/*
    * Copyright 2007-2008 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.ksb.messaging;
  
  import org.apache.log4j.Logger;
  import org.kuali.rice.ksb.messaging.service.MessageQueueService;
  import org.kuali.rice.ksb.service.KSBServiceLocator;
  import org.kuali.rice.ksb.util.KSBConstants;
  import org.springframework.transaction.TransactionStatus;
  import org.springframework.transaction.support.TransactionCallback;
  
  /**
   * Fetches messages from the db. Marks as 'R'. Gives messages to ThreadPool for execution
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   * 
   */
  public class MessageFetcher implements Runnable {
  
      private static final Logger LOG = Logger.getLogger(MessageFetcher.class);
  
      private Integer maxMessages;
      private Long routeQueueId;
  
      public MessageFetcher(Integer maxMessages) {
  	this.maxMessages = maxMessages;
      }
  
      public MessageFetcher(Long routeQueueId) {
  	this.routeQueueId = routeQueueId;
      }
  
      public void run() {
  	try {
  	    requeueDocument();
  	    requeueMessages();
  	} catch (Throwable t) {
  	    LOG.error("Failed to fetch messages.", t);
  	}
      }
  
      private void requeueMessages() {
  	if (this.routeQueueId == null) {
  	    try {
  		for (final PersistedMessage message : getRouteQueueService().getNextDocuments(maxMessages)) {
  		    markEnrouteAndSaveMessage(message);
  		    executeMessage(message);
  		}
  	    } catch (Throwable t) {
  		LOG.error("Failed to fetch or process some messages during requeueMessages", t);
  	    }
  	}
      }
  
      private void requeueDocument() {
  	try {
  	    if (this.routeQueueId != null) {
  		PersistedMessage message = getRouteQueueService().findByRouteQueueId(this.routeQueueId);
  		message.setQueueStatus(KSBConstants.ROUTE_QUEUE_ROUTING);
  		getRouteQueueService().save(message);
  		executeMessage(message);
  	    }
  	} catch (Throwable t) {
  	    LOG.error("Failed to fetch or process some messages during requeueDocument", t);
  	}
      }
  
      private void executeMessage(PersistedMessage message) {
  	try {
  	    KSBServiceLocator.getThreadPool().execute(new MessageServiceInvoker(message));
  	} catch (Throwable t) {
  	    LOG.error("Failed to place message " + message + " in thread pool for execution", t);
  	}
      }
  
      private void markEnrouteAndSaveMessage(final PersistedMessage message) {
  	try {
  	    KSBServiceLocator.getTransactionTemplate().execute(new TransactionCallback() {
  		public Object doInTransaction(TransactionStatus status) {
  		    message.setQueueStatus(KSBConstants.ROUTE_QUEUE_ROUTING);
  		    getRouteQueueService().save(message);
  		    return null;
  		}
  	    });
  	} catch (Throwable t) {
  	    LOG.error("Caught error attempting to mark message " + message + " as R", t);
 	}
     }
 
     private MessageQueueService getRouteQueueService() {
 	return KSBServiceLocator.getRouteQueueService();
     }
 
 }