| gvSIG desktop 1

/* gvSIG. Geographic Information System of the Valencian Government

 *

 * Copyright (C) 2007-2008 Infrastructures and Transports Department

 * of the Valencian Government (CIT)

 * 

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of 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.

 * 

 * 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.

 * 

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

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 

 * MA  02110-1301, USA.

 * 

 */

package org.gvsig.fmap.dal.feature.paging.impl;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * Abstract base implementation.

 * 

 * @author 2010- C?sar Ordi?ana - gvSIG team

 */

public abstract class AbstractPagingCalculator implements PagingCalculator {

        private static final Logger LOG =

                        LoggerFactory.getLogger(AbstractPagingCalculator.class);

        private int maxPageSize;

        private long currentPage;

        /**

         * Creates a new {@link AbstractPagingCalculator}, setting the current page

         * to the first one.

         * 

         * @param maxPageSize

         *            the maximum page size

         */

        public AbstractPagingCalculator(int maxPageSize) {

                this(maxPageSize, 0);

        }

        /**

         * Creates a new {@link AbstractPagingCalculator} .

         * 

         * @param maxPageSize

         *            the maximum page size

         * @param currentPage

         *            the current page

         */

        public AbstractPagingCalculator(int maxPageSize, long currentPage) {

                this.maxPageSize = maxPageSize;

                this.currentPage = currentPage;

        }

        public int getMaxPageSize() {

                return maxPageSize;

        }

        public void setMaxPageSize(int maxPageSize) {

                if (maxPageSize < 0) {

                        throw new IndexOutOfBoundsException(

                                        "Error, unable to set the max page size to a "

                                                        + "negative value: " + maxPageSize);

                }

                this.maxPageSize = maxPageSize;

        }

        public long getCurrentPage() {

                return currentPage;

        }

        public void setCurrentPage(long currentPage) {

                if (LOG.isDebugEnabled()) {

                        LOG.debug("Setting current page to: {}", Long.toString(currentPage));

                }

                if (currentPage < 0) {

                        throw new IndexOutOfBoundsException(

                                        "Error, unable to set current page to a "

                                                        + "negative value: " + currentPage);

                }

                if (currentPage >= getNumPages()) {

                        throw new IndexOutOfBoundsException(

                                        "Error, unable to set current page to the page num. "

                                                        + currentPage + ", as we have only "

                                                        + getNumPages() + " pages of data");

                }

                this.currentPage = currentPage;

        }

        public long getInitialIndex() {

                return getCurrentPage() * getMaxPageSize();

        }

        protected long getLastIndex() {

                return getInitialIndex() + getCurrentPageSize() - 1;

        }

        public long getNumPages() {

                return ((long) Math.floor(getTotalSize() / (long) getMaxPageSize())) + 1;

        }

        public int getCurrentPageSize() {

                long currentPage = getCurrentPage();

                if (currentPage < (getNumPages() - 1)) {

                        return getMaxPageSize();

                } else {

                        return (int) (getTotalSize() - (currentPage * getMaxPageSize()));

                }

        }

}