/*
 * Copyright (c) 1998, 2020 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 v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.sdo;

import java.io.IOException;
import java.io.ObjectInput;
import java.lang.reflect.Field;

import org.eclipse.persistence.exceptions.SDOException;
import org.eclipse.persistence.internal.security.PrivilegedGetField;
import org.eclipse.persistence.internal.security.PrivilegedGetValueFromField;
import org.eclipse.persistence.internal.security.PrivilegedSetValueInField;
import org.eclipse.persistence.sdo.helper.DataObjectInputStream;
import org.eclipse.persistence.sdo.helper.SDOHelperContext;

import commonj.sdo.helper.HelperContext;
import commonj.sdo.impl.ExternalizableDelegator.Resolvable;
import commonj.sdo.impl.HelperProvider;

public class SDOExternalizableDelegator extends AbstractExternalizableDelegator {

    static final PrivilegedGetField privilegedGetDelegateField = new PrivilegedGetField(AbstractExternalizableDelegator.class, "delegate", true);

    public SDOExternalizableDelegator() {
        super();
    }

    public SDOExternalizableDelegator(Object target) {
        super(target);
    }

    public SDOExternalizableDelegator(Object target, HelperContext aContext) {
        // JIRA129: pass the helperContext to the constructor to enable non-static contexts
        // check for context type (if non-static SDOHelperContext then we need to cast to use the non-interface createResolvable function
        // to remove this instanceof check - add createResolvable to the HelperContext interface
        if (aContext instanceof SDOHelperContext) {
            setDelegate(((SDOHelperContext)aContext).createResolvable(target));
        } else {
            // use static helper
            setDelegate(HelperProvider.createResolvable(target));
        }
    }

    @Override
    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        // This function is indirectly called by InputStream.readExternalData().
        // We reset the static helperContext set in the default constructor during is.readObject()
        // with the passed in context from the client (either static or dynamic instance)
        if (in instanceof DataObjectInputStream) {
            // only reset non-static implementations
            getDelegate().setHelperContext(((DataObjectInputStream)in).getHelperContext());
        }
        super.readExternal(in);
    }

    private SDOResolvable getDelegate() {
        try {
            Field delegateField = privilegedGetDelegateField.run();
            PrivilegedGetValueFromField privilegedGetValueFromDelegateField = new PrivilegedGetValueFromField(delegateField, this);
            return (SDOResolvable) privilegedGetValueFromDelegateField.run();
        }catch (NoSuchFieldException nsfException){
            throw SDOException.errorAccessingExternalizableDelegator("delegate", nsfException);
        }catch (IllegalAccessException iaException){
            throw SDOException.errorAccessingExternalizableDelegator("delegate", iaException);
        }
    }

    private void setDelegate(Resolvable resolvable) {
        try {
            Field delegateField = privilegedGetDelegateField.run();
            PrivilegedSetValueInField privilegedSetValueInDelegateField = new PrivilegedSetValueInField(delegateField, this, resolvable);
            privilegedSetValueInDelegateField.run();
        } catch (NoSuchFieldException nsfException){
            throw SDOException.errorAccessingExternalizableDelegator("delegate", nsfException);
        } catch (IllegalAccessException iaException){
            throw SDOException.errorAccessingExternalizableDelegator("delegate", iaException);
        }
    }
}