/*

 * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.beans.decoder;

import java.beans.XMLDecoder;

/**

 * This class is intended to handle <java> element.

 * Each element that appears in the body of this element

 * is evaluated in the context of the decoder itself.

 * Typically this outer context is used to retrieve the owner of the decoder,

 * which can be set before reading the archive.

 * <dl>

 * <dt>version

 * <dd>the Java version (not supported)

 * <dt>class

 * <dd>the type of preferable parser (not supported)

 * <dt>id

 * <dd>the identifier of the variable that is intended to store the result

 * </dl>

 *

 * @see DocumentHandler#getOwner

 * @see DocumentHandler#setOwner

 * @since 1.7

 *

 * @author Sergey A. Malenkov

 */

final class JavaElementHandler extends ElementHandler {

    private Class<?> type;

    private ValueObject value;

    /**

     * Parses attributes of the element.

     * <dl>

     * <dt>version

     * <dd>the Java version (not supported)

     * <dt>class

     * <dd>the type of preferable parser (not supported)

     * <dt>id

     * <dd>the identifier of the variable that is intended to store the result

     * </dl>

     *

     * @param name   the attribute name

     * @param value  the attribute value

     */

    @Override

    public void addAttribute(String name, String value) {

        if (name.equals("version")) { // NON-NLS: the attribute name

            // unsupported attribute

        } else if (name.equals("class")) { // NON-NLS: the attribute name

            // check class for owner

            this.type = getOwner().findClass(value);

        } else {

            super.addAttribute(name, value);

        }

    }

    /**

     * Adds the argument to the list of readed objects.

     *

     * @param argument  the value of the element that contained in this one

     */

    @Override

    protected void addArgument(Object argument) {

        getOwner().addObject(argument);

    }

    /**

     * Tests whether the value of this element can be used

     * as an argument of the element that contained in this one.

     *

     * @return {@code true} if the value of this element should be used

     *         as an argument of the element that contained in this one,

     *         {@code false} otherwise

     */

    @Override

    protected boolean isArgument() {

        return false; // do not use owner as object

    }

    /**

     * Returns the value of this element.

     *

     * @return the value of this element

     */

    @Override

    protected ValueObject getValueObject() {

        if (this.value == null) {

            this.value = ValueObjectImpl.create(getValue());

        }

        return this.value;

    }

    /**

     * Returns the owner of the owner document handler

     * as a value of <java> element.

     *

     * @return the owner of the owner document handler

     */

    private Object getValue() {

        Object owner = getOwner().getOwner();

        if ((this.type == null) || isValid(owner)) {

            return owner;

        }

        if (owner instanceof XMLDecoder) {

            XMLDecoder decoder = (XMLDecoder) owner;

            owner = decoder.getOwner();

            if (isValid(owner)) {

                return owner;

            }

        }

        throw new IllegalStateException("Unexpected owner class: " + owner.getClass().getName());

    }

    /**

     * Validates the owner of the <java> element.

     * The owner is valid if it is {@code null} or an instance

     * of the class specified by the {@code class} attribute.

     *

     * @param owner  the owner of the <java> element

     * @return {@code true} if the {@code owner} is valid;

     *         {@code false} otherwise

     */

    private boolean isValid(Object owner) {

        return (owner == null) || this.type.isInstance(owner);

    }

}