/* 
 * Created on Jan 19, 2006
 *
 * 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.
 *
 * Copyright @2006 the original author or authors.
 */
package org.springmodules.cache.config;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.xml.BeanDefinitionParser;
import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
import org.springframework.util.ClassUtils;

import org.springmodules.cache.FatalCacheException;
import org.springmodules.cache.util.SystemUtils;

/**
 * <p>
 * Template for handler of caching-related namespaces.
 * </p>
 * 
 * @author Alex Ruiz
 */
public abstract class AbstractCacheNamespaceHandler extends
    NamespaceHandlerSupport {

  /**
   * Logger available to subclasses.
   */
  protected Log logger = LogFactory.getLog(getClass());

  /**
   * Registers parsers for the elements:
   * <ul>
   * <li>annotations</li>
   * <li>commons-attributes</li>
   * <li>config</li>
   * <li>interceptors</li>
   * <li>proxy</li>
   * </ul>
   * 
   * @see org.springframework.beans.factory.xml.NamespaceHandler#init()
   */
  public final void init() {
    registerBeanDefinitionParser("config", getCacheProviderFacadeParser());

    CacheModelParser cacheModelParser = getCacheModelParser();
    registerAnnotationsElementParser(cacheModelParser);
    registerCommonsAttributesElementParser(cacheModelParser);
    registerProxyElementParser(cacheModelParser);
    registerInterceptorsElementParser(cacheModelParser);
  }

  protected abstract CacheModelParser getCacheModelParser();

  /**
   * @return the parser for the XML elements with name "config"
   */
  protected abstract BeanDefinitionParser getCacheProviderFacadeParser();

  private void registerAnnotationsElementParser(
      CacheModelParser cacheModelParser) {
    if (SystemUtils.atLeastJ2SE5()) {
      String thisPackage = AbstractCacheNamespaceHandler.class.getPackage()
          .getName();
      String annotationsParserClassName = thisPackage + ".AnnotationsParser";

      try {
        Class parserClass = ClassUtils.forName(annotationsParserClassName);

        Object parser = parserClass.newInstance();
        registerCacheSetupStrategyParser("annotations",
            (AbstractCacheSetupStrategyParser) parser, cacheModelParser);

      } catch (Exception exception) {
        String errorMessage = "Unable to create instance of "
            + annotationsParserClassName
            + ". Unable to load parser for namespace 'annotations'";
        throw new FatalCacheException(errorMessage, exception);
      }

    } else {
      logger.info("No support for JDK 1.5 Annotations. "
          + "Unable to load parser for namespace 'annotations'");
    }
  }

  private void registerCacheSetupStrategyParser(String elementName,
      AbstractCacheSetupStrategyParser parser, CacheModelParser cacheModelParser) {
    parser.setCacheModelParser(cacheModelParser);
    registerBeanDefinitionParser(elementName, parser);
  }

  private void registerCommonsAttributesElementParser(
      CacheModelParser cacheModelParser) {
    CommonsAttributesParser parser = new CommonsAttributesParser();
    registerCacheSetupStrategyParser("commons-attributes", parser,
        cacheModelParser);
  }

  private void registerInterceptorsElementParser(
      CacheModelParser cacheModelParser) {
    MethodMapInterceptorsParser parser = new MethodMapInterceptorsParser();
    registerCacheSetupStrategyParser("methodMapInterceptors", parser,
        cacheModelParser);
  }

  private void registerProxyElementParser(CacheModelParser cacheModelParser) {
    CacheProxyFactoryBeanParser parser = new CacheProxyFactoryBeanParser();
    registerCacheSetupStrategyParser("proxy", parser, cacheModelParser);
  }
}