ThemesPhotoCollectionProvider.java
/*
* *********************************************************************************************************************
*
* blueMarine II: Semantic Media Centre
* http://tidalwave.it/projects/bluemarine2
*
* Copyright (C) 2015 - 2021 by Tidalwave s.a.s. (http://tidalwave.it)
*
* *********************************************************************************************************************
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*
* *********************************************************************************************************************
*
* git clone https://bitbucket.org/tidalwave/bluemarine2-src
* git clone https://github.com/tidalwave-it/bluemarine2-src
*
* *********************************************************************************************************************
*/
package it.tidalwave.bluemarine2.service.stoppingdown.impl;
import javax.annotation.Nonnull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.concurrent.ConcurrentHashMap;
import java.util.List;
import java.util.Map;
import java.io.IOException;
import java.nio.file.Paths;
import java.nio.file.Path;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import it.tidalwave.util.annotation.VisibleForTesting;
import org.xml.sax.SAXException;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import it.tidalwave.bluemarine2.model.MediaFolder;
import it.tidalwave.bluemarine2.model.VirtualMediaFolder;
import it.tidalwave.bluemarine2.model.spi.PathAwareEntity;
import it.tidalwave.bluemarine2.model.spi.PathAwareFinder;
import lombok.extern.slf4j.Slf4j;
import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.*;
import static javax.xml.xpath.XPathConstants.*;
/***********************************************************************************************************************
*
* @author Fabrizio Giudici
*
**********************************************************************************************************************/
@Slf4j
public class ThemesPhotoCollectionProvider extends PhotoCollectionProviderSupport
{
private static final String URL_THEMES_TEMPLATE = "%s/themes/";
private static final Path PATH_SUBJECTS = Paths.get("subjects");
private static final Path PATH_PLACES = Paths.get("places");
@VisibleForTesting static final XPathExpression XPATH_SUBJECTS_THUMBNAIL_EXPR;
@VisibleForTesting static final XPathExpression XPATH_PLACES_THUMBNAIL_EXPR;
private static final XPathExpression XPATH_THUMBNAIL_URL_EXPR;
private static final XPathExpression XPATH_THUMBNAIL_DESCRIPTION_EXPR;
/**
* A local cache for themes is advisable because multiple calls will be performed.
*/
private final Map<XPathExpression, List<GalleryDescription>> themesCache = new ConcurrentHashMap<>();
/*******************************************************************************************************************
*
******************************************************************************************************************/
static
{
try
{
final XPath xpath = XPATH_FACTORY.newXPath();
// XPATH_SUBJECTS_THUMBNAIL_EXPR = xpath.compile("//div[@class='container-fluid']/h3[1]/following-sibling::div[@class='thumbnail']");
// XPATH_PLACES_THUMBNAIL_EXPR = xpath.compile("//div[@class='container-fluid']/h3[2]/following-sibling::div[@class='thumbnail']");
XPATH_SUBJECTS_THUMBNAIL_EXPR = xpath.compile("//div[@class='container-fluid']/div[@class='row'][1]//div[@class='thumbnail']");
XPATH_PLACES_THUMBNAIL_EXPR = xpath.compile("//div[@class='container-fluid']/div[@class='row'][2]//div[@class='thumbnail']");
XPATH_THUMBNAIL_URL_EXPR = xpath.compile("a/@href");
XPATH_THUMBNAIL_DESCRIPTION_EXPR = xpath.compile(".//div[@class='caption']/h3/text()");
}
catch (XPathExpressionException e)
{
throw new ExceptionInInitializerError(e);
}
}
/*******************************************************************************************************************
*
******************************************************************************************************************/
public ThemesPhotoCollectionProvider()
{
this(URL_STOPPINGDOWN);
}
/*******************************************************************************************************************
*
******************************************************************************************************************/
public ThemesPhotoCollectionProvider (@Nonnull final String baseUrl)
{
super(baseUrl);
}
/*******************************************************************************************************************
*
* {@inheritDoc}
*
******************************************************************************************************************/
@Override @Nonnull
public PathAwareFinder findPhotos (@Nonnull final MediaFolder parent)
{
return parent.finderOf(p -> List.of(
new VirtualMediaFolder(p, PATH_PLACES, "Places", this::placesFactory),
new VirtualMediaFolder(p, PATH_SUBJECTS, "Subjects", this::subjectsFactory)));
}
/*******************************************************************************************************************
*
* {@inheritDoc}
*
******************************************************************************************************************/
@Override
protected void clearCachesImpl()
{
super.clearCachesImpl();
themesCache.clear();
}
/*******************************************************************************************************************
*
******************************************************************************************************************/
@Nonnull
private Collection<PathAwareEntity> subjectsFactory (@Nonnull final MediaFolder parent)
{
return parseThemes(XPATH_SUBJECTS_THUMBNAIL_EXPR).stream()
.map(gallery -> gallery.createFolder(parent, this::findPhotos))
.collect(toList());
}
/*******************************************************************************************************************
*
******************************************************************************************************************/
@Nonnull
private Collection<PathAwareEntity> placesFactory (@Nonnull final MediaFolder parent)
{
return parseThemes(XPATH_PLACES_THUMBNAIL_EXPR).stream()
.map(gallery -> gallery.createFolder(parent, this::findPhotos))
.collect(toList());
}
/*******************************************************************************************************************
*
******************************************************************************************************************/
@Nonnull
@VisibleForTesting List<GalleryDescription> parseThemes (@Nonnull final XPathExpression expr)
{
final String themeUrl = String.format(URL_THEMES_TEMPLATE, baseUrl);
log.debug("parseThemes({}, {})", themeUrl, expr);
return themesCache.computeIfAbsent(expr, key ->
{
try
{
final Document document = downloadXml(themeUrl);
final NodeList thumbnailNodes = (NodeList)expr.evaluate(document, NODESET);
final List<GalleryDescription> galleryDescriptions = new ArrayList<>();
for (int i = 0; i < thumbnailNodes.getLength(); i++)
{
final Node thumbnailNode = thumbnailNodes.item(i);
final String description = (String)XPATH_THUMBNAIL_DESCRIPTION_EXPR.evaluate(thumbnailNode, STRING);
final String href = (String)XPATH_THUMBNAIL_URL_EXPR.evaluate(thumbnailNode, STRING);
final String url = String.format(URL_GALLERY_TEMPLATE, baseUrl, href).replace("//", "/")
.replace(":/", "://");
galleryDescriptions.add(new GalleryDescription(description, url));
}
galleryDescriptions.sort(comparing(GalleryDescription::getDisplayName));
return galleryDescriptions;
}
catch (SAXException | IOException | XPathExpressionException | ParserConfigurationException e)
{
throw new RuntimeException(e);
}
});
}
}