package uk.ac.vamsas.client.simpleclient;


public class ClientSessionFileWatcherElement extends SessionFileWatcherElement {

  private static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(VamsasFileWatcherElement.class);
  
 /**
  * count of watch cycle before considering there is no other active client.
  */
  private int timeoutBeforeLastCycle = -1;
  
  private boolean isTimeOutEnable = false;
  
  /**
   * @param watcher
   * @param handler
   */
  public ClientSessionFileWatcherElement(SessionFile watcher,
      WatcherCallBack handler) {
    super(watcher, handler);
  }

  /**
   * @param watcher
   * @param handler
   * @param enableWatching
   */
  public ClientSessionFileWatcherElement(SessionFile watcher,
      WatcherCallBack handler, boolean enableWatching) {
    super(watcher, handler, enableWatching);
  }

  /**
   * @see uk.ac.vamsas.client.simpleclient.WatcherElement#doWatch()
   * * @return true if the handler was called for a changeEvent
     */
  public boolean doWatch()
    {
      if (!watchForChange || handler==null)
      { //log.debug("!watchForChange || handler==null");
        return false;
      }
      if (watcher==null)
        initWatch(); // somehow not done the first time
      handlerCalled=false;
      Lock doclock=null;
      try 
        {
          doclock=watcher.getChangedState();
        } 
     catch (Exception e) {
        log.error("Whilst watching "+watcher.getSubject(), e);
      }
    // log.debug("got lock watcher");
     if (doclock==null)
       {//no change detected
          this.cycleCountSinceModif ++;
          if (this.isTimeOutEnable && cycleCountSinceModif > timeoutBeforeLastCycle)
            {
            if(this.handler != null )
              synchronized (this.handler)
              {
                this.callHandler(doclock);
              }
            }
        //log.debug("no modification");
          return false;
       }
     if (this.isTimeOutEnable) this.cycleCountSinceModif =0; //change detected
     if(this.handler != null )
       synchronized (this.handler)
       {
         this.callHandler(doclock);
       }
   
     return true;
    }
  
 
  /**
   * count of cycles since last modification on the file
   */
  protected int  cycleCountSinceModif  =0;
  
  /**
   * resets count of watch cycles  (default value : 0)
   *
   */
  protected void resetCycleCount ()
    {
      this.cycleCountSinceModif = 0;
    }
  
  /**
   * Increases the count of cycles
   *
   */
  protected void increaseCycleCount ()
    {
      this.cycleCountSinceModif ++;
    }

  /**
   * Enable the time out if the timeout is greater than zero
   * @param timeoutBeforeLastCycle the timeoutBeforeLastCycle to set
   */
  public void setTimeoutBeforeLastCycle(int timeoutBeforeLastCycle) {
    
    this.timeoutBeforeLastCycle = timeoutBeforeLastCycle;
    if (this.timeoutBeforeLastCycle>0)
      isTimeOutEnable = true;
  }
  
  /**
   * Disables the checking on the count of cycles
   *
   */
  public void disableCycleTimeOut ()
    {
    this.isTimeOutEnable = false;
    }
}