/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.maven.plugins.changes;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.text.DateFormat;
  import java.text.ParseException;
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.List;
  import java.util.Locale;
  import java.util.ResourceBundle;
  
  import com.rometools.rome.feed.synd.SyndContent;
  import com.rometools.rome.feed.synd.SyndContentImpl;
  import com.rometools.rome.feed.synd.SyndEntry;
  import com.rometools.rome.feed.synd.SyndEntryImpl;
  import com.rometools.rome.feed.synd.SyndFeed;
  import com.rometools.rome.feed.synd.SyndFeedImpl;
  import com.rometools.rome.io.FeedException;
  import com.rometools.rome.io.SyndFeedOutput;
  import org.apache.maven.doxia.util.DoxiaUtils;
  import org.apache.maven.plugins.changes.model.Release;
  
  /**
   * @author ltheussl
   */
  public class FeedGenerator {
      private final ResourceBundle rbundle;
  
      private final SyndFeed feed;
  
      private String link;
  
      private String title;
  
      private String author;
  
      private DateFormat dateFormat;
  
      /**
       * Initialize feedGenerator for a given locale.
       *
       * @param locale a locale for i18n
       */
      public FeedGenerator(final Locale locale) {
          this.feed = new SyndFeedImpl();
          this.rbundle = ResourceBundle.getBundle(
                  "changes-report", locale, this.getClass().getClassLoader());
      }
  
      /**
       * The author of the feed.
       *
       * @return the author
       */
      public String getAuthor() {
          return author;
      }
  
      /**
       * Set the author of the feed.
       *
       * @param author not null
       */
      public void setAuthor(final String author) {
          this.author = author.trim(); // this also assures that author is not null.
      }
  
      /**
       * The title of the feed.
       *
       * @return the title
       */
      public String getTitle() {
          return title;
      }
  
      /**
       * Set the title of the feed.
       *
       * @param title not null
      */
     public void setTitle(final String title) {
         this.title = title.trim(); // this also assures that title is not null.
     }
 
     /**
      * The DateFormat.
      *
      * @return may be null
      */
     public DateFormat getDateFormat() {
         return dateFormat;
     }
 
     /**
      * Set the date format. This should match the date format used for the release dates in changes.xml.
      *
      * @param dateFormat may be null
      */
     public void setDateFormat(final DateFormat dateFormat) {
         this.dateFormat = dateFormat;
     }
 
     /**
      * The main link of the feed.
      *
      * @return the link
      */
     public String getLink() {
         return link;
     }
 
     /**
      * Set the main link of the feed.
      *
      * @param link not null
      */
     public void setLink(final String link) {
         this.link = link.trim(); // this also assures that link is not null.
     }
 
     /**
      * Determine if a given feed type is supported. The currently supported values are:
      * <code>"rss_0.9", "rss_0.91N" (RSS 0.91 Netscape), "rss_0.91U" (RSS 0.91 Userland),
      * "rss_0.92", "rss_0.93", "rss_0.94", "rss_1.0", "rss_2.0", "atom_0.3", "atom_1.0"</code>.
      *
      * @param type the feed type to check. May be null.
      * @return true if the given type is supported by the rome library, false otherwise
      */
     public boolean isSupportedFeedType(final String type) {
         return getSupportedFeedTypes().contains(type);
     }
 
     /**
      * A List of supported feed types.
      *
      * @return a List of supported feed types
      * @see #isSupportedFeedType(java.lang.String)
      */
     public List<String> getSupportedFeedTypes() {
         return feed.getSupportedFeedTypes();
     }
 
     /**
      * Extract a feed and export it to a Writer.
      *
      * @param releases the List of Releases. Only the last release is used in the feed.
      * @param feedType The type of the feed to generate. See {@link #isSupportedFeedType(java.lang.String)} for
      *            supported values.
      * @param writer a Writer. Note that this is not flushed nor closed upon exit.
      * @throws IOException if an error occurs during export
      */
     public void export(final List<Release> releases, final String feedType, final Writer writer) throws IOException {
         feed.setFeedType(feedType);
         feed.setTitle(title);
         feed.setAuthor(author);
         feed.setPublishedDate(new Date());
         feed.setLink(link);
         feed.setDescription(rbundle.getString("report.changes.text.rssfeed.description"));
         feed.setLanguage(rbundle.getLocale().getLanguage());
         feed.setEntries(getEntries(releases));
 
         try {
             new SyndFeedOutput().output(feed, writer);
         } catch (FeedException ex) {
             throw new IOException(ex.getMessage(), ex);
         }
     }
 
     private List<SyndEntry> getEntries(final List<Release> releases) {
         final List<SyndEntry> entries = new ArrayList<>(1);
 
         if (!releases.isEmpty()) {
             final Release release = releases.get(0); // TODO: is this guaranteed to be the latest?
 
             final SyndEntry entry = new SyndEntryImpl();
             entry.setTitle(release.getVersion());
             entry.setLink(link + "#" + DoxiaUtils.encodeId(release.getVersion()));
             entry.setDescription(getSyndContent(release));
             entry.setPublishedDate(getDate(release.getDateRelease(), dateFormat));
 
             entries.add(entry);
         }
 
         return entries;
     }
 
     private static SyndContent getSyndContent(final Release release) {
         final SyndContent syndContent = new SyndContentImpl();
         syndContent.setType("text/html");
 
         final StringBuilder sb = new StringBuilder(512);
 
         final String description = release.getDescription();
 
         if (description != null && !description.trim().isEmpty()) {
             sb.append("<p>").append(description).append("</p>");
         }
 
         sb.append("<p>Version ").append(release.getVersion()).append(" is available with ");
         sb.append(release.getActions().size()).append(" fixed issues.</p>");
 
         syndContent.setValue(sb.toString());
 
         return syndContent;
     }
 
     private static Date getDate(final String dateRelease, final DateFormat dateFormat) {
         if (dateFormat == null) {
             return new Date();
         }
 
         try {
             return dateFormat.parse(dateRelease);
         } catch (ParseException ex) {
             return new Date();
         }
     }
 }