/*
    * 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 org.apache.commons.rng.UniformRandomProvider;
  import org.apache.commons.rng.sampling.RandomAssert;
  import org.apache.commons.rng.sampling.SharedStateSampler;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test for the {@link LogNormalSampler}. The tests hit edge cases for the sampler.
   */
  class LogNormalSamplerTest {
      /**
       * Test the constructor with a bad standard deviation.
       */
      @Test
      void testConstructorThrowsWithZeroShape() {
          final UniformRandomProvider rng = RandomAssert.seededRNG();
          final NormalizedGaussianSampler gauss = ZigguratSampler.NormalizedGaussian.of(rng);
          final double mu = 1;
          final double sigma = 0;
          Assertions.assertThrows(IllegalArgumentException.class,
              () -> LogNormalSampler.of(gauss, mu, sigma));
      }
  
      /**
       * Test the SharedStateSampler implementation.
       */
      @Test
      void testSharedStateSampler() {
          final UniformRandomProvider rng1 = RandomAssert.seededRNG();
          final UniformRandomProvider rng2 = RandomAssert.seededRNG();
          final NormalizedGaussianSampler gauss = ZigguratSampler.NormalizedGaussian.of(rng1);
          // Test a negative mean is allowed (see RNG-166)
          final double mu = -1.23;
          final double sigma = 4.56;
          final SharedStateContinuousSampler sampler1 =
              LogNormalSampler.of(gauss, mu, sigma);
          final SharedStateContinuousSampler sampler2 = sampler1.withUniformRandomProvider(rng2);
          RandomAssert.assertProduceSameSequence(sampler1, sampler2);
      }
  
      /**
       * Test the SharedStateSampler implementation throws if the underlying sampler is
       * not a SharedStateSampler.
       */
      @Test
      void testSharedStateSamplerThrowsIfUnderlyingSamplerDoesNotShareState() {
          final UniformRandomProvider rng2 = RandomAssert.seededRNG();
          final NormalizedGaussianSampler gauss = new NormalizedGaussianSampler() {
              @Override
              public double sample() {
                  return 0;
              }
          };
          final double mu = 1.23;
          final double sigma = 4.56;
          final SharedStateContinuousSampler sampler1 =
              LogNormalSampler.of(gauss, mu, sigma);
          Assertions.assertThrows(UnsupportedOperationException.class,
              () -> sampler1.withUniformRandomProvider(rng2));
      }
  
      /**
       * Test the SharedStateSampler implementation throws if the underlying sampler is
       * a SharedStateSampler that returns an incorrect type.
       */
      @Test
      void testSharedStateSamplerThrowsIfUnderlyingSamplerReturnsWrongSharedState() {
          final UniformRandomProvider rng2 = RandomAssert.seededRNG();
          final NormalizedGaussianSampler gauss = new BadSharedStateNormalizedGaussianSampler();
          final double mu = 1.23;
          final double sigma = 4.56;
          final SharedStateContinuousSampler sampler1 =
              LogNormalSampler.of(gauss, mu, sigma);
          Assertions.assertThrows(UnsupportedOperationException.class,
              () -> sampler1.withUniformRandomProvider(rng2));
      }
  
      /**
       * Test class to return an incorrect sampler from the SharedStateSampler method.
       *
       * <p>Note that due to type erasure the type returned by the SharedStateSampler is not
      * available at run-time and the LogNormalSampler has to assume it is the correct type.</p>
      */
     private static class BadSharedStateNormalizedGaussianSampler
             implements NormalizedGaussianSampler, SharedStateSampler<Integer> {
         @Override
         public double sample() {
             return 0;
         }
 
         @Override
         public Integer withUniformRandomProvider(UniformRandomProvider rng) {
             // Something that is not a NormalizedGaussianSampler
             return Integer.valueOf(44);
         }
     }
 }