/*
    * 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 org.apache.commons.math4.legacy.exception.DimensionMismatchException;
  import org.apache.commons.math4.legacy.exception.NotPositiveException;
  import org.apache.commons.math4.legacy.exception.NullArgumentException;
  import org.apache.commons.math4.legacy.exception.OutOfRangeException;
  import org.junit.Before;
  import org.junit.Test;
  
  public class HaltonSequenceGeneratorTest {
  
      private double[][] referenceValues = {
              { 0.0,    0.0,    0.0  },
              { 0.5,    0.6667, 0.6  },
              { 0.25,   0.3333, 0.2  },
              { 0.75,   0.2223, 0.8  },
              { 0.125,  0.8888, 0.4  },
              { 0.625,  0.5555, 0.12 },
              { 0.375,  0.1111, 0.72 },
              { 0.875,  0.7777, 0.32 },
              { 0.0625, 0.4444, 0.92 },
              { 0.5625, 0.0740, 0.52 }
      };
  
      private double[][] referenceValuesUnscrambled = {
              { 0.0,    0.0    },
              { 0.5,    0.3333 },
              { 0.25,   0.6666 },
              { 0.75,   0.1111 },
              { 0.125,  0.4444 },
              { 0.625,  0.7777 },
              { 0.375,  0.2222 },
              { 0.875,  0.5555 },
              { 0.0625, 0.8888 },
              { 0.5625, 0.0370 }
      };
  
      private HaltonSequenceGenerator generator;
  
      @Before
      public void setUp() {
          generator = new HaltonSequenceGenerator(3);
      }
  
      @Test
      public void test3DReference() {
          for (int i = 0; i < referenceValues.length; i++) {
              double[] result = generator.get();
              Assert.assertArrayEquals(referenceValues[i], result, 1e-3);
              Assert.assertEquals(i + 1, generator.getNextIndex());
          }
      }
  
      @Test
      public void test2DUnscrambledReference() {
          generator = new HaltonSequenceGenerator(2, new int[] {2, 3}, null);
          for (int i = 0; i < referenceValuesUnscrambled.length; i++) {
              double[] result = generator.get();
              Assert.assertArrayEquals(referenceValuesUnscrambled[i], result, 1e-3);
              Assert.assertEquals(i + 1, generator.getNextIndex());
          }
      }
  
      @Test
      public void testConstructor() {
          try {
              new HaltonSequenceGenerator(0);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
  
          try {
              new HaltonSequenceGenerator(41);
              Assert.fail("an exception should have been thrown");
          } catch (OutOfRangeException e) {
              // expected
          }
      }
  
      @Test
      public void testConstructor2() throws Exception{
         try {
             new HaltonSequenceGenerator(2, new int[] { 1 }, null);
             Assert.fail("an exception should have been thrown");
         } catch (OutOfRangeException e) {
             // expected
         }
 
         try {
             new HaltonSequenceGenerator(2, null, null);
             Assert.fail("an exception should have been thrown");
         } catch (NullArgumentException e) {
             // expected
         }
 
         try {
             new HaltonSequenceGenerator(2, new int[] { 1, 1 }, new int[] { 1 });
             Assert.fail("an exception should have been thrown");
         } catch (DimensionMismatchException e) {
             // expected
         }
     }
 
     @Test
     public void testSkip() {
         double[] result = generator.skipTo(5);
         Assert.assertArrayEquals(referenceValues[5], result, 1e-3);
         Assert.assertEquals(6, generator.getNextIndex());
 
         for (int i = 6; i < referenceValues.length; i++) {
             result = generator.get();
             Assert.assertArrayEquals(referenceValues[i], result, 1e-3);
             Assert.assertEquals(i + 1, generator.getNextIndex());
         }
     }
 
     @Test
     public void testSkipToNegative() {
         try {
             generator.skipTo(-4584);
             Assert.fail("an exception should have been thrown");
         } catch (NotPositiveException e) {
             // expected
         }
     }
 }