/*******************************************************************************
 * Copyright (c) 1998, 2013 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
 ******************************************************************************/  
package org.eclipse.persistence.mappings.converters;

import java.io.*;
import org.eclipse.persistence.mappings.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.mappings.foundation.AbstractDirectMapping;
import org.eclipse.persistence.sessions.*;
import org.eclipse.persistence.internal.sessions.AbstractSession;

/**
 * <p><b>Purpose</b>: The serialized object converter can be used to store an arbitrary object or set of objects into a database blob field.
 * It uses the Java serializer so the target must be serializable.
 *
 * @author James Sutherland
 * @since OracleAS TopLink 10<i>g</i> (10.0.3)
 */
public class SerializedObjectConverter implements Converter {
    protected DatabaseMapping mapping;

    /**
     * PUBLIC:
     * Default constructor.
     */
    public SerializedObjectConverter() {
    }

    /**
     * PUBLIC:
     * Default constructor.
     */
    public SerializedObjectConverter(DatabaseMapping mapping) {
        this.mapping = mapping;
    }

    /**
     * INTERNAL:
     * The fieldValue will be a byte array.  Create a ByteArrayInputStream
     * on the fieldValue.  Create an ObjectInputStream on the ByteArrayInputStream
     * to read in the objects.
     */
    public Object convertDataValueToObjectValue(Object fieldValue, Session session) throws DescriptorException {
        if (fieldValue == null) {
            return null;
        }
        byte[] bytes;
        try {
            bytes = (byte[])((AbstractSession)session).getDatasourcePlatform().convertObject(fieldValue, ClassConstants.APBYTE);
        } catch (ConversionException e) {
            throw ConversionException.couldNotBeConverted(mapping, mapping.getDescriptor(), e);
        }

        if ((bytes == null) || (bytes.length == 0)) {
            return null;
        }
        ByteArrayInputStream byteIn = new ByteArrayInputStream(bytes);
        Object object = null;
        try {
            // BUG# 2813583
            CustomObjectInputStream objectIn = new CustomObjectInputStream(byteIn, session);
            object = objectIn.readObject();
        } catch (Exception exception) {
            throw DescriptorException.notDeserializable(getMapping(), exception);
        }

        return object;
    }

    /**
     *  INTERNAL:
     *  Convert the object to a byte array through serialize.
     */
    public Object convertObjectValueToDataValue(Object attributeValue, Session session) {
        if (attributeValue == null) {
            return null;
        }
        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
        try {
            ObjectOutputStream objectOut = new ObjectOutputStream(byteOut);
            objectOut.writeObject(attributeValue);
            objectOut.flush();
        } catch (IOException exception) {
            throw DescriptorException.notSerializable(getMapping(), exception);
        }
        return byteOut.toByteArray();
    }

    /**
     * INTERNAL:
     * Set the mapping.
     */
    public void initialize(DatabaseMapping mapping, Session session) {
        this.mapping = mapping;
        // CR#... Mapping must also have the field classification.
        if (getMapping().isDirectToFieldMapping()) {
            AbstractDirectMapping directMapping = (AbstractDirectMapping)getMapping();

            // Allow user to specify field type to override computed value. (i.e. blob, nchar)
            if (directMapping.getFieldClassification() == null) {
                directMapping.setFieldClassification(ClassConstants.APBYTE);
            }
        }
    }

    /**
     * INTERNAL:
     * Return the mapping.
     */
    protected DatabaseMapping getMapping() {
        return mapping;
    }

    /**
     * INTERNAL:
     * If the converter converts the value to a non-atomic value, i.e.
     * a value that can have its' parts changed without being replaced,
     * then it must return false, serialization can be non-atomic.
     */
    public boolean isMutable() {
        return true;
    }
}