content: /*******************************************************************************
   * Copyright (c) 2000, 2008 IBM Corporation and others.
   * All rights reserved. This program and the accompanying materials
   * are made available under the terms of the Eclipse Public License v1.0
   * which accompanies this distribution, and is available at
   * http://www.eclipse.org/legal/epl-v10.html
   *
   * Contributors:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.internal.ui.util;
  
  import java.io.StringWriter;
  import java.lang.reflect.InvocationTargetException;
  
  import org.eclipse.core.runtime.CoreException;
  import org.eclipse.core.runtime.IStatus;
  import org.eclipse.core.runtime.Status;
  import org.eclipse.jface.dialogs.ErrorDialog;
  import org.eclipse.jface.dialogs.MessageDialog;
  import org.eclipse.swt.widgets.Shell;
  import org.eclipse.wst.jsdt.internal.ui.IJavaStatusConstants;
  import org.eclipse.wst.jsdt.internal.ui.JavaScriptPlugin;
  import org.eclipse.wst.jsdt.internal.ui.JavaUIMessages;
  
  /**
   * The default exception handler shows an error dialog when one of its handle methods
   * is called. If the passed exception is a <code>CoreException</code> an error dialog
   * pops up showing the exception's status information. For a <code>InvocationTargetException</code>
   * a normal message dialog pops up showing the exception's message. Additionally the exception
   * is written to the platform log.
   */
  public class ExceptionHandler {
  
  	private static ExceptionHandler fgInstance= new ExceptionHandler();
  	
  	/**
  	 * Logs the given exception using the platform's logging mechanism. The exception is
  	 * logged as an error with the error code <code>JavaStatusConstants.INTERNAL_ERROR</code>.
  	 */
  	public static void log(Throwable t, String message) {
  		JavaScriptPlugin.log(new Status(IStatus.ERROR, JavaScriptPlugin.getPluginId(), 
  			IJavaStatusConstants.INTERNAL_ERROR, message, t));
  	}
  	
  	/**
  	 * Handles the given <code>CoreException</code>. The workbench shell is used as a parent
  	 * for the dialog window.
  	 * 
  	 * @param e the <code>CoreException</code> to be handled
  	 * @param title the dialog window's window title
  	 * @param message message to be displayed by the dialog window
  	 */
  	public static void handle(CoreException e, String title, String message) {
  		handle(e, JavaScriptPlugin.getActiveWorkbenchShell(), title, message);
  	}
  	
  	/**
  	 * Handles the given <code>CoreException</code>. 
  	 * 
  	 * @param e the <code>CoreException</code> to be handled
  	 * @param parent the dialog window's parent shell
  	 * @param title the dialog window's window title
  	 * @param message message to be displayed by the dialog window
  	 */
  	public static void handle(CoreException e, Shell parent, String title, String message) {
  		fgInstance.perform(e, parent, title, message);
  	}
  	
  	/**
  	 * Handles the given <code>InvocationTargetException</code>. The workbench shell is used 
  	 * as a parent for the dialog window.
  	 * 
  	 * @param e the <code>InvocationTargetException</code> to be handled
  	 * @param title the dialog window's window title
  	 * @param message message to be displayed by the dialog window
  	 */
  	public static void handle(InvocationTargetException e, String title, String message) {
  		handle(e, JavaScriptPlugin.getActiveWorkbenchShell(), title, message);
  	}
  	
  	/**
  	 * Handles the given <code>InvocationTargetException</code>. 
  	 * 
  	 * @param e the <code>InvocationTargetException</code> to be handled
  	 * @param parent the dialog window's parent shell
  	 * @param title the dialog window's window title
  	 * @param message message to be displayed by the dialog window
  	 */
  	public static void handle(InvocationTargetException e, Shell parent, String title, String message) {
  		fgInstance.perform(e, parent, title, message);
  	}
  
  	//---- Hooks for subclasses to control exception handling ------------------------------------
  	
  	protected void perform(CoreException e, Shell shell, String title, String message) {
  		JavaScriptPlugin.log(e);
  		IStatus status= e.getStatus();
  		if (status != null) {
  			ErrorDialog.openError(shell, title, message, status);
  		} else {
  			displayMessageDialog(e, e.getMessage(), shell, title, message);
  		}
  	}
  
  	protected void perform(InvocationTargetException e, Shell shell, String title, String message) {
  		Throwable target= e.getTargetException();
  		if (target instanceof CoreException) {
  			perform((CoreException)target, shell, title, message);
  		} else {
  			JavaScriptPlugin.log(e);
  			if (e.getMessage() != null && e.getMessage().length() > 0) {
  				displayMessageDialog(e, e.getMessage(), shell, title, message);
  			} else {
  				displayMessageDialog(e, target.getMessage(), shell, title, message);
  			}
  		}
  	}
  
  	//---- Helper methods -----------------------------------------------------------------------
  	
  	private void displayMessageDialog(Throwable t, String exceptionMessage, Shell shell, String title, String message) {
  		StringWriter msg= new StringWriter();
  		if (message != null) {
  			msg.write(message);
  			msg.write("\n\n"); //$NON-NLS-1$
  		}
  		if (exceptionMessage == null || exceptionMessage.length() == 0)
  			msg.write(JavaUIMessages.ExceptionDialog_seeErrorLogMessage); 
  		else
  			msg.write(exceptionMessage);
  		MessageDialog.openError(shell, title, msg.toString());			
  	}	
  }
  