Copyright (c) 2005, 2017 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
/*******************************************************************************
 * Copyright (c) 2005, 2017 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
 *******************************************************************************/
package org.eclipse.team.core.mapping;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.IResourceDeltaVisitor;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.team.core.RepositoryProvider;
import org.eclipse.team.core.RepositoryProviderType;
import org.eclipse.team.internal.core.IRepositoryProviderListener;
import org.eclipse.team.internal.core.RepositoryProviderManager;
import org.eclipse.team.internal.core.TeamPlugin;

Supports the tracking of related changes for the purpose of grouping then using an IChangeGroupingRequestor. 

Clients may subclass this class.

See Also:
IChangeGroupingRequestor
Since:
3.3/**
 * Supports the tracking of related changes for the purpose of grouping then using an {@link IChangeGroupingRequestor}.
 * <p>
 * Clients may subclass this class.
 * </p>
 * @see IChangeGroupingRequestor
 * @since 3.3
 */
public abstract class ChangeTracker {

	private Map<IProject, IChangeGroupingRequestor> trackedProjects = new HashMap<>(); // Map IProject->IChangeGroupingRequestor
	private boolean disposed;
	private ChangeListener changeListener = new ChangeListener();

	private class ChangeListener implements IResourceChangeListener, IRepositoryProviderListener {
		
Handle a resource change event.
Update the set of projects for which we can track changes
by listening for project changes and project description changes.
Params:
event – the change event/**
		 * Handle a resource change event.
		 * Update the set of projects for which we can track changes
		 * by listening for project changes and project description changes.
		 * @param event the change event
		 */
		@Override
		public void resourceChanged(IResourceChangeEvent event) {
			if (disposed) return;
			IResourceDelta delta = event.getDelta();
			IResourceDelta[] projectDeltas = delta.getAffectedChildren(IResourceDelta.ADDED | IResourceDelta.CHANGED | IResourceDelta.REMOVED);
			for (IResourceDelta projectDelta : projectDeltas) {
				IResource resource = projectDelta.getResource();
				if (resource.getType() == IResource.PROJECT) {
					IProject project = (IProject)resource;
					if (isProjectOfInterest(project)) {
						if (isProjectTracked(project)) {
							IResource[] resources = getProjectChanges(project, projectDelta);
							if (resources.length > 0)
								handleChanges(project, resources);
						} else {
							trackProject(project);
						}
					} else {
						stopTrackingProject(project);
					}
				}
			}
		}

		
When a project is shared, start tracking it if it is of interest.
Params:
provider – the repository provider/**
		 * When a project is shared, start tracking it if it is of interest.
		 * @param provider the repository provider
		 */
		@Override
		public void providerMapped(RepositoryProvider provider) {
			if (disposed) return;
			if (isProjectOfInterest(provider.getProject())) {
				trackProject(provider.getProject());
			}
		}

		
When a project is no longer shared, stop tracking the project.
Params:
project – the project/**
		 * When a project is no longer shared, stop tracking the project.
		 * @param project the project
		 */
		@Override
		public void providerUnmapped(IProject project) {
			if (disposed) return;
			stopTrackingProject(project);
		}
	}

	
Create a change tracker
/**
	 * Create a change tracker
	 */
	public ChangeTracker() {
		super();
	}

	
Start tracking changes. This registers listeners with the workspace
and team.
/**
	 * Start tracking changes. This registers listeners with the workspace
	 * and team.
	 */
	public void start() {
		ResourcesPlugin.getWorkspace().addResourceChangeListener(changeListener, IResourceChangeEvent.POST_CHANGE);
		RepositoryProviderManager.getInstance().addListener(changeListener);
		IProject[] allProjects = ResourcesPlugin.getWorkspace().getRoot().getProjects();
		for (IProject project : allProjects) {
			if (isProjectOfInterest(project))
				trackProject(project);
		}
	}

	
Remove any listeners for this tracker. Subclasses
may extend this method but must call this method if they do.
/**
	 * Remove any listeners for this tracker. Subclasses
	 * may extend this method but must call this method if they do.
	 */
	public void dispose() {
		disposed = true;
		ResourcesPlugin.getWorkspace().removeResourceChangeListener(changeListener);
		RepositoryProviderManager.getInstance().removeListener(changeListener);
	}

	private IResource[] getProjectChanges(IProject project, IResourceDelta projectDelta) {
		final List<IResource> result = new ArrayList<>();
		try {
			projectDelta.accept(new IResourceDeltaVisitor() {
				@Override
				public boolean visit(IResourceDelta delta) throws CoreException {
					if (isResourceOfInterest(delta.getResource()) & isChangeOfInterest(delta)) {
						result.add(delta.getResource());
					}
					return true;
				}
			});
		} catch (CoreException e) {
			TeamPlugin.log(e);
		}
		return result.toArray(new IResource[result.size()]);
	}

	
Return whether the given delta represents a change of interest.
Params:
delta – the delta
Returns:
whether the given delta represents a change of interest/**
	 * Return whether the given delta represents a change of interest.
	 * @param delta the delta
	 * @return whether the given delta represents a change of interest
	 */
	protected boolean isChangeOfInterest(IResourceDelta delta) {
		return (delta.getKind() & (IResourceDelta.ADDED | IResourceDelta.REMOVED | IResourceDelta.CHANGED)) > 0;
	}

	
Stop tracking changes for the given project. Subclasses
may extend but must call this method.
Params:
project – the project/**
	 * Stop tracking changes for the given project. Subclasses
	 * may extend but must call this method.
	 * @param project the project
	 */
	protected void stopTrackingProject(IProject project) {
		trackedProjects.remove(project);
	}

	
Return whether the given project is being tracked.
Params:
project – the project
Returns:
whether the given project is being tracked/**
	 * Return whether the given project is being tracked.
	 * @param project the project
	 * @return whether the given project is being tracked
	 */
	protected final boolean isProjectTracked(IProject project) {
		return trackedProjects.containsKey(project);
	}

	
Return whether the given project is of interest to this
tracker. By default, true is returned if the project is accessible. Subclasses may extend but should still check for project accessibility either by calling IResource.isAccessible() or by invoking the overridden method. 
Params:
project – the project
Returns:
whether the given project is of interest to this
tracker/**
	 * Return whether the given project is of interest to this
	 * tracker. By default, <code>true</code> is returned if the
	 * project is accessible. Subclasses may extend but should
	 * still check for project accessibility either by calling
	 * {@link IResource#isAccessible()} or by invoking the
	 * overridden method.
	 * @param project the project
	 * @return whether the given project is of interest to this
	 * tracker
	 */
	protected boolean isProjectOfInterest(IProject project) {
		return project.isAccessible();
	}

	
Return whether the given resource is of interest to the tracker.
Params:
resource – the resource
Returns:
whether the given resource is of interest to the tracker/**
	 * Return whether the given resource is of interest to the tracker.
	 * @param resource the resource
	 * @return whether the given resource is of interest to the tracker
	 */
	protected abstract boolean isResourceOfInterest(IResource resource);

	
The given resources of interest have changed in the given project.
Params:
project – the project
resources – the resources/**
	 * The given resources of interest have changed in the given project.
	 * @param project the project
	 * @param resources the resources
	 */
	protected abstract void handleChanges(IProject project, IResource[] resources);

	
Resources of interest in the given project have changed but the
specific changes are not known. Implementors must search the project for
changes of interest.
Params:
project – the project/**
	 * Resources of interest in the given project have changed but the
	 * specific changes are not known. Implementors must search the project for
	 * changes of interest.
	 * @param project the project
	 */
	protected abstract void handleProjectChange(IProject project);

	
Track the given project if it has a change set collector. If the project
does not have a collector, the project is not tracked.
Params:
project – the project
Returns:
whether the project is being tracked/**
	 * Track the given project if it has a change set collector. If the project
	 * does not have a collector, the project is not tracked.
	 * @param project the project
	 * @return whether the project is being tracked
	 */
	protected final boolean trackProject(IProject project) {
		if (RepositoryProvider.isShared(project)) {
			try {
				String currentId = project.getPersistentProperty(TeamPlugin.PROVIDER_PROP_KEY);
				if (currentId != null) {
					RepositoryProviderType type = RepositoryProviderType.getProviderType(currentId);
					if (type != null) {
						IChangeGroupingRequestor collector = getCollector(type);
						if (collector != null) {
							trackedProjects.put(project, collector);
							// Ensure that an appropriate change set exists if needed
							// We can do this here because we know that the number of files
							// to test is small.
							projectTracked(project);
							return true;
						}
					}
				}
			} catch (CoreException e) {
				TeamPlugin.log(e);
			}
		}
		return false;
	}

	private IChangeGroupingRequestor getCollector(RepositoryProviderType type) {
		if (type != null) {
			IChangeGroupingRequestor o = type.getAdapter(IChangeGroupingRequestor.class);
			if (o != null) {
				return o;
			}
		}
		return null;
	}

	
Callback made from trackProject(IProject) when a project is tracked. By default, handleProjectChange(IProject) is called by subclasses may override. 
Params:
project – the project/**
	 * Callback made from {@link #trackProject(IProject)} when a project is tracked.
	 * By default, {@link #handleProjectChange(IProject)} is called by subclasses may override.
	 * @param project the project
	 */
	protected void projectTracked(IProject project) {
		handleProjectChange(project);
	}

	
Group the given modified file into a change set with the given name.
Params:
project – the project
name – the unique name used to identify the change set
files – the change files to be grouped
Throws:
CoreException – /**
	 * Group the given modified file into a change set with the given name.
	 * @param project the project
	 * @param name the unique name used to identify the change set
	 * @param files the change files to be grouped
	 * @throws CoreException
	 */
	protected void ensureGrouped(IProject project, String name, IFile[] files) throws CoreException {
		IChangeGroupingRequestor collector = getCollector(project);
		if (collector != null) {
			collector.ensureChangesGrouped(project, files, name);
		}
	}

	private IChangeGroupingRequestor getCollector(IProject project) {
		return trackedProjects.get(project);
	}

	
Return whether the given file is modified with respect to the
repository provider associated with the file's project.
Params:
file – the file
Throws:
CoreException – 
Returns:
whether the given file is modified/**
	 * Return whether the given file is modified with respect to the
	 * repository provider associated with the file's project.
	 * @param file the file
	 * @return whether the given file is modified
	 * @throws CoreException
	 */
	protected boolean isModified(IFile file) throws CoreException {
		IChangeGroupingRequestor collector = getCollector(file.getProject());
		if (collector != null)
			return collector.isModified(file);
		return false;
	}

}