/*
    *  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.api.ldap.model.schema.registries;
  
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  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.schema.ObjectClass;
  import org.apache.directory.api.ldap.model.schema.SchemaObject;
  import org.apache.directory.api.ldap.model.schema.SchemaObjectType;
  
  
  /**
   * An ObjectClass registry's service default implementation.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class DefaultObjectClassRegistry extends DefaultSchemaObjectRegistry<ObjectClass>
      implements ObjectClassRegistry
  {
      /** maps OIDs to a Set of descendants for that OID */
      private Map<String, Set<ObjectClass>> oidToDescendants;
  
  
      /**
       * Creates a new default ObjectClassRegistry instance.
       */
      public DefaultObjectClassRegistry()
      {
          super( SchemaObjectType.OBJECT_CLASS, new OidRegistry<ObjectClass>() );
          oidToDescendants = new HashMap<String, Set<ObjectClass>>();
      }
  
  
      /**
       * {@inheritDoc}
       */
      public boolean hasDescendants( String ancestorId ) throws LdapException
      {
          try
          {
              String oid = getOidByName( ancestorId );
              Set<ObjectClass> descendants = oidToDescendants.get( oid );
              return ( descendants != null ) && !descendants.isEmpty();
          }
          catch ( LdapException ne )
          {
              throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
          }
      }
  
  
      /**
       * {@inheritDoc}
       */
      @SuppressWarnings("unchecked")
      public Iterator<ObjectClass> descendants( String ancestorId ) throws LdapException
      {
          try
          {
              String oid = getOidByName( ancestorId );
              Set<ObjectClass> descendants = oidToDescendants.get( oid );
  
              if ( descendants == null )
              {
                  return Collections.EMPTY_SET.iterator();
              }
  
              return descendants.iterator();
          }
          catch ( LdapException ne )
          {
              throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
          }
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void registerDescendants( ObjectClass objectClass, List<ObjectClass> ancestors )
         throws LdapException
     {
         // add this attribute to descendant list of other attributes in superior chain
         if ( ( ancestors == null ) || ( ancestors.size() == 0 ) )
         {
             return;
         }
 
         for ( ObjectClass ancestor : ancestors )
         {
             // Get the ancestor's descendant, if any
             Set<ObjectClass> descendants = oidToDescendants.get( ancestor.getOid() );
 
             // Initialize the descendant Set to store the descendants for the attributeType
             if ( descendants == null )
             {
                 descendants = new HashSet<ObjectClass>( 1 );
                 oidToDescendants.put( ancestor.getOid(), descendants );
             }
 
             // Add the current ObjectClass as a descendant
             descendants.add( objectClass );
 
             try
             {
                 // And recurse until we reach the top of the hierarchy
                 registerDescendants( objectClass, ancestor.getSuperiors() );
             }
             catch ( LdapException ne )
             {
                 throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
             }
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void unregisterDescendants( ObjectClass attributeType, List<ObjectClass> ancestors )
         throws LdapException
     {
         // add this attribute to descendant list of other attributes in superior chain
         if ( ( ancestors == null ) || ( ancestors.size() == 0 ) )
         {
             return;
         }
 
         for ( ObjectClass ancestor : ancestors )
         {
             // Get the ancestor's descendant, if any
             Set<ObjectClass> descendants = oidToDescendants.get( ancestor.getOid() );
 
             if ( descendants != null )
             {
                 descendants.remove( attributeType );
 
                 if ( descendants.size() == 0 )
                 {
                     oidToDescendants.remove( ancestor.getOid() );
                 }
             }
 
             try
             {
                 // And recurse until we reach the top of the hierarchy
                 unregisterDescendants( attributeType, ancestor.getSuperiors() );
             }
             catch ( LdapException ne )
             {
                 throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
             }
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     public ObjectClass unregister( String numericOid ) throws LdapException
     {
         try
         {
             ObjectClass removed = super.unregister( numericOid );
 
             // Deleting an ObjectClass 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
             oidToDescendants.remove( numericOid );
 
             // Now recurse if needed
             unregisterDescendants( removed, removed.getSuperiors() );
 
             return removed;
         }
         catch ( LdapException ne )
         {
             throw new LdapNoSuchAttributeException( ne.getMessage(), ne );
         }
     }
 
 
     /**
      * {@inheritDoc}
      */
     public DefaultObjectClassRegistry copy()
     {
         DefaultObjectClassRegistry copy = new DefaultObjectClassRegistry();
 
         // Copy the base data
         copy.copy( this );
 
         return copy;
     }
 
 
     /**
      * {@inheritDoc}
      */
     public void clear()
     {
         // Clear the contained SchemaObjects
         for ( SchemaObject objectClass : oidRegistry )
         {
             objectClass.clear();
         }
 
         // First clear the shared elements
         super.clear();
 
         // and clear the descendant
         for ( String oid : oidToDescendants.keySet() )
         {
             Set<ObjectClass> descendants = oidToDescendants.get( oid );
 
             if ( descendants != null )
             {
                 descendants.clear();
             }
         }
 
         oidToDescendants.clear();
     }
 }