/*
    * Copyright 2006-2007 the original author or authors.
    *
    * 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 org.springframework.batch.core.listener;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.List;
  
  import org.springframework.core.Ordered;
  import org.springframework.core.annotation.AnnotationAwareOrderComparator;
  import org.springframework.core.annotation.AnnotationUtils;
  import org.springframework.core.annotation.Order;
  
  /**
   * @author Dave Syer
   * 
   */
  class OrderedComposite<S> {
  
  	private List<S> unordered = new ArrayList<S>();
  
  	private List<S> ordered = new ArrayList<S>();
  	
  	@SuppressWarnings("unchecked")
  	private Comparator<? super S> comparator = new AnnotationAwareOrderComparator();
  
  	private List<S> list = new ArrayList<S>();
  
  	/**
  	 * Public setter for the listeners.
  	 * 
  	 * @param items
  	 */
  	public void setItems(List<? extends S> items) {
  		unordered.clear();
  		ordered.clear();
  		for (S s : items) {
  			add(s);
  		}
  	}
  
  	/**
  	 * Register additional item.
  	 * 
  	 * @param item
  	 */
  	public void add(S item) {
  		if (item instanceof Ordered) {
  			if (!ordered.contains(item)) {
  				ordered.add(item);
  			}
  		}
  		else if (AnnotationUtils.isAnnotationDeclaredLocally(Order.class, item.getClass())) {
  			if (!ordered.contains(item)) {
  				ordered.add(item);
  			}
  		}
  		else if (!unordered.contains(item)) {
  			unordered.add(item);
  		}
  		Collections.sort(ordered, comparator);
  		list.clear();
  		list.addAll(ordered);
  		list.addAll(unordered);
  	}
  
  	/**
  	 * Public getter for the list of items. The {@link Ordered} items come
  	 * first, followed by any unordered ones.
  	 * @return an iterator over the list of items
  	 */
  	public Iterator<S> iterator() {
  		return new ArrayList<S>(list).iterator();
  	}
  
  	/**
  	 * Public getter for the list of items in reverse. The {@link Ordered} items
  	 * come last, after any unordered ones.
  	 * @return an iterator over the list of items
  	 */
  	public Iterator<S> reverse() {
  		ArrayList<S> result = new ArrayList<S>(list);
  		Collections.reverse(result);
  		return result.iterator();
 	}
 
 }