/*
    * 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.index;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.lucene.document.Document;
  import org.apache.lucene.document.StoredField;
  import org.apache.lucene.index.IndexWriter;
  import org.apache.lucene.index.IndexableField;
  import org.apache.lucene.index.Term;
  import org.apache.lucene.search.IndexSearcher;
  import org.apache.lucene.search.TermQuery;
  import org.apache.lucene.search.TopDocs;
  import org.apache.maven.index.context.IndexingContext;
  import org.apache.maven.index.creator.MinimalArtifactInfoIndexCreator;
  
  /**
   * A default {@link IndexerEngine} implementation.
   *
   * @author Tamas Cservenak
   */
  @Singleton
  @Named
  public class DefaultIndexerEngine implements IndexerEngine {
  
      public void index(IndexingContext context, ArtifactContext ac) throws IOException {
          // skip artifacts not obeying repository layout (whether m1 or m2)
          if (ac != null && ac.getGav() != null) {
              Document d = ac.createDocument(context);
  
              if (d != null) {
                  context.getIndexWriter().addDocument(d);
  
                  context.updateTimestamp();
              }
          }
      }
  
      public void update(IndexingContext context, ArtifactContext ac) throws IOException {
          if (ac != null && ac.getGav() != null) {
              Document d = ac.createDocument(context);
  
              if (d != null) {
                  Document old = getOldDocument(context, ac);
  
                  if (!equals(d, old)) {
                      IndexWriter w = context.getIndexWriter();
  
                      w.updateDocument(
                              new Term(ArtifactInfo.UINFO, ac.getArtifactInfo().getUinfo()), d);
  
                      updateGroups(context, ac);
  
                      context.updateTimestamp();
                  }
              }
          }
      }
  
      public void remove(IndexingContext context, ArtifactContext ac) throws IOException {
          if (ac != null) {
              final String uinfo = ac.getArtifactInfo().getUinfo();
  
              // add artifact deletion marker
              final Document doc = new Document();
  
              doc.add(new StoredField(ArtifactInfo.DELETED, uinfo));
              doc.add(new StoredField(
                      ArtifactInfo.LAST_MODIFIED, //
                      Long.toString(System.currentTimeMillis())));
  
              IndexWriter w = context.getIndexWriter();
              w.addDocument(doc);
              w.deleteDocuments(new Term(ArtifactInfo.UINFO, uinfo));
              context.updateTimestamp();
          }
     }
 
     // ==
 
     private boolean equals(final Document d1, final Document d2) {
         if (d1 == null && d2 == null) {
             return true;
         }
         if (d1 == null || d2 == null) {
             return false;
         }
 
         final Map<String, String> m1 = toMap(d1);
         final Map<String, String> m2 = toMap(d2);
 
         m1.remove(MinimalArtifactInfoIndexCreator.FLD_LAST_MODIFIED.getKey());
         m2.remove(MinimalArtifactInfoIndexCreator.FLD_LAST_MODIFIED.getKey());
 
         return m1.equals(m2);
     }
 
     private Map<String, String> toMap(Document d) {
         final HashMap<String, String> result = new HashMap<>();
 
         for (Object o : d.getFields()) {
             IndexableField f = (IndexableField) o;
             if (f.fieldType().stored()) {
                 result.put(f.name(), f.stringValue());
             }
         }
 
         return result;
     }
 
     private Document getOldDocument(IndexingContext context, ArtifactContext ac) {
         try {
             final IndexSearcher indexSearcher = context.acquireIndexSearcher();
             try {
                 TopDocs result = indexSearcher.search(
                         new TermQuery(new Term(
                                 ArtifactInfo.UINFO, ac.getArtifactInfo().getUinfo())),
                         2);
 
                 if (result.totalHits.value == 1) {
                     return indexSearcher.doc(result.scoreDocs[0].doc);
                 }
             } finally {
                 context.releaseIndexSearcher(indexSearcher);
             }
         } catch (IOException e) {
             // huh?
             throw new IllegalStateException(e);
         }
         return null;
     }
 
     private void updateGroups(IndexingContext context, ArtifactContext ac) throws IOException {
         String rootGroup = ac.getArtifactInfo().getRootGroup();
         Set<String> rootGroups = context.getRootGroups();
         if (!rootGroups.contains(rootGroup)) {
             rootGroups.add(rootGroup);
             context.setRootGroups(rootGroups);
         }
 
         Set<String> allGroups = context.getAllGroups();
         if (!allGroups.contains(ac.getArtifactInfo().getGroupId())) {
             allGroups.add(ac.getArtifactInfo().getGroupId());
             context.setAllGroups(allGroups);
         }
     }
 }