Copyright (c) 2004, 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) 2004, 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;

import java.util.LinkedList;
import java.util.Queue;
import org.eclipse.core.internal.utils.*;
import org.eclipse.core.internal.watson.*;
import org.eclipse.core.resources.*;
import org.eclipse.core.runtime.*;
import org.eclipse.core.runtime.content.IContentTypeManager;
import org.eclipse.core.runtime.content.IContentTypeManager.ContentTypeChangeEvent;
import org.eclipse.core.runtime.jobs.Job;
import org.osgi.framework.Bundle;

Detects changes to content types/project preferences and
broadcasts any corresponding encoding changes as resource deltas.
/**
 * Detects changes to content types/project preferences and
 * broadcasts any corresponding encoding changes as resource deltas.
 */

public class CharsetDeltaJob extends Job implements IContentTypeManager.IContentTypeChangeListener {

	// this is copied in the runtime tests - if changed here, has to be changed there too
	public final static String FAMILY_CHARSET_DELTA = ResourcesPlugin.PI_RESOURCES + "charsetJobFamily"; //$NON-NLS-1$

	interface ICharsetListenerFilter {

		
Returns the path for the node in the tree we are interested in. Returns null
if the visitor no longer wants to visit anything.
/**
		 * Returns the path for the node in the tree we are interested in. Returns <code>null</code>
		 * if the visitor no longer wants to visit anything.
		 */
		IPath getRoot();

		
Returns whether the corresponding resource is affected by this change.
/**
		 * Returns whether the corresponding resource is affected by this change.
		 */
		boolean isAffected(ResourceInfo info, IPathRequestor requestor);
	}

	private ThreadLocal<Boolean> disabled = new ThreadLocal<>();

	private final Bundle systemBundle = Platform.getBundle("org.eclipse.osgi"); //$NON-NLS-1$
	private Queue<ICharsetListenerFilter> work = new LinkedList<>();

	Workspace workspace;

	private static final int CHARSET_DELTA_DELAY = 500;

	public CharsetDeltaJob(Workspace workspace) {
		super(Messages.resources_charsetBroadcasting);
		this.workspace = workspace;
	}

	private void addToQueue(ICharsetListenerFilter filter) {
		synchronized (work) {
			work.add(filter);
		}
		schedule(CHARSET_DELTA_DELAY);
	}

	@Override
	public boolean belongsTo(Object family) {
		return FAMILY_CHARSET_DELTA.equals(family);
	}

	public void charsetPreferencesChanged(final IProject project) {
		// avoid reacting to changes made by ourselves
		if (isDisabled())
			return;
		ResourceInfo projectInfo = ((Project) project).getResourceInfo(false, false);
		//nothing to do if project has already been deleted
		if (projectInfo == null)
			return;
		final long projectId = projectInfo.getNodeId();
		// ensure all resources under the affected project are
		// reported as having encoding changes
		ICharsetListenerFilter filter = new ICharsetListenerFilter() {
			@Override
			public IPath getRoot() {
				//make sure it is still the same project - it could have been deleted and recreated
				ResourceInfo currentInfo = ((Project) project).getResourceInfo(false, false);
				if (currentInfo == null)
					return null;
				long currentId = currentInfo.getNodeId();
				if (currentId != projectId)
					return null;
				// visit the project subtree
				return project.getFullPath();
			}

			@Override
			public boolean isAffected(ResourceInfo info, IPathRequestor requestor) {
				// for now, mark all resources in the project as potential encoding resource changes
				return true;
			}
		};
		addToQueue(filter);
	}

	@Override
	public void contentTypeChanged(final ContentTypeChangeEvent event) {
		// check all files that may be affected by this change (taking
		// only the current content type state into account
		// dispatch a job to generate the deltas
		ICharsetListenerFilter filter = new ICharsetListenerFilter() {

			@Override
			public IPath getRoot() {
				// visit all resources in the workspace
				return Path.ROOT;
			}

			@Override
			public boolean isAffected(ResourceInfo info, IPathRequestor requestor) {
				if (info.getType() != IResource.FILE)
					return false;
				return event.getContentType().isAssociatedWith(requestor.requestName());
			}
		};
		addToQueue(filter);
	}

	private boolean isDisabled() {
		return disabled.get() != null;
	}

	private void processNextEvent(final ICharsetListenerFilter filter, IProgressMonitor monitor) throws CoreException {
		IElementContentVisitor visitor = (tree, requestor, elementContents) -> {
			ResourceInfo info = (ResourceInfo) elementContents;
			if (!filter.isAffected(info, requestor))
				return true;
			info = workspace.getResourceInfo(requestor.requestPath(), false, true);
			if (info == null)
				return false;
			info.incrementCharsetGenerationCount();
			return true;
		};
		try {
			IPath root = filter.getRoot();
			if (root != null)
				new ElementTreeIterator(workspace.getElementTree(), root).iterate(visitor);
		} catch (WrappedRuntimeException e) {
			throw (CoreException) e.getTargetException();
		}
		if (monitor.isCanceled())
			throw new OperationCanceledException();
	}

	private ICharsetListenerFilter removeFromQueue() {
		synchronized (work) {
			return work.poll();
		}
	}

	@Override
	public IStatus run(IProgressMonitor monitor) {
		monitor = Policy.monitorFor(monitor);
		try {
			String message = Messages.resources_charsetBroadcasting;
			monitor.beginTask(message, Policy.totalWork);
			try {
				workspace.prepareOperation(null, monitor);
				workspace.beginOperation(true);
				ICharsetListenerFilter next;
				//if the system is shutting down, don't broadcast
				while (systemBundle.getState() != Bundle.STOPPING && (next = removeFromQueue()) != null)
					processNextEvent(next, monitor);
			} catch (OperationCanceledException e) {
				workspace.getWorkManager().operationCanceled();
				return Status.CANCEL_STATUS;
			} finally {
				workspace.endOperation(null, true);
			}
			monitor.worked(Policy.opWork);
		} catch (CoreException sig) {
			return sig.getStatus();
		} finally {
			monitor.done();
		}
		return Status.OK_STATUS;
	}

	
Turns off reaction to changes in the preference file.
/**
	 * Turns off reaction to changes in the preference file.
	 */
	public void setDisabled(boolean disabled) {
		// using a thread local because this can be called by multiple threads concurrently
		this.disabled.set(disabled ? Boolean.TRUE : null);
	}

	public void shutdown() {
		IContentTypeManager contentTypeManager = Platform.getContentTypeManager();
		//if the service is already gone there is nothing to do
		if (contentTypeManager != null)
			contentTypeManager.removeContentTypeChangeListener(this);
	}

	public void startup() {
		Platform.getContentTypeManager().addContentTypeChangeListener(this);
	}
}