/*
    * Copyright 2014 Jin Kwon <jinahya_at_gmail.com>.
    *
    * Licensed 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 com.github.jinahya.simple.file.back;
  
  
  import com.github.jinahya.simple.file.back.FileContext.PropertyKey;
  import java.util.EnumMap;
  import java.util.Map;
  import java.util.Optional;
  
  
  /**
   * An abstract class partially implementing {@link FileContext}.
   *
   * @author Jin Kwon <jinahya_at_gmail.com>
   */
  public abstract class AbstractFileContext implements FileContext {
  
  
      @Override
      public Optional<Object> property(final PropertyKey key) {
  
          if (key == null) {
              throw new NullPointerException("null key");
          }
  
          return Optional.ofNullable(properties().get(key));
      }
  
  
      @Override
      public Optional<Object> property(final PropertyKey key,
                                       final Object value) {
  
          if (key == null) {
              throw new NullPointerException("null key");
          }
  
          if (value == null) {
              return Optional.ofNullable(properties().remove(key));
          }
  
          return Optional.ofNullable(properties().put(key, value));
      }
  
  
      /**
       * Returns a map of properties.
       *
       * @return properties.
       */
      protected Map<PropertyKey, Object> properties() {
  
          if (properties == null) {
              properties = new EnumMap<>(PropertyKey.class);
          }
  
          return properties;
      }
  
  
      private Map<PropertyKey, Object> properties;
  
  
  }