/*
    * 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.giraph.block_app.framework.piece.messages;
  
  import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;
  import org.apache.giraph.factories.DefaultMessageValueFactory;
  import org.apache.giraph.factories.MessageValueFactory;
  import org.apache.giraph.function.Function;
  import org.apache.giraph.writable.kryo.HadoopKryo;
  import org.apache.hadoop.io.Writable;
  
  /**
   * Supplier from configuration
   * @param <T> Type of object returned
   */
  public interface SupplierFromConf<T>
      extends Function<ImmutableClassesGiraphConfiguration, T> {
  
    /**
     * Supplier from configuration, by copying given instance every time.
     *
     * @param <T> Type of object returned
     */
    public static class SupplierFromConfByCopy<T> implements SupplierFromConf<T> {
      private final T value;
  
      public SupplierFromConfByCopy(T value) {
        this.value = value;
      }
  
      @Override
      public T apply(ImmutableClassesGiraphConfiguration conf) {
        return HadoopKryo.createCopy(value);
      }
    }
  
    /**
     * Supplier from configuration returning DefaultMessageValueFactory instances.
     *
     * @param <M> Message type
     */
    public static class DefaultMessageFactorySupplierFromConf<M extends Writable>
        implements SupplierFromConf<MessageValueFactory<M>> {
      private final Class<M> messageClass;
  
      public DefaultMessageFactorySupplierFromConf(Class<M> messageClass) {
        this.messageClass = messageClass;
      }
  
      @Override
      public MessageValueFactory<M> apply(
          ImmutableClassesGiraphConfiguration conf) {
        return new DefaultMessageValueFactory<>(messageClass, conf);
      }
    }
  }