PageableList.java

/*******************************************************************************
 * This file is part of OpenNMS(R).
 *
 * Copyright (C) 2010-2011 The OpenNMS Group, Inc.
 * OpenNMS(R) is Copyright (C) 1999-2011 The OpenNMS Group, Inc.
 *
 * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
 *
 * OpenNMS(R) 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 3 of the License,
 * or (at your option) any later version.
 *
 * OpenNMS(R) 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 OpenNMS(R).  If not, see:
 *      http://www.gnu.org/licenses/
 *
 * For more information contact:
 *     OpenNMS(R) Licensing <license@opennms.org>
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package org.opennms.features.poller.remote.gwt.client;

import org.opennms.features.poller.remote.gwt.client.events.LocationPanelSelectEvent;
import org.opennms.features.poller.remote.gwt.client.events.LocationPanelSelectEventHandler;

import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.resources.client.CssResource;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiField;
import com.google.gwt.uibinder.client.UiHandler;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HTMLTable.Cell;
import com.google.gwt.user.client.ui.Hyperlink;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.Panel;
import com.google.gwt.user.client.ui.Widget;

/**
 * The Basic building blocks for a simple Pageable List
 *
 * @author Donald Desloge
 * @version $Id: $
 * @since 1.8.1
 */
public abstract class PageableList extends Composite {

    private static PageableListUiBinder uiBinder = GWT.create(PageableListUiBinder.class);

    interface PageableListUiBinder extends UiBinder<Widget, PageableList> {}
    
    interface LocationDetailStyle extends CssResource{
        String detailContainerStyle();
        String iconStyle();
        String nameStyle();
        String areaStyle();
        String statusStyle();
        String alternateRowStyle();
    }
    
    private static final int TOTAL_LOCATIONS = 10;
    
    @UiField FlexTable dataList;
    @UiField Panel pagingControls;
    @UiField Hyperlink nextBtn;
    @UiField Label pageStatsLabel;
    @UiField Hyperlink prevBtn;
    @UiField LocationDetailStyle locationDetailStyle;
    
    private volatile boolean m_needsRefresh = true;
    private int m_currentPageIndex = 0;
    private int m_totalPages = 0;

    /**
     * <p>Constructor for PageableList.</p>
     */
    public PageableList() {
        initWidget(uiBinder.createAndBindUi(this));
        
        pagingControls.getElement().setId("pagingControls");
    }

    /** {@inheritDoc} */
    @Override
    protected void onLoad() {
        super.onLoad();
        new Timer() {
            @Override
            public void run() {
                if (isVisible() && m_needsRefresh) {
                    m_needsRefresh = false;
                    updateListDisplay(getCurrentPageIndex());
                }
            }
        }.scheduleRepeating(500);
    }

    /**
     * <p>refresh</p>
     */
    public void refresh() {
        m_needsRefresh = true;
    }

    /**
     * <p>showFirstPage</p>
     */
    protected void showFirstPage() {
        setCurrentPageIndex(0);
        refresh();
    }

    /**
     * <p>updateListDisplay</p>
     *
     * @param currentPageIndex a int.
     */
    protected void updateListDisplay(final int currentPageIndex) {
        getDataList().removeAllRows();

        int rowCount = 0;
        final int size = getListSize();
        final int showableLocations = ((currentPageIndex + 1) * getTotalListItemsPerPage()) > size ? size : ((currentPageIndex + 1) * getTotalListItemsPerPage());
        final int startIndex = currentPageIndex * getTotalListItemsPerPage(); 

        for(int i = startIndex; i < showableLocations; i++) {
            getDataList().setWidget(rowCount, 0, getListItemWidget(i));
            
            if(rowCount % 2 == 0) {
                getDataList().getRowFormatter().addStyleName(rowCount, getAlternateRowStyle());
            }
            
            rowCount++;
        }
        
        calculateAndSetTotalPages(size);
        updatePageStatsDisplay(startIndex + 1, showableLocations, getListSize());
    }

    protected void calculateAndSetTotalPages(final int size) {
        if(size > getTotalListItemsPerPage()) {
            int totalPages = (int) Math.ceil(size / getTotalListItemsPerPage());
            if(totalPages == 0) {
                totalPages = 1;
            }
            setTotalPages( totalPages );
            
        }else {
            setTotalPages(0);
        }
    }

    /**
     * <p>getAlternateRowStyle</p>
     *
     * @return a {@link java.lang.String} object.
     */
    protected String getAlternateRowStyle() {
        return locationDetailStyle.alternateRowStyle();
    }
    
    /**
     * <p>getListSize</p>
     *
     * @return a int.
     */
    protected abstract int getListSize();
    
    /**
     * <p>getListItemWidget</p>
     *
     * @param rowIndex a int.
     * @return a {@link com.google.gwt.user.client.ui.Widget} object.
     */
    protected abstract Widget getListItemWidget(final int rowIndex);

    /**
     * <p>onItemClickHandler</p>
     *
     * @param event a {@link com.google.gwt.event.dom.client.ClickEvent} object.
     */
    @UiHandler("dataList")
    public abstract void onItemClickHandler(final ClickEvent event);

    /**
     * <p>onPrevBtnClick</p>
     *
     * @param event a {@link com.google.gwt.event.dom.client.ClickEvent} object.
     */
    @UiHandler("prevBtn")
    public void onPrevBtnClick(final ClickEvent event) {
        final int newIndex = getCurrentPageIndex() - 1;
        setCurrentPageIndex(newIndex);
        //updateListDisplay(newIndex);
    }

    /**
     * <p>onNextBtnClick</p>
     *
     * @param event a {@link com.google.gwt.event.dom.client.ClickEvent} object.
     */
    @UiHandler("nextBtn")
    public void onNextBtnClick(final ClickEvent event) {
        final int newIndex = getCurrentPageIndex() + 1;
        setCurrentPageIndex(newIndex);
        //updateListDisplay(newIndex);
    }

    /**
     * <p>addLocationPanelSelectEventHandler</p>
     *
     * @param handler a {@link org.opennms.features.poller.remote.gwt.client.events.LocationPanelSelectEventHandler} object.
     */
    public void addLocationPanelSelectEventHandler(final LocationPanelSelectEventHandler handler) {
        addHandler(handler, LocationPanelSelectEvent.TYPE);
    }
    
    protected void setCurrentPageIndex(final int currentPageIndex) {
        calculateAndSetTotalPages(getListSize());
        if (currentPageIndex == 0) {
            m_currentPageIndex = currentPageIndex;
        } else if(currentPageIndex > 0 && currentPageIndex <= getTotalPages()) {
            m_currentPageIndex = currentPageIndex;
        }else if(currentPageIndex > getTotalPages()) {
            m_currentPageIndex = getTotalPages();
        }
        updateListDisplay(m_currentPageIndex);
    }

    /**
     * <p>getCurrentPageIndex</p>
     *
     * @return a int.
     */
    protected int getCurrentPageIndex() {
        return m_currentPageIndex;
    }

    private void setTotalPages(final int totalPages) {
        m_totalPages = totalPages;
    }

    private void updatePageStatsDisplay(final int startIndex, final int endIndex, final int total) {
        if (endIndex > 0) {
            pageStatsLabel.setText( startIndex + "-" + endIndex + " of " + total);
        } else {
            pageStatsLabel.setText("No matching items");
        }
    }

    private int getTotalPages() {
        return m_totalPages;
    }

    /**
     * <p>getTotalListItemsPerPage</p>
     *
     * @return a int.
     */
    protected int getTotalListItemsPerPage() {
        return TOTAL_LOCATIONS;
    }

    void setDataList(final FlexTable dataList) {
        this.dataList = dataList;
    }

    FlexTable getDataList() {
        return dataList;
    }

    /**
     * <p>getCellForEvent</p>
     *
     * @param event a {@link com.google.gwt.event.dom.client.ClickEvent} object.
     * @return a {@link com.google.gwt.user.client.ui.HTMLTable.Cell} object.
     */
    protected Cell getCellForEvent(final ClickEvent event) {
        return getDataList().getCellForEvent(event);
    }

}