/*

  * Copyright 2006-2011 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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.kuali.rice.core.api.resourceloader;

 import org.apache.commons.lang.StringUtils;

 import org.kuali.rice.core.api.config.property.ConfigContext;

 import org.kuali.rice.core.api.exception.RiceRuntimeException;

 import org.kuali.rice.core.api.exception.RiceRemoteServiceConnectionException;

 import org.kuali.rice.core.api.reflect.ObjectDefinition;

 import org.kuali.rice.core.util.ClassLoaderUtils;

 import javax.xml.namespace.QName;

 import java.util.HashMap;

 import java.util.Map;

 /**

  * Wrapper on all the Resource loaders.  This is what programmers typically use to get in the resource loading

  * framework.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class GlobalResourceLoader {

         private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(GlobalResourceLoader.class);

         private static Map<ClassLoader, ResourceLoader> rootResourceLoaders = new HashMap<ClassLoader, ResourceLoader>();

         private static boolean initializing;

         public static synchronized ResourceLoader getResourceLoader() {

                 ClassLoader classLoader = ClassLoaderUtils.getDefaultClassLoader();

                 return getResourceLoaderCheckParent(classLoader);

         }

         private static synchronized ResourceLoader getResourceLoaderCheckParent(ClassLoader classLoader) {

         ResourceLoader resourceLoader = getResourceLoader(classLoader);

         if (resourceLoader != null && classLoader.getParent() != null) {

             ResourceLoader parentResourceLoader = getResourceLoaderCheckParent(classLoader.getParent());

             if (parentResourceLoader != null) {

                 resourceLoader = new ParentChildResourceLoader(parentResourceLoader, resourceLoader);

                     }

             }

             if (resourceLoader == null && classLoader.getParent() != null) {

                     resourceLoader = getResourceLoaderCheckParent(classLoader.getParent());

             }

             return resourceLoader;

         }

         public static synchronized ResourceLoader getResourceLoader(ClassLoader classloader) {

                 return rootResourceLoaders.get(classloader);

         }

         public static synchronized void start() throws Exception {

                 try {

                         initializing = true;

                         ResourceLoader internalResourceLoader = getResourceLoader();

                         if (internalResourceLoader == null) {

                                 throw new RiceRuntimeException("Cannot start GlobalResourceLoader because no resource loaders have been added for the current ContextClassLoader :" + Thread.currentThread().getContextClassLoader());

                         }

                         internalResourceLoader.start();

                 } finally {

                         initializing = false;

                 }

         }

         public static synchronized void addResourceLoader(ResourceLoader resourceLoader) {

                 initialize();

                 LOG.info("Adding ResourceLoader " + resourceLoader.getName() + " to GlobalResourceLoader");

                 if (resourceLoader == null) {

                         throw new ResourceLoaderException("Attempted to add a null resource loader to the Global resource loader.");

                 }

                 getResourceLoader().addResourceLoader(resourceLoader);

         }

         public static synchronized void addResourceLoaderFirst(ResourceLoader resourceLoader) {

                 initialize();

                 LOG.info("Adding ResourceLoader " + resourceLoader.getName() + " to GlobalResourceLoader");

                 if (resourceLoader == null) {

                         throw new ResourceLoaderException("Attempted to add a null resource loader to the Global resource loader.");

                 }

                 getResourceLoader().addResourceLoaderFirst(resourceLoader);

         }

         protected static synchronized void initialize() {

                 if (getResourceLoader(ClassLoaderUtils.getDefaultClassLoader()) == null) {

                         LOG.info("Creating CompositeResourceLoader in GlobalResourceLoader");

                         rootResourceLoaders.put(ClassLoaderUtils.getDefaultClassLoader(), new ResourceLoaderContainer(new QName(ConfigContext.getCurrentContextConfig().getServiceNamespace(), ResourceLoader.ROOT_RESOURCE_LOADER_NAME)));

                 }

         }

         public static synchronized ResourceLoader getResourceLoader(QName name) {

                 return getResourceLoader().getResourceLoader(name);

         }

         /**

          * Stop the resource loader for the current context classloader.  Don't stop or clear them all

          * because the stop was issued from the context of a single classloader.

          *

          * @throws Exception

          */

         public static synchronized void stop() throws Exception {

                 LOG.info("Stopping the GlobalResourceLoader...");

                 if (getResourceLoader() != null) {

                         LOG.info("Destroying GlobalResourceLoader");

                         getResourceLoader().stop();

                         rootResourceLoaders.remove(ClassLoaderUtils.getDefaultClassLoader());

                 }

                 LOG.info("...GlobalResourceLoader successfully stopped.");

         }

         public static synchronized <T extends Object> T getService(QName serviceName) {

                 if (serviceName == null) {

                         throw new IllegalArgumentException("The service name must be non-null.");

                 }

                 LOG.debug("GlobalResourceLoader fetching service " + serviceName);

                 try {

                         return getResourceLoader().<T>getService(serviceName);

                 } catch (RiceRemoteServiceConnectionException ex) {

                         LOG.warn(ex.getMessage());

                         return null;

                 }

         }

         public static synchronized <T extends Object> T getService(String localServiceName) {

                 if (StringUtils.isEmpty(localServiceName)) {

                         throw new IllegalArgumentException("The service name must be non-null.");

                 }

                 return GlobalResourceLoader.<T>getService(new QName(localServiceName));

         }

         public static synchronized <T extends Object> T getObject(ObjectDefinition objectDefinition) {

                 return getResourceLoader().<T>getObject(objectDefinition);

         }

         public static synchronized boolean isInitialized() {

                 return getResourceLoader() != null;

         }

         public static synchronized void logContents() {

                 if (LOG.isInfoEnabled()) {

                         LOG.info(getResourceLoader().getContents("", false));

                 }

         }

         public static synchronized boolean isInitializing() {

                 return initializing;

         }

         public static synchronized void setInitializing(boolean initializing) {

                 GlobalResourceLoader.initializing = initializing;

         }

 }