/*

  * $Source$

  * $Revision$

  *

  * Copyright (C) 2000 William Chesters

  *

  * 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:

  *

  *     William Chesters <williamc At paneris.org>

  *     http://paneris.org/~williamc

  *     Obrechtstraat 114, 2517VX Den Haag, The Netherlands

  */

 package org.melati.util;

 import java.util.Enumeration;

 import java.util.Vector;

 import org.melati.poem.util.EnumUtils;

 /**

  * A {@link PagedEnumeration} which doesn't know how big it is.

  * Ideally SQL would allow you to start at an offset.

  */

 public class DumbPagedEnumeration<T> extends PagedEnumerationBase<T> {

   private boolean totalCountIsMinimum;

   /**

    * Constructor.

    * @param base underlying Enumeration

    * @param pageStart index of start of page 

    * @param pageSize  how many Elements to include upon a page 

    * @param countHorizon where to count to, may be less than total size of underlying Enumeration

    */

   public DumbPagedEnumeration(Enumeration<T> base,

                              int pageStart, int pageSize, int countHorizon) {

     pageStart = Math.max(pageStart, 1);

     this.pageStart = pageStart;

     this.pageSize = pageSize;

     int offset = EnumUtils.skip(base, pageStart - 1);

     page = EnumUtils.initial(base, pageSize);

     // NOTE This is the bit that makes it dumb!

     totalCount = offset + page.size() +

                      EnumUtils.skip(base, countHorizon - (offset + page.size()));

     totalCountIsMinimum = base.hasMoreElements();

     us = page.elements();

     currentPosition = pageStart - 1; 

   }

   @Override

   public Integer getNextPageStart() {

     int it = pageStart + pageSize;

     return (totalCountIsMinimum || it <= totalCount) ? new Integer(it) : null;

   }

   /**

    * @return whether there are more elements to come beyond horizon 

    */

   public boolean getTotalCountIsMinimum() {

     return totalCountIsMinimum;

   }

   public Vector<Page> getPageStartList() {

     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;

   }

 }