/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Portions Copyright 2006 Sun Microsystems, Inc.
 */
package org.opends.server.backends.jeb;

import static org.opends.server.loggers.Debug.debugException;

import org.opends.server.api.OrderingMatchingRule;
import org.opends.server.core.DirectoryException;
import org.opends.server.protocols.asn1.ASN1OctetString;
import org.opends.server.types.Attribute;
import org.opends.server.types.AttributeType;
import org.opends.server.types.AttributeValue;
import org.opends.server.types.Entry;
import org.opends.server.types.Modification;

import com.sleepycat.je.Transaction;
import com.sleepycat.je.DatabaseException;

import java.util.*;

/**
 * An implementation of an Indexer for attribute ordering.
 */
public class OrderingIndexer extends Indexer
{
  /**
   * The fully-qualified name of this class for debugging purposes.
   */
  private static final String CLASS_NAME =
       "org.opends.server.backends.jeb.OrderingIndexer";


  /**
   * The attribute index configuration for which this instance will
   * generate index keys.
   */
  private IndexConfig indexConfig;

  /**
   * The attribute type ordering matching rule which is also the
   * comparator for the index keys generated by this class.
   */
  private OrderingMatchingRule orderingRule;


  /**
   * Create a new attribute ordering indexer for the given index configuration.
   * @param indexConfig The index configuration for which an indexer is
   * required.
   */
  public OrderingIndexer(IndexConfig indexConfig)
  {
    this.indexConfig = indexConfig;
    orderingRule = indexConfig.getAttributeType().getOrderingMatchingRule();
  }

  /**
   * Get a string representation of this object.  The returned value is
   * used to name an index created using this object.
   * @return A string representation of this object.
   */
  public String toString()
  {
    return indexConfig.getAttributeType().getNameOrOID() + ".ordering";
  }

  /**
   * Get the comparator that must be used to compare index keys
   * generated by this class.
   *
   * @return A byte array comparator.
   */
  public Comparator<byte[]> getComparator()
  {
    return orderingRule;
  }

  /**
   * Generate the set of index keys for an entry.
   *
   * @param txn A database transaction to be used if the database need to be
   * accessed in the course of generating the index keys.
   * @param entry The entry.
   * @param keys The set into which the generated keys will be inserted.
   */
  public void indexEntry(Transaction txn, Entry entry,
                       Set<ASN1OctetString> keys)
  {
    List<Attribute> attrList =
         entry.getAttribute(indexConfig.getAttributeType());
    if (attrList != null)
    {
      indexAttribute(attrList, keys);
    }
  }

  /**
   * Generate the set of index keys to be added and the set of index keys
   * to be deleted for an entry that has been replaced.
   *
   * @param txn A database transaction to be used if the database need to be
   * accessed in the course of generating the index keys.
   * @param oldEntry The original entry contents.
   * @param newEntry The new entry contents.
   * @param addKeys The set into which the keys to be added will be inserted.
   * @param delKeys The set into which the keys to be deleted will be inserted.
   */
  public void replaceEntry(Transaction txn,
                           Entry oldEntry, Entry newEntry,
                           Set<ASN1OctetString> addKeys,
                           Set<ASN1OctetString> delKeys)
  {
    List<Attribute> attrList;

    attrList = oldEntry.getAttribute(indexConfig.getAttributeType());
    Set<ASN1OctetString> oldSet = new HashSet<ASN1OctetString>();
    indexAttribute(attrList, oldSet);

    attrList = newEntry.getAttribute(indexConfig.getAttributeType());
    Set<ASN1OctetString> newSet = new HashSet<ASN1OctetString>();
    indexAttribute(attrList, newSet);

    HashSet<ASN1OctetString> removeSet = new HashSet<ASN1OctetString>(oldSet);
    removeSet.removeAll(newSet);
    for (ASN1OctetString k : removeSet)
    {
      delKeys.add(k);
    }

    HashSet<ASN1OctetString> addSet = new HashSet<ASN1OctetString>(newSet);
    addSet.removeAll(oldSet);
    for (ASN1OctetString k : addSet)
    {
      addKeys.add(k);
    }
  }

  /**
   * Generate the set of index keys to be added and the set of index keys
   * to be deleted for an entry that was modified.
   *
   * @param txn A database transaction to be used if the database need to be
   * accessed in the course of generating the index keys.
   * @param oldEntry The original entry contents.
   * @param newEntry The new entry contents.
   * @param mods The set of modifications that were applied to the entry.
   * @param addKeys The set into which the keys to be added will be inserted.
   * @param delKeys The set into which the keys to be deleted will be inserted.
   * @throws DatabaseException If an error occurs in the JE database.
   */
  public void modifyEntry(Transaction txn, Entry oldEntry, Entry newEntry,
                          List<Modification> mods,
                          Set<ASN1OctetString> addKeys,
                          Set<ASN1OctetString> delKeys)
       throws DatabaseException
  {
    List<Attribute> beforeList;
    beforeList = oldEntry.getAttribute(indexConfig.getAttributeType());

    // Pick out the modifications that apply to this indexed attribute

    /**
     * FIXME unusual modifications can insert spurious index values
     * The following sequence of modifications will insert A into the
     * index, yet A is not a resulting value for the attribute.
     *
     * add: cn
     * cn: A
     * -
     * replace: cn
     * cn: B
     * -
     *
     */

    for (Modification mod : mods)
    {
      Attribute modAttr = mod.getAttribute();
      AttributeType modAttrType = modAttr.getAttributeType();
      if (modAttrType.equals(indexConfig.getAttributeType()))
      {
        switch (mod.getModificationType())
        {
          case REPLACE:
          case INCREMENT:
            if (beforeList != null)
            {
              for (Attribute attr : beforeList)
              {
                if (attr.hasOptions(modAttr.getOptions()))
                {
                  indexValues(attr.getValues(), delKeys);
                }
              }
            }
            indexValues(modAttr.getValues(), addKeys);
            break;

          case ADD:
            indexValues(modAttr.getValues(), addKeys);
            break;

          case DELETE:
            if (!modAttr.hasValue())
            {
              if (beforeList != null)
              {
                for (Attribute attr : beforeList)
                {
                  if (attr.hasOptions(modAttr.getOptions()))
                  {
                    indexValues(attr.getValues(), delKeys);
                  }
                }
              }
            }
            else
            {
              indexValues(modAttr.getValues(), delKeys);
            }
            break;
        }
      }
    }
  }


  /**
   * Generate the set of index keys for a set of attribute values.
   * @param values The set of attribute values to be indexed.
   * @param keys The set into which the keys will be inserted.
   */
  private void indexValues(Set<AttributeValue> values,
                           Set<ASN1OctetString> keys)
  {
    if (values == null) return;

    for (AttributeValue value : values)
    {
      try
      {
        byte[] keyBytes =
             orderingRule.normalizeValue(value.getValue()).value();

        keys.add(new ASN1OctetString(keyBytes));
      }
      catch (DirectoryException e)
      {
        assert debugException(CLASS_NAME, "indexAttribute", e);
      }
    }
  }

  /**
   * Generate the set of index keys for an attribute.
   * @param attrList The attribute to be indexed.
   * @param keys The set into which the keys will be inserted.
   */
  private void indexAttribute(List<Attribute> attrList,
                              Set<ASN1OctetString> keys)
  {
    if (attrList == null) return;

    for (Attribute attr : attrList)
    {
      indexValues(attr.getValues(), keys);
    }
  }

}