/*
 * $Id: ModuleConfigFactory.java 54929 2004-10-16 16:38:42Z germuska $ 
 *
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed 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.struts.util.RequestUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A factory interface for creating {@link ModuleConfig}s.
 *
 * @version $Rev: 54929 $ $Date: 2004-10-16 09:38:42 -0700 (Sat, 16 Oct 2004) $ 
 *
 * @see ModuleConfig
 */
public abstract class ModuleConfigFactory {
    
    /**
     * 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;

    }


    /**
     * 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";


}