Copyright (c) 2006, 2015 IBM Corporation and others.
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:
    IBM Corporation - initial API and implementation
    James Blackburn (Broadcom Corp.) - ongoing development
    Lars Vogel  - Bug 473427
/*******************************************************************************
 * Copyright (c) 2006, 2015 IBM Corporation and others.
 *
 * 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:
 *     IBM Corporation - initial API and implementation
 *     James Blackburn (Broadcom Corp.) - ongoing development
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 473427
 *******************************************************************************/
package org.eclipse.core.internal.resources.mapping;

import java.util.*;
import org.eclipse.core.resources.*;
import org.eclipse.core.runtime.IPath;

A description of the changes found in a delta
/**
 * A description of the changes found in a delta
 */
public class ChangeDescription {

	private List<IResource> addedRoots = new ArrayList<>();
	private List<IResource> changedFiles = new ArrayList<>();
	private List<IResource> closedProjects = new ArrayList<>();
	private List<IResource> copiedRoots = new ArrayList<>();
	private List<IResource> movedRoots = new ArrayList<>();
	private List<IResource> removedRoots = new ArrayList<>();

	private IResource createSourceResource(IResourceDelta delta) {
		IPath sourcePath = delta.getMovedFromPath();
		IResource resource = delta.getResource();
		IWorkspaceRoot wsRoot = ResourcesPlugin.getWorkspace().getRoot();
		switch (resource.getType()) {
			case IResource.PROJECT :
				return wsRoot.getProject(sourcePath.segment(0));
			case IResource.FOLDER :
				return wsRoot.getFolder(sourcePath);
			case IResource.FILE :
				return wsRoot.getFile(sourcePath);
		}
		return null;
	}

	private void ensureResourceCovered(IResource resource, List<IResource> list) {
		IPath path = resource.getFullPath();
		for (IResource root : list) {
			if (root.getFullPath().isPrefixOf(path)) {
				return;
			}
		}
		list.add(resource);
	}

	public IResource[] getRootResources() {
		Set<IResource> result = new HashSet<>();
		result.addAll(addedRoots);
		result.addAll(changedFiles);
		result.addAll(closedProjects);
		result.addAll(copiedRoots);
		result.addAll(movedRoots);
		result.addAll(removedRoots);
		return result.toArray(new IResource[result.size()]);
	}

	private void handleAdded(IResourceDelta delta) {
		if ((delta.getFlags() & IResourceDelta.MOVED_FROM) != 0) {
			handleMove(delta);
		} else if ((delta.getFlags() & IResourceDelta.COPIED_FROM) != 0) {
			handleCopy(delta);
		} else {
			ensureResourceCovered(delta.getResource(), addedRoots);
		}
	}

	private void handleChange(IResourceDelta delta) {
		if ((delta.getFlags() & IResourceDelta.REPLACED) != 0) {
			// A replace was added in place of a removed resource
			handleAdded(delta);
		} else if (delta.getResource().getType() == IResource.FILE) {
			ensureResourceCovered(delta.getResource(), changedFiles);
		}
	}

	private void handleCopy(IResourceDelta delta) {
		if ((delta.getFlags() & IResourceDelta.COPIED_FROM) != 0) {
			IResource source = createSourceResource(delta);
			ensureResourceCovered(source, copiedRoots);
		}
	}

	private void handleMove(IResourceDelta delta) {
		if ((delta.getFlags() & IResourceDelta.MOVED_TO) != 0) {
			movedRoots.add(delta.getResource());
		} else if ((delta.getFlags() & IResourceDelta.MOVED_FROM) != 0) {
			IResource source = createSourceResource(delta);
			ensureResourceCovered(source, movedRoots);
		}
	}

	private void handleRemoved(IResourceDelta delta) {
		if ((delta.getFlags() & IResourceDelta.OPEN) != 0) {
			closedProjects.add(delta.getResource());
		} else if ((delta.getFlags() & IResourceDelta.MOVED_TO) != 0) {
			handleMove(delta);
		} else {
			ensureResourceCovered(delta.getResource(), removedRoots);
		}
	}

	
Record the change and return whether any child changes should be visited.
Params:
delta – the change
Returns:
whether any child changes should be visited/**
	 * Record the change and return whether any child changes should be visited.
	 * @param delta the change
	 * @return whether any child changes should be visited
	 */
	public boolean recordChange(IResourceDelta delta) {
		switch (delta.getKind()) {
			case IResourceDelta.ADDED :
				handleAdded(delta);
				return true; // Need to traverse children to look  for moves or other changes under added roots
			case IResourceDelta.REMOVED :
				handleRemoved(delta);
				// No need to look for further changes under a remove (such as moves).
				// Changes will be discovered in corresponding destination delta
				return false;
			case IResourceDelta.CHANGED :
				handleChange(delta);
				return true;
		}
		return true;
	}

}