/*
    *  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
    *  
   *    https://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.api.ldap.model.schema.registries;
  
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.directory.api.i18n.I18n;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.api.ldap.model.exception.LdapNoSuchAttributeException;
  import org.apache.directory.api.ldap.model.exception.LdapSchemaException;
  import org.apache.directory.api.ldap.model.exception.LdapSchemaExceptionCodes;
  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.SchemaObjectType;
  import org.apache.directory.api.ldap.model.schema.normalizers.NoOpNormalizer;
  import org.apache.directory.api.ldap.model.schema.normalizers.OidNormalizer;
  import org.apache.directory.api.util.Strings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * An AttributeType registry service default implementation.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class DefaultAttributeTypeRegistry extends DefaultSchemaObjectRegistry<AttributeType> implements
      AttributeTypeRegistry
  {
      /** static class logger */
      private static final Logger LOG = LoggerFactory.getLogger( DefaultAttributeTypeRegistry.class );
  
      /** cached Oid/normalizer mapping */
      private Map<String, OidNormalizer> oidNormalizerMap;
  
      /** maps OIDs to a Set of descendants for that OID */
      private Map<String, Set<AttributeType>> oidToDescendantSet;
  
  
      /**
       * Creates a new default AttributeTypeRegistry instance.
       */
      public DefaultAttributeTypeRegistry()
      {
          super( SchemaObjectType.ATTRIBUTE_TYPE, new OidRegistry<AttributeType>() );
          oidNormalizerMap = new HashMap<>();
          oidToDescendantSet = new HashMap<>();
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Map<String, OidNormalizer> getNormalizerMapping()
      {
          return Collections.unmodifiableMap( oidNormalizerMap );
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean hasDescendants( String ancestorId ) throws LdapException
      {
          try
          {
              String oid = getOidByName( ancestorId );
              Set<AttributeType> descendants = oidToDescendantSet.get( oid );
              return ( descendants != null ) && !descendants.isEmpty();
          }
          catch ( LdapException ne )
          {
              throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
          }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean hasDescendants( AttributeType ancestor ) throws LdapException
     {
         String oid = ancestor.getOid();
         Set<AttributeType> descendants = oidToDescendantSet.get( oid );
         return ( descendants != null ) && !descendants.isEmpty();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @SuppressWarnings("unchecked")
     @Override
     public Iterator<AttributeType> descendants( String ancestorId ) throws LdapException
     {
         try
         {
             String oid = getOidByName( ancestorId );
             Set<AttributeType> descendants = oidToDescendantSet.get( oid );
 
             if ( descendants == null )
             {
                 return Collections.EMPTY_SET.iterator();
             }
 
             return descendants.iterator();
         }
         catch ( LdapException ne )
         {
             throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @SuppressWarnings("unchecked")
     @Override
     public Iterator<AttributeType> descendants( AttributeType ancestor ) throws LdapException
     {
         String oid = ancestor.getOid();
         Set<AttributeType> descendants = oidToDescendantSet.get( oid );
 
         if ( descendants == null )
         {
             return Collections.EMPTY_SET.iterator();
         }
 
         return descendants.iterator();
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void registerDescendants( AttributeType attributeType, AttributeType ancestor ) throws LdapException
     {
         // add this attribute to descendant list of other attributes in superior chain
         if ( ancestor == null )
         {
             return;
         }
         
         // Check if the ancestor is not the attribute type itself
         if ( attributeType.getOid().equals( ancestor.getOid() ) )
         {
             throw new LdapSchemaException( LdapSchemaExceptionCodes.AT_CYCLE_TYPE_HIERARCHY );
         }
 
         // Get the ancestor's descendant, if any
         Set<AttributeType> descendants = oidToDescendantSet.get( ancestor.getOid() );
 
         // Initialize the descendant Set to store the descendants for the attributeType
         if ( descendants == null )
         {
             descendants = new HashSet<>( 1 );
             oidToDescendantSet.put( ancestor.getOid(), descendants );
         }
 
         // Add the current type as a descendant
         descendants.add( attributeType );
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void unregisterDescendants( AttributeType attributeType, AttributeType ancestor ) throws LdapException
     {
         // add this attribute to descendant list of other attributes in superior chain
         if ( ancestor == null )
         {
             return;
         }
 
         // Get the ancestor's descendant, if any
         Set<AttributeType> descendants = oidToDescendantSet.get( ancestor.getOid() );
 
         if ( descendants != null )
         {
             descendants.remove( attributeType );
 
             if ( descendants.isEmpty() )
             {
                 oidToDescendantSet.remove( ancestor.getOid() );
             }
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public AttributeType unregister( String numericOid ) throws LdapException
     {
         try
         {
             AttributeType removed = super.unregister( numericOid );
 
             removeMappingFor( removed );
 
             // Deleting an AT which might be used as a superior means we have
             // to recursively update the descendant map. We also have to remove
             // the at.oid -> descendant relation
             oidToDescendantSet.remove( numericOid );
 
             // Now recurse if needed
             unregisterDescendants( removed, removed.getSuperior() );
 
             return removed;
         }
         catch ( LdapException ne )
         {
             throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void addMappingFor( AttributeType attributeType ) throws LdapException
     {
         MatchingRule equality = attributeType.getEquality();
         OidNormalizer oidNormalizer;
         String oid = attributeType.getOid();
 
         if ( equality == null )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.msg( I18n.MSG_13703_AT_WITHOUT_EQ_MR, attributeType.getName() ) );
             }
             
             oidNormalizer = new OidNormalizer( oid, new NoOpNormalizer( attributeType.getOid() ) );
         }
         else
         {
             oidNormalizer = new OidNormalizer( oid, equality.getNormalizer() );
         }
 
         oidNormalizerMap.put( oid, oidNormalizer );
 
         // Also inject the attributeType's short names in the map
         for ( String name : attributeType.getNames() )
         {
             oidNormalizerMap.put( Strings.toLowerCaseAscii( name ), oidNormalizer );
         }
     }
 
 
     /**
      * Remove the AttributeType normalizer from the OidNormalizer map 
      */
     @Override
     public void removeMappingFor( AttributeType attributeType ) throws LdapException
     {
         if ( attributeType == null )
         {
             return;
         }
 
         oidNormalizerMap.remove( attributeType.getOid() );
 
         // We also have to remove all the short names for this attribute
         for ( String name : attributeType.getNames() )
         {
             oidNormalizerMap.remove( Strings.toLowerCaseAscii( name ) );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public AttributeType lookup( String oid ) throws LdapException
     {
         try
         {
             return super.lookup( oid );
         }
         catch ( LdapException ne )
         {
             throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public DefaultAttributeTypeRegistry copy()
     {
         DefaultAttributeTypeRegistry copy = new DefaultAttributeTypeRegistry();
 
         // Copy the base data
         copy.copy( this );
 
         return copy;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void clear()
     {
         // First clear the shared elements
         super.clear();
 
         // clear the OidNormalizer map
         oidNormalizerMap.clear();
 
         // and clear the descendant
         for ( Map.Entry<String, Set<AttributeType>> entry : oidToDescendantSet.entrySet() )
         {
             Set<AttributeType> descendants = entry.getValue();
 
             if ( descendants != null )
             {
                 descendants.clear();
             }
         }
 
         oidToDescendantSet.clear();
     }
 }