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.apache.kafka.test;
  
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.kstream.KeyValueMapper;
  import org.apache.kafka.streams.kstream.ValueMapper;
  
  import java.util.Collections;
  
  public class MockMapper {
  
      private static class NoOpKeyValueMapper<K, V> implements KeyValueMapper<K, V, KeyValue<K, V>> {
          @Override
          public KeyValue<K, V> apply(final K key, final V value) {
              return KeyValue.pair(key, value);
          }
      }
  
      private static class NoOpFlatKeyValueMapper<K, V> implements KeyValueMapper<K, V, Iterable<KeyValue<K, V>>> {
          @Override
          public Iterable<KeyValue<K, V>> apply(final K key, final V value) {
              return Collections.singletonList(KeyValue.pair(key, value));
          }
      }
  
      private static class SelectValueKeyValueMapper<K, V> implements KeyValueMapper<K, V, KeyValue<V, V>> {
          @Override
          public KeyValue<V, V> apply(final K key, final V value) {
              return KeyValue.pair(value, value);
          }
      }
  
      private static class SelectValueMapper<K, V> implements KeyValueMapper<K, V, V> {
          @Override
          public V apply(final K key, final V value) {
              return value;
          }
      }
  
      private static class SelectKeyMapper<K, V> implements KeyValueMapper<K, V, K> {
          @Override
          public K apply(final K key, final V value) {
              return key;
          }
      }
  
      private static class NoOpValueMapper<V> implements ValueMapper<V, V> {
          @Override
          public V apply(final V value) {
              return value;
          }
      }
  
      public static <K, V> KeyValueMapper<K, V, K> selectKeyKeyValueMapper() {
          return new SelectKeyMapper<>();
      }
  
      public static <K, V> KeyValueMapper<K, V, Iterable<KeyValue<K, V>>> noOpFlatKeyValueMapper() {
          return new NoOpFlatKeyValueMapper<>();
      }
  
      public static <K, V> KeyValueMapper<K, V, KeyValue<K, V>> noOpKeyValueMapper() {
          return new NoOpKeyValueMapper<>();
      }
  
      public static <K, V> KeyValueMapper<K, V, KeyValue<V, V>> selectValueKeyValueMapper() {
          return new SelectValueKeyValueMapper<>();
      }
  
      public static <K, V> KeyValueMapper<K, V, V> selectValueMapper() {
          return new SelectValueMapper<>();
      }
  
      public static <V> ValueMapper<V, V> noOpValueMapper() {
          return new NoOpValueMapper<>();
      }
  }