/*
    * 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.struts2.components;
  
  import com.opensymphony.xwork2.util.ValueStack;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.struts2.components.Param.UnnamedParametric;
  import org.apache.struts2.util.AppendIteratorFilter;
  import org.apache.struts2.util.MakeIterator;
  import org.apache.struts2.views.annotations.StrutsTag;
  import org.apache.struts2.views.annotations.StrutsTagAttribute;
  
  import java.io.Writer;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * <!-- START SNIPPET: javadoc -->
   * <p>Component for AppendIteratorTag, which jobs is to append iterators to form an
   * appended iterator whereby entries goes from one iterator to another after each
   * respective iterator is exhausted of entries.</p>
   *
   * <p>For example, if there are 3 iterator appended (each iterator has 3 entries),
   * the following will be how the appended iterator entries will be arranged:</p>
   *
   * <ol>
   *      <li>First Entry of the First Iterator</li>
   *      <li>Second Entry of the First Iterator</li>
   *      <li>Third Entry of the First Iterator</li>
   *      <li>First Entry of the Second Iterator</li>
   *      <li>Second Entry of the Second Iterator</li>
   *      <li>Third Entry of the Second Iterator</li>
   *      <li>First Entry of the Third Iterator</li>
   *      <li>Second Entry of the Third Iterator</li>
   *      <li>Third Entry of the Third ITerator</li>
   * </ol>
   * <!-- END SNIPPET: javadoc -->
   *
   * <!-- START SNIPPET: params -->
   * <ul>
   *      <li>var (String) - the name of which if supplied will have the resultant
   *                        appended iterator stored under in the stack's context</li>
   * </ul>
   * <!-- END SNIPPET: params -->
   *
   *
   * <!-- START SNIPPET: code -->
   * public class AppendIteratorTagAction extends ActionSupport {
   *
   *  private List myList1;
   *  private List myList2;
   *  private List myList3;
   *
   *
   *  public String execute() throws Exception {
   *
   *      myList1 = new ArrayList();
   *      myList1.add("1");
   *      myList1.add("2");
   *      myList1.add("3");
   *
   *      myList2 = new ArrayList();
   *      myList2.add("a");
   *      myList2.add("b");
   *      myList2.add("c");
   *
   *      myList3 = new ArrayList();
   *      myList3.add("A");
   *      myList3.add("B");
   *      myList3.add("C");
   *
   *      return "done";
   *  }
   *
   *  public List getMyList1() { return myList1; }
   *  public List getMyList2() { return myList2; }
   *  public List getMyList3() { return myList3; }
   *}
   * <!-- END SNIPPET: code -->
   *
   * <!-- START SNIPPET: example -->
  * &lt;s:append var="myAppendIterator"&gt;
  *      &lt;s:param value="%{myList1}" /&gt;
  *      &lt;s:param value="%{myList2}" /&gt;
  *      &lt;s:param value="%{myList3}" /&gt;
  * &lt;/s:append&gt;
  * &lt;s:iterator value="%{#myAppendIterator}"&gt;
  *      &lt;s:property /&gt;
  * &lt;/s:iterator&gt;
  * <!-- END SNIPPET: example -->
  *
  *
  * @see org.apache.struts2.util.AppendIteratorFilter
  * @see org.apache.struts2.views.jsp.iterator.AppendIteratorTag
  *
  */
 @StrutsTag(name="append", tldTagClass="org.apache.struts2.views.jsp.iterator.AppendIteratorTag", description="Append the values of a list of iterators to one iterator")
 public class AppendIterator extends ContextBean implements UnnamedParametric {
 
     private static final Logger LOG = LogManager.getLogger(AppendIterator.class);
 
     private AppendIteratorFilter appendIteratorFilter= null;
     private List _parameters;
 
     public AppendIterator(ValueStack stack) {
         super(stack);
     }
 
     public boolean start(Writer writer) {
         _parameters = new ArrayList();
         appendIteratorFilter = new AppendIteratorFilter();
 
         return super.start(writer);
     }
 
     public boolean end(Writer writer, String body) {
 
         for (Iterator paramEntries = _parameters.iterator(); paramEntries.hasNext(); ) {
 
             Object iteratorEntryObj = paramEntries.next();
             if (! MakeIterator.isIterable(iteratorEntryObj)) {
                 LOG.warn("param with value resolved as {} cannot be make as iterator, it will be ignored and hence will not appear in the merged iterator", iteratorEntryObj);
                 continue;
             }
             appendIteratorFilter.setSource(MakeIterator.convert(iteratorEntryObj));
         }
 
         appendIteratorFilter.execute();
 
         putInContext(appendIteratorFilter);
 
         appendIteratorFilter = null;
 
         return super.end(writer, body);
     }
 
     // UnnamedParametric implementation --------------------------------------
     public void addParameter(Object value) {
         _parameters.add(value);
     }
 
     @StrutsTagAttribute(description="The name of which if supplied will have the resultant appended iterator stored under in the stack's context")
     public void setVar(String var) {
         super.setVar(var);
     }
 }