/*
 *  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 com.googlecode.openbeans;

import com.googlecode.openbeans.DefaultPersistenceDelegate;
import com.googlecode.openbeans.Encoder;
import com.googlecode.openbeans.Expression;
import com.googlecode.openbeans.PersistenceDelegate;
import com.googlecode.openbeans.Statement;
import java.util.Collection;
import java.util.Iterator;

class UtilCollectionPersistenceDelegate extends
        DefaultPersistenceDelegate {
    @Override
    @SuppressWarnings("nls")
    protected void initialize(Class<?> type, Object oldInstance,
            Object newInstance, Encoder enc) {

        Collection<?> oldList = (Collection<?>) oldInstance;
        Collection<?> newList = (Collection<?>) newInstance;
        Iterator<?> oldIterator = oldList.iterator(), newIterator = newList.iterator();
        for (; oldIterator.hasNext();) {
            Expression getterExp = new Expression(oldIterator, "next", null);
            try {
                // Calculate the old value of the property
                Object oldVal = getterExp.getValue();

                Object newVal = null;
                try {
                    newVal = new Expression(newIterator, "next", null).getValue();
                } catch (ArrayIndexOutOfBoundsException ex) {
                    // The newInstance has no elements, so current property
                    // value remains null
                }
                /*
                 * Make the target value and current property value equivalent
                 * in the new environment
                 */
                if (null == oldVal) {
                    if (null != newVal) {
                        // Set to null
                        Statement setterStm = new Statement(oldInstance, "add",
                                new Object[] { null });
                        enc.writeStatement(setterStm);
                    }
                } else {
                    PersistenceDelegate pd = enc
                            .getPersistenceDelegate(oldVal.getClass());
                    if (!pd.mutatesTo(oldVal, newVal)) {
                        Statement setterStm = new Statement(oldInstance, "add",
                                new Object[] { oldVal });
                        enc.writeStatement(setterStm);
                    }
                }
            } catch (Exception ex) {
                enc.getExceptionListener().exceptionThrown(ex);
            }
        }
    }
}