/*
   * 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.crypto.random;
  
  import java.lang.Thread.State;
  import java.security.GeneralSecurityException;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.Timeout;
  
  public abstract class AbstractRandomTest {
  
      /**
       * Test will timeout if secure random implementation always returns a constant value.
       */
      private void checkRandomBytes(final CryptoRandom random, final int len) {
          final byte[] bytes = new byte[len];
          final byte[] bytes1 = new byte[len];
          random.nextBytes(bytes);
          random.nextBytes(bytes1);
  
          while (Arrays.equals(bytes1, new byte[len]) || Arrays.equals(bytes, bytes1)) {
              random.nextBytes(bytes1);
          }
      }
  
      public abstract CryptoRandom getCryptoRandom() throws GeneralSecurityException;
  
      @Test
      @Timeout(value = 120000, unit = TimeUnit.MILLISECONDS)
      public void testRandomBytes() throws Exception {
          try (CryptoRandom random = getCryptoRandom()) {
              // len = 16
              checkRandomBytes(random, 16);
              // len = 32
              checkRandomBytes(random, 32);
              // len = 128
              checkRandomBytes(random, 128);
              // len = 256
              checkRandomBytes(random, 256);
          }
      }
  
      @Test
      @Timeout(value = 120000, unit = TimeUnit.MILLISECONDS)
      public void testRandomBytesMultiThreaded() throws Exception {
          final int threadCount = 100;
          try (final CryptoRandom random = getCryptoRandom()) {
              final List<Thread> threads = new ArrayList<>(threadCount);
  
              for (int i = 0; i < threadCount; i++) {
                  final Thread t = new Thread(() -> {
                      checkRandomBytes(random, 10);
                      checkRandomBytes(random, 1000);
                      checkRandomBytes(random, 100000);
                  });
                  t.start();
                  threads.add(t);
              }
  
              for (final Thread t : threads) {
                  if (!t.getState().equals(State.NEW)) {
                      t.join();
                  }
              }
  
          }
      }
  }