/*

  * $Source$

  * $Revision$

  *

  * Copyright (C) 2003 Tim Pizey

  *

  * Part of Melati (http://melati.org), a framework for the rapid

  * development of clean, maintainable web applications.

  *

  * Melati is free software; Permission is granted to copy, distribute

  * and/or modify this software under the terms either:

  *

  * a) the GNU General Public License as published by the Free Software

  *    Foundation; either version 2 of the License, or (at your option)

  *    any later version,

  *

  *    or

  *

  * b) any version of the Melati Software License, as published

  *    at http://melati.org

  *

  * You should have received a copy of the GNU General Public License and

  * the Melati Software License along with this program;

  * if not, write to the Free Software Foundation, Inc.,

  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the

  * GNU General Public License and visit http://melati.org to obtain the

  * Melati Software License.

  *

  * Feel free to contact the Developers of Melati (http://melati.org),

  * if you would like to work out a different arrangement than the options

  * outlined here.  It is our intention to allow Melati to be used by as

  * wide an audience as possible.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * Contact details for copyright holder:

  *

  *     Tim Pizey <timp At paneris.org>

  */

 package org.melati.util;

 import java.util.Vector;

 import java.util.Enumeration;

 /**

  * All the code common to {@link CountedDumbPagedEnumeration}

  * and {@link DumbPagedEnumeration}.

  */

 public abstract class PagedEnumerationBase<T> implements PagedEnumeration<T> {

   int pageStart, pageSize;

   Vector<T> page;

   int totalCount;

   Enumeration<T> us;

   int currentPosition;

   // 

   // -------------

   //  Enumeration

   // -------------

   // 

   /**

    * {@inheritDoc}

    * @see java.util.Enumeration#hasMoreElements()

    */

   public boolean hasMoreElements() {

     return us.hasMoreElements();

   }

   /**

    * {@inheritDoc}

    * @see java.util.Enumeration#nextElement()

    */

   public T nextElement() {

     currentPosition++;

     return us.nextElement();

   }

   // 

   // -----------------

   //  PagedEnumeration

   // -----------------

   // 

   @Override

   public int getPageStart() {

     return pageStart;

   }

   @Override

   public int getPageEnd() {

     return pageStart + page.size() - 1;

   }

   @Override

   public int getTotalCount() {

     return totalCount;

   }

   @Override

   public Integer getPrevPageStart() {

     int it = pageStart - pageSize;

     return it < 0 ? null : new Integer(it);

   }

   @Override

   public int getCurrentPosition() {

     return currentPosition;

   }

   @Override

   public int getNextPosition() {

     return hasMoreElements() ? currentPosition + 1 : 0;

   }

   @Override

   public boolean nextElementOnThisPage() {

     return hasMoreElements() && getPageEnd() >= getNextPosition();

   }

   @Override

   public int getPageSize() {

     return page.size();

   }

   /**

    * @return All Pages

    */

   public Vector<Page> getPages() {

     Vector<Page> ret = new Vector<Page>(totalCount / pageSize);

     int i = 1;

     while(((i - 1) * pageSize) < totalCount) {

       ret.addElement(new Page(i, ((i - 1) * pageSize) + 1));

       i++;

     }

     return ret;

   }

 }