/*
    * 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.rng.sampling.distribution;
  
  import java.util.concurrent.ThreadLocalRandom;
  import org.apache.commons.rng.UniformRandomProvider;
  import org.apache.commons.rng.sampling.RandomAssert;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.RepeatedTest;
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.ValueSource;
  
  /**
   * Tests the default methods in the {@link ContinuousSampler} interface.
   */
  class ContinuousSamplerTest {
      @Test
      void testSamplesUnlimitedSize() {
          final ContinuousSampler s = RandomAssert.createRNG()::nextDouble;
          Assertions.assertEquals(Long.MAX_VALUE, s.samples().spliterator().estimateSize());
      }
  
      @RepeatedTest(value = 3)
      void testSamples() {
          final UniformRandomProvider[] rngs = RandomAssert.createRNG(2);
          final ContinuousSampler s1 = rngs[0]::nextDouble;
          final ContinuousSampler s2 = rngs[1]::nextDouble;
          final int count = ThreadLocalRandom.current().nextInt(3, 13);
          Assertions.assertArrayEquals(createSamples(s1, count),
                                       s2.samples().limit(count).toArray());
      }
  
      @ParameterizedTest
      @ValueSource(ints = {0, 1, 2, 5, 13})
      void testSamples(int streamSize) {
          final UniformRandomProvider[] rngs = RandomAssert.createRNG(2);
          final ContinuousSampler s1 = rngs[0]::nextDouble;
          final ContinuousSampler s2 = rngs[1]::nextDouble;
          Assertions.assertArrayEquals(createSamples(s1, streamSize),
                                       s2.samples(streamSize).toArray());
      }
  
      /**
       * Creates an array of samples.
       *
       * @param sampler Source of samples.
       * @param count Number of samples.
       * @return the samples
       */
      private static double[] createSamples(ContinuousSampler sampler, int count) {
          final double[] data = new double[count];
          for (int i = 0; i < count; i++) {
              data[i] = sampler.sample();
          }
          return data;
      }
  }