001// Copyright 2007, 2008, 2009, 2010, 2011, 2012 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.corelib.components;
016
017import org.apache.tapestry5.*;
018import org.apache.tapestry5.annotations.Events;
019import org.apache.tapestry5.annotations.Parameter;
020import org.apache.tapestry5.commons.Messages;
021import org.apache.tapestry5.dom.Element;
022import org.apache.tapestry5.grid.GridDataSource;
023import org.apache.tapestry5.http.Link;
024import org.apache.tapestry5.http.services.Request;
025import org.apache.tapestry5.internal.InternalConstants;
026import org.apache.tapestry5.ioc.annotations.Inject;
027
028/**
029 * Generates a series of links used to jump to a particular page index within the overall data set.
030 *
031 * @tapestrydoc
032 */
033@Events(InternalConstants.GRID_INPLACE_UPDATE + " (internal event)")
034public class GridPager
035{
036    /**
037     * The source of the data displayed by the grid (this is used to determine {@link GridDataSource#getAvailableRows()
038     * how many rows are available}, which in turn determines the page count).
039     */
040    @Parameter(required = true)
041    private GridDataSource source;
042
043    /**
044     * The number of rows displayed per page.
045     */
046    @Parameter(required = true)
047    private int rowsPerPage;
048
049    /**
050     * The current page number (indexed from 1).
051     */
052    @Parameter(required = true)
053    private int currentPage;
054
055    /**
056     * Number of pages before and after the current page in the range. The pager always displays links for 2 * range + 1
057     * pages, unless that's more than the total number of available pages.
058     */
059    @Parameter(BindingConstants.SYMBOL + ":" + ComponentParameterConstants.GRIDPAGER_PAGE_RANGE)
060    private int range;
061
062    /**
063     * If not null, then each link is output as a link to update the specified zone.
064     */
065    @Parameter
066    private String zone;
067
068    private int lastIndex;
069
070    private int maxPages;
071
072    @Inject
073    private ComponentResources resources;
074
075    @Inject
076    private Messages messages;
077
078    @Inject
079    private Request request;
080
081    void beginRender(MarkupWriter writer)
082    {
083        int availableRows = source.getAvailableRows();
084
085        maxPages = ((availableRows - 1) / rowsPerPage) + 1;
086
087        if (maxPages < 2) return;
088
089        writer.element("ul", "class", "pagination");
090
091        if (zone != null)
092        {
093            writer.attributes("data-inplace-grid-links", true);
094        }
095
096        lastIndex = 0;
097
098        for (int i = 1; i <= 2; i++)
099            writePageLink(writer, i);
100
101        int low = currentPage - range;
102        int high = currentPage + range;
103
104        if (low < 1)
105        {
106            low = 1;
107            high = 2 * range + 1;
108        } else
109        {
110            if (high > maxPages)
111            {
112                high = maxPages;
113                low = high - 2 * range;
114            }
115        }
116
117        for (int i = low; i <= high; i++)
118            writePageLink(writer, i);
119
120        for (int i = maxPages - 1; i <= maxPages; i++)
121            writePageLink(writer, i);
122
123        writer.end();    // ul
124    }
125
126    private void writePageLink(MarkupWriter writer, int pageIndex)
127    {
128        if (pageIndex < 1 || pageIndex > maxPages) return;
129
130        if (pageIndex <= lastIndex) return;
131
132        if (pageIndex != lastIndex + 1)
133        {
134            writer.element("li", "class", "disabled");
135            writer.element("a", "href", "#");
136            writer.write(" ... ");
137            writer.end();
138            writer.end();
139        }
140
141        lastIndex = pageIndex;
142
143        if (pageIndex == currentPage)
144        {
145            writer.element("li", "class", "active");
146            writer.element("a", "href", "#");
147            writer.write(Integer.toString(pageIndex));
148            writer.end();
149            writer.end();
150            return;
151        }
152
153        writer.element("li");
154
155        Link link = resources.createEventLink(EventConstants.ACTION, pageIndex);
156
157        if (zone != null)
158        {
159            link.addParameter("t:inplace", "true");
160        }
161
162        Element element = writer.element("a",
163                "href", link,
164                "data-update-zone", zone,
165                "title", messages.format("core-goto-page", pageIndex));
166
167
168        writer.write(Integer.toString(pageIndex));
169
170        writer.end();
171
172        writer.end();   // li
173    }
174
175    /**
176     * Repaging event handler.
177     */
178    boolean onAction(int newPage)
179    {
180        // TODO: Validate newPage in range
181
182        currentPage = newPage;
183
184        if (request.isXHR())
185        {
186            resources.triggerEvent(InternalConstants.GRID_INPLACE_UPDATE, null, null);
187        }
188
189        return true;     // abort event
190    }
191}