/**
    * Copyright 2005-2013 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.krms.util;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * @author Kuali Student Team
   */
  public class AlphaIterator implements Serializable, Iterator {
  
      private List<Inner> list = new ArrayList<Inner>();
      private String prefix;
  
      public AlphaIterator(String prefix){
          super();
          this.prefix = prefix;
      }
  
      @Override
      public boolean hasNext() {
          return true;
      }
  
      @Override
      public Object next() {
  
          //Add an initial value to the list
          if (list.isEmpty()) {
              list.add(new Inner());
          } else {
  
              //Increment the value
              for (int i = list.size() - 1; i >= 0; i--) {
                  Inner in = list.get(i);
                  if (in.increment()>0) {
                      break;
                  } else {
                      in.reset();
                      if (i == 0) {
                          list.add(new Inner());
                      }
                  }
              }
          }
  
          //Create the return string
          StringBuilder returnValue = new StringBuilder();
          for (Inner in : list) {
              returnValue.append((char)in.current());
          }
  
          return prefix + returnValue;
      }
  
      @Override
      public void remove() {
          //To change body of implemented methods use File | Settings | File Templates.
      }
  
      private class Inner implements Serializable{
  
          private final static int START = 'A';
          private final static int END = 'Z';
  
          private int value;
  
          public Inner() {
              value = START;
          }
  
          public void reset() {
              value = START;
          }
  
          public int current() {
              return value;
          }
  
          public int increment() {
              if (value == END) {
                  return -1;
              } else {
                 return value++;
             }
         }
 
     }
 }