/* 
 * Copyright (c) 2006 Stiftung Deutsches Elektronen-Synchroton, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
package org.csstudio.sds;

import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.FileLocator;
import org.eclipse.core.runtime.Path;
import org.osgi.framework.Bundle;

/**
 * This services provides some basic workspace operations.
 * 
 * @author Alexander Will
 * @version $Revision$
 * 
 */
public final class ResourceService {
	/**
	 * The shared instance.
	 */
	private static ResourceService _instance;

	/**
	 * List that holds all listeners that will be informed about resource
	 * changes.
	 */
	private ArrayList<IResourceChangeListener> _targetResourceChangeListeners;

	/**
	 * The change listener that is used to centrally collect workspace changes.
	 */
	private IResourceChangeListener _resourceChangeListener;

	/**
	 * Return the shared instance.
	 * 
	 * @return The shared instance.
	 */
	public static ResourceService getInstance() {
		if (_instance == null) {
			_instance = new ResourceService();
		}

		return _instance;
	}

	/**
	 * Private constructor due to singleton pattern.
	 */
	private ResourceService() {
		_targetResourceChangeListeners = new ArrayList<IResourceChangeListener>();
		_resourceChangeListener = new CssResourceChangeListener();
	}

	/**
	 * Create a workspace project with the given name (if it does not exist
	 * already).
	 * 
	 * @param projectName
	 *            The name of the project.
	 * @return a handle to the given project.
	 */
	public IProject createWorkspaceProject(final String projectName) {
		IProject result = ResourcesPlugin.getWorkspace().getRoot().getProject(
				projectName);
		if (!result.exists()) {
			try {
				result.create(null);
				result.open(null);
			} catch (CoreException e) {
			}
		}

		return result;
	}

	/**
	 * Copy the resourcces from the given folder in the given bundle into the
	 * given workspace project.
	 * 
	 * @param targetProject
	 *            workspace project to copy the resources to.
	 * @param sourceBundle
	 *            source bundle.
	 * @param sourceFolderName
	 *            source folder in the source bundle.
	 */
	public void copyResources(final IProject targetProject,
			final Bundle sourceBundle, final String sourceFolderName) {

		Enumeration<URL> fileEntries = sourceBundle.findEntries(sourceFolderName,
				"*.*", false); //$NON-NLS-1$

		while (fileEntries.hasMoreElements()) {
			URL url = fileEntries.nextElement();
			String filePath = url.getFile();
			String fileName = filePath
					.substring(filePath.indexOf(sourceFolderName + "/") + sourceFolderName.length() + 1); //$NON-NLS-1$

			IFile file = targetProject.getFile(fileName);
			if (!file.exists()) {
				try {
					file.create(FileLocator.openStream(sourceBundle, new Path(
							filePath), false), true, null);
				} catch (Exception e) {
				}
			}
		}
	}

	/**
	 * Add a resource change listener.
	 * 
	 * @param listener
	 *            the resource change listener to add.
	 */
	public void addResourceChangeListener(final IResourceChangeListener listener) {
		if (!_targetResourceChangeListeners.contains(listener)) {
			_targetResourceChangeListeners.add(listener);

			if (_targetResourceChangeListeners.size() == 1) {
				ResourcesPlugin.getWorkspace().addResourceChangeListener(
						_resourceChangeListener);
			}
		}
	}

	/**
	 * Remove a resource change listener.
	 * 
	 * @param listener
	 *            the resource change listener to remove.
	 */
	public void removeResourceChangeListener(
			final IResourceChangeListener listener) {
		if (_targetResourceChangeListeners.contains(listener)) {
			_targetResourceChangeListeners.remove(listener);

			if (_targetResourceChangeListeners.size() == 0) {
				ResourcesPlugin.getWorkspace().removeResourceChangeListener(
						_resourceChangeListener);
			}
		}
	}

	/**
	 * Central resource change listener that forwards workspace changes to the
	 * registered listeners.
	 * 
	 * @author Alexander Will
	 * @version $Revision$
	 */
	private class CssResourceChangeListener implements IResourceChangeListener {
		@Override
		public void resourceChanged(IResourceChangeEvent event) {
			for (IResourceChangeListener listener : _targetResourceChangeListeners) {
				listener.resourceChanged(event);
			}
		}
	}
}