package org.apache.maven.index.context;
   
   /*
    * 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.
   */
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Date;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.index.IndexWriter;
  import org.apache.lucene.search.IndexSearcher;
  import org.apache.lucene.store.Directory;
  import org.apache.lucene.store.FSDirectory;
  import org.apache.maven.index.artifact.GavCalculator;
  import org.apache.maven.index.artifact.M2GavCalculator;
  
  /**
   * A merged indexing context that offers read only "view" on multiple other indexing contexts merged and presented as
   * one. Usable for searching and publishing, but all write operations are basically noop.
   * 
   * @author cstamas
   */
  public class MergedIndexingContext
      extends AbstractIndexingContext
  {
      private final String id;
  
      private final String repositoryId;
  
      private final File repository;
  
      private final ContextMemberProvider membersProvider;
  
      private final GavCalculator gavCalculator;
  
      private final Directory directory;
  
      private File directoryFile;
  
      private boolean searchable;
  
      private MergedIndexingContext( ContextMemberProvider membersProvider, String id, String repositoryId,
                                     File repository, Directory indexDirectory, boolean searchable )
          throws IOException
      {
          this.id = id;
          this.repositoryId = repositoryId;
          this.repository = repository;
          this.membersProvider = membersProvider;
          this.gavCalculator = new M2GavCalculator();
          this.directory = indexDirectory;
          this.searchable = searchable;
          setIndexDirectoryFile( null );
      }
  
      public MergedIndexingContext( String id, String repositoryId, File repository, File indexDirectoryFile,
                                    boolean searchable, ContextMemberProvider membersProvider )
          throws IOException
      {
          this( membersProvider, id, repositoryId, repository, FSDirectory.open( indexDirectoryFile.toPath() ),
                searchable );
  
          setIndexDirectoryFile( indexDirectoryFile );
      }
  
      @Deprecated
      public MergedIndexingContext( String id, String repositoryId, File repository, Directory indexDirectory,
                                    boolean searchable, ContextMemberProvider membersProvider )
          throws IOException
      {
          this( membersProvider, id, repositoryId, repository, indexDirectory, searchable );
  
          if ( indexDirectory instanceof FSDirectory )
          {
              setIndexDirectoryFile( ( (FSDirectory) indexDirectory ).getDirectory().toFile() );
          }
     }
 
     public Collection<IndexingContext> getMembers()
     {
         return membersProvider.getMembers();
     }
 
     public String getId()
     {
         return id;
     }
 
     public String getRepositoryId()
     {
         return repositoryId;
     }
 
     public File getRepository()
     {
         return repository;
     }
 
     public String getRepositoryUrl()
     {
         return null;
     }
 
     public String getIndexUpdateUrl()
     {
         return null;
     }
 
     public boolean isSearchable()
     {
         return searchable;
     }
 
     public void setSearchable( boolean searchable )
     {
         this.searchable = searchable;
     }
 
     public Date getTimestamp()
     {
         Date ts = null;
 
         for ( IndexingContext ctx : getMembers() )
         {
             Date cts = ctx.getTimestamp();
 
             if ( cts != null )
             {
                 if ( ts == null || cts.after( ts ) )
                 {
                     ts = cts;
                 }
             }
         }
 
         return ts;
     }
 
     public void updateTimestamp()
         throws IOException
     {
         // noop
     }
 
     public void updateTimestamp( boolean save )
         throws IOException
     {
         // noop
     }
 
     public void updateTimestamp( boolean save, Date date )
         throws IOException
     {
         // noop
     }
 
     public int getSize()
         throws IOException
     {
         int size = 0;
 
         for ( IndexingContext ctx : getMembers() )
         {
             size += ctx.getSize();
         }
 
         return size;
     }
 
     public IndexSearcher acquireIndexSearcher()
         throws IOException
     {
         final NexusIndexMultiReader mr = new NexusIndexMultiReader( getMembers() );
         return new NexusIndexMultiSearcher( mr );
     }
 
     public void releaseIndexSearcher( IndexSearcher indexSearcher )
         throws IOException
     {
         if ( indexSearcher instanceof NexusIndexMultiSearcher )
         {
             ( (NexusIndexMultiSearcher) indexSearcher ).release();
         }
         else
         {
             throw new IllegalArgumentException( String.format(
                 "Illegal argument to merged idexing context: it emits class %s but and cannot release class %s!",
                 NexusIndexMultiSearcher.class.getName(), indexSearcher.getClass().getName() ) );
         }
 
     }
 
     public IndexWriter getIndexWriter()
         throws IOException
     {
         throw new UnsupportedOperationException( getClass().getName() + " indexing context is read-only!" );
     }
 
     public List<IndexCreator> getIndexCreators()
     {
         HashSet<IndexCreator> creators = new HashSet<>();
 
         for ( IndexingContext ctx : getMembers() )
         {
             creators.addAll( ctx.getIndexCreators() );
         }
 
         return new ArrayList<>( creators );
     }
 
     public Analyzer getAnalyzer()
     {
         return new NexusAnalyzer();
     }
 
     public void commit()
         throws IOException
     {
         // noop
     }
 
     public void rollback()
         throws IOException
     {
         // noop
     }
 
     public void optimize()
         throws IOException
     {
         // noop
     }
 
     public void close( boolean deleteFiles )
         throws IOException
     {
         // noop
     }
 
     public void purge()
         throws IOException
     {
         // noop
     }
 
     public void merge( Directory directory )
         throws IOException
     {
         // noop
     }
 
     public void merge( Directory directory, DocumentFilter filter )
         throws IOException
     {
         // noop
     }
 
     public void replace( Directory directory )
         throws IOException
     {
         // noop
     }
 
     public void replace( Directory directory, Set<String> allGroups, Set<String> rootGroups )
         throws IOException
     {
         // noop
     }
 
     public Directory getIndexDirectory()
     {
         return directory;
     }
 
     public File getIndexDirectoryFile()
     {
         return directoryFile;
     }
 
     /**
      * Sets index location. As usually index is persistent (is on disk), this will point to that value, but in
      * some circumstances (ie, using RAMDisk for index), this will point to an existing tmp directory.
      */
     protected void setIndexDirectoryFile( File dir )
         throws IOException
     {
         if ( dir == null )
         {
             // best effort, to have a directory through the life of a ctx
             this.directoryFile = Files.createTempDirectory( "mindexer-ctx" + id ).toFile();
             this.directoryFile.deleteOnExit();
         }
         else
         {
             this.directoryFile = dir;
         }
     }
 
     public GavCalculator getGavCalculator()
     {
         return gavCalculator;
     }
 
     public void setAllGroups( Collection<String> groups )
         throws IOException
     {
         // noop
     }
 
     public Set<String> getAllGroups()
         throws IOException
     {
         HashSet<String> result = new HashSet<>();
 
         for ( IndexingContext ctx : getMembers() )
         {
             result.addAll( ctx.getAllGroups() );
         }
 
         return result;
     }
 
     public void setRootGroups( Collection<String> groups )
         throws IOException
     {
         // noop
     }
 
     public Set<String> getRootGroups()
         throws IOException
     {
         HashSet<String> result = new HashSet<>();
 
         for ( IndexingContext ctx : getMembers() )
         {
             result.addAll( ctx.getRootGroups() );
         }
 
         return result;
     }
 
     public void rebuildGroups()
         throws IOException
     {
         // noop
     }
 }