content: /*
   * 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.quicktheories.impl;
  
  import java.util.Objects;
  import java.util.Random;
  
  import org.quicktheories.core.DetatchedRandomnessSource;
  import org.quicktheories.core.RandomnessSource;
  
  /**
   * The {@link Constraint} class does not expose {@link Constraint#min()} or {@link Constraint#max()} outside the package, so
   * the only way to build a {@link RandomnessSource} is to define it in the package "org.quicktheories.impl"
   */
  public class JavaRandom implements RandomnessSource, DetatchedRandomnessSource
  {
      private final Random random;
  
      public JavaRandom(long seed)
      {
          this.random = new Random(seed);
      }
  
      public JavaRandom(Random random)
      {
          this.random = Objects.requireNonNull(random);
      }
  
      public void setSeed(long seed)
      {
          this.random.setSeed(seed);
      }
  
      public static JavaRandom wrap(RandomnessSource rnd)
      {
          if (rnd instanceof JavaRandom)
              return (JavaRandom) rnd;
          return new JavaRandom(rnd.next(Constraint.none().withNoShrinkPoint()));
      }
  
      @Override
      public long next(Constraint constraint)
      {
          long max = constraint.max();
          return nextLong(constraint.min(), max == Long.MAX_VALUE ? max : max + 1);
      }
  
      private long nextLong(long minInclusive, long maxExclusive)
      {
          // pulled from accord.utils.RandomSource#nextLong(long, long)...
          // long term it will be great to unify the two and drop QuickTheories classes all together
          // this is diff behavior than ThreadLocalRandom, which returns nextLong
          if (minInclusive >= maxExclusive)
              throw new IllegalArgumentException(String.format("Min (%s) should be less than max (%d).", minInclusive, maxExclusive));
  
          long result = random.nextLong();
          long delta = maxExclusive - minInclusive;
          long mask = delta - 1;
          if ((delta & mask) == 0L) // power of two
              result = (result & mask) + minInclusive;
          else if (delta > 0L)
          {
              // reject over-represented candidates
              for (long u = result >>> 1;                 // ensure nonnegative
                   u + mask - (result = u % delta) < 0L;  // rejection check
                   u = random.nextLong() >>> 1)                  // retry
                  ;
              result += minInclusive;
          }
          else
          {
              // range not representable as long
              while (result < minInclusive || result >= maxExclusive)
                  result = random.nextLong();
          }
          return result;
      }
  
      @Override
      public DetatchedRandomnessSource detach()
      {
          return this;
      }
  
      @Override
      public void registerFailedAssumption()
      {
  
      }
  
      @Override
      public void commit()
      {
          // no-op
      }
  }
  