/**
    * This file Copyright (c) 2003-2013 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.module.rssaggregator.generator;
  
  import info.magnolia.commands.MgnlCommand;
  import info.magnolia.context.Context;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.jcr.util.NodeTypes;
  import info.magnolia.jcr.util.NodeUtil;
  import info.magnolia.jcr.util.PropertyUtil;
  import info.magnolia.jcr.util.VersionUtil;
  import info.magnolia.module.rssaggregator.RSSAggregatorConstants;
  import info.magnolia.module.rssaggregator.RSSAggregatorNodeTypes;
  import info.magnolia.module.rssaggregator.importhandler.FilterPredicate;
  import info.magnolia.module.rssaggregator.importhandler.FilterPredicateContentMapper;
  import info.magnolia.module.rssaggregator.importhandler.PlanetFilter;
  import info.magnolia.module.rssaggregator.util.PlanetUtil;
  
  import java.math.BigInteger;
  import java.security.MessageDigest;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import javax.jcr.Node;
  import javax.jcr.NodeIterator;
  import javax.jcr.RepositoryException;
  import javax.jcr.Session;
  
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.syndication.feed.synd.SyndContentImpl;
  import com.sun.syndication.feed.synd.SyndEntry;
  import com.sun.syndication.feed.synd.SyndEntryImpl;
  
  /**
   * Generates the data for the planet stuff.
   *
   * @author lfischer
   */
  public class PlanetDataGenerator extends MgnlCommand {
  
      private static final Logger log = LoggerFactory.getLogger(PlanetDataGenerator.class);
  
      private static final String PLANET_DATANODE_NAME = "planetData";
      private static final String POSTS_PREFIX = "posts-";
      private static final String POSTS_FIRST = POSTS_PREFIX + "00000";
      private static final String POST_ENTRY_PREFIX = "entry-";
      private static final int MAX_NODE_ENTRIES = 999;
  
      private Session session;
  
      @Override
      public boolean execute(Context context) throws Exception {
          log.info("Starting command for Planet post archive.");
          session = MgnlContext.getJCRSession(RSSAggregatorConstants.WORKSPACE);
          generatePlanetFeedData(session.getRootNode());
          log.info("Finished generating Planet archive.");
          return true;
      }
  
      /**
       * Process all RSS Aggregator feeds and create an archive of feed items if the feed is marked as planet feed.
       */
      void generatePlanetFeedData(Node root) {
          try {
             NodeIterator feeds = root.getNodes();
             while (feeds.hasNext()) {
                 Node feedOrFolderNode = feeds.nextNode();
                 if (NodeUtil.isNodeType(feedOrFolderNode, RSSAggregatorNodeTypes.RSSAggregator.NAME)) {
                     doGeneratePlanetDataForRSSAggregator(feedOrFolderNode);
                 } else if (NodeUtil.isNodeType(feedOrFolderNode, NodeTypes.Folder.NAME)) {
                     generatePlanetFeedData(feedOrFolderNode);
                 }
             }
         } catch (RepositoryException e) {
             log.error("Problem while copying feed data for planet: " + e.getMessage());
         }
     }
 
     private void doGeneratePlanetDataForRSSAggregator(Node feedNode) throws RepositoryException {
         // only generate feed archive if the feed is marked as planet feed in the data module dialog
         if (PlanetUtil.isPlanetNode(feedNode)) {
             log.info("Storing data for planet feed " + feedNode.getName());
             // create planetDataMode if it not exists
             Node planetData = NodeUtil.createPath(feedNode, PLANET_DATANODE_NAME, NodeTypes.Content.NAME, true);
 
             if (feedNode.hasNode("data")) {
                 // Get the node with the feeds for Hackergotchi lookup
                 NodeIterator channels = feedNode.getNode("data").getNodes();
                 // load filters
                 Set<FilterPredicate> planetFilters = loadPlanetFilters(feedNode);
 
                 while (channels.hasNext()) {
                     Node channel = channels.nextNode();
                     processChannelEntries(planetData, channel, planetFilters);
                 }
             }
         } else {
             log.info("Items of feed " + feedNode.getName() + " will not be archived because the feed is not marked as Planet feed.");
         }
     }
 
     /**
      * Iterate through feed data and create items in the planet archive.
      *
      * @param planetData Parent node where feed items are stored.
      * @param channel The current feed channel where current feed data are stored.
      * @param planetFilters Filter list from data dialog.
      */
     void processChannelEntries(Node planetData, Node channel, Set<FilterPredicate> planetFilters) {
         try {
             String postsParentNode = getPostsParent(planetData, channel.getNodes().getSize());
 
             Node target = NodeUtil.createPath(planetData, postsParentNode, NodeTypes.Content.NAME, true);
             long entryCount = target.getNodes().getSize();
             NodeIterator entries = channel.getNodes();
             while (entries.hasNext()) {
                 Node entry = entries.nextNode();
                 entryCount += 1;
                 createPlanetEntry(target, entry, entryCount, planetFilters);
             }
         } catch (RepositoryException e) {
             log.error("Problem while processing channel entries: " + e.getMessage());
         }
     }
 
     /**
      * Store a feed item within the planet archive.
      *
      * @param targetPath Parent node of the feed item.
      * @param srcEntry Original feed item imported by the RSS feed fetcher.
      * @param currEntry Number of current entry to be stored.
      * @param planetFilters Filter list from data dialog.
      */
     void createPlanetEntry(Node targetPath, Node srcEntry, long currEntry, Set<FilterPredicate> planetFilters) {
         try {
             String author = PlanetUtil.formatName(srcEntry, "author");
             String channelTitle = PlanetUtil.formatName(srcEntry, "channelTitle");
             String title = PropertyUtil.getString(srcEntry, "title", "");
             String description;
             if (StringUtils.isNotBlank(PropertyUtil.getString(srcEntry, "content", ""))) {
                 description = PropertyUtil.getString(srcEntry, "content", "");
             } else {
                 description = PropertyUtil.getString(srcEntry, "description", "");
             }
 
             String link = PropertyUtil.getString(srcEntry, "link", "");
             Long pubDate = srcEntry.hasProperty("pubDate") ? srcEntry.getProperty("pubDate").getLong() : null;
 
             // only store the post entry if all necessary attributes are there
             if ((StringUtils.isBlank(author) || StringUtils.isBlank(channelTitle)) || StringUtils.isBlank(title)
                     || StringUtils.isBlank(description) || StringUtils.isBlank(link) || pubDate == null) {
                 log.error("Found entry with missing mandatory attributes. The post will not be included in the planet archive.");
             } else {
                 // build the checksums
                 String checksum1 = getPostChecksum(author + channelTitle + title + description + link + String.valueOf(pubDate));
                 String checksum2 = getPostChecksum(author + description);
 
                 // sibling to the target path, will also be checked for duplicates
                 Node targetSibling = NodeUtil.getSiblingBefore(targetPath);
 
                 // only add the post if it doesn't exist
                 if (!postExists(targetPath, checksum1, checksum2) && !postExists(targetSibling, checksum1, checksum2)) {
                     // get the parent node for more information
 
                     if (includePost(planetFilters, srcEntry)) {
                         Node channelNode = srcEntry.getParent();
                         while (targetPath.hasNode(POST_ENTRY_PREFIX + currEntry)) {
                             currEntry++;
                         }
                         Node trgEntry = NodeUtil.createPath(targetPath, POST_ENTRY_PREFIX + currEntry, NodeTypes.Content.NAME, true);
                         PropertyUtil.setProperty(trgEntry, "checksum1", checksum1);
                         PropertyUtil.setProperty(trgEntry, "checksum2", checksum2);
                         PropertyUtil.setProperty(trgEntry, "author", author);
                         PropertyUtil.setProperty(trgEntry, "channelTitle", channelTitle);
                         PropertyUtil.setProperty(trgEntry, "title", title);
                         PropertyUtil.setProperty(trgEntry, "description", description);
                         PropertyUtil.setProperty(trgEntry, "link", link);
                         PropertyUtil.setProperty(trgEntry, "pubDate", pubDate);
                         PropertyUtil.setProperty(trgEntry, "authorLink", PropertyUtil.getString(channelNode, "link", ""));
                         PropertyUtil.setProperty(trgEntry, "rssLink", PropertyUtil.getString(channelNode, "rss", ""));
                         PropertyUtil.setProperty(trgEntry, "hidden", false);
 
                         session.save();
                     } else {
                         log.info("Post was not included because filter setting didn't match: " + StringUtils.abbreviate(title, 60));
                     }
                 } else {
                     log.info("Found already existing post: " + StringUtils.abbreviate(title, 60));
                 }
             }
         } catch (RepositoryException e) {
             log.error("Problem while creating planet entry: " + e.getMessage());
         }
     }
 
     /**
      * Determine if a feed item already exists based on checksums of the content.
      *
      * @param targetPath Archive node (parent) containing the entries to be checked.
      * @param check1 First checksum to compare.
      * @param check2 Second checksum to compare.
      * @return true, if the entry already exists, otherwise false
      */
     boolean postExists(Node targetPath, String check1, String check2) {
         boolean found = false;
         if (targetPath != null) {
             try {
                 NodeIterator targetEntries = targetPath.getNodes();
                 while (targetEntries.hasNext()) {
                     Node existing = targetEntries.nextNode();
 
                     String extCheck1 = "";
                     if (existing.hasProperty("checksum1")) {
                         extCheck1 = existing.getProperty("checksum1").getString();
                     }
                     String extCheck2 = "";
                     if (existing.hasProperty("checksum2")) {
                         extCheck2 = existing.getProperty("checksum2").getString();
                     }
 
                     if (StringUtils.equals(extCheck1, check1) || StringUtils.equals(extCheck2, check2)) {
                         found = true;
                         break;
                     }
                 }
             } catch (RepositoryException e) {
                 log.error("Problem while searching for post: " + e.getMessage());
             }
         }
         return found;
     }
 
     boolean includePost(Set<FilterPredicate> planetFilters, Node srcNode) {
         if (planetFilters != null && planetFilters.size() > 0) {
 
             try {
                 PlanetFilter planetFilter = new PlanetFilter(planetFilters);
 
                 SyndEntry entry = new SyndEntryImpl();
                 String author = PlanetUtil.formatName(srcNode, "author");
                 if (StringUtils.isNotBlank(author)) {
                     entry.setAuthor(author);
                 } else {
                     entry.setAuthor(PlanetUtil.formatName(srcNode, "channelTitle"));
                 }
                 entry.setTitle(PropertyUtil.getString(srcNode, "title"));
                 SyndContentImpl description = new SyndContentImpl();
                 description.setValue(PropertyUtil.getString(srcNode, "description", ""));
                 entry.setDescription(description);
 
                 return planetFilter.include(entry);
             } catch (RepositoryException e) {
                 log.error("Problem while filtering planet feed content: " + e.getMessage());
             }
         }
 
         return true;
     }
 
     /**
      * Create the name for the parent folder of archived post entries.
      *
      * This method is used to avoid having to many node entries under one parent node.
      * It retrieves the newest archive folder and checks if the total number of existing entries under this node
      * plus the additional ones from the current run will exceed the number of maximum nodes allowed under one node.
      *
      * If the calculated number is below the maximum, the latest archive folder will be used. If the number reaches the
      * maximum, a new node will be created for storage.
      *
      * @param pdNode Parent node where planet archive data are stored in
      * @param entryCount number of entries that need to be added
      * @return Name of the archive storage node
      */
     String getPostsParent(Node pdNode, long entryCount) {
         String postsFolder = POSTS_FIRST;
         int archCount;
         try {
             // get latest folder with posts
             archCount = pdNode.getNodes().getSize() > 0 ? (int) (pdNode.getNodes().getSize() - 1) : 0;
             postsFolder = POSTS_PREFIX + StringUtils.leftPad(String.valueOf(archCount), 5, "0");
 
             // check how many entries this node already has
             Node postsNode = NodeUtil.createPath(pdNode, postsFolder, NodeTypes.Content.NAME, true);
             long existingEntries = postsNode.getNodes().getSize();
 
             // check if we need a new parent node to avoid having to many netries under one parent node
             if ((existingEntries + entryCount) > MAX_NODE_ENTRIES) {
                 postsFolder = POSTS_PREFIX + StringUtils.leftPad(String.valueOf(archCount + 1), 5, "0");
             }
         } catch (RepositoryException e) {
             log.error("Problem while getting number of highest posts node: " + e.getMessage());
         }
         return postsFolder;
     }
 
     /**
      * Create a checksum from a String input.
      *
      * @param postContent String content as checkusm input
      * @return MD5 checksum
      */
     String getPostChecksum(String postContent) {
         String checksum = null;
         MessageDigest md;
 
         try {
             md = MessageDigest.getInstance("MD5");
             md.reset();
             md.update(postContent.getBytes(), 0, postContent.length());
             checksum = new BigInteger(1, md.digest()).toString(16);
         } catch (Exception e) {
             log.error("Problem while creating checksum for post: " + e.getMessage());
         }
         return checksum;
     }
 
     Set<FilterPredicate> loadPlanetFilters(Node feedNode) {
         Set<FilterPredicate> planetFilters = new HashSet<FilterPredicate>();
 
         try {
             Node filtersNode = feedNode.hasNode("filters") ? feedNode.getNode("filters") : null;
 
             if (filtersNode != null) {
                 FilterPredicateContentMapper filterPredicateMapper = new FilterPredicateContentMapper();
                 List<Node> filterNodes = NodeUtil.asList(NodeUtil.getNodes(filtersNode, VersionUtil.getNodeTypeName(filtersNode)));
 
                 for (Node n : filterNodes) {
                     FilterPredicate filterPredicate = filterPredicateMapper.map(n);
                     if (filterPredicate == null) {
                         continue;
                     }
                     planetFilters.add(filterPredicate);
                 }
             }
         } catch (RepositoryException e) {
             log.error("Problem while retrieving planet feed node filters: " + e.getMessage());
         }
 
         return planetFilters;
     }
 
 }