/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2006-2010 Sun Microsystems, Inc.
 * Portions Copyright 2012-2016 ForgeRock AS.
 */
package org.opends.server.replication.plugin;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.forgerock.opendj.ldap.Assertion;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.opendj.ldap.ConditionResult;
import org.forgerock.opendj.ldap.DecodeException;
import org.forgerock.opendj.ldap.schema.MatchingRuleImpl;
import org.forgerock.opendj.ldap.schema.Schema;
import org.forgerock.opendj.ldap.schema.SchemaBuilder;
import org.forgerock.opendj.ldap.spi.IndexQueryFactory;
import org.forgerock.opendj.ldap.spi.Indexer;
import org.forgerock.opendj.ldap.spi.IndexingOptions;
import org.opends.server.replication.common.CSN;

import static org.forgerock.opendj.ldap.Assertion.*;
import static org.opends.messages.ReplicationMessages.*;
import static org.opends.server.util.StaticUtils.*;

/**
 * Matching rule used to establish an order between historical information and index them.
 */
public final class HistoricalCsnOrderingMatchingRuleImpl implements MatchingRuleImpl
{
  private static final String ORDERING_ID = "changeSequenceNumberOrderingMatch";

  private final Collection<? extends Indexer> indexers = Collections.singleton(new HistoricalIndexer());

  /** Indexer for the matching rule. */
  private final class HistoricalIndexer implements Indexer
  {
    @Override
    public void createKeys(Schema schema, ByteSequence value, Collection<ByteString> keys) throws DecodeException
    {
      keys.add(normalizeAttributeValue(schema, value));
    }

    @Override
    public String getIndexID()
    {
      return ORDERING_ID;
    }

    @Override
    public String keyToHumanReadableString(ByteSequence key)
    {
      ByteStringBuilder bsb = new ByteStringBuilder();
      bsb.appendBytes(key.subSequence(2, 10));
      bsb.appendBytes(key.subSequence(0, 2));
      bsb.appendBytes(key.subSequence(10, 14));
      CSN csn = CSN.valueOf(bsb.toByteString());
      return csn.toStringUI();
    }
  }

  /** {@inheritDoc} */
  @Override
  public ByteString normalizeAttributeValue(Schema schema, ByteSequence value) throws DecodeException
  {
    /*
     * Change the format of the value to index and start with the serverId. In
     * that manner, the search response time is optimized for a particular
     * serverId. The format of the key is now : serverId + timestamp + seqNum
     */
    try
    {
      int csnIndex = value.toString().indexOf(':') + 1;
      String csn = value.subSequence(csnIndex, csnIndex + 28).toString();
      ByteStringBuilder builder = new ByteStringBuilder(14);
      builder.appendBytes(hexStringToByteArray(csn.substring(16, 20)));
      builder.appendBytes(hexStringToByteArray(csn.substring(0, 16)));
      builder.appendBytes(hexStringToByteArray(csn.substring(20, 28)));
      return builder.toByteString();
    }
    catch (Exception e)
    {
      // This should never occur in practice since these attributes are managed
      // internally.
      throw DecodeException.error(WARN_INVALID_SYNC_HIST_VALUE.get(value), e);
    }
  }

  /** {@inheritDoc} */
  @Override
  public Assertion getAssertion(final Schema schema, final ByteSequence value) throws DecodeException
  {
    final ByteString normAssertion = normalizeAttributeValue(schema, value);
    return new Assertion()
    {
      @Override
      public ConditionResult matches(final ByteSequence attributeValue)
      {
        return ConditionResult.valueOf(attributeValue.compareTo(normAssertion) < 0);
      }

      @Override
      public <T> T createIndexQuery(IndexQueryFactory<T> factory) throws DecodeException
      {
        return factory.createRangeMatchQuery(ORDERING_ID, ByteString.empty(), normAssertion, false, false);
      }
    };
  }

  /** {@inheritDoc} */
  @Override
  public Assertion getSubstringAssertion(Schema schema, ByteSequence subInitial,
      List<? extends ByteSequence> subAnyElements, ByteSequence subFinal) throws DecodeException
  {
    return UNDEFINED_ASSERTION;
  }

  /** {@inheritDoc} */
  @Override
  public Assertion getGreaterOrEqualAssertion(Schema schema, ByteSequence value) throws DecodeException
  {
    final ByteString normAssertion = normalizeAttributeValue(schema, value);
    return new Assertion()
    {
      @Override
      public ConditionResult matches(final ByteSequence normalizedAttributeValue)
      {
        return ConditionResult.valueOf(normalizedAttributeValue.compareTo(normAssertion) >= 0);
      }

      @Override
      public <T> T createIndexQuery(IndexQueryFactory<T> factory) throws DecodeException
      {
        return factory.createRangeMatchQuery(ORDERING_ID, normAssertion, ByteString.empty(), true, false);
      }
    };
  }

  /** {@inheritDoc} */
  @Override
  public Assertion getLessOrEqualAssertion(Schema schema, ByteSequence value) throws DecodeException
  {
    final ByteString normAssertion = normalizeAttributeValue(schema, value);
    return new Assertion()
    {
      @Override
      public ConditionResult matches(final ByteSequence normalizedAttributeValue)
      {
        return ConditionResult.valueOf(normalizedAttributeValue.compareTo(normAssertion) <= 0);
      }

      @Override
      public <T> T createIndexQuery(IndexQueryFactory<T> factory) throws DecodeException
      {
        return factory.createRangeMatchQuery(ORDERING_ID, ByteString.empty(), normAssertion, false, true);
      }
    };
  }

  @Override
  public Collection<? extends Indexer> createIndexers(IndexingOptions options)
  {
    return indexers;
  }

  /**
   * Adds the historical csn ordering matching rule to the provided schema builder.
   *
   * @param builder
   *          where to add the historical csn ordering matching rule
   * @return the provided builder
   */
  public static SchemaBuilder addHistoricalCsnOrderingMatchingRule(SchemaBuilder builder)
  {
    return builder
        .buildMatchingRule("1.3.6.1.4.1.26027.1.4.4")
        .names("historicalCsnOrderingMatch")
        .syntaxOID("1.3.6.1.4.1.1466.115.121.1.40")
        .implementation(new HistoricalCsnOrderingMatchingRuleImpl())
        .addToSchema();
  }
}