Copyright (c) 2000, 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) 2000, 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.internal.core.subscribers;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.resources.mapping.ResourceTraversal;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.osgi.util.NLS;
import org.eclipse.team.core.ITeamStatus;
import org.eclipse.team.core.TeamStatus;
import org.eclipse.team.core.diff.DiffFilter;
import org.eclipse.team.core.diff.IDiff;
import org.eclipse.team.core.mapping.IResourceDiffTree;
import org.eclipse.team.core.mapping.ISynchronizationScopeManager;
import org.eclipse.team.core.mapping.provider.ResourceDiffTree;
import org.eclipse.team.core.subscribers.Subscriber;
import org.eclipse.team.internal.core.Messages;
import org.eclipse.team.internal.core.Policy;
import org.eclipse.team.internal.core.TeamPlugin;

A subscriber event handler whose output is a diff tree
/**
 * A subscriber event handler whose output is a diff tree
 */
public class SubscriberDiffTreeEventHandler extends SubscriberEventHandler {

	// State constants for the event handler
	private static final int STATE_NEW = 0;
	public static final int STATE_STARTED = 1;
	private static final int STATE_OK_TO_INITIALIZE = 3;
	private static final int STATE_COLLECTING_CHANGES = 5;
	private static final int STATE_SHUTDOWN = 8;

	// state constants for exceptions
	private static final int EXCEPTION_NONE = 0;
	private static final int EXCEPTION_CANCELED = 1;
	private static final int EXCEPTION_ERROR = 2;

	private ResourceDiffTree tree;
	private SubscriberDiffCollector collector;
	private ISynchronizationScopeManager manager;
	private Object family;
	private DiffFilter filter;
	private int state = STATE_NEW;
	private int exceptionState = EXCEPTION_NONE;

	/*
	 * An event used to represent a change in a diff
	 */
	private class SubscriberDiffChangedEvent extends SubscriberEvent {
		private final IDiff node;

		public SubscriberDiffChangedEvent(IResource resource, int type, int depth, IDiff node) {
			super(resource, type, depth);
			this.node = node;
		}
		public IDiff getChangedNode() {
			return node;
		}
	}

	/*
	 * Collects resource and subscriber changes
	 */
	private class SubscriberDiffCollector extends SubscriberResourceCollector {

		public SubscriberDiffCollector(Subscriber subscriber) {
			super(subscriber);
		}

		@Override
		protected boolean hasMembers(IResource resource) {
			return tree.members(resource).length > 0;
		}

		@Override
		protected void remove(IResource resource) {
			SubscriberDiffTreeEventHandler.this.remove(resource);
		}

		@Override
		protected void change(IResource resource, int depth) {
			SubscriberDiffTreeEventHandler.this.change(resource, depth);
		}
	}

	
Create the handler
Params:
subscriber – the subscriber for the handler
manager – the scope of the handler
tree – the tree to be populated by this handler
filter – a filter/**
	 * Create the handler
	 * @param subscriber the subscriber for the handler
	 * @param manager the scope of the handler
	 * @param tree the tree to be populated by this handler
	 * @param filter a filter
	 */
	public SubscriberDiffTreeEventHandler(Subscriber subscriber, ISynchronizationScopeManager manager, ResourceDiffTree tree, DiffFilter filter) {
		super(subscriber, manager.getScope());
		this.manager = manager;
		this.tree = tree;
		this.collector = new SubscriberDiffCollector(subscriber);
		this.filter = filter;
	}

	@Override
	protected void reset(ResourceTraversal[] traversals, int type) {
		// Reset the exception state since we are reseting
		exceptionState = EXCEPTION_NONE;
		if (!manager.isInitialized() && state == STATE_OK_TO_INITIALIZE) {
			// This means the scope has not been initialized
			queueEvent(new RunnableEvent(monitor -> {
				// Only initialize the scope if we are in the STARTED state
				if (state == STATE_OK_TO_INITIALIZE) {
					try {
						prepareScope(monitor);
						state = STATE_COLLECTING_CHANGES;
					} finally {
						// If the initialization didn't complete,
						// return to the STARTED state.
						if (state != STATE_COLLECTING_CHANGES) {
							state = STATE_STARTED;
							if (exceptionState == EXCEPTION_NONE)
								exceptionState = EXCEPTION_CANCELED;
						}
					}
				}
			}, true), true);
		} else if (manager.isInitialized()) {
			state = STATE_COLLECTING_CHANGES;
			super.reset(traversals, type);
		}
	}

	public void reset(){
		reset(getScope().getTraversals(),
				SubscriberEventHandler.SubscriberEvent.INITIALIZE);
	}

	protected void prepareScope(IProgressMonitor monitor) {
		try {
			manager.initialize(monitor);
		} catch (CoreException e) {
			handleException(e);
		}
		ResourceTraversal[] traversals = manager.getScope().getTraversals();
		if (traversals.length > 0)
			reset(traversals, SubscriberEvent.INITIALIZE);
	}

	@Override
	protected void handleChange(IResource resource) throws CoreException {
		IDiff node = getSubscriber().getDiff(resource);
		if (node == null) {
			queueDispatchEvent(
				new SubscriberEvent(resource, SubscriberEvent.REMOVAL, IResource.DEPTH_ZERO));
		} else {
			if (isInScope(resource))
				queueDispatchEvent(
					new SubscriberDiffChangedEvent(resource, SubscriberEvent.CHANGE, IResource.DEPTH_ZERO, node));
		}
	}

	private boolean isInScope(IResource resource) {
		return manager.getScope().contains(resource);
	}

	@Override
	protected void collectAll(IResource resource, int depth,
			final IProgressMonitor monitor) {
		Policy.checkCanceled(monitor);
		monitor.beginTask(null, IProgressMonitor.UNKNOWN);
		ResourceTraversal[] traversals = new ResourceTraversal[] { new ResourceTraversal(new IResource[] { resource }, depth, IResource.NONE) };
		try {
			getSubscriber().accept(traversals, diff -> {
				Policy.checkCanceled(monitor);
				monitor.subTask(NLS.bind(Messages.SubscriberDiffTreeEventHandler_0, tree.getResource(diff).getFullPath().toString()));
				// Queue up any found diffs for inclusion into the output tree
				queueDispatchEvent(
						new SubscriberDiffChangedEvent(tree.getResource(diff), SubscriberEvent.CHANGE, IResource.DEPTH_ZERO, diff));
				// Handle any pending dispatches
				handlePreemptiveEvents(monitor);
				handlePendingDispatch(monitor);
				return true;
			});
		} catch (CoreException e) {
			if (resource.getProject().isAccessible())
				handleException(e, resource, ITeamStatus.SYNC_INFO_SET_ERROR, e.getMessage());
		} finally {
			monitor.done();
		}
	}

	@Override
	protected void dispatchEvents(SubscriberEvent[] events,
			IProgressMonitor monitor) {
		try {
			tree.beginInput();
			for (SubscriberEvent event : events) {
				switch (event.getType()) {
					case SubscriberEvent.CHANGE :
						if (event instanceof SubscriberDiffChangedEvent) {
							SubscriberDiffChangedEvent se = (SubscriberDiffChangedEvent) event;
							IDiff changedNode = se.getChangedNode();
							if (changedNode.getKind() == IDiff.NO_CHANGE) {
								tree.remove(changedNode.getPath());
							} else {
								addDiff(changedNode, monitor);
							}
						}
						break;
					case SubscriberEvent.REMOVAL:
						IDiff[] nodesToRemove = tree.getDiffs(new ResourceTraversal[] { event.asTraversal() });
						for (IDiff node : nodesToRemove) {
							tree.remove(node.getPath());
						}
						break;
				}
			}
		} finally {
			tree.endInput(monitor);
		}
	}

	private void addDiff(IDiff diff, IProgressMonitor monitor) {
		if (filter == null || filter.select(diff, monitor)) {
			tree.add(diff);
		} else {
			tree.remove(diff.getPath());
		}
	}

	
Return the resource diff tree that contains the out-of-sync diffs for the
subscriber.
Returns:
the resource diff tree/**
	 * Return the resource diff tree that contains the out-of-sync diffs for the
	 * subscriber.
	 * @return the resource diff tree
	 */
	public IResourceDiffTree getTree() {
		return tree;
	}

	@Override
	public Subscriber getSubscriber() {
		return super.getSubscriber();
	}

	@Override
	public void shutdown() {
		state = STATE_SHUTDOWN;
		collector.dispose();
		super.shutdown();
	}

	@Override
	protected Object getJobFamiliy() {
		return family;
	}

	
Set the family of this handler to the given object
Params:
family – the family of the handler's job/**
	 * Set the family of this handler to the given object
	 * @param family the family of the handler's job
	 */
	public void setJobFamily(Object family) {
		this.family = family;
	}

	@Override
	protected void handleException(CoreException e, IResource resource, int code, String message) {
		super.handleException(e, resource, code, message);
		tree.reportError(new TeamStatus(IStatus.ERROR, TeamPlugin.ID, code, message, e, resource));
		exceptionState = EXCEPTION_ERROR;
	}

	@Override
	protected void handleCancel(OperationCanceledException e) {
		super.handleCancel(e);
		tree.reportError(new TeamStatus(IStatus.ERROR, TeamPlugin.ID, ITeamStatus.SYNC_INFO_SET_CANCELLATION, Messages.SubscriberEventHandler_12, e, ResourcesPlugin.getWorkspace().getRoot()));
		if (exceptionState == EXCEPTION_NONE)
			exceptionState = EXCEPTION_CANCELED;
	}

	public DiffFilter getFilter() {
		return filter;
	}

	public void setFilter(DiffFilter filter) {
		this.filter = filter;
	}

	
If the handler is not initialized or not in the process
of initializing, start the initialization process.
/**
	 * If the handler is not initialized or not in the process
	 * of initializing, start the initialization process.
	 */
	public synchronized void initializeIfNeeded() {
		if (state == STATE_STARTED) {
			state = STATE_OK_TO_INITIALIZE;
			reset(getScope().getTraversals(), SubscriberEvent.INITIALIZE);
		} else if (exceptionState != EXCEPTION_NONE) {
			reset(getScope().getTraversals(), SubscriberEvent.INITIALIZE);
		}
	}

	@Override
	public synchronized void start() {
		super.start();
		if (state == STATE_NEW)
			state = STATE_STARTED;
	}

	public int getState() {
		return state;
	}

	@Override
	protected boolean isSystemJob() {
		if (manager != null && !manager.isInitialized())
			return false;
		return super.isSystemJob();
	}

	@Override
	public synchronized void remove(IResource resource) {
		// Don't queue changes if we haven't been initialized
		if (state == STATE_STARTED)
			return;
		super.remove(resource);
	}

	@Override
	public void change(IResource resource, int depth) {
		// Don't queue changes if we haven't been initialized
		if (state == STATE_STARTED)
			return;
		super.change(resource, depth);
	}
}