/*
    * 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.simple;
  
  import org.apache.commons.rng.UniformRandomProvider;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.BeforeAll;
  import org.junit.jupiter.api.Test;
  
  import java.util.EnumSet;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  
  /**
   * Tests for {@link ThreadLocalRandomSource}.
   */
  class ThreadLocalRandomSourceTest {
      /**
       * A set of all the RandomSource options that requires arguments. This should be
       * ignored in certain tests since they are not supported.
       */
      private static EnumSet<RandomSource> toIgnore;
  
      @BeforeAll
      public static void createToIgnoreSet() {
          toIgnore = EnumSet.of(RandomSource.TWO_CMRES_SELECT);
      }
  
      @Test
      void testCurrentThrowsForNullRandomSource() {
          Assertions.assertThrows(IllegalArgumentException.class, () -> ThreadLocalRandomSource.current(null));
      }
  
      @Test
      void testCurrentThrowsForRandomSourceWithDataArguments() {
          Assertions.assertThrows(IllegalArgumentException.class,
              () -> ThreadLocalRandomSource.current(RandomSource.TWO_CMRES_SELECT));
      }
  
      @Test
      void testCurrentForAllRandomSources()
              throws InterruptedException, ExecutionException, TimeoutException {
          final RandomSource[] sources = RandomSource.values();
          final UniformRandomProvider[] rngs = new UniformRandomProvider[sources.length];
  
          for (int i = 0; i < sources.length; i++) {
              final RandomSource source = sources[i];
              if (toIgnore.contains(source)) {
                  continue;
              }
              final UniformRandomProvider rng = getCurrent(source);
              Assertions.assertNotNull(rng, () -> "Failed to create source: " + source);
              rngs[i] = rng;
          }
          for (int i = 0; i < sources.length; i++) {
              final RandomSource source = sources[i];
              if (toIgnore.contains(source)) {
                  continue;
              }
              final UniformRandomProvider rng = getCurrent(source);
              Assertions.assertSame(rngs[i], rng, () -> "Failed to return same source: " + source);
          }
  
          // Build on a new thread
          final UniformRandomProvider[] rngs2 = new UniformRandomProvider[rngs.length];
          final ExecutorService executor = Executors.newFixedThreadPool(1);
          final Future<?> future = executor.submit(
              new Runnable() {
                  @Override
                  public void run() {
                      for (int i = 0; i < sources.length; i++) {
                          if (toIgnore.contains(sources[i])) {
                              continue;
                          }
                          rngs2[i] = getCurrent(sources[i]);
                      }
                  }
              });
  
          // Shutdown and wait for task to end
          executor.shutdown();
         future.get(30, TimeUnit.SECONDS);
 
         // The RNG from the new thread should be different
         for (int i = 0; i < sources.length; i++) {
             final RandomSource source = sources[i];
             if (toIgnore.contains(source)) {
                 continue;
             }
             Assertions.assertNotSame(rngs[i], rngs2[i], () -> "Failed to return different source: " + source);
         }
     }
 
     private static UniformRandomProvider getCurrent(RandomSource source) {
         try {
             return ThreadLocalRandomSource.current(source);
         } catch (final RuntimeException ex) {
             throw new RuntimeException("Failed to get current: " + source, ex);
         }
     }
 }