/*
    * 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.context;
  
  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 merge(Directory directory, DocumentFilter filter, Set<String> allGroups, Set<String> rootGroups)
             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
     }
 }