/*
    * 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);
     }
   }
 }