/* Copyright (C) 2004 - 2008  db4objects Inc.  http://www.db4o.com

This file is part of the db4o open source object database.

db4o is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL 
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.

db4o is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. */
package com.db4o.internal.handlers;

import com.db4o.ext.*;
import com.db4o.foundation.*;
import com.db4o.internal.*;
import com.db4o.internal.delete.*;
import com.db4o.internal.marshall.*;
import com.db4o.marshall.*;
import com.db4o.typehandlers.*;


/**
 * Tyehandler for naked plain objects (java.lang.Object).
 */
public class PlainObjectHandler implements TypeHandler4, ReadsObjectIds, EmbeddedTypeHandler{

    public void defragment(DefragmentContext context) {
        context.copySlotlessID();
    }

    public void delete(DeleteContext context) throws Db4oIOException {
        // do nothing
    }

    public Object read(ReadContext context) {
        int id = context.readInt();
        Transaction transaction = context.transaction();
        Object obj = transaction.objectForIdFromCache(id);
        if(obj != null){
            return obj;
        }
        obj = new Object();
        addReference(context, obj, id);
        return obj;
    }

    public void write(WriteContext context, Object obj) {
        Transaction transaction = context.transaction();
        ObjectContainerBase container = transaction.container();
        int id = container.getID(transaction, obj);
        if(id <= 0){
            id = container.newUserObject();
            
            // TODO: Free on rollback
            
            addReference(context, obj, id);
        }
        context.writeInt(id);
    }

    private void addReference(Context context, Object obj, int id) {
        Transaction transaction = context.transaction();
        ObjectReference ref = new ObjectReference(id);
        ref.setObjectWeak(transaction.container(), obj);
        transaction.addNewReference(ref);
    }

    public PreparedComparison prepareComparison(Context context, Object obj) {
        throw new NotImplementedException();
    }

    public ObjectID readObjectID(InternalReadContext context) {
        return ObjectID.read(context);
    }

}
