/*******************************************************************************
 * Copyright (c) 2005, 2007 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.debug.internal.ui.viewers.model;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.debug.internal.core.commands.Request;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IPresentationContext;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputRequestor;
import org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputUpdate;
import org.eclipse.jface.viewers.TreePath;
import org.eclipse.ui.progress.WorkbenchJob;

/**
 * Internal implementation of the {@link IViewerInputUpdate} interface.  Allows
 * implementors to translate the active debug context into an appropriate viewer
 * input.
 * 
 * @since 3.4
 * @see IViewerInputUpdate
 */
public class ViewerInputUpdate extends Request implements IViewerInputUpdate {

    /**
     * Presentation context
     */
    private IPresentationContext fContext;
    
    /**
     * New viewer input
     */
    private Object fSource;
    
    /**
     * Whether this update is done
     */
    private boolean fDone;
    
    /**
     * Viewer input to use
     */
    private Object fInputElement;
    
    /**
     * Viewer input at the time the request was made
     */
    private Object fViewerInput;
    
    /**
     * Client making request
     */
    private IViewerInputRequestor fRequestor;
    
    /**
     * When <code>done()</code> is called, the viewer must be informed that the update is complete in the UI thread.
     */
    protected WorkbenchJob fViewerInputUpdateJob = new WorkbenchJob("Asynchronous viewer input update") { //$NON-NLS-1$
        public IStatus runInUIThread(IProgressMonitor monitor) {
            fRequestor.viewerInputComplete(ViewerInputUpdate.this);
            return Status.OK_STATUS;
        }
    };
    
    /**
     * Constructs a viewer input update request.
     * 
     * @param context presentation context
     * @param viewerInput viewer input at the time the request was made
     * @param requestor client making the request
     * @param source source from which to derive a viewer input
     */
    public ViewerInputUpdate(IPresentationContext context, Object viewerInput, IViewerInputRequestor requestor, Object source){
    	fContext = context;
    	fSource = source;
    	fRequestor = requestor;
    	fViewerInputUpdateJob.setSystem(true);
    	fViewerInput = viewerInput;
    }

	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputUpdate#getPresentationContext()
	 */
	public IPresentationContext getPresentationContext() {
		return fContext;
	}
	
	/* (non-Javadoc)
     * @see org.eclipse.core.runtime.IProgressMonitor#done()
     */
    public final void done() {
    	synchronized (this) {
    		if (isDone()) {
    			return;
    		}
    		fDone = true;
		}
        fViewerInputUpdateJob.schedule();
	}
    
    /**
     * Returns whether this request is done yet.
     * 
     * @return whether this request is done yet
     */
    protected synchronized boolean isDone() {
    	return fDone;
    }

	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputUpdate#getElement()
	 */
	public Object getElement() {
		return fSource;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerUpdate#getElementPath()
	 */
	public TreePath getElementPath() {
		return TreePath.EMPTY;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputUpdate#setViewerInput(java.lang.Object)
	 */
	public void setInputElement(Object element) {
		fInputElement = element;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerInputUpdate#getViewerInput()
	 */
	public Object getInputElement() {
		return fInputElement;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.debug.internal.ui.viewers.model.provisional.IViewerUpdate#getViewerInput()
	 */
	public Object getViewerInput() {
		return fViewerInput;
	}
	
	

}