/*
    * 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.chemistry.opencmis.client.bindings.spi.atompub;
  
  import java.io.OutputStream;
  import java.math.BigInteger;
  import java.util.ArrayList;
  
  import javax.xml.stream.XMLStreamWriter;
  
  import org.apache.chemistry.opencmis.client.bindings.spi.BindingSession;
  import org.apache.chemistry.opencmis.client.bindings.spi.atompub.objects.AtomElement;
  import org.apache.chemistry.opencmis.client.bindings.spi.atompub.objects.AtomEntry;
  import org.apache.chemistry.opencmis.client.bindings.spi.atompub.objects.AtomFeed;
  import org.apache.chemistry.opencmis.client.bindings.spi.atompub.objects.AtomLink;
  import org.apache.chemistry.opencmis.client.bindings.spi.http.Output;
  import org.apache.chemistry.opencmis.client.bindings.spi.http.Response;
  import org.apache.chemistry.opencmis.commons.data.ExtensionsData;
  import org.apache.chemistry.opencmis.commons.data.ObjectData;
  import org.apache.chemistry.opencmis.commons.data.ObjectList;
  import org.apache.chemistry.opencmis.commons.enums.CmisVersion;
  import org.apache.chemistry.opencmis.commons.enums.IncludeRelationships;
  import org.apache.chemistry.opencmis.commons.exceptions.CmisObjectNotFoundException;
  import org.apache.chemistry.opencmis.commons.impl.Constants;
  import org.apache.chemistry.opencmis.commons.impl.UrlBuilder;
  import org.apache.chemistry.opencmis.commons.impl.XMLConverter;
  import org.apache.chemistry.opencmis.commons.impl.XMLUtils;
  import org.apache.chemistry.opencmis.commons.impl.dataobjects.ObjectListImpl;
  import org.apache.chemistry.opencmis.commons.impl.dataobjects.QueryTypeImpl;
  import org.apache.chemistry.opencmis.commons.spi.DiscoveryService;
  import org.apache.chemistry.opencmis.commons.spi.ExtendedHolder;
  import org.apache.chemistry.opencmis.commons.spi.Holder;
  
  /**
   * Discovery Service AtomPub client.
   */
  public class DiscoveryServiceImpl extends AbstractAtomPubService implements DiscoveryService {
  
      /**
       * Constructor.
       */
      public DiscoveryServiceImpl(BindingSession session) {
          setSession(session);
      }
  
      @Override
      public ObjectList getContentChanges(String repositoryId, Holder<String> changeLogToken, Boolean includeProperties,
              String filter, Boolean includePolicyIds, Boolean includeACL, BigInteger maxItems, ExtensionsData extension) {
          ObjectListImpl result = new ObjectListImpl();
  
          // find the link
          String link = null;
          UrlBuilder url = null;
  
          // if the application doesn't know the change log token but the link to
          // the next Atom feed
          if (changeLogToken instanceof ExtendedHolder && changeLogToken.getValue() == null) {
              link = (String) ((ExtendedHolder<String>) changeLogToken).getExtraValue(Constants.REP_REL_CHANGES);
              if (link != null) {
                  url = new UrlBuilder(link);
              }
          }
  
          // if the application didn't provide a link to next Atom feed
          if (link == null) {
              link = loadRepositoryLink(repositoryId, Constants.REP_REL_CHANGES);
              if (link != null) {
                  url = new UrlBuilder(link);
                  url.addParameter(Constants.PARAM_CHANGE_LOG_TOKEN,
                          (changeLogToken == null ? null : changeLogToken.getValue()));
                  url.addParameter(Constants.PARAM_PROPERTIES, includeProperties);
                  url.addParameter(Constants.PARAM_FILTER, filter);
                  url.addParameter(Constants.PARAM_POLICY_IDS, includePolicyIds);
                  url.addParameter(Constants.PARAM_ACL, includeACL);
                  url.addParameter(Constants.PARAM_MAX_ITEMS, maxItems);
              }
          }
  
          if (link == null) {
              throw new CmisObjectNotFoundException("Unknown repository or content changes not supported!");
          }
  
          // read and parse
         Response resp = read(url);
         AtomFeed feed = parse(resp.getStream(), AtomFeed.class);
         String lastChangeLogToken = null;
 
         // handle top level
         String nextLink = null;
         for (AtomElement element : feed.getElements()) {
             if (element.getObject() instanceof AtomLink) {
                 if (isNextLink(element)) {
                     result.setHasMoreItems(Boolean.TRUE);
                     nextLink = ((AtomLink) element.getObject()).getHref();
                 }
             } else if (isInt(NAME_NUM_ITEMS, element)) {
                 result.setNumItems((BigInteger) element.getObject());
             } else if (isStr("changeLogToken", element)) {
                 lastChangeLogToken = (String) element.getObject();
             }
         }
 
         // get the changes
         if (!feed.getEntries().isEmpty()) {
             result.setObjects(new ArrayList<ObjectData>(feed.getEntries().size()));
 
             for (AtomEntry entry : feed.getEntries()) {
                 ObjectData hit = null;
 
                 // walk through the entry
                 for (AtomElement element : entry.getElements()) {
                     if (element.getObject() instanceof ObjectData) {
                         hit = (ObjectData) element.getObject();
                     }
                 }
 
                 if (hit != null) {
                     result.getObjects().add(hit);
                 }
             }
         }
 
         if (changeLogToken != null) {
             // the AtomPub binding cannot return a new change log token,
             // but an OpenCMIS server uses a proprietary tag
             changeLogToken.setValue(lastChangeLogToken);
 
             // but we can provide the link to the next Atom feed
             if (changeLogToken instanceof ExtendedHolder && nextLink != null) {
                 ((ExtendedHolder<String>) changeLogToken).setExtraValue(Constants.REP_REL_CHANGES, nextLink);
             }
         }
 
         return result;
     }
 
     @Override
     public ObjectList query(String repositoryId, String statement, Boolean searchAllVersions,
             Boolean includeAllowableActions, IncludeRelationships includeRelationships, String renditionFilter,
             BigInteger maxItems, BigInteger skipCount, ExtensionsData extension) {
         ObjectListImpl result = new ObjectListImpl();
 
         // find the link
         String link = loadCollection(repositoryId, Constants.COLLECTION_QUERY);
 
         if (link == null) {
             throw new CmisObjectNotFoundException("Unknown repository or query not supported!");
         }
 
         UrlBuilder url = new UrlBuilder(link);
 
         // compile query request
         final QueryTypeImpl query = new QueryTypeImpl();
         query.setStatement(statement);
         query.setSearchAllVersions(searchAllVersions);
         query.setIncludeAllowableActions(includeAllowableActions);
         query.setIncludeRelationships(includeRelationships);
         query.setRenditionFilter(renditionFilter);
         query.setMaxItems(maxItems);
         query.setSkipCount(skipCount);
 
         final CmisVersion cmisVersion = getCmisVersion(repositoryId);
 
         // post the query and parse results
         Response resp = post(url, Constants.MEDIATYPE_QUERY, new Output() {
             @Override
             public void write(OutputStream out) throws Exception {
                 XMLStreamWriter writer = XMLUtils.createWriter(out);
                 XMLUtils.startXmlDocument(writer);
                 XMLConverter.writeQuery(writer, cmisVersion, query);
                 XMLUtils.endXmlDocument(writer);
             }
         });
         AtomFeed feed = parse(resp.getStream(), AtomFeed.class);
 
         // handle top level
         for (AtomElement element : feed.getElements()) {
             if (element.getObject() instanceof AtomLink) {
                 if (isNextLink(element)) {
                     result.setHasMoreItems(Boolean.TRUE);
                 }
             } else if (isInt(NAME_NUM_ITEMS, element)) {
                 result.setNumItems((BigInteger) element.getObject());
             }
         }
 
         // get the result set
         if (!feed.getEntries().isEmpty()) {
             result.setObjects(new ArrayList<ObjectData>(feed.getEntries().size()));
 
             for (AtomEntry entry : feed.getEntries()) {
                 ObjectData hit = null;
 
                 // walk through the entry
                 for (AtomElement element : entry.getElements()) {
                     if (element.getObject() instanceof ObjectData) {
                         hit = (ObjectData) element.getObject();
                     }
                 }
 
                 if (hit != null) {
                     result.getObjects().add(hit);
                 }
             }
         }
 
         return result;
     }
 }