/*

  * Copyright 2011 The Kuali Foundation

  *

  * Licensed under the Educational Community License, Version 1.0 (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/ecl1.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.ksb.impl.registry.diff;

 import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import javax.xml.namespace.QName;

 import org.apache.log4j.Logger;

 import org.kuali.rice.ksb.api.registry.ServiceInfo;

 import org.kuali.rice.ksb.api.registry.ServiceRegistry;

 import org.kuali.rice.ksb.impl.bus.LocalService;

 import org.kuali.rice.ksb.impl.bus.RemoteService;

 /**

  * Default implementation of the {@link ServiceRegistryDiffCalculator} which calculates

  * differences between client service bus state and service registry state.

  * 

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

  *

  */

 public class ServiceRegistryDiffCalculatorImpl implements ServiceRegistryDiffCalculator {

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

         private ServiceRegistry serviceRegistry;

         public void setServiceRegistry(ServiceRegistry serviceRegistry) {

                 this.serviceRegistry = serviceRegistry;

         }

         @Override

         public CompleteServiceDiff diffServices(String instanceId, List<LocalService> localServices, List<RemoteService> clientRegistryCache) {

                 List<ServiceInfo> allRegistryServicesForInstance = serviceRegistry.getAllServicesForInstance(instanceId);

                 LocalServicesDiff localServicesDiff = calculateLocalServicesDiff(allRegistryServicesForInstance, instanceId, localServices);

                 List<ServiceInfo> allRegistryServices = serviceRegistry.getAllOnlineServices();

                 RemoteServicesDiff remoteServicesDiff = calculateRemoteServicesDiff(allRegistryServices, clientRegistryCache);

                 return new CompleteServiceDiff(localServicesDiff, remoteServicesDiff);

         }

         protected LocalServicesDiff calculateLocalServicesDiff(List<ServiceInfo> allRegistryServicesForInstance, String instanceId, List<LocalService> localServices) {

                 List<ServiceInfo> servicesToRemoveFromRegistry = new ArrayList<ServiceInfo>();

                 List<LocalService> localServicesToPublish = new ArrayList<LocalService>();

                 Map<LocalService, ServiceInfo> localServicesToUpdate = new HashMap<LocalService, ServiceInfo>();

                 Map<QName, LocalService> localServiceIndex = indexLocalServices(instanceId, localServices);

                 for (ServiceInfo serviceInfo : allRegistryServicesForInstance) {

                         // first validate that the service has a valid instance id

                         if (!instanceId.equals(serviceInfo.getInstanceId())) {

                                 throw new IllegalArgumentException("ServiceInfo given for local service diff does not have a valid instance id.  Should have been '" + instanceId + "' but was '" + serviceInfo.getInstanceId() + "'");

                         }

                         LocalService localService = localServiceIndex.get(serviceInfo.getServiceName());

                         if (localService == null) {

                                 // this means the registry has the service but there is no local service, it has been unregistered

                                 servicesToRemoveFromRegistry.add(serviceInfo);

                         } else {

                                 // if the LocalService is not null, that means that it exists but it may have changed, or this may be the first time the service

                                 // is being published upon startup in which case it's service id will be null

                                 if (!localService.getServiceEndpoint().getInfo().equals(serviceInfo)) {

                                         // if the service infos don't match, that means we need to re-publish our current copy of the local service

                                         localServicesToUpdate.put(localService, serviceInfo);

                                 }

                                 // whether or not it matches, remove it from the index

                                 localServiceIndex.remove(serviceInfo.getServiceName());

                         }

                 }

                 // what's left in the localServiceIndex will be services that weren't in the registry at all, they need to be published

                 localServicesToPublish.addAll(localServiceIndex.values());

                 if (LOG.isDebugEnabled()) {

                         LOG.info("For instance '" + instanceId + "', found " + servicesToRemoveFromRegistry.size() + " services to remove from registry, "+

                                 localServicesToPublish.size() + " local services to publish");

                 }

                 return new LocalServicesDiff(servicesToRemoveFromRegistry, localServicesToPublish, localServicesToUpdate);

         }

         private Map<QName, LocalService> indexLocalServices(String instanceId, List<LocalService> localServices) {

                 Map<QName, LocalService> localServiceIndex = new HashMap<QName, LocalService>(localServices.size());

                 for (LocalService localService : localServices) {

                         String localServiceInstanceId = localService.getServiceEndpoint().getInfo().getInstanceId(); 

                         if (!instanceId.equals(localServiceInstanceId)) {

                                 throw new IllegalStateException("Instance id of local service (" + localServiceInstanceId + ") does not match instance id given to the diff calculator (" + instanceId + ")");

                         }

                         localServiceIndex.put(localService.getServiceName(), localService);

                 }

                 return localServiceIndex;

         }

         protected List<ServiceInfo> filterServicesForInstance(String instanceId, List<ServiceInfo> allServices) {

                 List<ServiceInfo> filteredServices = new ArrayList<ServiceInfo>();

                 for (ServiceInfo serviceInfo : allServices) {

                         if (instanceId.equals(serviceInfo.getInstanceId())) {

                                 filteredServices.add(serviceInfo);

                         }

                 }

                 return filteredServices;

         }

         protected RemoteServicesDiff calculateRemoteServicesDiff(List<ServiceInfo> allRegistryServices, List<RemoteService> clientRegistryCache) {

                 List<ServiceInfo> servicesToAddToClientRegistryCache = new ArrayList<ServiceInfo>(allRegistryServices);

                 List<RemoteService> servicesToRemoveFromClientRegistryCache = new ArrayList<RemoteService>();

                 Map<String, ServiceInfo> indexedRegistryServices = indexRegistryServices(allRegistryServices);

                 for (RemoteService remoteService : clientRegistryCache) {

                         ServiceInfo indexedRegistryService = indexedRegistryServices.get(remoteService.getServiceInfo().getServiceId());

                         if (indexedRegistryService == null) {

                                 servicesToRemoveFromClientRegistryCache.add(remoteService);

                         } else {

                                 if (!remoteService.getServiceInfo().getChecksum().equals(indexedRegistryService.getChecksum())) {

                                         servicesToRemoveFromClientRegistryCache.add(remoteService);

                                 } else {

                                         servicesToAddToClientRegistryCache.remove(remoteService.getServiceInfo());

                                 }

                         }

                 }

                 if (LOG.isDebugEnabled()) {

                         LOG.debug("For instance found " + servicesToRemoveFromClientRegistryCache.size() + " services to remove from client registry cache, "+

                                 servicesToAddToClientRegistryCache.size() + " services to add to client registry cache");

                 }

                 return new RemoteServicesDiff(servicesToAddToClientRegistryCache, servicesToRemoveFromClientRegistryCache);

         }

         private Map<String, ServiceInfo> indexRegistryServices(List<ServiceInfo> allRegistryServices) {

                 Map<String, ServiceInfo> indexedRegistryServices = new HashMap<String, ServiceInfo>(allRegistryServices.size());

                 for (ServiceInfo serviceInfo : allRegistryServices) {

                         indexedRegistryServices.put(serviceInfo.getServiceId(), serviceInfo);

                 }

                 return indexedRegistryServices;

         }

 }