/*

  * 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.kew.plugin;

 import org.kuali.rice.core.api.config.CoreConfigHelper;

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

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

 import org.kuali.rice.core.api.resourceloader.ResourceLoader;

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

 import org.kuali.rice.kew.plugin.PluginUtils.PluginZipFileFilter;

 import javax.xml.namespace.QName;

 import java.io.File;

 import java.util.ArrayList;

 import java.util.HashSet;

 import java.util.List;

 import java.util.Map;

 import java.util.Set;

 import java.util.TreeMap;

 import java.util.concurrent.Executors;

 import java.util.concurrent.ScheduledExecutorService;

 import java.util.concurrent.ScheduledFuture;

 import java.util.concurrent.ThreadFactory;

 import java.util.concurrent.TimeUnit;

 /**

  * A PluginRegistry implementation which loads plugins from the file system on the server.

  *

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

  */

 public class ServerPluginRegistry extends BasePluginRegistry {

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

         private List<String> pluginDirectories = new ArrayList<String>();

         private File sharedPluginDirectory;

         private Reloader reloader;

         private HotDeployer hotDeployer;

         private ScheduledExecutorService scheduledExecutor;

         private ScheduledFuture<?> reloaderFuture;

         private ScheduledFuture<?> hotDeployerFuture;

         public ServerPluginRegistry() {

                 super(new QName(CoreConfigHelper.getApplicationId(), ResourceLoader.PLUGIN_REGISTRY_LOADER_NAME));

         }

         public void start() throws Exception {

                 LOG.info("Starting server Plugin Registry...");

                 scheduledExecutor = Executors.newScheduledThreadPool(2, new KEWThreadFactory());

                 sharedPluginDirectory = loadSharedPlugin();

                 reloader = new Reloader();

                 hotDeployer = new HotDeployer(PluginUtils.getPluginRegistry(), sharedPluginDirectory, pluginDirectories);

                 loadPlugins(sharedPluginDirectory);

                 // TODO make the delay configurable

                 this.reloaderFuture = scheduledExecutor.scheduleWithFixedDelay(reloader, 5, 5, TimeUnit.SECONDS);

                 this.hotDeployerFuture = scheduledExecutor.scheduleWithFixedDelay(hotDeployer, 5, 5, TimeUnit.SECONDS);

                 super.start();

                 LOG.info("...server Plugin Registry successfully started.");

         }

         public void stop() throws Exception {

                 LOG.info("Stopping server Plugin Registry...");

                 stopReloader();

                 stopHotDeployer();

                 reloader = null;

                 hotDeployer = null;

                 if (scheduledExecutor != null) {

                         scheduledExecutor.shutdownNow();

                         scheduledExecutor = null;

                 }

                 super.stop();

                 LOG.info("...server Plugin Registry successfully stopped.");

         }

         protected void stopReloader() {

                 if (reloaderFuture != null) {

                         if (!reloaderFuture.cancel(true)) {

                                 LOG.warn("Failed to cancel the plugin reloader.");

                         }

                         reloaderFuture = null;

                 }

         }

         protected void stopHotDeployer() {

                 if (hotDeployerFuture != null) {

                         if (!hotDeployerFuture.cancel(true)) {

                                 LOG.warn("Failed to cancel the hot deployer.");

                         }

                         hotDeployerFuture = null;

                 }

         }

         protected void loadPlugins(File sharedPluginDirectory) {

         Map<String, File> pluginLocations = new TreeMap<String, File>(new PluginNameComparator());

                 PluginZipFileFilter pluginFilter = new PluginZipFileFilter();

         //PluginDirectoryFilter pluginFilter = new PluginDirectoryFilter(sharedPluginDirectory);

         Set<File> visitedFiles = new HashSet<File>();

         for (String pluginDir : pluginDirectories) {

             LOG.info("Reading plugins from " + pluginDir);

             File file = new File(pluginDir);

             if (visitedFiles.contains(file)) {

                 LOG.info("Skipping visited directory: " + pluginDir);

                 continue;

             }

             visitedFiles.add(file);

             if (!file.exists() || !file.isDirectory()) {

                 LOG.warn(file.getAbsoluteFile()+" is not a valid plugin directory.");

                 continue;

             }

             File[] pluginZips = file.listFiles(pluginFilter);

             for (int i = 0; i < pluginZips.length; i++) {

                 File pluginZip = pluginZips[i];

                 int indexOf = pluginZip.getName().lastIndexOf(".zip");

                 String pluginName = pluginZip.getName().substring(0, indexOf);

                 if (pluginLocations.containsKey(pluginName)) {

                         LOG.warn("There already exists an installed plugin with the name '"+ pluginName + "', ignoring plugin " + pluginZip.getAbsolutePath());

                         continue;

                 }

                 pluginLocations.put(pluginName, pluginZip);

             }

         }

         for (String pluginName : pluginLocations.keySet()) {

                 File pluginZipFile = pluginLocations.get(pluginName);

                 try {

                         LOG.info("Loading plugin '" + pluginName + "'");

                         ClassLoader parentClassLoader = ClassLoaderUtils.getDefaultClassLoader();

                         Config parentConfig = ConfigContext.getCurrentContextConfig();

                         ZipFilePluginLoader loader = new ZipFilePluginLoader(pluginZipFile,

                                         sharedPluginDirectory,

                                         parentClassLoader,

                                         parentConfig);

                         PluginEnvironment environment = new PluginEnvironment(loader, this);

                         try {

                             environment.load();

                         } finally {

                             // regardless of whether the plugin loads or not, let's add it to the environment

                             addPluginEnvironment(environment);

                         }                        

                 } catch (Exception e) {

                         LOG.error("Failed to read workflow plugin '"+pluginName+"'", e);

                 }

         }

     }

         @Override

         public void addPluginEnvironment(PluginEnvironment pluginEnvironment) {

                 super.addPluginEnvironment(pluginEnvironment);

                 reloader.addReloadable(pluginEnvironment);

         }

         @Override

         public PluginEnvironment removePluginEnvironment(String pluginName) {

                 PluginEnvironment environment = super.removePluginEnvironment(pluginName);

                 reloader.removeReloadable(environment);

                 return environment;

         }

         public File loadSharedPlugin() {

                 return PluginUtils.findSharedDirectory(pluginDirectories);

         }

         public void setPluginDirectories(List<String> pluginDirectories) {

                 this.pluginDirectories = pluginDirectories;

         }

         public void setSharedPluginDirectory(File sharedPluginDirectory) {

                 this.sharedPluginDirectory = sharedPluginDirectory;

         }

         protected HotDeployer getHotDeployer() {

                 return hotDeployer;

         }

         protected Reloader getReloader() {

                 return reloader;

         }

         private static class KEWThreadFactory implements ThreadFactory {

                 private ThreadFactory defaultThreadFactory = Executors.defaultThreadFactory();

                 public Thread newThread(Runnable runnable) {

                         Thread thread = defaultThreadFactory.newThread(runnable);

                         thread.setName("ServerPluginRegistry-" + thread.getName());

                         return thread;

             }

         }

 }