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.core.variants;

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

import org.eclipse.core.resources.IContainer;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.Assert;
import org.eclipse.team.core.TeamException;

A ResourceVariantByteStore that caches the variant bytes in
memory and does not persist them over workbench invocations.
Since:
3.0
@noextend
This class is not intended to be subclassed by clients./**
 * A <code>ResourceVariantByteStore</code> that caches the variant bytes in
 * memory and does not persist them over workbench invocations.
 *
 * @since 3.0
 * @noextend This class is not intended to be subclassed by clients.
 */
public class SessionResourceVariantByteStore extends ResourceVariantByteStore {

	private static final byte[] NO_REMOTE = new byte[0];
	private Map<IResource, List<IResource>> membersCache = new HashMap<>();

	private Map<IResource, byte[]> syncBytesCache = new HashMap<>();

	@Override
	public boolean deleteBytes(IResource resource) throws TeamException {
		return flushBytes(resource, IResource.DEPTH_ZERO);
	}

	@Override
	public void dispose() {
		syncBytesCache.clear();
		membersCache.clear();
	}

	@Override
	public boolean flushBytes(IResource resource, int depth) throws TeamException {
		if (getSyncBytesCache().containsKey(resource)) {
			if (depth != IResource.DEPTH_ZERO) {
				IResource[] members = members(resource);
				for (IResource child : members) {
					flushBytes(child, (depth == IResource.DEPTH_INFINITE) ? IResource.DEPTH_INFINITE: IResource.DEPTH_ZERO);
				}
			}
			getSyncBytesCache().remove(resource);
			internalRemoveFromParent(resource);
			return true;
		}
		return false;
	}

	@Override
	public byte[] getBytes(IResource resource) throws TeamException {
		byte[] syncBytes = internalGetSyncBytes(resource);
		if (syncBytes != null && equals(syncBytes, NO_REMOTE)) {
			// If it is known that there is no remote, return null
			return null;
		}
		return syncBytes;
	}

	
Return true if no bytes are contained in this tree.
Returns:
true if no bytes are contained in this tree./**
	 * Return <code>true</code> if no bytes are contained in this tree.
	 * @return <code>true</code> if no bytes are contained in this tree.
	 */
	public boolean isEmpty() {
		return syncBytesCache.isEmpty();
	}

	@Override
	public IResource[] members(IResource resource) {
		List<IResource> members = membersCache.get(resource);
		if (members == null) {
			return new IResource[0];
		}
		return members.toArray(new IResource[members.size()]);
	}

	@Override
	public boolean setBytes(IResource resource, byte[] bytes) throws TeamException {
		Assert.isNotNull(bytes);
		byte[] oldBytes = internalGetSyncBytes(resource);
		if (oldBytes != null && equals(oldBytes, bytes)) return false;
		internalSetSyncInfo(resource, bytes);
		return true;
	}

	private Map<IResource, byte[]> getSyncBytesCache() {
		return syncBytesCache;
	}

	private void internalAddToParent(IResource resource) {
		IContainer parent = resource.getParent();
		if (parent == null) return;
		List<IResource> members = membersCache.get(parent);
		if (members == null) {
			members = new ArrayList<>();
			membersCache.put(parent, members);
		}
		members.add(resource);
	}

	private byte[] internalGetSyncBytes(IResource resource) {
		return getSyncBytesCache().get(resource);
	}

	private void internalRemoveFromParent(IResource resource) {
		IContainer parent = resource.getParent();
		List members = membersCache.get(parent);
		if (members != null) {
			members.remove(resource);
			if (members.isEmpty()) {
				membersCache.remove(parent);
			}
		}
	}

	private void internalSetSyncInfo(IResource resource, byte[] bytes) {
		getSyncBytesCache().put(resource, bytes);
		internalAddToParent(resource);
	}
}