EDIT

// $Id$

/**

* Copyright (C) 2007 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.taxeditor.store;

import java.io.File;

import java.io.FileNotFoundException;

import org.eclipse.core.runtime.IPath;

import org.eclipse.core.runtime.IProgressMonitor;

import org.eclipse.core.runtime.ListenerList;

import org.eclipse.ui.IMemento;

import org.eclipse.ui.IWorkbench;

import org.eclipse.ui.IWorkbenchListener;

import org.eclipse.ui.PlatformUI;

import org.eclipse.ui.XMLMemento;

import eu.etaxonomy.taxeditor.model.IContextListener;

import eu.etaxonomy.taxeditor.model.MementoHelper;

import eu.etaxonomy.taxeditor.store.internal.TaxeditorStorePlugin;

/**

 * The context manager mediates context start/stop and workbench shutdowns to all registered listeners.

 *

 * @author n.hoffmann

 * @created Sep 30, 2010

 * @version 1.0

 */

public class ContextManager implements IWorkbenchListener{

	private ListenerList contextListeners = new ListenerList();

	private IMemento memento;

	/**

	 * <p>Constructor for ContextManager.</p>

	 */

	protected ContextManager() {

		PlatformUI.getWorkbench().addWorkbenchListener(this);

	}

	/**

	 * <p>addContextListener</p>

	 *

	 * @param listener a {@link eu.etaxonomy.taxeditor.model.IContextListener} object.

	 */

	public void addContextListener(IContextListener listener){

		contextListeners.add(listener);

	}

	/**

	 * <p>removeContextListener</p>

	 *

	 * @param listener a {@link eu.etaxonomy.taxeditor.model.IContextListener} object.

	 */

	public void removeContextListener(IContextListener listener) {

		contextListeners.remove(listener);

	}

	/**

	 * <p>notifyContextStart</p>

	 *

	 * @param monitor a {@link org.eclipse.core.runtime.IProgressMonitor} object.

	 */

	public void notifyContextStart(IProgressMonitor monitor) {

		IProgressMonitor subMonitor = StoreUtil.getSubProgressMonitor(monitor, 1);

		subMonitor.beginTask("Starting context", contextListeners.size());

		StoreUtil.info("Notifying context listeners, that the context has started.");

		readMemento();				

		for(final Object listener : contextListeners.getListeners()){

			((IContextListener) listener).contextStart(memento, monitor);

			subMonitor.worked(1);

		}

		subMonitor.done();

	}

	/**

	 * <p>notifyContextAboutToStop</p>

	 *

	 * @param monitor a {@link org.eclipse.core.runtime.IProgressMonitor} object.

	 */

	public void notifyContextAboutToStop(IProgressMonitor monitor){

		IProgressMonitor subMonitor = StoreUtil.getSubProgressMonitor(monitor, 1);

		subMonitor.beginTask("Stoping context", contextListeners.size());

		// we are creating the memento here; even if the context is not stopped

		createMemento();

		for(Object listener : contextListeners.getListeners()){

			((IContextListener) listener).contextAboutToStop(memento, monitor);

			subMonitor.worked(1);

		}	

		subMonitor.done();

	}

	/**

	 * <p>notifyContextStop</p>

	 *

	 * @param monitor a {@link org.eclipse.core.runtime.IProgressMonitor} object.

	 */

	public void notifyContextStop(IProgressMonitor monitor) {

		IProgressMonitor subMonitor = StoreUtil.getSubProgressMonitor(monitor, 1);

		subMonitor.beginTask("Stoping context", contextListeners.size());

		StoreUtil.info("Notifying context listeners, that the context has stopped.");

		for(Object listener : contextListeners.getListeners()){

			((IContextListener) listener).contextStop(memento, subMonitor);

		}	

		saveMemento();

		subMonitor.done();

	}

	/* (non-Javadoc)

	 * @see org.eclipse.ui.IWorkbenchListener#preShutdown(org.eclipse.ui.IWorkbench, boolean)

	 */

	/** {@inheritDoc} */

	@Override

	public boolean preShutdown(IWorkbench workbench, boolean forced) {

		createMemento();

		IProgressMonitor monitor = null;

		for(Object listener : contextListeners.getListeners()){

			((IContextListener) listener).workbenchShutdown(memento, monitor);

		}	

		saveMemento();

		// return true in any case, otherwise the application will not stop

		return true;

	}

	/* (non-Javadoc)

	 * @see org.eclipse.ui.IWorkbenchListener#postShutdown(org.eclipse.ui.IWorkbench)

	 */

	/** {@inheritDoc} */

	@Override

	public void postShutdown(IWorkbench workbench) {

	}

	private void readMemento(){

		try {

			memento = MementoHelper.readMementoFromFile(getStateFileForCurrentDatabase());

		} catch (FileNotFoundException e) {

			// no memento -> no previous state

			StoreUtil.info("No state file for datasource");

		}

	}

	private void createMemento(){

		if (CdmStore.getDataSource() != null) {

			try {

				memento = XMLMemento.createWriteRoot(CdmStore.getDataSource().getName());

				StoreUtil.info("DataSource found. Memento created.");

			} catch (Exception e) {

				// The memento could not be created, but a not closable editor is avoided for this case.

				StoreUtil.error(this.getClass(), "The memento could not be created", e);

			}

		} else {

			StoreUtil.info("Not storing state data, because no DataSource present.");

		}

	}

	private boolean saveMemento(){

		return MementoHelper.saveMementoToFile(memento, getStateFileForCurrentDatabase()) != null;

	}

	/**

	 * <p>getStateFileForCurrentDatabase</p>

	 *

	 * @return a {@link java.io.File} object.

	 */

	protected File getStateFileForCurrentDatabase() {

		if(CdmStore.getDataSource() == null){

			return null;

		}

		IPath path = TaxeditorStorePlugin.getDefault().getStateLocation();

		if (path == null) {

			return null;

		}

		path = path.append("editor_state_" + CdmStore.getDataSource().getName() + ".xml");

		return path.toFile();

	}

}