package fr.in2p3.jsaga.impl.resource.task;
   
   import java.util.HashMap;
   import java.util.Map;
   import java.util.Set;
   import java.util.Map.Entry;
   
   import org.apache.log4j.Logger;
   import fr.in2p3.jsaga.adaptor.resource.ResourceAdaptor;
  import fr.in2p3.jsaga.adaptor.resource.ResourceStatus;
  
  public class IndividualResourceStatusPoller implements Runnable {
  
      private static Logger s_logger = Logger.getLogger(IndividualResourceStatusPoller.class);
      private ResourceAdaptor m_adaptor;
      private ResourceStatusPollerTask m_pollerTask;
      // a map but only one entry is used???
      protected final Map<String,ResourceMonitorCallback> m_subscribedResources;
      
      public IndividualResourceStatusPoller(ResourceAdaptor adaptor) {
          m_adaptor = adaptor;
          m_subscribedResources = new HashMap<String,ResourceMonitorCallback>();
      }
  
      public void subscribeResource(String nativeResourceId, ResourceMonitorCallback callback) {
          synchronized(m_subscribedResources) {
              boolean toBeStarted = m_subscribedResources.isEmpty();
  
              // subscribe job
              m_subscribedResources.put(nativeResourceId, callback);
  
              // may start timer
              if (toBeStarted) {
                  m_pollerTask = new ResourceStatusPollerTask(this);
                  m_pollerTask.start();
              }
          }
      }
  
      public void unsubscribeResource(String nativeResourceId) {
          synchronized(m_subscribedResources) {
              // unsubscribe job
              m_subscribedResources.remove(nativeResourceId);
  
              // may stop timer
              if (m_subscribedResources.isEmpty() && m_pollerTask!=null) {
                  m_pollerTask.stop();
                  m_pollerTask = null;
              }
          }
      }
  
      @Override
      public void run() {
          //TODO: should be multi-threaded
          Set<Entry<String, ResourceMonitorCallback>> entries;
          synchronized(m_subscribedResources) {
              entries = m_subscribedResources.entrySet();
          }
          for (Entry<String, ResourceMonitorCallback> entry : entries) {
              String nativeResourceId = (String) entry.getKey();
              ResourceMonitorCallback callback = (ResourceMonitorCallback) entry.getValue();
              try {
                  ResourceStatus status = m_adaptor.getResourceStatus(nativeResourceId);
                  callback.setState(status.getSagaState(), status.getStateDetail());
              } catch (Exception e) {
                  s_logger.warn("Failed to get status for resource: "+ nativeResourceId, e);
              }
          }
      }
  }