/**
    * This file Copyright (c) 2017 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.googlesitemap.config.mapping;
  
  import info.magnolia.context.SystemContext;
  import info.magnolia.jcr.predicate.AbstractPredicate;
  import info.magnolia.jcr.util.NodeUtil;
  import info.magnolia.module.googlesitemap.GoogleSiteMapConfiguration;
  import info.magnolia.module.googlesitemap.SiteMapNodeTypes;
  import info.magnolia.observation.WorkspaceEventListenerRegistration;
  import info.magnolia.virtualuri.VirtualUriMapping;
  
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Optional;
  
  import javax.inject.Inject;
  import javax.jcr.Node;
  import javax.jcr.RepositoryException;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Virtual URI mapping that compares source URI to names of sitemaps available in google-sitemap workspace
   * and prepends the prefix.
   */
  public class SiteMapVirtualUriMapping implements VirtualUriMapping {
  
      public static final String XML_EXTENSION = ".xml";
  
      private static final Logger log = LoggerFactory.getLogger(SiteMapVirtualUriMapping.class);
  
      private final SystemContext context;
  
      private final Map<URI, String> siteMapUrlMappings = new HashMap();
  
      private String prefix;
  
      private AbstractPredicate<Node> siteMapNodePredicate = new AbstractPredicate<Node>() {
          @Override
          public boolean evaluateTyped(Node node) {
              try {
                  return NodeUtil.isNodeType(node, SiteMapNodeTypes.SiteMap.NAME);
              } catch (RepositoryException e) {
                  return false;
              }
          }
      };
  
      @Inject
      public SiteMapVirtualUriMapping(SystemContext context) {
          this.context = context;
  
          try {
              WorkspaceEventListenerRegistration.observe(GoogleSiteMapConfiguration.WORKSPACE, "/", events -> reloadSiteMapNames())
                      .withSubNodes(true).register();
          } catch (RepositoryException e) {
              log.error("Cannot register workspace listener.", e);
          }
          reloadSiteMapNames();
      }
  
      private void reloadSiteMapNames() {
         try {
             siteMapUrlMappings.clear();
             Node root = context.getJCRSession(GoogleSiteMapConfiguration.WORKSPACE).getRootNode();
             final Iterator<Node> it = NodeUtil.collectAllChildren(root, siteMapNodePredicate).iterator();
             while (it.hasNext()) {
                 Node node = it.next();
                 if (SiteMapNodeTypes.SiteMap.getUrl(node) != null) {
                     URI uri = new URI(SiteMapNodeTypes.SiteMap.getUrl(node));
                     siteMapUrlMappings.put(uri, node.getPath() + XML_EXTENSION);
                 }
             }
         } catch (RepositoryException | URISyntaxException e) {
             log.warn("Failed to collect sitemap names: ", e.getMessage());
         }
     }
 
     @Override
     public Optional<Result> mapUri(URI uri) {
         String mapping = siteMapUrlMappings.get(uri);
         return mapping == null ? Optional.empty() : Optional.of(new Result(prefix + mapping, uri.getPath().length(), this));
     }
 
     @Override
     public boolean isValid() {
         return StringUtils.isNotEmpty(prefix);
     }
 
     public void setPrefix(String prefix) {
         this.prefix = prefix;
     }
 }