/*
 * $Id: ModuleConfigFactory.java 471754 2006-11-06 14:55:09Z husted $
 *
 * 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 org.apache.struts.config;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.util.RequestUtils;

/**
 * A factory interface for creating {@link ModuleConfig}s.
 *
 * @version $Rev: 471754 $ $Date: 2005-05-07 12:11:38 -0400 (Sat, 07 May 2005)
 *          $
 * @see ModuleConfig
 */
public abstract class ModuleConfigFactory {
    /**
     * The Java class to be used for <code>ModuleConfigFactory</code>
     * instances.
     */
    protected static Class clazz = null;

    /**
     * Commons Logging instance.
     */
    private static final Log LOG = LogFactory.getLog(ModuleConfigFactory.class);

    /**
     * The fully qualified class name to be used for <code>ModuleConfigFactory</code>
     * instances.
     */
    protected static String factoryClass =
        "org.apache.struts.config.impl.DefaultModuleConfigFactory";

    /**
     * Create and return a newly instansiated {@link ModuleConfig}. This
     * method must be implemented by concrete subclasses.
     *
     * @param prefix Module prefix for Configuration
     */
    public abstract ModuleConfig createModuleConfig(String prefix);

    // ------------------------------------------------------ Static Properties

    /**
     * The fully qualified class name that is used for <code>ModuleConfigFactory</code>
     * instances.
     *
     * @return class name that is used for <code>ModuleConfigFactory</code>
     *         instances
     */
    public static String getFactoryClass() {
        return (ModuleConfigFactory.factoryClass);
    }

    /**
     * Set the fully qualified class name that is used for
     * <code>ModuleConfigFactory</code> instances.
     *
     * @param factoryClass name that is used for <code>ModuleConfigFactory</code>
     *                     instances
     */
    public static void setFactoryClass(String factoryClass) {
        ModuleConfigFactory.factoryClass = factoryClass;
        ModuleConfigFactory.clazz = null;
    }

    // --------------------------------------------------------- Static Methods

    /**
     * Create and return a <code>ModuleConfigFactory</code> instance of the
     * appropriate class, which can be used to create customized
     * <code>ModuleConfig</code> instances.  If no such factory can be
     * created, return <code>null</code> instead.
     */
    public static ModuleConfigFactory createFactory() {
        ModuleConfigFactory factory = null;

        try {
            if (clazz == null) {
                clazz = RequestUtils.applicationClass(factoryClass);
            }

            factory = (ModuleConfigFactory) clazz.newInstance();
        } catch (ClassNotFoundException e) {
            LOG.error("ModuleConfigFactory.createFactory()", e);
        } catch (InstantiationException e) {
            LOG.error("ModuleConfigFactory.createFactory()", e);
        } catch (IllegalAccessException e) {
            LOG.error("ModuleConfigFactory.createFactory()", e);
        }

        return factory;
    }
}