package org.apache.maven.index.reader;
   
   /*
    * 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 org.apache.maven.index.reader.WritableResourceHandler.WritableResource;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.text.ParseException;
  import java.util.Date;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Properties;
  import java.util.UUID;
  
  import static org.apache.maven.index.reader.Utils.loadProperties;
  import static org.apache.maven.index.reader.Utils.storeProperties;
  
  /**
   * Maven 2 Index writer that writes chunk and maintains published property file.
   * <p/>
   * <strong>Currently no incremental update is supported, as the deleteion states should be maintained by
   * caller</strong>. Hence, this writer will always produce the "main" chunk only.
   *
   * @since 5.1.2
   */
  public class IndexWriter
      implements Closeable
  {
      private static final int INDEX_V1 = 1;
  
      private final WritableResourceHandler local;
  
      private final Properties localIndexProperties;
  
      private final boolean incremental;
  
      private final String nextChunkCounter;
  
      private final String nextChunkName;
  
      public IndexWriter( final WritableResourceHandler local, final String indexId, final boolean incrementalSupported )
          throws IOException
      {
          Objects.requireNonNull( local, "local resource handler null" );
          Objects.requireNonNull( indexId, "indexId null" );
          this.local = local;
          Properties indexProperties = loadProperties( local.locate( Utils.INDEX_FILE_PREFIX + ".properties" ) );
          if ( incrementalSupported && indexProperties != null )
          {
              this.localIndexProperties = indexProperties;
              // existing index, this is incremental publish, and we will add new chunk
              String localIndexId = localIndexProperties.getProperty( "nexus.index.id" );
              if ( localIndexId == null || !localIndexId.equals( indexId ) )
              {
                  throw new IllegalArgumentException(
                      "index already exists and indexId mismatch or unreadable: " + localIndexId + ", " + indexId );
              }
              this.incremental = true;
              this.nextChunkCounter = calculateNextChunkCounter();
              this.nextChunkName = Utils.INDEX_FILE_PREFIX + "." + nextChunkCounter + ".gz";
          }
          else
          {
              // non-existing index, create published index from scratch
              this.localIndexProperties = new Properties();
              this.localIndexProperties.setProperty( "nexus.index.id", indexId );
              this.localIndexProperties.setProperty( "nexus.index.chain-id", UUID.randomUUID().toString() );
              this.incremental = false;
              this.nextChunkCounter = null;
              this.nextChunkName = Utils.INDEX_FILE_PREFIX + ".gz";
          }
      }
  
      /**
       * Returns the index context ID that published index has set.
       */
      public String getIndexId()
      {
          return localIndexProperties.getProperty( "nexus.index.id" );
      }
 
     /**
      * Returns the {@link Date} when index was last published or {@code null} if this is first publishing. In other
      * words,returns {@code null} when {@link #isIncremental()} returns {@code false}. After this writer is closed, the
      * return value is updated to "now" (in {@link #close() method}.
      */
     public Date getPublishedTimestamp()
     {
         try
         {
             String timestamp = localIndexProperties.getProperty( "nexus.index.timestamp" );
             if ( timestamp != null )
             {
                 return Utils.INDEX_DATE_FORMAT.parse( timestamp );
             }
             return null;
         }
         catch ( ParseException e )
         {
             throw new RuntimeException( "Corrupt date", e );
         }
     }
 
     /**
      * Returns {@code true} if incremental publish is about to happen.
      */
     public boolean isIncremental()
     {
         return incremental;
     }
 
     /**
      * Returns the chain id of published index. If {@link #isIncremental()} is {@code false}, this is the newly
      * generated chain ID.
      */
     public String getChainId()
     {
         return localIndexProperties.getProperty( "nexus.index.chain-id" );
     }
 
     /**
      * Returns the next chunk name about to be published.
      */
     public String getNextChunkName()
     {
         return nextChunkName;
     }
 
     /**
      * Writes out the record iterator and returns the written record count.
      */
     public int writeChunk( final Iterator<Map<String, String>> iterator )
         throws IOException
     {
         int written;
 
         try ( WritableResource writableResource = local.locate( nextChunkName ) )
         {
             try ( ChunkWriter chunkWriter = new ChunkWriter( nextChunkName, writableResource.write(), INDEX_V1,
                     new Date() ) )
             {
                 written = chunkWriter.writeChunk( iterator );
             }
             if ( incremental )
             {
                 // TODO: update main gz file
             }
             return written;
         }
     }
 
     /**
      * Closes the underlying {@link ResourceHandler} and synchronizes published index properties, so remote clients
      * becomes able to consume newly published index. If sync is not desired (ie. due to aborted publish), then this
      * method should NOT be invoked, but rather the {@link ResourceHandler} that caller provided in constructor of
      * this class should be closed manually.
      */
     public void close()
         throws IOException
     {
         try
         {
             if ( incremental )
             {
                 localIndexProperties.setProperty( "nexus.index.last-incremental", nextChunkCounter );
             }
             localIndexProperties.setProperty( "nexus.index.timestamp", Utils.INDEX_DATE_FORMAT.format( new Date() ) );
             storeProperties( local.locate( Utils.INDEX_FILE_PREFIX + ".properties" ), localIndexProperties );
         }
         finally
         {
             local.close();
         }
     }
 
     /**
      * Calculates the chunk names that needs to be fetched.
      */
     private String calculateNextChunkCounter()
     {
         String lastChunkCounter = localIndexProperties.getProperty( "nexus.index.last-incremental" );
         if ( lastChunkCounter != null )
         {
             return String.valueOf( Integer.parseInt( lastChunkCounter ) + 1 );
         }
         else
         {
             return "1";
         }
     }
 }