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package org.codehaus.plexus.classworlds;

/*
 * Copyright 2001-2006 Codehaus Foundation.
 *
 * Licensed 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.
 */

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;

/**
 * A collection of ClassRealms, indexed by id.
 *
 * @author bob mcwhirter
 * @version $Id$
 */
public class ClassWorld
{
    private Map realms;

    private final List listeners = new ArrayList();

    public ClassWorld( String realmId,
                       ClassLoader classLoader )
    {
        this();

        try
        {
            newRealm( realmId, classLoader );
        }
        catch ( DuplicateRealmException e )
        {
            // Will never happen as we are just creating the world.
        }
    }

    public ClassWorld()
    {
        this.realms = new LinkedHashMap();
    }

    public ClassRealm newRealm( String id )
        throws DuplicateRealmException
    {
        return newRealm( id, getClass().getClassLoader() );
    }

    public synchronized ClassRealm newRealm( String id, ClassLoader classLoader )
        throws DuplicateRealmException
    {
        if ( realms.containsKey( id ) )
        {
            throw new DuplicateRealmException( this, id );
        }

        ClassRealm realm;

        realm = new ClassRealm( this, id, classLoader );

        realms.put( id, realm );

        for ( int i = 0; i < listeners.size(); i++ )
        {
            ClassWorldListener listener = (ClassWorldListener) listeners.get( i );
            listener.realmCreated( realm );
        }

        return realm;
    }

    public synchronized void disposeRealm( String id )
        throws NoSuchRealmException
    {
        ClassRealm realm = (ClassRealm) realms.remove( id );

        if ( realm != null )
        {
            for ( int i = 0; i < listeners.size(); i++ )
            {
                ClassWorldListener listener = (ClassWorldListener) listeners.get( i );
                listener.realmDisposed( realm );
            }
        }
    }

    public synchronized ClassRealm getRealm( String id )
        throws NoSuchRealmException
    {
        if ( realms.containsKey( id ) )
        {
            return (ClassRealm) realms.get( id );
        }
        
        throw new NoSuchRealmException( this, id );
    }

    public synchronized Collection getRealms()
    {
        return Collections.unmodifiableList( new ArrayList(realms.values()) );
    }
    
    // from exports branch
    public synchronized ClassRealm getClassRealm( String id )                                                                                                      
    {                                                                                                                                                              
        if ( realms.containsKey( id ) )                                                                                                                            
        {                                                                                                                                                          
            return (ClassRealm) realms.get( id );                                                                                                                  
        }                                                                                                                                                          
                                                                                                                                                                   
        return null;                                                                                                                                               
    }         

    public synchronized void addListener( ClassWorldListener listener )
    {
        // TODO ideally, use object identity, not equals
        if ( !listeners.contains( listener ) )
        {
            listeners.add( listener );
        }
    }
    
    public synchronized void removeListener( ClassWorldListener listener )
    {
        listeners.remove( listener );
    }
}