/*******************************************************************************
 * Copyright (c) 2007, 2010 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:
 *     Foster Wheeler Energia Oy - initial API and implementation
 *******************************************************************************/
package org.simantics.interop.test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Session;
import org.simantics.db.Statement;
import org.simantics.db.common.request.ReadRequest;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.exception.DoesNotContainValueException;
import org.simantics.db.exception.ManyObjectsForFunctionalRelationException;
import org.simantics.db.exception.ServiceException;
import org.simantics.db.exception.ValidationException;
import org.simantics.layer0.Layer0;
import org.simantics.utils.datastructures.BijectionMap;
import org.simantics.utils.datastructures.MapList;
import org.simantics.utils.datastructures.Pair;

/**
 * Compares two subgraphs and reports differences.
 * 
 * Assumes that subgraphs (defined using traverse relations) are not cyclic.
 * 
 * Assumes that properties can be used to identify objects, if relation type is not enough.
 * 
 * 
 * 
 * @author Marko Luukkainen <marko.luukkainen@vtt.fi>
 *
 */
public class GraphComparator {

	private Resource r1;
	private Resource r2;
	private Set<Resource> strong = new HashSet<Resource>();       // List of relations that identify object, if subject is already identified. 
	private List<Resource> traversed = new ArrayList<Resource>(); // list of relations that are traversed (and tested)
	private List<Resource> tested = new ArrayList<Resource>();    // list of relations that are tested, but not traversed
	private List<Resource> nonTraversed = new ArrayList<Resource>(); // list of relations that are not traversed
	private List<Resource> nonTested = new ArrayList<Resource>(); // list of relations that are not tested
	
	private List<Statement> changes1 = new ArrayList<Statement>();
	private List<Statement> changes2 = new ArrayList<Statement>();
	private List<Pair<Statement,Statement>> modifications = new ArrayList<Pair<Statement,Statement>>();
	private Set<Statement> changes1Set = new HashSet<Statement>();
	private Set<Statement> changes2Set = new HashSet<Statement>();
	private Set<Pair<Statement,Statement>> modificationsSet = new HashSet<Pair<Statement,Statement>>();

	private BijectionMap<Statement, Statement> comparableStatements = new BijectionMap<Statement, Statement>();
	private BijectionMap<Resource, Resource> comparableResources = new BijectionMap<Resource, Resource>();
	private Set<Resource> processedResources = new HashSet<Resource>();
	
	private ResourceComparator comparator;
	
	private Comparator<Statement> scomp = new PredicateComparator();
	private Comparator<Resource> rcomp = new ResComparator();
	
	// runtime attributes
	
	private ReadGraph g;
	private Layer0 b;
	
	public GraphComparator(Resource r1, Resource r2) {
		this.r1 = r1;
		this.r2 = r2;
		comparator = new TypeComparator();
	}
	
	public GraphComparator(Resource r1, Resource r2, ResourceComparator comparator) {
		this.r1 = r1;
		this.r2 = r2;
		this.comparator = comparator;
	}
	
	ArrayList<Statement> ss1 = new ArrayList<Statement>();
	ArrayList<Statement> ss2 = new ArrayList<Statement>();
	
	
	public Comparator<Resource> getResourceComparator() {
		return rcomp;
	}
	
	public Comparator<Statement> getStatementComparator() {
		return scomp;
	}
	
	public Resource getR1() {
		return r1;
	}
	
	public Resource getR2() {
		return r2;
	}
	
	public void addTraversed(Resource rel) {
		traversed.add(rel);
	}
	
	public void addTraversed(Collection<Resource> rels) {
		traversed.addAll(rels);
	}
	
	public void addNonTraversed(Resource rel) {
		nonTraversed.add(rel);
	}
	
	public void addNonTraversed(Collection<Resource> rels) {
		nonTraversed.addAll(rels);
	}
	
	public void addTested(Resource rel) {
		tested.add(rel);
	}
	
	public void addTested(Collection<Resource> rels) {
		tested.addAll(rels);
	}
	
	public void addNonTested(Resource rel) {
		nonTested.add(rel);
	}
	
	public void addNonTested(Collection<Resource> rels) {
		nonTested.addAll(rels);
	}
	
	public void addComparableResources(Resource r1, Resource r2) {
		comparableResources.map(r1, r2);
	}
	
	public void addComparableResources(BijectionMap<Resource, Resource> matching) {
		comparableResources.addAll(matching);
	}
	
	public void addStrong(Resource r) {
		strong.add(r);
	}
	
	public void addStrong(Collection<Resource> rels) {
		strong.addAll(rels);
	}
	
	
	public void test(ReadGraph g) throws DatabaseException {
		this.g = g;
		this.b = Layer0.getInstance(g);
		comparator.setComparator(this);
		
		Stack<Resource> objectsLeft = new Stack<Resource>();
		Stack<Resource> objectsRight = new Stack<Resource>();
		objectsLeft.push(r1);
		objectsRight.push(r2);
		
		Set<Statement> unreliableLeft = new HashSet<Statement>();
		Set<Statement> unreliableRight = new HashSet<Statement>();
		
		while (true) {
			if (objectsLeft.isEmpty())
				break;
			
			
			// process compares objects that are identified and searches for more resources to process. 
			process(objectsLeft, objectsRight, unreliableLeft, unreliableRight);
			// process unreliable handles cases where unidentified statements subject and object have been identified 
			processUnreliable(unreliableLeft, unreliableRight);
			// process unreliable handles cases where unidentified resources have path of length one to identified resource
			processUnreliable(unreliableLeft, unreliableRight,objectsLeft,objectsRight);
			if (objectsLeft.isEmpty() && unreliableLeft.size() > 0 && unreliableRight.size() > 0) {
				// comparison is ending, but we have still unprocessed unidentified resources left.
				// These cases have longer path than one to identified objects.
				processUnreliableDeep(unreliableLeft, unreliableRight, objectsLeft, objectsRight);
			}
			
		}
		for (Statement s : unreliableLeft) {
			if (!comparableStatements.containsLeft(s))
				addDeletion(s);
		}
		for (Statement s : unreliableRight) {
			if (!comparableStatements.containsRight(s))
				addAddition(s);
		}
		
		
 	}
	
	public void test(Session session) throws DatabaseException {
		
		comparator.setComparator(this);
		
		comparableResources.map(r1, r2);
		
		final Stack<Resource> objectsLeft = new Stack<Resource>();
		final Stack<Resource> objectsRight = new Stack<Resource>();
		objectsLeft.push(r1);
		objectsRight.push(r2);
		
		final Set<Statement> unreliableLeft = new HashSet<Statement>();
		final Set<Statement> unreliableRight = new HashSet<Statement>();
		
		while (true) {
			if (objectsLeft.isEmpty())
				break;
			session.syncRequest(new ReadRequest() {
				
				@Override
				public void run(ReadGraph graph) throws DatabaseException {
					g = graph;
					b = Layer0.getInstance(graph);
					// process compares objects that are identified and searches for more resources to process. 
					process(objectsLeft, objectsRight, unreliableLeft, unreliableRight);
					// process unreliable handles cases where unidentified statements subject and object have been identified 
					processUnreliable(unreliableLeft, unreliableRight);
					// process unreliable handles cases where unidentified resources have path of length one to identified resource
					processUnreliable(unreliableLeft, unreliableRight,objectsLeft,objectsRight);
					if (objectsLeft.isEmpty() && unreliableLeft.size() > 0 && unreliableRight.size() > 0) {
						// comparison is ending, but we have still unprocessed unidentified resources left.
						// These cases have longer path than one to identified objects.
						processUnreliableDeep(unreliableLeft, unreliableRight, objectsLeft, objectsRight);
					}
				}
			});
			
			
			
		}
		for (Statement s : unreliableLeft) {
			if (!comparableStatements.containsLeft(s))
				addDeletion(s);
		}
		for (Statement s : unreliableRight) {
			if (!comparableStatements.containsRight(s))
				addAddition(s);
		}
		
		
 	}
	
	private void process(Stack<Resource> objectsLeft, Stack<Resource> objectsRight, Set<Statement> unreliableLeft, Set<Statement> unreliableRight) throws DatabaseException {
		List<Statement> ss1 = new ArrayList<Statement>();
		List<Statement> ss2 = new ArrayList<Statement>();
		
		while (!objectsLeft.isEmpty()) {
			Resource r1 = objectsLeft.pop();
			Resource r2 = objectsRight.pop();
			
			if (r1.equals(r2))
				continue;
			
			if (processedResources.contains(r1))
				continue;
			processedResources.add(r1);
			
		
			if(!comparableResources.contains(r1, r2) && (comparableResources.containsLeft(r1)||comparableResources.containsRight(r2))) {
				throw new DatabaseException("Comparator error: Trying to map " + r1 + " to " + r2 + " while mappings " + r1 + " to " + comparableResources.getRight(r1) + " and " + comparableResources.getLeft(r2) + " to " + r2 + " exist.");
			}
			
			//System.out.println("test " + NameUtils.getSafeName(g, r1) + " " + NameUtils.getSafeName(g, r2));
			compareProps(r1, r2);
			
			for (Resource rel : tested) {
				ss1.addAll(g.getStatements(r1, rel));
				ss2.addAll(g.getStatements(r2, rel));
				ss1 = filterAsserted(r1, ss1);
				ss2 = filterAsserted(r2, ss2);
				ss1 = filterTraversed(ss1);
				ss2 = filterTraversed(ss2);
				ss1 = filterNonTested(ss1);
				ss2 = filterNonTested(ss2);
				
				compareStatements(ss1, ss2, null, null,null,null);
				ss1.clear();
				ss2.clear();
			}
			
			for (Resource rel : traversed) {
				ss1.addAll(g.getStatements(r1, rel));
				ss2.addAll(g.getStatements(r2, rel));
				ss1 = filterAsserted(r1, ss1);
				ss2 = filterAsserted(r2, ss2);
				compareStatements(ss1, ss2, objectsLeft, objectsRight,unreliableLeft,unreliableRight);
				ss1.clear();
				ss2.clear();
				
			}
		}
	}
	
	private void processUnreliable(Set<Statement> unreliableLeft, Set<Statement> unreliableRight) {
		MapList<Resource,Statement> subjectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> subjectRight = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectRight = new MapList<Resource, Statement>();
		
		for (Statement s : unreliableLeft) {
			subjectLeft.add(s.getSubject(),s);
			objectLeft.add(s.getObject(),s);
		}
		for (Statement s : unreliableRight) {
			subjectRight.add(s.getSubject(),s);
			objectRight.add(s.getObject(),s);
		}
		
		for (Resource left : subjectLeft.getKeys()) {
			if (!comparableResources.containsLeft(left))
				continue;
			Resource right = comparableResources.getRight(left);
			for (Statement leftS : subjectLeft.getValues(left)) {
				Resource leftO = leftS.getObject();
				if (!comparableResources.containsLeft(leftO)) 
					continue;
				if (!unreliableLeft.contains(leftS))
					continue;
				Resource rightO = comparableResources.getRight(leftO);
				for (Statement rightS : subjectRight.getValues(right)) {
					if (!rightS.getObject().equals(rightO))
						continue;
					if (!unreliableRight.contains(rightS))
						continue;
					if (leftS.getPredicate().equals(rightS.getPredicate()) ||
						comparableResources.contains(leftS.getPredicate(), rightS.getPredicate())) {
						unreliableLeft.remove(leftS);
						unreliableRight.remove(rightS);
						addComparable(leftS, rightS, false);
					}
				}
			}
			
		}
	}
	
	private void processUnreliable(Set<Statement> unreliableLeft, Set<Statement> unreliableRight, Stack<Resource> objectsLeft, Stack<Resource> objectsRight) {
		MapList<Resource,Statement> subjectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> subjectRight = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectRight = new MapList<Resource, Statement>();
		
		for (Statement s : unreliableLeft) {
			subjectLeft.add(s.getSubject(),s);
			objectLeft.add(s.getObject(),s);
		}
		for (Statement s : unreliableRight) {
			subjectRight.add(s.getSubject(),s);
			objectRight.add(s.getObject(),s);
		}
		
		for (Resource ol : objectLeft.getKeys()) {
			// all statements to the left side object
			List<Statement> left = objectLeft.getValues(ol);
			// all subjects that have statements to the left side object (ol)
			Set<Resource> sLeft = new HashSet<Resource>();
			// all matching subjects on the right side
			Set<Resource> sRight = new HashSet<Resource>();
			for (Statement s : left) {
				sLeft.add(s.getSubject());
				sRight.add(comparableResources.getRight(s.getSubject()));
			}
			
			// check if object left can be reliably identified by available statements
			// if there are any objects on the left side with similar statements, object left cannot be mapped.
			boolean hasSimilar = false;
			MapList<Resource, Statement> comparableOLeft = new MapList<Resource, Statement>();
			for (Resource sl : sLeft) {
				for (Statement s : subjectLeft.getValues(sl)) {
					if (!s.getObject().equals(ol)) {
						comparableOLeft.add(s.getObject(),s);
					}
				}
			}
			
			for (Resource similarOl : comparableOLeft.getKeys()) {
				List<Statement> similarLeft = comparableOLeft.getValues(similarOl);
				if (similarLeft.size() == left.size()) {
					boolean useL[] = new boolean[left.size()];
					boolean useSL[] = new boolean[left.size()];
					for (int i = 0; i < left.size(); i++) {
						useL[i] = false;
						useSL[i] = false;
					}
					for (int i = 0; i < left.size(); i++) {
						for (int j = 0; j < left.size(); j++) {
							if (useSL[j])
								continue;
							Resource pl = left.get(i).getPredicate();
							Resource psl = similarLeft.get(j).getPredicate();
							if (pl.equals(psl)) {
								useL[i] = true;
								useSL[j] = true;
								break;
							}
						}
					}
					boolean diff = false;
					for (int i = 0; i < left.size(); i++) {
						if (!useL[i] || !useSL[i]) {
							diff = true;
						}
					}
					if (!diff) {
						hasSimilar = true;
						break;
					}
				}
			}
			
			if (hasSimilar)
				continue;
				
			
			// all objects that subjects on the right side point to. Object left has its matching resource among these, if it has matching resource
			MapList<Resource,Statement> possibleOR = new MapList<Resource, Statement>();
			for (Resource sr : sRight) {
				for (Statement s : subjectRight.getValues(sr))
					possibleOR.add(s.getObject(),s);
			}
			
			// filter possible right side objects to those that have same amount of statements as the left side object
			for (Resource or : possibleOR.getKeys().toArray(new Resource[possibleOR.getKeys().size()])) {
				List<Statement> right = possibleOR.getValues(or);
				if (right.size() != left.size())
					possibleOR.remove(or);
					
			}
			
			// check for matching statements (comparable subjects, matching predicates)
			MapList<Resource,Statement> matchingOR = new MapList<Resource, Statement>(); // list of objects that have matching statements
			Map<Resource,Pair<int[], int[]>> matchingStatements = new HashMap<Resource, Pair<int[], int[]>>(); // matching statements
			for (Resource or : possibleOR.getKeys()) {
				List<Statement> right = possibleOR.getValues(or);
				int iLeft[] = new int[left.size()];
				int iRight[] = new int[right.size()];
				
				for (int i = 0; i < left.size(); i++) {
					iLeft[i] = -1;
					iRight[i] = -1;
				}
				
				for (int l = 0; l < left.size(); l++) {
					Statement ls = left.get(l);
					for (int r = 0; r < right.size(); r++) {
						if (iRight[r] >= 0)
							continue;
						Statement rs = right.get(r);
						if (!comparableResources.contains(ls.getSubject(), rs.getSubject()))
							continue;
						if (rcomp.compare(ls.getPredicate(),rs.getPredicate()) == 0) {
							iLeft[l] = r;
							iRight[r] = l;
							break;
						}
					}
					
				}
				boolean success = true;
				for (int i = 0; i < left.size(); i++) {
					if (iLeft[i] < 0) {
						success = false;
						break;
					}
					if (iRight[i] < 0) {
						success = false;
						break;
					}
						
				}
				if (success) {
					for (Statement s : right) 
						matchingOR.add(or,s);
					matchingStatements.put(or, new Pair<int[], int[]>(iLeft, iRight));
				}
			}
			// if there is only one matching right side object, we have found a match 
			if (matchingOR.getKeySize() == 1) {
				Resource or = matchingOR.getKeys().iterator().next();
				List<Statement> right = matchingOR.getValues(or);
				Pair<int[], int[]> indices = matchingStatements.get(or);
				
				comparableResources.map(ol, or);
				objectsLeft.add(ol);
				objectsRight.add(or);
				for (int l = 0; l < left.size(); l++) {
					int r = indices.first[l];
					Statement sl = left.get(l);
					Statement sr = right.get(r);
					addComparable(sl, sr, true);
					unreliableLeft.remove(sl);
					unreliableRight.remove(sr);
				}
				
			}

		}
		
		
	}
	
	private void processUnreliableDeep(Set<Statement> unreliableLeft, Set<Statement> unreliableRight, Stack<Resource> objectsLeft, Stack<Resource> objectsRight) throws ManyObjectsForFunctionalRelationException, ServiceException {
		MapList<Resource,Statement> subjectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> subjectRight = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectLeft = new MapList<Resource, Statement>();
		MapList<Resource,Statement> objectRight = new MapList<Resource, Statement>();
		
		for (Statement s : unreliableLeft) {
			subjectLeft.add(s.getSubject(),s);
			objectLeft.add(s.getObject(),s);
		}
		for (Statement s : unreliableRight) {
			subjectRight.add(s.getSubject(),s);
			objectRight.add(s.getObject(),s);
		}
		for (Resource ol : objectLeft.getKeys()) {
			Set<Path> pathsLeft = new HashSet<Path>();
			for (Resource rel : traversed) {
				pathsLeft.addAll(Path.create(g.getStatements(ol, rel)));
			}
			while (true) {
				expand(pathsLeft);
				if (pathsLeft.size() == 0)
					break;
				Collection<Path> endPaths = new ArrayList<Path>(1);
				for (Path p : pathsLeft) {
					if (comparableResources.containsLeft(p.getEnd())) {
						endPaths.add(p);
					}
				}
				if (endPaths.size() > 0) {
					pathsLeft.clear();
					pathsLeft.addAll(endPaths);
					break;
				}	
			}
			if (pathsLeft.size() > 0) {
				Resource sl = objectLeft.getValues(ol).get(0).getSubject();
				Resource sr = comparableResources.getRight(sl);
				Collection<Resource> possibleOR = new ArrayList<Resource>();
				for (Statement s : subjectRight.getValues(sr)) {
					possibleOR.add(s.getObject());
				}
				Map<Resource,Set<Path>> matchingPaths = new HashMap<Resource, Set<Path>>();
				for (Resource or : possibleOR) {
					Set<Path> possiblePathsRight = new HashSet<Path>();
					for (Path leftPath : pathsLeft) {
						possiblePathsRight.addAll(findComparableRight(leftPath, or));
					}
					if (possiblePathsRight.size() == pathsLeft.size()) {
						matchingPaths.put(or, possiblePathsRight);
					}
				}
				if (matchingPaths.size() > 0) {
					if (matchingPaths.size() == 1) {
						Resource or = matchingPaths.keySet().iterator().next();
						objectsLeft.add(ol);
						objectsRight.add(or);
						comparableResources.map(ol, or);
						Collection<Statement> statementsLeft = objectLeft.getValues(ol);
						Collection<Statement> statementsRight = objectRight.getValues(or);
						unreliableLeft.removeAll(statementsLeft);
						unreliableRight.removeAll(statementsRight);
						System.out.println("Compare not implemented");
					} else {
						System.out.println("Compare not implemented");
					}
				}
			}
			
		}
		
	}
	
	private void expand(Set<Path> paths) throws ManyObjectsForFunctionalRelationException, ServiceException {
		Set<Path> stepPathsLeft = new HashSet<Path>();
		if (paths.size() == 0)
			return;
		int length = paths.iterator().next().getLength() + 1;
		for (Path p : paths) {
			for (Resource rel : traversed) {
				stepPathsLeft.addAll(Path.expand(p,g.getStatements(p.getEnd(), rel)));
			}
		}
		paths.clear();
		for (Path p : stepPathsLeft) {
			if (p.getLength() == length)
				paths.add(p);
		}
	}
	
	private Collection<Path> findComparableRight(Path leftPath, Resource beginRight) throws ManyObjectsForFunctionalRelationException, ServiceException {
		Set<Path> rightPaths = new HashSet<Path>();
		rightPaths.addAll(Path.create(g.getStatements(beginRight, getRight(leftPath.getStatements().get(0).getPredicate()))));
		for (int i = 1; i < leftPath.getLength(); i++) {
			if (rightPaths.size() == 0)
				return rightPaths;
			Set<Path> stepPaths = new HashSet<Path>();
			for (Path p : rightPaths) {
				stepPaths.addAll(Path.expand(p, g.getStatements(p.getEnd(), getRight(leftPath.getStatements().get(i).getPredicate()))));
			}
			rightPaths.clear();
			for (Path p : stepPaths)
				if (p.getLength() == i+1) 
					rightPaths.add(p);
		}
		return rightPaths;
		
	}
	
	private Resource getRight(Resource r) {
		if (comparableResources.containsLeft(r))
			return comparableResources.getRight(r);
		return r;
	}
	

	
	public BijectionMap<Statement, Statement> getComparableStatements() {
		return comparableStatements;
	}
	
	public GraphChanges getChanges() {
		return new GraphChanges(r1,r2,changes1,changes2,modifications,comparableResources);
	}
	
	private void addComparable(Statement left, Statement right, boolean process) {
		comparableStatements.map(left, right);
		comparableResources.map(left.getObject(), right.getObject());
	}
	
	public List<Statement> filterAsserted(Resource r, Collection<Statement> in) throws ServiceException {
		List<Statement> out = new ArrayList<Statement>();
		for (Statement s : in) {
			if (!s.isAsserted(r))
				out.add(s);
			
		}
		return out;
	}

	private String printStatement(ReadGraph graph, Statement s) throws ValidationException, ServiceException {
		return NameUtils.getSafeName(graph, s.getSubject()) + " " + NameUtils.getSafeName(graph, s.getPredicate()) + " " + NameUtils.getSafeName(graph, s.getObject());
	}
	
	private List<Statement> filterTraversed(List<Statement> in) throws ServiceException {
		return filter(traversed, in);
	}
	
	private List<Statement> filterNonTested(List<Statement> in) throws ServiceException {
		return filter(nonTested, in);
	}
	
	private List<Statement> filter(Collection<Resource> toFilter, List<Statement> in) throws ServiceException {
		if (toFilter.size() == 0)
			return in;
		List<Statement> out = new ArrayList<Statement>();
		for (Statement s : in) {
			boolean usable = true;
			for (Resource r : toFilter) {
				if (g.isSubrelationOf(s.getPredicate(),r)) {
					usable = false;
					break;
				}
			}
			if (usable) {
				out.add(s);
			}
			
		}
		return out;
	}
	
	
	private void addDeletion(Statement s) {
		if (!changes1Set.contains(s)) {
			changes1Set.add(s);
			changes1.add(s);
		}
	}
	
	private void addAddition(Statement s) {
		if (!changes2Set.contains(s)) {
			changes2Set.add(s);
			changes2.add(s);
		}
	}
	
	private void addModification(Statement s1, Statement s2) {
		Pair<Statement, Statement> mod = new Pair<Statement, Statement>(s1,s2);
		if (!modificationsSet.contains(mod)) {
			modificationsSet.add(mod);
			modifications.add(mod);
		}
	}
	
	public void sortStatement(List<Statement> list1, List<Statement> list2) {
		sortStatement(list1, list2, scomp);
	}
	
	public void sortStatement(List<Statement> list1, List<Statement> list2, Comparator<Statement> scomp) {
		Collections.sort(list1,scomp);
		Collections.sort(list2,scomp);
		
		List<Statement> sorted1 = new ArrayList<Statement>(list1.size());
		List<Statement> sorted2 = new ArrayList<Statement>(list2.size());
		sorted1.addAll(list1);
		sorted2.addAll(list2);
		
		int ss1 = 0;
		int ss2 = 0;
		for (int i = 0; i < list1.size(); ) {
			Statement s1 = list1.get(i);
			int same1 = sameRel(list1, i);	
			for (int j = 0; j < list2.size(); j++) {
				Statement s2 = list2.get(j);
				if (scomp.compare(s1, s2) == 0) {
					int same2 = sameRel(list2, j);
					copy(sorted1,ss1,list1,i,same1);
					ss1 += same1;
					copy(sorted2,ss2,list2,j,same2);
					ss2 += same2;
					break;
				}
			}
			i+= same1;
		}
		if (ss1 < sorted1.size()) {
			for (Statement s : list1) {
				if (!sorted1.contains(s)) {
					sorted1.set(ss1,s);
					ss1++;
				}
			}
		}
		if (ss2 < sorted2.size()) {
			for (Statement s : list2) {
				if (!sorted2.contains(s)) {
					sorted2.set(ss2,s);
					ss2++;
				}
			}
		}
		
		list1.clear();
		list2.clear();
		list1.addAll(sorted1);
		list2.addAll(sorted2);
	}
	
	public <T> void copy(List<T> to, int toIndex, List<T> from, int fromIndex, int amount) {
		for (int i = 0; i <  amount; i++) {
			to.set(toIndex + i, from.get(fromIndex+ i));
		}
	}
	
	public void sortResource(List<Resource> list1, List<Resource> list2) {
		Collections.sort(list1,rcomp);
		int js = 0;
		for (int i = 0; i < list1.size(); i++) {
			Resource s1 = list1.get(i);
			for (int j = js; j < list2.size(); j++) {
				Resource s2 = list2.get(j);
				if (rcomp.compare(s1, s2) == 0) {
					Resource t = list2.get(js);
					list2.set(js, s2);
					list2.set(j, t);
					break;
				}
			}
			js++;
		}
	}
	
	private void compareStatements(List<Statement> ss1, List<Statement> ss2, Stack<Resource> objectsLeft, Stack<Resource> objectsRight, Collection<Statement> unreliableLeft, Collection<Statement> unreliableRight) throws DatabaseException {
		sortStatement(ss1, ss2);
		
		int i1 = 0;
		int i2 = 0;
		
		while (true) {
			if (i1 >= ss1.size()) {
				if (i2 >= ss2.size()) {
					break;
				} else {
					while (i2 < ss2.size()) {
						System.out.println("Compare Statements diff2 " + printStatement(g,ss2.get(i2)));
						
						addAddition(ss2.get(i2));
						i2++;
					}
					break;
				}
			} else if (i2 >= ss2.size()) {
				while (i1 < ss1.size()) {
					System.out.println("Compare Statements diff1 " + printStatement(g,ss1.get(i1)));
					addDeletion(ss1.get(i1));
					i1++;
				}
				break;
			}
			int same1 = sameRel(ss1, i1);
			int same2 = sameRel(ss2, i2);
			int c = rcomp.compare(ss1.get(i1).getPredicate(),ss2.get(i2).getPredicate());
			if (c == 0) {
				compareStatements(ss1, i1, same1, ss2, i2, same2,objectsLeft,objectsRight,unreliableLeft,unreliableRight);
				i1+=same1;
				i2+=same2;
			} else if (c < 0) {
				for (int i = 0; i < same1; i++) {
					System.out.println("Compare Statements diff1 " + printStatement(g,ss1.get(i+i1)));
					addDeletion(ss1.get(i+i1));
				}
				i1 += same1;
			} else {
				for (int i = 0; i < same2; i++) {
					System.out.println("Compare Statements diff2 " + printStatement(g,ss2.get(i+i2)));
					addAddition(ss2.get(i+i2));
				}
				
				i2 += same2;
			}
		}
	}
	

	
	private int sameRel(List<Statement> statements, int off) {
		if (statements.size() <= off)
			return 0;
		int same = 1;
		long id = statements.get(off).getPredicate().getResourceId();
		for (int i = off+1; i <statements.size(); i++) {
			if (statements.get(i).getPredicate().getResourceId() == id)
				same++;
			else 
				break;
		}
		return same;
		
	}

	private int compareObject(Resource o1, Resource o2) throws DatabaseException {
		if (o1.equals(o2))
			return -1;
		if (comparableResources.contains(o1, o2))
			return (-1);
		if (comparableResources.containsLeft(o1))
			return Integer.MAX_VALUE;
		if (comparableResources.containsRight(o2))
			return Integer.MAX_VALUE;
		return comparator.compare(g, o1, o2);
	}
	
	private void compareStatements(List<Statement> ss1, int off1, int len1, List<Statement> ss2, int off2, int len2, Collection<Resource> objectsLeft, Collection<Resource> objectsRight, Collection<Statement> unreliableLeft, Collection<Statement> unreliableRight) throws DatabaseException {
		boolean[] used1 = new boolean[len1];
		for (int i = 0; i < used1.length; i++) {
			used1[i] = false;
		}
		
		boolean[] used2 = new boolean[len2];
		for (int i = 0; i < used2.length; i++) {
			used2[i] = false;
		}
		
		// left, right, difference
		List<List<Integer>> differences = new ArrayList<List<Integer>>();
		for (int i1 = off1; i1 < off1 + len1; i1++) {
			Statement s1 = ss1.get(i1);
			List<Integer> diff = new ArrayList<Integer>();
			for (int i2 = off2; i2 < off2 + len2; i2++) {
				Statement s2 = ss2.get(i2);
				int d = compareObject(s1.getObject(), s2.getObject());
				if (d == 0) {
					for (Resource t : strong) {
						 if (s1.getPredicate().equals(t) || g.isSubrelationOf(s1.getPredicate(), t)) {
							 d = 1;
							 break;
						 }
					}
				}
				diff.add(d);
			}
			differences.add(diff);
		}
		// difference, left
		MapList<Integer, Integer> priorities = new MapList<Integer, Integer>();
		for (int i = 0; i < differences.size(); i++) {
			List<Integer> list = differences.get(i);
			for (int j = 0; j < list.size(); j++) {
				priorities.add(list.get(j), i);
			}
		}
		
		Integer[] pris = priorities.getKeys(new Integer[]{});
		Arrays.sort(pris);
		
		for (Integer pri : pris) {
			if (pri == Integer.MAX_VALUE) {

			} else if (pri == 0) {
				
			} else {
				List<Integer> i1s = priorities.getValues(pri);
				for (Integer i1 : i1s) {
					if (used1[i1])
						continue;
					List<Integer> i2diff = differences.get(i1);
					for (int i2 = 0; i2 < i2diff.size(); i2++) {
						if (i2diff.get(i2) == pri) {
							if (used2[i2])
								continue;
							used1[i1] = true;
							used2[i2] = true;
							Statement s1  = ss1.get(i1+off1);
							Statement s2  = ss2.get(i2+off2);
							
							if (objectsLeft != null) {
								objectsLeft.add(s1.getObject());
								objectsRight.add(s2.getObject());
							} 
							addComparable(s1, s2, true);
							break;
						}
					}
				}
			}
		}
		
		for (Integer pri : pris) {
			if (pri != 0)
				continue;
			Set<Statement> s1s = new HashSet<Statement>();
			Set<Statement> s2s = new HashSet<Statement>();
			Set<Integer> s1i = new HashSet<Integer>();
			Set<Integer> s2i = new HashSet<Integer>();
			List<Integer> i1s = priorities.getValues(pri);
			for (Integer i1 : i1s) {
				if (used1[i1])
					continue;
				List<Integer> i2diff = differences.get(i1);
				for (int i2 = 0; i2 < i2diff.size(); i2++) {
					if (i2diff.get(i2) == pri) {
						if (used2[i2])
							continue;
						Statement s1  = ss1.get(i1+off1);
						Statement s2  = ss2.get(i2+off2);
						s1s.add(s1);
						s2s.add(s2);
						s1i.add(i1);
						s2i.add(i2);
					}
				}
			}
			if (unreliableLeft != null) {
				unreliableLeft.addAll(s1s);
				unreliableRight.addAll(s2s);
			}
			for (Integer i : s1i)
				used1[i] = true;
			for (Integer i : s2i)
				used2[i] = true;

		}
		for (int i1 = off1; i1 < off1 + len1; i1++) {
			if (!used1[i1-off1]) {
				System.out.println("Compare Object diff1 " + printStatement(g,ss1.get(i1)));
				addDeletion(ss1.get(i1));
			}
		}
		for (int i2 = off2; i2 < off2 + len2; i2++) {
			if (!used2[i2-off2]) {
				System.out.println("Compare Object diff2 " + printStatement(g,ss2.get(i2)));
				addAddition(ss2.get(i2));
			}
		}
	}
	
	
	
	/**
	 * compares properties, assumes functional relations
	 * @param r1
	 * @param r2
	 * @throws ServiceException
	 * @throws DoesNotContainValueException
	 * @throws ValidationException 
	 */
	private void compareProps(Resource r1, Resource r2) throws ServiceException, DoesNotContainValueException, ValidationException {
		System.out.println("compareProps " + r1 + " " + NameUtils.getSafeName(g, r1) + " " + r2 + " " + NameUtils.getSafeName(g, r2));
		ArrayList<Statement> ss1 = new ArrayList<Statement>();
		ArrayList<Statement> ss2 = new ArrayList<Statement>();
		ss1.addAll(g.getStatements(r1, b.HasProperty));
		ss2.addAll(g.getStatements(r2, b.HasProperty));
		sortStatement(ss1, ss2);
		
		int i1 = 0; 
		int i2 = 0;
		
		while (true) {
			if (i1 >= ss1.size()) {
				if (i2 >= ss2.size())
					break;
				else {
					while (i2 < ss2.size()) {
						System.out.println("Compare Prop diff2 " + printStatement(g,ss2.get(i2)));
						addAddition(ss2.get(i2));
						i2++;
					}
					break;
				}
			} else if (i2 >= ss2.size()) {
				while (i1 < ss1.size()) {
					System.out.println("Compare Prop diff1 " + printStatement(g,ss1.get(i1)));
					addDeletion(ss1.get(i1));
					i1++;
				}
				break;
			}
			Statement s1 = ss1.get(i1);
			Statement s2 = ss2.get(i2);
			if (s1.isAsserted(r1) && s2.isAsserted(r2)) {
				i1++;
				i2++;
				continue;
			}
			int c = scomp.compare(s1, s2);
			switch (c) {
				case 0:{
					boolean b1 = g.hasValue(s1.getObject());
					boolean b2 = g.hasValue(s2.getObject());
					if (b1 == b2) {
						if (b1) {
							Object v1 = g.getValue(s1.getObject());
							Object v2 = g.getValue(s2.getObject());
							boolean eq = compareValue(v1, v2);
							if (!eq) {
								addModification(s1, s2);
								addComparable(s1, s2, false);
							}
						} else {
							if (!s1.getObject().equals(s1.getSubject()) && !s2.getObject().equals(s2.getSubject()))
								compareProps(s1.getObject(), s2.getObject());
						}
					} else {
						addModification(s1, s2);
						addComparable(s1, s2, false);
					}
					i1++;
					i2++;
					break;
				}
				case -1:{
					System.out.println("Compare Prop diff1s " + printStatement(g,s1));
					addDeletion(s1);
					i1++;
					break;
				}
					
				case 1:{
					System.out.println("Compare Prop diff2s " + printStatement(g,s2));
					addAddition(s2);
					i2++;
					break;
				}
			}

		}
		
		ss1.clear();
		ss2.clear();
		
	}
	
	public static boolean compareValue(Object v1, Object v2) {
		if (v1 instanceof Object[] && v2 instanceof Object[])
			return Arrays.deepEquals((Object[])v1, (Object[])v2);
		else if (v1 instanceof int[] && v2 instanceof int[]) 
			return Arrays.equals((int[])v1, (int[])v2);
		else if (v1 instanceof float[] && v2 instanceof float[]) 
			return Arrays.equals((float[])v1, (float[])v2);
		else if (v1 instanceof double[] && v2 instanceof double[]) 
			return Arrays.equals((double[])v1, (double[])v2);
		else if (v1 instanceof long[] && v2 instanceof long[]) 
			return  Arrays.equals((long[])v1, (long[])v2);
		else if (v1 instanceof byte[] && v2 instanceof byte[]) 
			return Arrays.equals((byte[])v1, (byte[])v2);
		else if (v1 instanceof boolean[] && v2 instanceof boolean[]) 
			return Arrays.equals((boolean[])v1, (boolean[])v2);
		else
			return v1.equals(v2);
	}

	
	public class PredicateComparator implements Comparator<Statement> {
		@Override
		public int compare(Statement o1, Statement o2) {
			if (comparableResources.contains(o1.getPredicate(), o2.getPredicate()))
				return 0;
			if (o1.getPredicate().getResourceId() < o2.getPredicate().getResourceId())
				return -1;
			if (o1.getPredicate().getResourceId() > o2.getPredicate().getResourceId())
				return 1;
			return 0;
		}
	}
	
	public class SubjectComparator implements Comparator<Statement> {
		@Override
		public int compare(Statement o1, Statement o2) {
			if (comparableResources.contains(o1.getSubject(), o2.getSubject()))
				return 0;
			if (o1.getSubject().getResourceId() < o2.getSubject().getResourceId())
				return -1;
			if (o1.getSubject().getResourceId() > o2.getSubject().getResourceId())
				return 1;
			return 0;
		}
	}
	
	public class ObjectComparator implements Comparator<Statement> {
		@Override
		public int compare(Statement o1, Statement o2) {
			if (comparableResources.contains(o1.getObject(), o2.getObject()))
				return 0;
			if (o1.getObject().getResourceId() < o2.getObject().getResourceId())
				return -1;
			if (o1.getObject().getResourceId() > o2.getObject().getResourceId())
				return 1;
			return 0;
		}
	}
	
	public static class FullStatementComparator implements Comparator<Statement> {
		@Override
		public int compare(Statement o1, Statement o2) {
			if (o1.getSubject().getResourceId() < o2.getSubject().getResourceId())
				return -1;
			if (o1.getSubject().getResourceId() > o2.getSubject().getResourceId())
				return 1;
			if (o1.getPredicate().getResourceId() < o2.getPredicate().getResourceId())
				return -1;
			if (o1.getPredicate().getResourceId() > o2.getPredicate().getResourceId())
				return 1;
			if (o1.getObject().getResourceId() < o2.getObject().getResourceId())
				return -1;
			if (o1.getObject().getResourceId() > o2.getObject().getResourceId())
				return 1;
			return 0;
		}
	}
	
	public class ResComparator implements Comparator<Resource> {
		@Override
		public int compare(Resource o1, Resource o2) {
			if (comparableResources.contains(o1, o2))
				return 0;
			if (o1.getResourceId() < o2.getResourceId())
				return -1;
			if (o1.getResourceId() > o2.getResourceId())
				return 1;
			return 0;
		}
	}

}