IndexRssView.java

/*
 * Copyright 2015-2016 EuregJUG.
 *
 * 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.
 */
package eu.euregjug.site.web;

import ac.simons.syndication.utils.SyndicationGuid;
import ac.simons.syndication.utils.SyndicationLink;
import com.rometools.modules.atom.modules.AtomLinkModuleImpl;
import com.rometools.rome.feed.atom.Link;
import com.rometools.rome.feed.rss.Channel;
import com.rometools.rome.feed.rss.Content;
import com.rometools.rome.feed.rss.Item;
import eu.euregjug.site.posts.Post;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.stream.Collectors;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.context.MessageSource;
import org.springframework.data.domain.Page;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.view.feed.AbstractRssFeedView;

/**
 * @author Michael J. Simons, 2015-12-30
 */
@Component("index.rss")
@SuppressWarnings({"squid:MaximumInheritanceDepth"}) // Cannot change this...
class IndexRssView extends AbstractRssFeedView {

    private static final ZoneId UTC = ZoneId.of("UTC");

    private final MessageSource messageSource;

    private final DateTimeFormatter permalinkDateFormatter;

    IndexRssView(final MessageSource messageSource) {
        this.messageSource = messageSource;
        this.permalinkDateFormatter = DateTimeFormatter.ofPattern("/y/M/d", Locale.ENGLISH);
    }

    String getAbsoluteUrl(final HttpServletRequest request, final String relativeUrl) {
        final int port = request.getServerPort();
        final String hostWithPort = String.format("%s://%s%s",
                request.isSecure() ? "https" : "http",
                request.getServerName(),
                Arrays.asList(80, 443).contains(port) ? "" : String.format(":%d", port)
        );
        return String.format("%s%s%s", hostWithPort, request.getContextPath(), relativeUrl);
    }

    @Override
    protected void buildFeedMetadata(final Map<String, Object> model, final Channel feed, final HttpServletRequest request) {
        final Page<Post> posts = (Page<Post>) model.get("posts");

        final Locale locale = request.getLocale();
        feed.setEncoding("UTF-8");
        feed.setTitle(String.format("%s - %s", messageSource.getMessage("siteTitle", null, locale), messageSource.getMessage("siteSubTitle", null, locale)));
        feed.setDescription(messageSource.getMessage("feedDescription", null, locale));
        feed.setLink(getAbsoluteUrl(request, ""));
        if (posts.hasContent()) {
            final Date pubDate = Date.from(posts.getContent().get(0).getPublishedOn().atStartOfDay(UTC).toInstant());
            feed.setLastBuildDate(pubDate);
            feed.setPubDate(pubDate);
        }
        feed.setGenerator("https://github.com/EuregJUG-Maas-Rhine/site");

        final String hrefFormat = "%s?page=%d";
        final String self = getAbsoluteUrl(request, "/feed.rss");
        final List<Link> atomLinks = new ArrayList<>();
        atomLinks.add(new SyndicationLink().withRel("self").withType(super.getContentType()).withHref(String.format(hrefFormat, self, posts.getNumber())).getLink());
        if (posts.hasPrevious()) {
            atomLinks.add(new SyndicationLink()
                    .withRel("previous")
                    .withType(super.getContentType())
                    .withHref(String.format(hrefFormat, self, posts.previousPageable().getPageNumber()))
                    .getLink()
            );
        }
        if (posts.hasNext()) {
            atomLinks.add(new SyndicationLink()
                    .withRel("next")
                    .withType(super.getContentType())
                    .withHref(String.format(hrefFormat, self, posts.nextPageable().getPageNumber()))
                    .getLink()
            );
        }
        feed.getModules().addAll(atomLinks.stream().map(l -> {
            final AtomLinkModuleImpl rv = new AtomLinkModuleImpl();
            rv.setLink(l);
            return rv;
        }).collect(Collectors.toList()));
    }

    @Override
    protected List<Item> buildFeedItems(final Map<String, Object> model, final HttpServletRequest request, final HttpServletResponse response) throws Exception {
        final Page<Post> posts = (Page<Post>) model.get("posts");

        return posts.map(post -> {
            final Item rv = new Item();
            final Content content = new Content();
            content.setType(Content.HTML);
            content.setValue(post.getContent());
            final String link = getAbsoluteUrl(request, String.format("%s/%s", permalinkDateFormatter.format(post.getPublishedOn()), post.getSlug()));

            rv.setAuthor("euregjug.eu");
            rv.setContent(content);
            rv.setGuid(new SyndicationGuid().withPermaLink(true).withValue(link).getGuid());
            rv.setLink(link);
            rv.setPubDate(Date.from(post.getPublishedOn().atStartOfDay(UTC).toInstant()));
            rv.setTitle(post.getTitle());
            return rv;
        }).getContent();
    }
}