/*

  * 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.framework.persistence.ojb;

 import org.apache.commons.lang.StringUtils;

 import org.apache.log4j.Logger;

 import org.apache.ojb.broker.metadata.ConnectionRepository;

 import org.apache.ojb.broker.metadata.DescriptorRepository;

 import org.apache.ojb.broker.metadata.JdbcConnectionDescriptor;

 import org.apache.ojb.broker.metadata.MetadataManager;

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

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

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

 import org.kuali.rice.core.api.lifecycle.BaseLifecycle;

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

 import org.springframework.beans.factory.InitializingBean;

 import org.springframework.core.io.DefaultResourceLoader;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 import org.w3c.dom.NodeList;

 import org.xml.sax.InputSource;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.dom.DOMSource;

 import javax.xml.transform.stream.StreamResult;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathFactory;

 import java.io.BufferedInputStream;

 import java.io.BufferedOutputStream;

 import java.io.ByteArrayInputStream;

 import java.io.ByteArrayOutputStream;

 import java.io.InputStream;

 import java.util.Iterator;

 import java.util.List;

 /**

  * Base Ojb Configurer implementation which configures OJB for a particular rice module.

  *

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

  */

 public class BaseOjbConfigurer extends BaseLifecycle implements InitializingBean {

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

     public static final String RICE_OJB_PROPERTIES_PARAM = "rice.custom.ojb.properties";

     public static final String OJB_PROPERTIES_PROP = "OJB.properties";

     /**

      * The OJB JCD aliases 

      */

     protected String[] jcdAliases;

     /**

      * The location of the OJB repository/metadata descriptor

      */

     protected String metadataLocation;

     /**

      * No-arg constructor

      */

     public BaseOjbConfigurer() {

         // nothing

     }

     /**

      * Constructor that derives jcd aliases and repository metadata location from the module name

      * jcdAliases = [ moduleName.toLowerCase() + "DataSource" ]

      * metadataLocation = "classpath:OJB-repository-" + moduleName.toLowerCase() + ".xml";

      * 

      * @param moduleName the module name

      */

     public BaseOjbConfigurer(String moduleName) {

         this.metadataLocation = "classpath:org/kuali/rice/" + moduleName.toLowerCase() + "/config/OJB-repository-" + moduleName.toLowerCase() + ".xml";

         this.jcdAliases = new String[] { moduleName.toLowerCase() + "DataSource" };

     }

     /**

      * Constructor which takes the jcdAliases and metadata location

      * 

      * @param jcdAliases the jcd aliases

      * @param metadataLocation the metadata location

      */

     public BaseOjbConfigurer(String[] jcdAliases, String metadataLocation) {

         this.jcdAliases = jcdAliases;

         this.metadataLocation = metadataLocation;

     }

     @Override

     public void start() throws Exception {

         // if OJB has not already been loaded, let's trigger a load using our built-in OJB properties file

         String currentValue = System.getProperty(OJB_PROPERTIES_PROP);

         try {

             System.setProperty(OJB_PROPERTIES_PROP, getOjbPropertiesLocation());

             MetadataManager mm = MetadataManager.getInstance();

             establishConnectionMetaData(mm);

             establishRepositoryMetaData(mm);

         } finally {

             if (currentValue == null) {

                 System.getProperties().remove(OJB_PROPERTIES_PROP);

             } else {

                 System.setProperty(OJB_PROPERTIES_PROP, currentValue);

             }

         }

         super.start();

     }

     @Override

     public void stop() throws Exception {

         super.stop();

     }

     protected String getOjbPropertiesLocation() {

         String ojbPropertiesLocation = ConfigContext.getCurrentContextConfig().getProperty(RICE_OJB_PROPERTIES_PARAM);

         return ojbPropertiesLocation;

     }

     protected void establishConnectionMetaData(MetadataManager mm) throws Exception {

         String connMetadata = getMetadataLocation();

         if (StringUtils.isBlank(connMetadata)) {

             LOG.info("No OJB connection metadata loaded.");

             return;

         }

         if (!isConnectionAlreadyConfigured(mm)) {

             LOG.info("Loading OJB Connection Metadata from " + connMetadata);

             DefaultResourceLoader resourceLoader = new DefaultResourceLoader(ClassLoaderUtils.getDefaultClassLoader());

             InputStream is = resourceLoader.getResource(connMetadata).getInputStream();

             is = preprocessConnectionMetadata(is);

             ConnectionRepository cr = mm.readConnectionRepository(is);

             mm.mergeConnectionRepository(cr);

             try {

                 is.close();

             } catch (Exception e) {

                 LOG.warn("Failed to close stream to file " + connMetadata, e);

             }

         } else {

             LOG.info("OJB Connections already configured for jcd aliases '" + StringUtils.join(getJcdAliases(), ", ") + "', skipping Metadata merge.");

         }

     }

     protected InputStream preprocessConnectionMetadata(InputStream inputStream) throws Exception {

         Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new InputSource(inputStream));

         XPath xpath = XPathFactory.newInstance().newXPath();

         NodeList connectionDescriptors = (NodeList)xpath.evaluate("/descriptor-repository/jdbc-connection-descriptor", document, XPathConstants.NODESET);

         for (int index = 0; index < connectionDescriptors.getLength(); index++) {

             Element descriptor = (Element)connectionDescriptors.item(index);

             String currentPlatform = descriptor.getAttribute("platform");

             if (StringUtils.isBlank(currentPlatform)) {

                 String ojbPlatform = ConfigContext.getCurrentContextConfig().getProperty(Config.OJB_PLATFORM);

                 if (StringUtils.isEmpty(ojbPlatform)) {

                     throw new ConfigurationException("Could not configure OJB, the '" + Config.OJB_PLATFORM + "' configuration property was not set.");

                 }

                 LOG.info("Setting OJB connection descriptor database platform to '" + ojbPlatform + "'");

                 descriptor.setAttribute("platform", ojbPlatform);

             }

         }

         Transformer transformer = TransformerFactory.newInstance().newTransformer();

         ByteArrayOutputStream baos = new ByteArrayOutputStream();

         transformer.transform(new DOMSource(document), new StreamResult(new BufferedOutputStream(baos)));

         return new BufferedInputStream(new ByteArrayInputStream(baos.toByteArray()));

     }

     @SuppressWarnings("unchecked")

         protected boolean isConnectionAlreadyConfigured(MetadataManager mm) {

         List descriptors = mm.connectionRepository().getAllDescriptor();

         for (Iterator iterator = descriptors.iterator(); iterator.hasNext();) {

             JdbcConnectionDescriptor descriptor = (JdbcConnectionDescriptor) iterator.next();

             for (String jcdAlias : getJcdAliases()) {

                 if (descriptor.getJcdAlias().equals(jcdAlias)) {

                     return true;

                 }

             }

         }

         return false;

     }

     protected InputStream preprocessRepositoryMetadata(InputStream inputStream) throws Exception {

         return inputStream;

     }

     protected void establishRepositoryMetaData(MetadataManager mm) throws Exception {

         String repoMetadata = getMetadataLocation();

         if (StringUtils.isBlank(repoMetadata)) {

             LOG.info("No OJB repository metadata loaded.");

             return;

         }

         LOG.info("Loading OJB Metadata from " + repoMetadata);

         DefaultResourceLoader resourceLoader = new DefaultResourceLoader(ClassLoaderUtils.getDefaultClassLoader());

         InputStream is = resourceLoader.getResource(repoMetadata).getInputStream();

         is = preprocessRepositoryMetadata(is);

         DescriptorRepository dr = mm.readDescriptorRepository(is);

         mm.mergeDescriptorRepository(dr);

         try {

             is.close();

         } catch (Exception e) {

             LOG.warn("Failed to close stream to file " + repoMetadata, e);

         }

     }

     /**

      * Return the jcd alias of the connection loaded by the connection metadata.

      * The default implementation returns the jcd alias with which the instance was created (if any) 

      * @return the jcd alias of the connection loaded by the connection metadata.

      */

     protected String[] getJcdAliases() {

         return jcdAliases;

     }

     /**

      * Should return a String representing the location of a file to load OJB connection and

      * repository metadata from.  If null or empty than no metadata will be loaded.

      * The default implementation returns the metadata location with which the instance was created (if any)

      */

     protected String getMetadataLocation() {

         return metadataLocation;

     }

         /***

          * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()

          */

         public void afterPropertiesSet() throws Exception {

                 this.start();

         }

         /**

          * @param jcdAliases the jcdAliases to set

          */

         public void setJcdAliases(String[] jcdAliases) {

                 this.jcdAliases = jcdAliases;

         }

         /**

          * @param metadataLocation the metadataLocation to set

          */

         public void setMetadataLocation(String metadataLocation) {

                 this.metadataLocation = metadataLocation;

         }

 }