/*******************************************************************************
 * Copyright (c) 2019 Association for Decentralized Information Management in
 * Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *     Semantum Oy - Reorganization
 *******************************************************************************/
package org.simantics.issues.common;

import java.util.Map;
import java.util.Set;

import org.eclipse.core.runtime.IProgressMonitor;
import org.simantics.Simantics;
import org.simantics.db.Issue;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.Statement;
import org.simantics.db.VirtualGraph;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.request.WriteRequest;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.util.RemoverUtil;
import org.simantics.db.service.VirtualGraphSupport;
import org.simantics.issues.ontology.IssueResource;
import org.simantics.layer0.Layer0;

import gnu.trove.set.hash.THashSet;

public class BatchValidations {

	private static final boolean PERF = false;

	public static Map<Resource, Set<Issue>> validate(IProgressMonitor monitor, BatchIssueSource source, BatchIssueValidationContext context) throws DatabaseException {
		Session session = Simantics.getSession();
		return session.syncRequest(new ComposedValidation(monitor, source, context));
	}

	/**
	 * @param monitor
	 * @param source
	 * @param issues
	 * @return
	 * @throws DatabaseException
	 */
	public static int store(final IProgressMonitor monitor,
			final Resource source, final Map<Resource, Set<Issue>> issues)
			throws DatabaseException {
		return store(monitor, source, issues, Integer.MAX_VALUE);
	}

	/**
	 * @param monitor
	 * @param source
	 * @param issues
	 * @param maxIssuesToWrite
	 * @return number of issues written (added)
	 * @throws DatabaseException
	 */
	public static int store(final IProgressMonitor monitor,
			final Resource source, final Map<Resource, Set<Issue>> issues,
			final int maxIssuesToWrite) throws DatabaseException {

		if (issues.isEmpty() || maxIssuesToWrite <= 0)
			return 0;

		Session session = Simantics.getSession();
		VirtualGraphSupport support = session.getService(VirtualGraphSupport.class);
		VirtualGraph vg = support.getWorkspacePersistent(IssueConstants.ISSUE_VG);
		final int[] writtenIssues = { 0 };

		session.syncRequest(new WriteRequest(vg) {

			@Override
			public void perform(WriteGraph graph) throws DatabaseException {

				for(Map.Entry<Resource, Set<Issue>> entry : issues.entrySet()) {

					if (monitor.isCanceled())
						return;

					Resource context = entry.getKey();

					Set<Issue> current = entry.getValue();
					Set<Issue> existing = graph.sync(new BatchIssueDescriptions(source, context));

					if(!existing.equals(current)) {

						Set<Issue> added = new THashSet<Issue>(current);
						Set<Issue> removed = new THashSet<Issue>(existing);
						added.removeAll(existing);
						removed.removeAll(current);

						for(Issue add : added) {
							add.write(graph, source);
							// Stop if write limit is reached.
							if (++writtenIssues[0] >= maxIssuesToWrite)
								return;
						}
						for(Issue remove : removed) {
							Resource issue = graph.sync(new IssueByList(source, remove));
							if (issue == null)
								// FIXME: when can this happen and what should be done in this case?
								continue;
							graph.deny(issue, Layer0.getInstance(graph).PartOf);
							graph.deny(source, IssueResource.getInstance(graph).IssueSource_Manages, issue);
							RemoverUtil.remove(graph, issue);
						}

					}

				}

			}
		});

		return writtenIssues[0];

	}

	/**
	 * @param map
	 * @return
	 */
	@SuppressWarnings("rawtypes")
	private static int count(Map map) {
		int result = 0;
		for (Object obj : map.values()) {
			if (obj instanceof Set<?>) {
				Set<?> set = (Set<?>) obj;
				result += set.size();
			}
		}
		return result;
	}

	/**
	 * Checks if the specified <code>resourceToCheckForLinks</code> is linked to
	 * anything else besides itself and <code>excludeLinksTo</code>.
	 * 
	 * <p>
	 * This is used to if an issue context is still valid. We consider any issue
	 * context that is not attached to something else besides its issue context to
	 * be an invalid issue. Assertions and L0.InstanceOf do not count as external
	 * links.
	 * 
	 * @param graph database access handle
	 * @param resourceToCheckForLinks the resource to check for "external" links
	 * @param excludeLinksTo exclude links to this resource from evaluation
	 * @return <code>true</code> if there are links, <code>false</code> otherwise
	 * @throws DatabaseException 
	 */
	public static boolean isLinkedToOtherThan(ReadGraph graph, Resource resourceToCheckForLinks,
			Resource excludeLinksTo)
					throws DatabaseException
	{
		Layer0 L0 = Layer0.getInstance(graph);
		for (Statement stm : graph.getStatements(resourceToCheckForLinks, L0.IsWeaklyRelatedTo)) {
			if (stm.isAsserted(resourceToCheckForLinks))
				continue;
			if (stm.getPredicate().equals(L0.InstanceOf))
				continue;
			Resource o = stm.getObject();
			if (o.equals(excludeLinksTo) || o.equals(resourceToCheckForLinks))
				continue;

			return true;
		}
		return false;
	}

}