cdo/bundles/org.eclipse.papyrus.cdo.ui.customization.properties/src/org/eclipse/papyrus/cdo/internal/ui/customization/properties/storage/CDOContextStorageProvider.java

/*****************************************************************************
 * Copyright (c) 2013, 2017 CEA LIST and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *   CEA LIST - Initial API and implementation
 *   Christian W. Damus (CEA) - bug 443830
 *   Eike Stepper (CEA) - bug 466520
 *
 *****************************************************************************/
package org.eclipse.papyrus.cdo.internal.ui.customization.properties.storage;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.emf.cdo.common.util.CDOResourceNodeNotFoundException;
import org.eclipse.emf.cdo.eresource.CDOResourceFolder;
import org.eclipse.emf.cdo.eresource.CDOTextResource;
import org.eclipse.emf.cdo.explorer.CDOExplorerUtil;
import org.eclipse.emf.cdo.explorer.checkouts.CDOCheckout;
import org.eclipse.emf.cdo.explorer.checkouts.CDOCheckoutManager;
import org.eclipse.emf.cdo.util.CDOURIUtil;
import org.eclipse.emf.cdo.view.CDOView;
import org.eclipse.emf.cdo.view.CDOViewInvalidationEvent;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.net4j.util.event.IEvent;
import org.eclipse.net4j.util.event.IListener;
import org.eclipse.papyrus.cdo.core.util.CDOFunctions;
import org.eclipse.papyrus.cdo.core.util.CDOPredicates;
import org.eclipse.papyrus.cdo.internal.core.CDOUtils;
import org.eclipse.papyrus.cdo.internal.ui.customization.properties.Activator;
import org.eclipse.papyrus.infra.properties.contexts.Context;
import org.eclipse.papyrus.views.properties.storage.AbstractContextStorageProvider;

import com.google.common.base.Function;
import com.google.common.base.Predicates;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;


/**
 * This is the CDOContextStorageProvider type. Enjoy.
 */
public class CDOContextStorageProvider extends AbstractContextStorageProvider {

	public static final String CONTEXTS_PATH = Activator.PLUGIN_ID + ".contexts"; //$NON-NLS-1$

	public static final String CONTEXT_EXTENSION = "ctx"; //$NON-NLS-1$

	private ResourceSet resourceSet;

	private CDOTextURIHandler uriHandler;

	private final IListener checkoutManagerListener = new IListener() {

		@Override
		public void notifyEvent(IEvent event) {
			if (event instanceof CDOCheckoutManager.CheckoutStateEvent) {
				CDOCheckoutManager.CheckoutStateEvent e = (CDOCheckoutManager.CheckoutStateEvent) event;
				CDOCheckout checkout = e.getCheckout();

				switch (e.getNewState()) {
				case Opening:
					break;

				case Open:
					CDOView view = checkout.openView(true, resourceSet);
					view.addListener(this);

					Collection<? extends Context> added = ImmutableList.copyOf(getContexts(checkout));
					if (!added.isEmpty()) {
						fireContextsAdded(added);
					}
					break;

				case Closing:
					break;

				case Closed:
					Collection<? extends Context> removed = ImmutableList.copyOf(contexts.get(checkout));
					if (!removed.isEmpty()) {
						contexts.removeAll(checkout);
						fireContextsRemoved(removed);
					}
					break;

				default:
					break;
				}
			} else if (event instanceof CDOViewInvalidationEvent) {
				CDOViewInvalidationEvent e = (CDOViewInvalidationEvent) event;
				CDOView view = e.getSource();

				if (view.hasResource(CONTEXTS_PATH)) {
					CDOResourceFolder folder = view.getResourceFolder(CONTEXTS_PATH);
					URI prefix = folder.getURI();
					if (!prefix.isPrefix()) {
						prefix = prefix.appendSegment(""); // add a trailing slash
					}

					// usually, it is XWT resources that change, so we have to find the contexts that own them
					Collection<CDOTextResource> contextResources = Lists.newArrayList();
					Iterable<CDOTextResource> textResources = Iterables.filter(Iterables.filter(e.getDirtyObjects(), CDOTextResource.class), CDOPredicates.hasURIPrefix(prefix));
					for (CDOTextResource next : textResources) {
						// get the context resource
						URI relative = next.getURI().deresolve(prefix);
						URI contextURI = prefix.appendSegment(relative.segment(0)).appendSegment(relative.segment(0)).appendFileExtension(CONTEXT_EXTENSION);
						String path = CDOURIUtil.extractResourcePath(contextURI);
						if (view.hasResource(path)) {
							try {
								contextResources.add(view.getTextResource(path));
							} catch (Exception ex) {
								// it's not a text resource. OK, there's something going on that we don't understand
							}
						}
					}

					Collection<Context> changed = ImmutableList.copyOf(getContexts(contextResources));
					if (!changed.isEmpty()) {
						fireContextsChanged(changed);
					}
				}
			}
		}
	};

	private final Multimap<CDOCheckout, Context> contexts = HashMultimap.create();

	public CDOContextStorageProvider() {
		super();
	}

	@Override
	public void initialize(ResourceSet resourceSet) throws CoreException {
		this.resourceSet = resourceSet;

		uriHandler = CDOTextURIHandler.install(resourceSet);

		CDOExplorerUtil.getCheckoutManager().addListener(checkoutManagerListener);
	}

	@Override
	public void dispose() {
		if (uriHandler != null) {
			CDOExplorerUtil.getCheckoutManager().removeListener(checkoutManagerListener);

			uriHandler.uninstall();
			uriHandler = null;

			resourceSet = null;
		}
		
		super.dispose();
	}

	@Override
	public boolean providesFor(Context context) {
		URI uri = EcoreUtil.getURI(context);
		return uri != null && (CDOUtils.isCDOURI(uri) || CDOTextURIHandler.SCHEME.equals(uri.scheme()));
	}

	@Override
	public Collection<? extends Context> loadContexts() throws CoreException {
		return ImmutableList.copyOf(Iterables.concat(Iterables.transform(getCheckouts(), getContexts())));
	}

	Iterable<? extends CDOCheckout> getCheckouts() {
		return Arrays.asList(CDOExplorerUtil.getCheckoutManager().getCheckouts());
	}

	Function<CDOCheckout, Iterable<? extends Context>> getContexts() {
		return new Function<CDOCheckout, Iterable<? extends Context>>() {

			@Override
			public Iterable<? extends Context> apply(CDOCheckout input) {
				return getContexts(input);
			}
		};
	}

	Iterable<? extends Context> getContexts(CDOCheckout checkout) {
		Iterable<? extends Context> result;

		if (!checkout.isOpen()) {
			result = Collections.emptyList();
		} else {
			CDOResourceFolder folder = null;

			try {
				folder = checkout.getView().getResourceFolder(CONTEXTS_PATH);
			} catch (CDOResourceNodeNotFoundException e) {
				// normal consequence when the folder doesn't exist
			}

			if (folder == null) {
				result = Collections.emptyList();
			} else {
				Iterable<CDOTextResource> textNodes = Iterables.concat(Iterables.transform(folder.getNodes(), CDOFunctions.getFolderContents(CDOTextResource.class)));

				result = getContexts(textNodes);

				contexts.replaceValues(checkout, result);
			}
		}

		return result;
	}

	Iterable<? extends Context> getContexts(Iterable<CDOTextResource> textResources) {
		return Iterables.filter( // null filter
				Iterables.transform( // root transform
						Iterables.transform( // resource transform
								Iterables.filter( // .ctx extension filter
										textResources, CDOPredicates.hasExtension(CONTEXT_EXTENSION)), // filter
								getContextResource()), // transform
						CDOFunctions.getRoot(Context.class)), // transform
				Predicates.notNull()); // filter
	}

	private Function<CDOTextResource, Resource> getContextResource() {
		return new Function<CDOTextResource, Resource>() {

			@Override
			public Resource apply(CDOTextResource input) {
				return resourceSet.getResource(CDOTextURIHandler.createURI(input.getURI()), true);
			}
		};
	}

	@Override
	public void refreshContext(Context context) throws CoreException {
		// nothing to do
	}
}