/*
    * 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.examples.stress;
  
  import org.apache.commons.rng.UniformRandomProvider;
  import org.apache.commons.rng.core.source64.SplitMix64;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests for {@link RNGUtils}.
   */
  class RNGUtilsTest {
      @Test
      void testCreateIntProviderLongThrows() {
          final SplitMix64 rng = new SplitMix64(42);
          Assertions.assertThrows(IllegalArgumentException.class,
              () -> RNGUtils.createIntProvider(rng, Source64Mode.LONG));
      }
  
      @Test
      void testCreateIntProviderInt() {
          final long seed = 236784264237894L;
          final UniformRandomProvider rng1 = new SplitMix64(seed);
          final UniformRandomProvider rng2 =
              RNGUtils.createIntProvider(new SplitMix64(seed), Source64Mode.INT);
          for (int i = 0; i < 50; i++) {
              Assertions.assertEquals(rng1.nextInt(), rng2.nextInt());
          }
      }
  
      @Test
      void testCreateIntProviderLoHi() {
          final long seed = 236784264237894L;
          final UniformRandomProvider rng1 = new SplitMix64(seed);
          final UniformRandomProvider rng2 =
              RNGUtils.createIntProvider(new SplitMix64(seed), Source64Mode.LO_HI);
          for (int i = 0; i < 50; i++) {
              final long l = rng1.nextLong();
              final int hi = (int) (l >>> 32);
              final int lo = (int) l;
              Assertions.assertEquals(lo, rng2.nextInt());
              Assertions.assertEquals(hi, rng2.nextInt());
          }
      }
  
      @Test
      void testCreateIntProviderHiLo() {
          final long seed = 2367234237894L;
          final UniformRandomProvider rng1 = new SplitMix64(seed);
          final UniformRandomProvider rng2 =
              RNGUtils.createIntProvider(new SplitMix64(seed), Source64Mode.HI_LO);
          for (int i = 0; i < 50; i++) {
              final long l = rng1.nextLong();
              final int hi = (int) (l >>> 32);
              final int lo = (int) l;
              Assertions.assertEquals(hi, rng2.nextInt());
              Assertions.assertEquals(lo, rng2.nextInt());
          }
      }
  
      @Test
      void testCreateIntProviderHi() {
          final long seed = 2367234237894L;
          final UniformRandomProvider rng1 = new SplitMix64(seed);
          final UniformRandomProvider rng2 =
              RNGUtils.createIntProvider(new SplitMix64(seed), Source64Mode.HI);
          for (int i = 0; i < 50; i++) {
              final int hi = (int) (rng1.nextLong() >>> 32);
              Assertions.assertEquals(hi, rng2.nextInt());
          }
      }
  
      @Test
      void testCreateIntProviderLo() {
          final long seed = 2367234237894L;
          final UniformRandomProvider rng1 = new SplitMix64(seed);
          final UniformRandomProvider rng2 =
              RNGUtils.createIntProvider(new SplitMix64(seed), Source64Mode.LO);
          for (int i = 0; i < 50; i++) {
              final int lo = (int) rng1.nextLong();
              Assertions.assertEquals(lo, rng2.nextInt());
          }
      }
  
     /**
      * Test that the default source64 mode matches the nextInt implementation for a LongProvider.
      * If this changes then the default mode should be updated. The value is used as
      * the default for the stress test application.
      */
     @Test
     void testCreateIntProviderDefault() {
         final long seed = 236784264237894L;
         final UniformRandomProvider rng1 = new SplitMix64(seed);
         final UniformRandomProvider rng2 =
             RNGUtils.createIntProvider(new SplitMix64(seed), RNGUtils.getSource64Default());
         for (int i = 0; i < 50; i++) {
             final int a = rng1.nextInt();
             final int b = rng1.nextInt();
             Assertions.assertEquals(a, rng2.nextInt());
             Assertions.assertEquals(b, rng2.nextInt());
         }
     }
 }