package org.kuali.student.common.ui.client.security;
   
   import org.kuali.student.common.ui.client.service.exceptions.VersionMismatchClientException;
   import org.kuali.student.common.ui.client.widgets.KSErrorDialog;
   
   import com.google.gwt.core.client.GWT;
   import com.google.gwt.user.client.Window;
   
   /**
   * Default KS implementation of failure handling.
   * <p>
   * Implementing institution should override this class to 
   * custom handle failures.
   */
  public class AsyncCallbackFailureHandler {
    
      /**
       * Attempt to provide default session timeout handling.
       */
      protected static final SessionTimeoutHandler sessionTimeoutHandler = GWT.create(SpringSecurityLoginDialogHandler.class);
      
      public void onFailure(Throwable caught) {
          // This code attempts to handle session timeouts
          // it appears to be half finished.  The implementing
          // institution may wish to override the method to
          // to properly detect session timeout
          
          // The idea with the if/else below is to attempt to detect
          // the type of error and handle it appropriately. It was
          // not finished, so only these two errors are detected.  
          // There is also inconsistent handling of errors in the 
          // individual widgets as well. 
          if (sessionTimeoutHandler.isSessionTimeout(caught)){
               handleTimeout(caught);
               sessionTimeoutHandler.handleSessionTimeout();
          } else if (caught instanceof VersionMismatchClientException){
               handleVersionMismatch(caught);
           }else {        
               handleFailure(caught);
           } 
      }
       
      /**
       * Override this method to process any exceptions you wish to handle. The default implementation displays 
       * an error dialog with the message and logs the exception.
       * 
       * @param caught
       */
      public void handleFailure(Throwable caught){
          if (!sessionTimeoutHandler.isSessionTimeout(caught)){
              KSErrorDialog.show(caught);
          }
          GWT.log("Exception:", caught);
      }
  
      /**
       * By default this defers to handleFailure. Override this handle a rpc failure due to timeout differently
       * from other exceptions.
       * 
       * @param caught
       */
      public void handleTimeout(Throwable caught){
          handleFailure(caught);
      }
          
      public void handleVersionMismatch(Throwable caught){
          String message = null;
          if (caught.getMessage() != null){
              message = "Version Error: " + caught.getMessage() + "\n\n";
          }
          message += "This page has been updated by another user since you loaded it. Please refresh and re-apply changes before saving.";
          Window.alert(message);
      }
      
  }