/*
    * 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.core.source32.RandomIntSource;
  import org.apache.commons.rng.core.source64.RandomLongSource;
  import org.apache.commons.rng.simple.RandomSource;
  import org.apache.commons.rng.simple.internal.ProviderBuilder.RandomSourceInternal;
  
  import java.util.ArrayList;
  import java.util.EnumMap;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * Default list of generators defined by the {@link RandomSource}. Any source that
   * requires arguments will have a default set of arguments.
   */
  class StressTestDataList implements Iterable<StressTestData> {
      /**
       * The example arguments for RandomSource values that require them.
       */
      private static final EnumMap<RandomSource, Object[]> EXAMPLE_ARGUMENTS =
              new EnumMap<>(RandomSource.class);
  
      static {
          // Currently we cannot detect if the source requires arguments,
          // e.g. RandomSource.TWO_CMRES_SELECT. So example arguments must
          // be manually added here.
          EXAMPLE_ARGUMENTS.put(RandomSource.TWO_CMRES_SELECT, new Object[] {1, 2});
      }
  
      /** List of generators. */
      private final List<StressTestData> list = new ArrayList<>();
  
      /**
       * Creates an empty list.
       */
      private StressTestDataList() {
          // Do nothing
      }
  
      /**
       * Creates the list. The number of trials will be set if the source does not require arguments.
       *
       * @param idPrefix The id prefix prepended to each ID.
       * @param numberOfTrials The number of trials (ignored if {@code <= 0}).
       */
      StressTestDataList(String idPrefix,
                         int numberOfTrials) {
          // Auto-generate using the order of the RandomSource enum
          for (final RandomSource source : RandomSource.values()) {
              final Object[] args = EXAMPLE_ARGUMENTS.get(source);
              StressTestData data = new StressTestData(source, args).withIDPrefix(idPrefix);
              if (args == null && numberOfTrials > 0) {
                  data = data.withTrials(numberOfTrials);
              }
              list.add(data);
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public Iterator<StressTestData> iterator() {
          return list.iterator();
      }
  
      /**
       * Create a subset of the list containing only instances of {@link RandomIntSource}.
       *
       * @return the stress test data list
       */
      public StressTestDataList subsetIntSource() {
          return subsetOf(RandomIntSource.class);
      }
  
      /**
       * Create a subset of the list containing only instances of {@link RandomLongSource}.
       *
       * @return the stress test data list
       */
      public StressTestDataList subsetLongSource() {
          return subsetOf(RandomLongSource.class);
      }
  
     /**
      * Create a subset of the list containing only instances of the specified type.
      *
      * @param type The instance type.
      * @return the stress test data list
      */
     private StressTestDataList subsetOf(Class<?> type) {
         final StressTestDataList subset = new StressTestDataList();
         for (final StressTestData data : list) {
             // This makes a big assumption that the two enums have the same name
             RandomSourceInternal source;
             try {
                 source = RandomSourceInternal.valueOf(data.getRandomSource().name());
             } catch (IllegalArgumentException ex) {
                 throw new ApplicationException("Unknown internal source: " + data.getRandomSource(), ex);
             }
             if (type.isAssignableFrom(source.getRng())) {
                 subset.list.add(data);
             }
         }
         return subset;
     }
 
     /**
      * Create a subset of the list containing only instances of RandomSource within the
      * specified range of the enum. The first value in the enum corresponds to entry 1.
      *
      * @param min Minimum entry (inclusive)
      * @param max Maximum entry (inclusive)
      * @return the stress test data list
      */
     public StressTestDataList subsetRandomSource(int min, int max) {
         final StressTestDataList subset = new StressTestDataList();
         for (final StressTestData data : list) {
             final int entry = data.getRandomSource().ordinal() + 1;
             if (min <= entry && entry <= max) {
                 subset.list.add(data);
             }
         }
         return subset;
     }
 }