// Copyright 2005 The Apache Software Foundation

 //

 // Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0

 //

 // 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.trails.record;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.hivemind.util.Defense;

 import org.apache.tapestry.engine.ServiceEncoding;

 import org.apache.tapestry.record.PropertyChange;

 import org.apache.tapestry.record.PropertyPersistenceStrategy;

 import org.apache.tapestry.record.RecordUtils;

 import org.apache.tapestry.record.WebSessionAttributeCallback;

 import org.apache.tapestry.web.WebRequest;

 import org.apache.tapestry.web.WebSession;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.Collections;

 /**

  * A basic {@link org.apache.tapestry.record.PropertyPersistenceStrategy},

  * which stores properties in the HttpSession as attributes. This is a clone of

  * {@link org.apache.tapestry.record.SessionPropertyPersistenceStrategy} with one difference, it allows you to specify

  * a different strategyId

  */

 public abstract class AbstractSessionPropertyPersistenceStrategy implements PropertyPersistenceStrategy

 {

         private static final Log LOG = LogFactory.getLog(AbstractSessionPropertyPersistenceStrategy.class);

         private String applicationId;

         private WebRequest request;

         protected abstract String getStrategyId();

         // Really, the name of the servlet; used as a prefix on all

         // HttpSessionAttribute keys

         // to keep things straight if multiple Tapestry apps are deployed

         // in the same WAR.

         public void store(String pageName, String idPath, String propertyName, Object newValue)

         {

                 Defense.notNull(pageName, "pageName");

                 Defense.notNull(propertyName, "propertyName");

                 WebSession session = request.getSession(true);

                 String attributeName = RecordUtils.buildChangeKey(getStrategyId(), applicationId, pageName, idPath, propertyName);

                 session.setAttribute(attributeName, newValue);

         }

         public Collection getStoredChanges(String pageName)

         {

                 Defense.notNull(pageName, "pageName");

                 WebSession session = request.getSession(false);

                 if (session == null)

                         return Collections.EMPTY_LIST;

                 final Collection result = new ArrayList();

                 WebSessionAttributeCallback callback = new WebSessionAttributeCallback()

                 {

                         public void handleAttribute(WebSession sess, String name)

                         {

                                 PropertyChange change = RecordUtils.buildChange(name, sess.getAttribute(name));

                                 result.add(change);

                         }

                 };

                 RecordUtils.iterateOverMatchingAttributes(getStrategyId(), applicationId, pageName, session, callback);

                 return result;

         }

         public void discardStoredChanges(String pageName)

         {

                 WebSession session = request.getSession(false);

                 if (session == null) return;

                 WebSessionAttributeCallback callback = new WebSessionAttributeCallback()

                 {

                         public void handleAttribute(WebSession sess, String name)

                         {

                                 sess.setAttribute(name, null);

                         }

                 };

                 RecordUtils.iterateOverMatchingAttributes(getStrategyId(), applicationId, pageName, session, callback);

         }

         /**

          * Does nothing; session persistence does not make use of query parameters.

          */

         public void addParametersForPersistentProperties(ServiceEncoding encoding,

                                                                                                          boolean post)

         {

         }

         public void setApplicationId(String applicationName)

         {

                 this.applicationId = applicationName;

         }

         public void setRequest(WebRequest request)

         {

                 this.request = request;

         }

 }