/*

 * 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 com.sun.beans.finder.FieldFinder;

import java.lang.reflect.Field;

/**

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

 * This element simplifies access to the fields.

 * If the {@code class} attribute is specified

 * this element accesses static field of specified class.

 * This element defines getter if it contains no argument.

 * It returns the value of the field in this case.

 * For example:<pre>

 * &lt;field name="TYPE" class="java.lang.Long"/&gt;</pre>

 * is equivalent to {@code Long.TYPE} in Java code.

 * This element defines setter if it contains one argument.

 * It does not return the value of the field in this case.

 * For example:<pre>

 * &lt;field name="id"&gt;&lt;int&gt;0&lt;/int&gt;&lt;/field&gt;</pre>

 * is equivalent to {@code id = 0} in Java code.

 * <dl>

 * <dt>name

 * <dd>the field name

 * <dt>class

 * <dd>the type is used for static fields only

 * <dt>id

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

 * </dl>

 *

 * @since 1.7

 *

 * @author Sergey A. Malenkov

 */

final class FieldElementHandler extends AccessorElementHandler {

    private Class<?> type;

    /**

     * Parses attributes of the element.

     * <dl>

     * <dt>name

     * <dd>the field name

     * <dt>class

     * <dd>the type is used for static fields only

     * <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("class")) { // NON-NLS: the attribute name

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

        } else {

            super.addAttribute(name, value);

        }

    }

    /**

     * 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 super.isArgument() && (this.type != null); // only static accessor can be used an argument

    }

    /**

     * Returns the context of the field.

     * The context of the static field is the class object.

     * The context of the non-static field is the value of the parent element.

     *

     * @return the context of the field

     */

    @Override

    protected Object getContextBean() {

        return (this.type != null)

                ? this.type

                : super.getContextBean();

    }

    /**

     * Returns the value of the field with specified {@code name}.

     *

     * @param name  the name of the field

     * @return the value of the specified field

     */

    @Override

    protected Object getValue(String name) {

        try {

            return getFieldValue(getContextBean(), name);

        }

        catch (Exception exception) {

            getOwner().handleException(exception);

        }

        return null;

    }

    /**

     * Sets the new value for the field with specified {@code name}.

     *

     * @param name   the name of the field

     * @param value  the new value for the specified field

     */

    @Override

    protected void setValue(String name, Object value) {

        try {

            setFieldValue(getContextBean(), name, value);

        }

        catch (Exception exception) {

            getOwner().handleException(exception);

        }

    }

    /**

     * Performs the search of the field with specified {@code name}

     * in specified context and returns its value.

     *

     * @param bean  the context bean that contains field

     * @param name  the name of the field

     * @return the value of the field

     * @throws IllegalAccessException if the field is not accesible

     * @throws NoSuchFieldException   if the field is not found

     */

    static Object getFieldValue(Object bean, String name) throws IllegalAccessException, NoSuchFieldException {

        return findField(bean, name).get(bean);

    }

    /**

     * Performs the search of the field with specified {@code name}

     * in specified context and updates its value.

     *

     * @param bean   the context bean that contains field

     * @param name   the name of the field

     * @param value  the new value for the field

     * @throws IllegalAccessException if the field is not accesible

     * @throws NoSuchFieldException   if the field is not found

     */

    private static void setFieldValue(Object bean, String name, Object value) throws IllegalAccessException, NoSuchFieldException {

        findField(bean, name).set(bean, value);

    }

    /**

     * Performs the search of the field

     * with specified {@code name} in specified context.

     *

     * @param bean  the context bean that contains field

     * @param name  the name of the field

     * @return field object that represents found field

     * @throws NoSuchFieldException if the field is not found

     */

    private static Field findField(Object bean, String name) throws NoSuchFieldException {

        return (bean instanceof Class<?>)

                ? FieldFinder.findStaticField((Class<?>) bean, name)

                : FieldFinder.findField(bean.getClass(), name);

    }

}