGenerator(0);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
  
          try {
              new SobolSequenceGenerator(21202);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
      }
  
      @Test
      public void testConstructor2() throws Exception{
          try {
              final InputStream is = getClass().getResourceAsStream(RESOURCE_NAME);
              new SobolSequenceGenerator(21202, is);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
  
          try {
              new SobolSequenceGenerator(21202);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
      }
  
      @Test
      public void testSkip() {
          double[] result = generator.skipTo(5);
          Assert.assertArrayEquals(referenceValues[5], result, 1e-6);
          Assert.assertEquals(6, generator.getNextIndex());
  
         for (int i = 6; i < referenceValues.length; i++) {
             result = generator.get();
             Assert.assertArrayEquals(referenceValues[i], result, 1e-6);
             Assert.assertEquals(i + 1, generator.getNextIndex());
         }
     }
 }