/**
    * Copyright 2005-2015 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.krad.datadictionary;
  
  import no.geosoft.cc.io.FileListener;
  import no.geosoft.cc.io.FileMonitor;
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.kuali.rice.core.api.config.property.ConfigurationService;
  import org.kuali.rice.krad.service.KRADServiceLocator;
  import org.kuali.rice.krad.uif.util.UifBeanFactoryPostProcessor;
  import org.springframework.beans.BeansException;
  import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.ApplicationContextAware;
  import org.springframework.context.ApplicationListener;
  import org.springframework.context.ConfigurableApplicationContext;
  import org.springframework.context.event.ContextClosedEvent;
  import org.springframework.core.io.FileSystemResource;
  import org.springframework.core.io.InputStreamResource;
  import org.springframework.core.io.Resource;
  
  import java.io.File;
  import java.io.InputStream;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.List;
  
  
  /**
   * Extends the DataDictionary to add reloading of changed dictionary files
   * without a restart of the web container
   * 
   * <p>
   * To use modify the "dataDictionaryService" spring definition
   * (KRADSpringBeans.xml) and change the constructor arg bean class from
   * "org.kuali.rice.krad.datadictionary.DataDictionary" to
   * "ReloadingDataDictionary"
   * </p>
   * 
   * <p>
   * NOTE: For Development Purposes Only!
   * </p>
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class ReloadingDataDictionary extends DataDictionary implements FileListener, URLMonitor.URLContentChangedListener, ApplicationContextAware {
  	private static final Log LOG = LogFactory.getLog(DataDictionary.class);
  
  	private static final String CLASS_DIR_CONFIG_PARM = "reload.data.dictionary.classes.dir";
  	private static final String SOURCE_DIR_CONFIG_PARM = "reload.data.dictionary.source.dir";
  	private static final String INTERVAL_CONFIG_PARM = "reload.data.dictionary.interval";
  
      private URLMonitor dictionaryUrlMonitor;
  
  
  	public ReloadingDataDictionary() {
  		super();
  	}
  
  	/**
  	 * After dictionary has been loaded, determine the source files and add them
  	 * to the monitor
  	 * 
  	 * @see org.kuali.rice.krad.datadictionary.DataDictionary#parseDataDictionaryConfigurationFiles(boolean)
  	 */
  	@Override
  	public void parseDataDictionaryConfigurationFiles(boolean allowConcurrentValidation) {
  		ConfigurationService configurationService = KRADServiceLocator.getKualiConfigurationService();
  
  		// class directory part of the path that should be replaced
  		String classesDir = configurationService.getPropertyValueAsString(CLASS_DIR_CONFIG_PARM);
  
  		// source directory where dictionary files are found
  		String sourceDir = configurationService.getPropertyValueAsString(SOURCE_DIR_CONFIG_PARM);
  
  		// interval to poll for changes in milliseconds
  		int reloadInterval = Integer.parseInt(configurationService.getPropertyValueAsString(INTERVAL_CONFIG_PARM));
  
  		FileMonitor dictionaryFileMonitor = new FileMonitor(reloadInterval);
  
          dictionaryUrlMonitor = new URLMonitor(reloadInterval);
          dictionaryUrlMonitor.addListener(this);
  
  		// need to copy the configFileLocations list here because it gets
 		// cleared out after processing by super
 		List<String> configLocations = new ArrayList<String>(configFileLocations);
 
 		super.parseDataDictionaryConfigurationFiles(allowConcurrentValidation);
 		for (String configLocation : configLocations) {
 			Resource classFileResource = getFileResource(configLocation);
 			try {
                 if (classFileResource.getURI().toString().startsWith("jar:")) {
                     LOG.debug("Monitoring dictionary file at URI: " + classFileResource.getURI().toString());
                     dictionaryUrlMonitor.addURI(classFileResource.getURL());
                 } else {
                     String filePathClassesDir = classFileResource.getFile().getAbsolutePath();
                     String sourceFilePath = StringUtils.replace(filePathClassesDir, classesDir, sourceDir);
                     File dictionaryFile = new File(filePathClassesDir);
                     if (dictionaryFile.exists()) {
                         LOG.debug("Monitoring dictionary file: " + dictionaryFile.getName());
                         dictionaryFileMonitor.addFile(dictionaryFile);
                     }
                 }
 			}
 			catch (Exception e) {
 				LOG.info("Exception in picking up dictionary file for monitoring:  " + e.getMessage(), e);
 			}
 		}
 
 		// add the dictionary as a listener for file changes
 		dictionaryFileMonitor.addListener(this);
 	}
 
 	/**
 	 * Call back when a dictionary file is changed. Calls the spring bean reader
 	 * to reload the file (which will override beans as necessary and destroy
 	 * singletons) and runs the indexer
 	 * 
 	 * @see no.geosoft.cc.io.FileListener#fileChanged(java.io.File)
 	 */
 	@Override
 	public void fileChanged(File file) {
 		LOG.info("reloading dictionary configuration for " + file.getName());
 		try {
 			Resource resource = new FileSystemResource(file);
 			xmlReader.loadBeanDefinitions(resource);
 
             UifBeanFactoryPostProcessor factoryPostProcessor = new UifBeanFactoryPostProcessor();
             factoryPostProcessor.postProcessBeanFactory(ddBeans);
 
 			// re-index
 			ddIndex.run();
 		}
 		catch (Exception e) {
 			LOG.info("Exception in dictionary hot deploy: " + e.getMessage(), e);
 		}
 	}
 
     public void urlContentChanged(final URL url) {
         LOG.info("reloading dictionary configuration for " + url.toString());
         try {
             InputStream urlStream = url.openStream();
             InputStreamResource resource = new InputStreamResource(urlStream);
 
             int originalValidationMode = xmlReader.getValidationMode();
             xmlReader.setValidationMode(XmlBeanDefinitionReader.VALIDATION_XSD);
             xmlReader.loadBeanDefinitions(resource);
             xmlReader.setValidationMode(originalValidationMode);
 
             UifBeanFactoryPostProcessor factoryPostProcessor = new UifBeanFactoryPostProcessor();
             factoryPostProcessor.postProcessBeanFactory(ddBeans);
 
             // re-index
             ddIndex.run();
         }
         catch (Exception e) {
             LOG.info("Exception in dictionary hot deploy: " + e.getMessage(), e);
         }
     }
 
     @Override
     public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
         // register a context close handler
         if (applicationContext instanceof ConfigurableApplicationContext) {
             ConfigurableApplicationContext context = (ConfigurableApplicationContext) applicationContext;
             context.addApplicationListener(new ApplicationListener<ContextClosedEvent>() {
                 @Override
                 public void onApplicationEvent(ContextClosedEvent e) {
                     LOG.info("Context '" + e.getApplicationContext().getDisplayName() + "' closed, shutting down URLMonitor scheduler");
                     dictionaryUrlMonitor.shutdownScheduler();
                 }
             });
         }
     }
 }