/*
    *  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.directory.server.core.partition.impl.btree.mavibot;
  
  
  import java.io.File;
  import java.io.IOException;
  import java.net.URI;
  import java.util.Comparator;
  
  import org.apache.directory.api.ldap.model.constants.SchemaConstants;
  import org.apache.directory.api.ldap.model.cursor.Cursor;
  import org.apache.directory.api.ldap.model.cursor.CursorException;
  import org.apache.directory.api.ldap.model.cursor.EmptyCursor;
  import org.apache.directory.api.ldap.model.cursor.Tuple;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.api.ldap.model.exception.LdapOtherException;
  import org.apache.directory.api.ldap.model.schema.AttributeType;
  import org.apache.directory.api.ldap.model.schema.MatchingRule;
  import org.apache.directory.api.ldap.model.schema.SchemaManager;
  import org.apache.directory.api.ldap.model.schema.comparators.SerializableComparator;
  import org.apache.directory.mavibot.btree.RecordManager;
  import org.apache.directory.mavibot.btree.serializer.ByteArraySerializer;
  import org.apache.directory.mavibot.btree.serializer.ElementSerializer;
  import org.apache.directory.mavibot.btree.serializer.StringSerializer;
  import org.apache.directory.server.core.api.partition.PartitionTxn;
  import org.apache.directory.server.core.partition.impl.btree.AbstractBTreePartition;
  import org.apache.directory.server.core.partition.impl.btree.IndexCursorAdaptor;
  import org.apache.directory.server.i18n.I18n;
  import org.apache.directory.server.xdbm.AbstractIndex;
  import org.apache.directory.server.xdbm.IndexEntry;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A Mavibot based index implementation. It creates an Index for a give AttributeType.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class MavibotIndex<K> extends AbstractIndex<K, String>
  {
      /** A logger for this class */
      private static final Logger LOG = LoggerFactory.getLogger( MavibotIndex.class.getSimpleName() );
  
      /**  the key used for the forward btree name */
      public static final String FORWARD_BTREE = "_forward";
  
      /**  the key used for the reverse btree name */
      public static final String REVERSE_BTREE = "_reverse";
  
      /**
       * the forward btree where the btree key is the value of the indexed attribute and
       * the value of the btree is the entry id of the entry containing an attribute with
       * that value
       */
      protected MavibotTable<K, String> forward;
  
      /**
       * the reverse btree where the btree key is the entry id of the entry containing a
       * value for the indexed attribute, and the btree value is the value of the indexed
       * attribute
       */
      protected MavibotTable<String, K> reverse;
  
      /** a custom working directory path when specified in configuration */
      protected File wkDirPath;
  
      protected RecordManager recordMan;
  
  
      // ------------------------------------------------------------------------
      // C O N S T R U C T O R S
      // ----------------------------------------------------------------------
      /**
       * Creates a JdbmIndex instance for a give AttributeId
       * 
       * @param attributeId The Attribute ID
       * @param withReverse If we want a reverse index to be created
       */
      public MavibotIndex( String attributeId, boolean withReverse )
      {
         super( attributeId, withReverse );
 
         initialized = false;
     }
 
 
     /**
      * Initialize the index for an Attribute, with a specific working directory (may be null).
      *
      * @param schemaManager The schemaManager to use to get back the Attribute
      * @param attributeType The attributeType this index is created for
      * @throws IOException If the initialization failed
      * @throws LdapException If the initialization failed
      */
     public void init( SchemaManager schemaManager, AttributeType attributeType ) throws LdapException, IOException
     {
         LOG.debug( "Initializing an Index for attribute '{}'", attributeType.getName() );
 
         // check if the RecordManager reference is null, if yes, then throw an IllegalStateException
         if ( recordMan == null )
         {
             throw new IllegalStateException( "No RecordManager reference was set in the index " + getAttributeId() );
         }
 
         this.attributeType = attributeType;
 
         if ( attributeId == null )
         {
             setAttributeId( attributeType.getName() );
         }
 
         if ( this.wkDirPath == null )
         {
             throw new NullPointerException( "The index working directory has not be set" );
         }
 
         try
         {
             initTables( schemaManager );
         }
         catch ( IOException e )
         {
             // clean up
             close( null );
             throw e;
         }
 
         initialized = true;
     }
 
 
     /**
      * Initializes the forward and reverse tables used by this Index.
      *
      * @param schemaManager The server schemaManager
      * @throws IOException if we cannot initialize the forward and reverse
      * tables
      */
     private void initTables( SchemaManager schemaManager ) throws IOException
     {
         MatchingRule mr = attributeType.getEquality();
 
         if ( mr == null )
         {
             throw new IOException( I18n.err( I18n.ERR_574, attributeType.getName() ) );
         }
 
         SerializableComparator<K> comp = new SerializableComparator<>( mr.getOid() );
         comp.setSchemaManager( schemaManager );
 
         /*
          * The forward key/value map stores attribute values to master table
          * primary keys.  A value for an attribute can occur several times in
          * different entries so the forward map can have more than one value.
          */
 
         ElementSerializer<K> forwardKeySerializer = null;
 
         if ( !attributeType.getSyntax().isHumanReadable() )
         {
             forwardKeySerializer = ( ElementSerializer<K> ) new ByteArraySerializer( ( Comparator<byte[]> ) comp );
         }
         else
         {
             forwardKeySerializer = ( ElementSerializer<K> ) new StringSerializer( ( Comparator<String> ) comp );
         }
 
         boolean forwardDups = true;
 
         String oid = attributeType.getOid();
         // disable duplicates for entryCSN and entryUUID attribute indices
         if ( oid.equals( SchemaConstants.ENTRY_CSN_AT_OID ) || oid.equals( SchemaConstants.ENTRY_UUID_AT_OID ) )
         {
             forwardDups = false;
         }
 
         String forwardTableName = attributeType.getOid() + FORWARD_BTREE;
         forward = new MavibotTable<>( recordMan, schemaManager, forwardTableName, forwardKeySerializer,
             StringSerializer.INSTANCE, forwardDups, AbstractBTreePartition.DEFAULT_CACHE_SIZE );
 
         /*
          * Now the reverse map stores the primary key into the master table as
          * the key and the values of attributes as the value.  If an attribute
          * is single valued according to its specification based on a schema
          * then duplicate keys should not be allowed within the reverse table.
          */
         if ( withReverse )
         {
             String reverseTableName = attributeType.getOid() + REVERSE_BTREE;
             reverse = new MavibotTable<>( recordMan, schemaManager, reverseTableName, StringSerializer.INSTANCE,
                 forwardKeySerializer, !attributeType.isSingleValued() );
         }
     }
 
 
     /**
      * Sets the RecordManager
      *
      * @param rm the RecordManager instance
      */
     public void setRecordManager( RecordManager rm )
     {
         this.recordMan = rm;
     }
 
 
     // ------------------------------------------------------------------------
     // C O N F I G U R A T I O N   M E T H O D S
     // ------------------------------------------------------------------------
 
     /**
      * Sets the working directory path to something other than the default. Sometimes more
      * performance is gained by locating indices on separate disk spindles.
      *
      * @param wkDirPath optional working directory path
      */
     public void setWkDirPath( URI wkDirPath )
     {
         //.out.println( "IDX Defining a WorkingDir : " + wkDirPath );
         protect( "wkDirPath" );
         this.wkDirPath = new File( wkDirPath );
     }
 
 
     /**
      * Gets the working directory path to something other than the default. Sometimes more
      * performance is gained by locating indices on separate disk spindles.
      *
      * @return optional working directory path
      */
     public URI getWkDirPath()
     {
         return wkDirPath != null ? wkDirPath.toURI() : null;
     }
 
 
     // ------------------------------------------------------------------------
     // Scan Count Methods
     // ------------------------------------------------------------------------
     /**
      * {@inheritDoc}
      */
     public long count( PartitionTxn partitionTxn ) throws LdapException
     {
         return forward.count( partitionTxn );
     }
 
 
     /**
      * {@inheritDoc}
      */
     public long count( PartitionTxn partitionTxn, K attrVal ) throws LdapException
     {
         return forward.count( partitionTxn, attrVal );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public long greaterThanCount( PartitionTxn partitionTxn, K attrVal ) throws LdapException
     {
         return forward.greaterThanCount( partitionTxn, attrVal );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public long lessThanCount( PartitionTxn partitionTxn, K attrVal ) throws LdapException
     {
         return forward.lessThanCount( partitionTxn, attrVal );
     }
 
 
     // ------------------------------------------------------------------------
     // Forward and Reverse Lookups
     // ------------------------------------------------------------------------
 
     /**
      * Do a lookup using the forward table
      * 
      * @param partitionTxn The Transaction to use
      * @param attrVal The Key we are looking for
      * @return The found value
      * @throws LdapException If the lookup failed
      */
     public String forwardLookup( PartitionTxn partitionTxn, K attrVal ) throws LdapException
     {
         return forward.get( partitionTxn, attrVal );
     }
 
 
     /**
      * {@inheritDoc}
      */
     public K reverseLookup( PartitionTxn partitionTxn, String id ) throws LdapException
     {
         if ( withReverse )
         {
             return reverse.get( partitionTxn, id );
         }
         else
         {
             return null;
         }
     }
 
 
     // ------------------------------------------------------------------------
     // Add/Drop Methods
     // ------------------------------------------------------------------------
 
     /**
      * {@inheritDoc}
      */
     public synchronized void add( PartitionTxn partitionTxn, K attrVal, String id ) throws LdapException
     {
         // The pair to be removed must exists
         forward.put( partitionTxn, attrVal, id );
 
         if ( withReverse )
         {
             reverse.put( partitionTxn, id, attrVal );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public synchronized void drop( PartitionTxn partitionTxn, K attrVal, String id ) throws LdapException
     {
         // The pair to be removed must exists
         if ( forward.has( partitionTxn, attrVal, id ) )
         {
             forward.remove( partitionTxn, attrVal, id );
 
             if ( withReverse )
             {
                 reverse.remove( partitionTxn, id, attrVal );
             }
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void drop( PartitionTxn partitionTxn, String entryId ) throws LdapException
     {
         if ( withReverse )
         {
             if ( isDupsEnabled() )
             {
                 // Build a cursor to iterate on all the keys referencing
                 // this entryId
                 Cursor<Tuple<String, K>> values = reverse.cursor( partitionTxn, entryId );
 
                 try
                 {
                     while ( values.next() )
                     {
                         // Remove the Key -> entryId from the index
                         forward.remove( partitionTxn, values.get().getValue(), entryId );
                     }
     
                     values.close();
                 }
                 catch ( CursorException | IOException e )
                 {
                     throw new LdapOtherException( e.getMessage(), e );
                 }
             }
             else
             {
                 K key = reverse.get( partitionTxn, entryId );
 
                 forward.remove( partitionTxn, key );
             }
 
             // Remove the id -> key from the reverse index
             reverse.remove( partitionTxn, entryId );
         }
     }
 
 
     // ------------------------------------------------------------------------
     // Index Cursor Operations
     // ------------------------------------------------------------------------
     @SuppressWarnings("unchecked")
     public Cursor<IndexEntry<K, String>> forwardCursor( PartitionTxn partitionTxn ) throws LdapException
     {
         return new IndexCursorAdaptor<>( partitionTxn, ( Cursor ) forward.cursor(), true );
     }
 
 
     public Cursor<IndexEntry<K, String>> forwardCursor( PartitionTxn partitionTxn, K key ) throws LdapException
     {
         return new IndexCursorAdaptor<>( partitionTxn, ( Cursor ) forward.cursor( partitionTxn, key ), true );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Cursor<K> reverseValueCursor( PartitionTxn partitionTxn, String id ) throws LdapException
     {
         if ( withReverse )
         {
             return reverse.valueCursor( partitionTxn, id );
         }
         else
         {
             return new EmptyCursor<>();
         }
     }
 
 
     public Cursor<String> forwardValueCursor( PartitionTxn partitionTxn, K key ) throws LdapException
     {
         return forward.valueCursor( partitionTxn, key );
     }
 
 
     // ------------------------------------------------------------------------
     // Value Assertion (a.k.a Index Lookup) Methods //
     // ------------------------------------------------------------------------
     /**
      * {@inheritDoc}
      */
     public boolean forward( PartitionTxn partitionTxn, K attrVal ) throws LdapException
     {
         return forward.has( partitionTxn, attrVal );
     }
 
 
     /**
      * {@inheritDoc}
      */
     public boolean forward( PartitionTxn partitionTxn, K attrVal, String id ) throws LdapException
     {
         return forward.has( partitionTxn, attrVal, id );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean reverse( PartitionTxn partitionTxn, String id ) throws LdapException
     {
         if ( withReverse )
         {
             return reverse.has( partitionTxn, id );
         }
         else
         {
             return false;
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean reverse( PartitionTxn partitionTxn, String id, K attrVal ) throws LdapException
     {
         return forward.has( partitionTxn, attrVal, id );
     }
 
 
     // ------------------------------------------------------------------------
     // Maintenance Methods
     // ------------------------------------------------------------------------
     /**
      * {@inheritDoc}
      */
     @Override
     public synchronized void close( PartitionTxn partitionTxn ) throws IOException
     {
         try
         {
             if ( forward != null )
             {
                 forward.close( partitionTxn );
             }
 
             if ( reverse != null )
             {
                 reverse.close( partitionTxn );
             }
         }
         catch ( Exception e )
         {
             throw new IOException( e );
         }
     }
 
 
     /**
      * Force the flush of this index
      * 
      * @throws IOException If the flush failed
      */
     public synchronized void sync() throws IOException
     {
         forward.getBTree().flush();
         
         if ( reverse != null )
         {
             reverse.getBTree().flush();
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isDupsEnabled()
     {
         if ( withReverse )
         {
             return reverse.isDupsEnabled();
         }
         else
         {
             return false;
         }
     }
 
 
     /**
      * @see Object#toString()
      */
     public String toString()
     {
         return "Index<" + attributeId + ">";
     }
 }