/*

  * Copyright 2005-2007 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 java.io.File;

 import java.io.FileNotFoundException;

 import java.io.IOException;

 import java.net.MalformedURLException;

 import java.net.URL;

 import javax.xml.namespace.QName;

 import org.apache.log4j.Logger;

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

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

 import org.kuali.rice.core.resourceloader.ContextClassLoaderBinder;

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

 import org.kuali.rice.kew.exception.InvalidXmlException;

 import org.kuali.rice.kew.util.Utilities;

 /**

  * Abstract base PluginLoader implementation.

  * Delegates to template methods to obtain plugin ClassLoader and plugin config file URL,

  * then load the config under the plugin ClassLoader, and constructs a Plugin object.

  *

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

  */

 public abstract class BasePluginLoader implements PluginLoader {

     private static final Logger LOG = Logger.getLogger(BasePluginLoader.class);

     private static final String META_INF_PATH = "META-INF";

     private static final String PLUGIN_CONFIG_PATH = META_INF_PATH + "/workflow.xml";

     protected final String simplePluginName;

     protected String logPrefix;

     protected final ClassLoader parentClassLoader;

     protected final Config parentConfig;

     protected final File sharedPluginDirectory;

     protected String pluginConfigPath = PLUGIN_CONFIG_PATH;

     public BasePluginLoader(String simplePluginName, File sharedPluginDirectory, ClassLoader parentClassLoader, Config parentConfig) {

         this.sharedPluginDirectory = sharedPluginDirectory;

         if (parentClassLoader == null) {

             parentClassLoader = ClassLoaderUtils.getDefaultClassLoader();

         }

         this.parentClassLoader = parentClassLoader;

         this.parentConfig = parentConfig;

         this.simplePluginName = simplePluginName;

         this.logPrefix = simplePluginName;

     }

     protected String getLogPrefix() {

         return logPrefix;

     }

     public String getPluginName() {

         return simplePluginName;

     }

     public void setPluginConfigPath(String pluginConfigPath) {

         this.pluginConfigPath = pluginConfigPath;

     }

     protected String getSimplePluginName() {

             return simplePluginName;

     }

     /**

      * Template method that subclasses should implement to supply an appropriate

      * plugin ClassLoader

      * @return an appropriate PluginClassLoader

      * @throws IOException if anything goes awry

      */

     protected abstract PluginClassLoader createPluginClassLoader() throws IOException;

     /**

      * Template method that subclasses should implement to supply an appropriate

      * URL to the plugin's configuration

      * @return an appropriate URL to the plugin's configuration

      * @throws IOException if anything goes awry

      */

     protected abstract URL getPluginConfigURL() throws PluginException, IOException;

     /**

      * Loads and creates the Plugin.

      */

     public Plugin load() throws Exception {

         PluginClassLoader classLoader = createPluginClassLoader();

         LOG.info("Created plugin ClassLoader: " + classLoader);

         ContextClassLoaderBinder.bind(classLoader);

         try {

             return loadWithinContextClassLoader(classLoader);

         } finally {

             ContextClassLoaderBinder.unbind();

         }

     }

     public boolean isRemoved() {

             return false;

     }

     /**

      * Executes loading of the plugin within the current context classloader set to the Plugin's classloader.

      */

     protected Plugin loadWithinContextClassLoader(PluginClassLoader classLoader) throws PluginException, IOException {

             URL url = getPluginConfigURL();

         PluginConfig pluginConfig = loadPluginConfig(url);

         QName qPluginName = getPluginName(pluginConfig);

         classLoader.setConfig(pluginConfig);

         ConfigContext.init(classLoader, pluginConfig);

         configureExtraClasspath(classLoader, pluginConfig);

         this.logPrefix = PluginUtils.getLogPrefix(qPluginName).toString();

         LOG.info("Constructing plugin '" + simplePluginName + "' with classloader: " + classLoader);

         Plugin plugin = new Plugin(qPluginName, pluginConfig, classLoader);

         installResourceLoader(plugin);

         installPluginListeners(plugin);

         return plugin;

     }

     protected void installResourceLoader(Plugin plugin) {

             PluginUtils.installResourceLoader(plugin);

     }

     protected void installPluginListeners(Plugin plugin) {

             PluginUtils.installPluginListeners(plugin);

     }

     protected void configureExtraClasspath(PluginClassLoader classLoader, PluginConfig config) throws MalformedURLException {

                 String extraClassesDirs = config.getProperty(Config.EXTRA_CLASSES_DIR);

                 if (!Utilities.isEmpty(extraClassesDirs)) {

                         String[] extraClasses = extraClassesDirs.split(",");

                         for (int index = 0; index < extraClasses.length; index++) {

                                 File extraClassesDir = new File(extraClasses[index]);

                                 if (extraClassesDir.exists()) {

                                         classLoader.addClassesDirectory(extraClassesDir);

                                 }

                         }

                 }

                 String extraLibDirs = config.getProperty(Config.EXTRA_LIB_DIR);

                 if (!Utilities.isEmpty(extraLibDirs)) {

                         String[] extraLibs = extraLibDirs.split(",");

                         for (int index = 0; index < extraLibs.length; index++) {

                                 File extraLibDir = new File(extraLibs[index]);

                                 if (extraLibDir.exists()) {

                                         classLoader.addLibDirectory(extraLibDir);

                                 }

                         }

                 }

         }

     protected QName getPluginName(PluginConfig pluginConfig) {

             String serviceNamespace = pluginConfig.getServiceNamespace();

             QName qPluginName = null;

         if (serviceNamespace == null) {

                 qPluginName = new QName(ConfigContext.getCurrentContextConfig().getServiceNamespace(), simplePluginName);

         } else {

                 qPluginName = new QName(serviceNamespace, simplePluginName);

         }

             return qPluginName;

     }

     protected PluginConfig loadPluginConfig(URL url) {

         PluginConfigParser parser = new PluginConfigParser();

         try {

             PluginConfig pluginConfig  = parser.parse(url, parentConfig);

             pluginConfig.parseConfig();

             return pluginConfig;

         } catch (FileNotFoundException e) {

             throw new PluginException(getLogPrefix() + " Could not locate the plugin config file at path " + url, e);

         } catch (IOException ioe) {

             throw new PluginException(getLogPrefix() + " Could not read the plugin config file", ioe);

         } catch (InvalidXmlException ixe) {

             throw new PluginException(getLogPrefix() + " Could not parse the plugin config file", ixe);

         }

     }

 }