/*
    * 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.logging.log4j.core.filter;
  
  import java.util.Iterator;
  
  import org.apache.logging.log4j.core.AbstractLifeCycle;
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.LogEvent;
  
  /**
   * Enhances a Class by allowing it to contain Filters.
   */
  public abstract class AbstractFilterable extends AbstractLifeCycle implements Filterable {
  
      /**
       * May be null.
       */
      private volatile Filter filter;
  
      protected AbstractFilterable(final Filter filter) {
          this.filter = filter;
      }
  
      protected AbstractFilterable() {
      }
  
      /**
       * Returns the Filter.
       * @return the Filter or null.
       */
      @Override
      public Filter getFilter() {
          return filter;
      }
  
      /**
       * Adds a filter.
       * @param filter The Filter to add.
       */
      @Override
      public synchronized void addFilter(final Filter filter) {
          if (filter == null) {
              return;
          }
          if (this.filter == null) {
              this.filter = filter;
          } else if (this.filter instanceof CompositeFilter) {
              this.filter = ((CompositeFilter) this.filter).addFilter(filter);
          } else {
              final Filter[] filters = new Filter[] {this.filter, filter};
              this.filter = CompositeFilter.createFilters(filters);
          }
      }
  
      /**
       * Removes a Filter.
       * @param filter The Filter to remove.
       */
      @Override
      public synchronized void removeFilter(final Filter filter) {
          if (this.filter == null || filter == null) {
              return;
          }
          if (this.filter == filter || this.filter.equals(filter)) {
              this.filter = null;
          } else if (this.filter instanceof CompositeFilter) {
              CompositeFilter composite = (CompositeFilter) this.filter;
              composite = composite.removeFilter(filter);
              if (composite.size() > 1) {
                  this.filter = composite;
              } else if (composite.size() == 1) {
                  final Iterator<Filter> iter = composite.iterator();
                  this.filter = iter.next();
              } else {
                  this.filter = null;
              }
          }
      }
  
      /**
       * Determines if a Filter is present.
       * @return false if no Filter is present.
       */
      @Override
     public boolean hasFilter() {
         return filter != null;
     }
 
     /**
      * Make the Filter available for use.
      */
     @Override
     public void start() {
         this.setStarting();
         if (filter != null) {
             filter.start();
         }
         this.setStarted();
     }
 
     /**
      * Cleanup the Filter.
      */
     @Override
     public void stop() {
         this.setStopping();
        if (filter != null) {
            filter.stop();
        }
        this.setStopped();
     }
 
     /**
      * Determine if the LogEvent should be processed or ignored.
      * @param event The LogEvent.
      * @return true if the LogEvent should be processed.
      */
     @Override
     public boolean isFiltered(final LogEvent event) {
         return filter != null && filter.filter(event) == Filter.Result.DENY;
     }
 
 }