/*
    * 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 java.io.IOException;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.lucene.document.Document;
  import org.apache.lucene.index.CorruptIndexException;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.MultiBits;
  import org.apache.lucene.index.Term;
  import org.apache.lucene.search.IndexSearcher;
  import org.apache.lucene.search.TermQuery;
  import org.apache.lucene.search.TopScoreDocCollector;
  import org.apache.lucene.util.Bits;
  import org.apache.maven.index.context.IndexingContext;
  
  /**
   * A default scanning listener
   *
   * @author Eugene Kuleshov
   */
  public class DefaultScannerListener implements ArtifactScanningListener {
      private final IndexingContext context;
  
      private final IndexerEngine indexerEngine;
  
      private final boolean update;
  
      private final ArtifactScanningListener listener;
  
      private final Set<String> uinfos = new HashSet<>();
  
      private final Set<String> processedUinfos = new HashSet<>();
  
      private final Set<String> allGroups = new HashSet<>();
  
      private final Set<String> groups = new HashSet<>();
  
      private final List<Exception> exceptions = new ArrayList<>();
  
      private int count = 0;
  
      public DefaultScannerListener(
              IndexingContext context, //
              IndexerEngine indexerEngine,
              boolean update, //
              ArtifactScanningListener listener) {
          this.context = context;
          this.indexerEngine = indexerEngine;
          this.update = update;
          this.listener = listener;
      }
  
      public void scanningStarted(IndexingContext ctx) {
          try {
              if (update) {
                  initialize(ctx);
              }
          } catch (IOException ex) {
              exceptions.add(ex);
          }
  
          if (listener != null) {
              listener.scanningStarted(ctx);
          }
      }
  
      public void artifactDiscovered(ArtifactContext ac) {
          String uinfo = ac.getArtifactInfo().getUinfo();
  
          // TODO: scattered across commented out changes while I was fixing NEXUS-2712, cstamas
          // These changes should be applied by borks too much the fragile indexer
  
          // if ( VersionUtils.isSnapshot( ac.getArtifactInfo().version ) && processedUinfos.contains( uinfo ) )
          if (processedUinfos.contains(uinfo)) {
              return; // skip individual snapshots
          }
  
         boolean adding = processedUinfos.add(uinfo);
 
         if (uinfos.contains(uinfo)) {
             // already indexed
             uinfos.remove(uinfo);
             return;
         }
 
         try {
             if (listener != null) {
                 listener.artifactDiscovered(ac);
             }
 
             if (adding) {
                 indexerEngine.index(context, ac);
             } else {
                 indexerEngine.update(context, ac);
             }
 
             for (Exception e : ac.getErrors()) {
                 artifactError(ac, e);
             }
 
             groups.add(ac.getArtifactInfo().getRootGroup());
             allGroups.add(ac.getArtifactInfo().getGroupId());
 
             count++;
         } catch (IOException ex) {
             artifactError(ac, ex);
         }
     }
 
     public void scanningFinished(IndexingContext ctx, ScanningResult result) {
         result.setTotalFiles(count);
 
         for (Exception ex : exceptions) {
             result.addException(ex);
         }
 
         try {
             context.optimize();
 
             context.setRootGroups(groups);
 
             context.setAllGroups(allGroups);
 
             if (update && !context.isReceivingUpdates()) {
                 removeDeletedArtifacts(context, result, result.getRequest().getStartingPath());
             }
         } catch (IOException ex) {
             result.addException(ex);
         }
 
         if (listener != null) {
             listener.scanningFinished(ctx, result);
         }
 
         if (result.getDeletedFiles() > 0 || result.getTotalFiles() > 0) {
             try {
                 context.updateTimestamp(true);
 
                 context.optimize();
             } catch (Exception ex) {
                 result.addException(ex);
             }
         }
     }
 
     public void artifactError(ArtifactContext ac, Exception e) {
         exceptions.add(e);
 
         if (listener != null) {
             listener.artifactError(ac, e);
         }
     }
 
     private void initialize(IndexingContext ctx) throws IOException, CorruptIndexException {
         final IndexSearcher indexSearcher = ctx.acquireIndexSearcher();
         try {
             final IndexReader r = indexSearcher.getIndexReader();
             Bits liveDocs = MultiBits.getLiveDocs(r);
 
             for (int i = 0; i < r.maxDoc(); i++) {
                 if (liveDocs == null || liveDocs.get(i)) {
                     Document d = r.document(i);
 
                     String uinfo = d.get(ArtifactInfo.UINFO);
 
                     if (uinfo != null) {
                         // if ctx is receiving updates (in other words, is a proxy),
                         // there is no need to build a huge Set of strings with all uinfo's
                         // as deletion detection in those cases have no effect. Also, the
                         // removeDeletedArtifacts() method, that uses info gathered in this set
                         // is invoked with same condition. As indexes of Central are getting huge,
                         // the set grows enormously too, but is actually not used
                         if (!ctx.isReceivingUpdates()) {
                             uinfos.add(uinfo);
                         }
 
                         // add all existing groupIds to the lists, as they will
                         // not be "discovered" and would be missing from the new list..
                         String groupId = uinfo.substring(0, uinfo.indexOf('|'));
                         int n = groupId.indexOf('.');
                         groups.add(n == -1 ? groupId : groupId.substring(0, n));
                         allGroups.add(groupId);
                     }
                 }
             }
         } finally {
             ctx.releaseIndexSearcher(indexSearcher);
         }
     }
 
     private void removeDeletedArtifacts(IndexingContext context, ScanningResult result, String contextPath)
             throws IOException {
         int deleted = 0;
 
         final IndexSearcher indexSearcher = context.acquireIndexSearcher();
         try {
             for (String uinfo : uinfos) {
                 TopScoreDocCollector collector = TopScoreDocCollector.create(1, Integer.MAX_VALUE);
 
                 indexSearcher.search(new TermQuery(new Term(ArtifactInfo.UINFO, uinfo)), collector);
 
                 if (collector.getTotalHits() > 0) {
                     String[] ra = ArtifactInfo.FS_PATTERN.split(uinfo);
 
                     ArtifactInfo ai = new ArtifactInfo();
 
                     ai.setRepository(context.getRepositoryId());
 
                     ai.setGroupId(ra[0]);
 
                     ai.setArtifactId(ra[1]);
 
                     ai.setVersion(ra[2]);
 
                     if (ra.length > 3) {
                         ai.setClassifier(ArtifactInfo.renvl(ra[3]));
                     }
 
                     if (ra.length > 4) {
                         ai.setPackaging(ArtifactInfo.renvl(ra[4]));
                     }
 
                     // minimal ArtifactContext for removal
                     ArtifactContext ac = new ArtifactContext(null, null, null, ai, ai.calculateGav());
 
                     for (int i = 0; i < collector.getTotalHits(); i++) {
                         if (contextPath == null
                                 || context.getGavCalculator()
                                         .gavToPath(ac.getGav())
                                         .startsWith(contextPath)) {
                             indexerEngine.remove(context, ac);
                         }
 
                         deleted++;
                     }
                 }
             }
         } finally {
             context.releaseIndexSearcher(indexSearcher);
         }
 
         if (deleted > 0) {
             context.commit();
         }
 
         result.setDeletedFiles(deleted);
     }
 }