/*

  * 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.conf;

 import org.apache.hadoop.conf.Configuration;

 import com.google.common.base.Objects;

 /**

  * Enum Configuration option

  *

  * @param <T> Enum class

  */

 public class EnumConfOption<T extends Enum<T>> extends AbstractConfOption {

   /** Enum class */

   private final Class<T> klass;

   /** Default value */

   private final T defaultValue;

   /**

    * Constructor

    *

    * @param key Configuration key

    * @param klass Enum class

    * @param defaultValue default value

    * @param description description of the option

    */

   public EnumConfOption(String key, Class<T> klass, T defaultValue,

       String description) {

     super(key, description);

     this.klass = klass;

     this.defaultValue = defaultValue;

   }

   /**

    * Create new EnumConfOption

    *

    * @param key String configuration key

    * @param klass enum class

    * @param defaultValue default enum value

    * @param description description of the option

    * @param <X> enum type

    * @return EnumConfOption

    */

   public static <X extends Enum<X>> EnumConfOption<X>

   create(String key, Class<X> klass, X defaultValue, String description) {

     return new EnumConfOption<X>(key, klass, defaultValue, description);

   }

   @Override public boolean isDefaultValue(Configuration conf) {

     return Objects.equal(get(conf), defaultValue);

   }

   @Override public String getDefaultValueStr() {

     return defaultValue.name();

   }

   @Override public ConfOptionType getType() {

     return ConfOptionType.ENUM;

   }

   /**

    * Lookup value

    *

    * @param conf Configuration

    * @return enum value

    */

   public T get(Configuration conf) {

     String valueStr = conf.get(getKey(), getDefaultValueStr());

     return T.valueOf(klass, valueStr);

   }

   /**

    * Set value

    *

    * @param conf Configuration

    * @param value to set

    */

   public void set(Configuration conf, Enum<T> value) {

     conf.set(getKey(), value.name());

   }

   /**

    * Set value if it's not already present

    *

    * @param conf Configuration

    * @param value to set

    */

   public void setIfUnset(Configuration conf, Enum<T> value) {

     if (!contains(conf)) {

       set(conf, value);

     }

   }

 }