001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.data.osm;
003
004import static org.openstreetmap.josm.tools.I18n.tr;
005
006import java.util.ArrayList;
007import java.util.Collection;
008import java.util.HashMap;
009import java.util.HashSet;
010import java.util.Iterator;
011import java.util.LinkedList;
012import java.util.List;
013import java.util.Map;
014import java.util.Set;
015
016import org.openstreetmap.josm.data.conflict.Conflict;
017import org.openstreetmap.josm.data.conflict.ConflictCollection;
018import org.openstreetmap.josm.gui.progress.ProgressMonitor;
019import org.openstreetmap.josm.tools.CheckParameterUtil;
020
021/**
022 * A dataset merger which takes a target and a source dataset and merges the source data set
023 * onto the target dataset.
024 *
025 */
026public class DataSetMerger {
027
028    /** the collection of conflicts created during merging */
029    private final ConflictCollection conflicts;
030
031    /** the target dataset for merging */
032    private final DataSet targetDataSet;
033    /** the source dataset where primitives are merged from */
034    private final DataSet sourceDataSet;
035
036    /**
037     * A map of all primitives that got replaced with other primitives.
038     * Key is the PrimitiveId in their dataset, the value is the PrimitiveId in my dataset
039     */
040    private final Map<PrimitiveId, PrimitiveId> mergedMap;
041    /** a set of primitive ids for which we have to fix references (to nodes and
042     * to relation members) after the first phase of merging
043     */
044    private final Set<PrimitiveId> objectsWithChildrenToMerge;
045    private final Set<OsmPrimitive> objectsToDelete;
046
047    /**
048     * constructor
049     *
050     * The visitor will merge <code>sourceDataSet</code> onto <code>targetDataSet</code>
051     *
052     * @param targetDataSet dataset with my primitives. Must not be null.
053     * @param sourceDataSet dataset with their primitives. Ignored, if null.
054     * @throws IllegalArgumentException if myDataSet is null
055     */
056    public DataSetMerger(DataSet targetDataSet, DataSet sourceDataSet) {
057        CheckParameterUtil.ensureParameterNotNull(targetDataSet, "targetDataSet");
058        this.targetDataSet = targetDataSet;
059        this.sourceDataSet = sourceDataSet;
060        conflicts = new ConflictCollection();
061        mergedMap = new HashMap<>();
062        objectsWithChildrenToMerge = new HashSet<>();
063        objectsToDelete = new HashSet<>();
064    }
065
066    /**
067     * Merges a primitive onto primitives dataset.
068     *
069     * If other.id != 0 it tries to merge it with an corresponding primitive from
070     * my dataset with the same id. If this is not possible a conflict is remembered
071     * in {@link #conflicts}.
072     *
073     * If other.id == 0 (new primitive) it tries to find a primitive in my dataset with id == 0 which
074     * is semantically equal. If it finds one it merges its technical attributes onto
075     * my primitive.
076     *
077     * @param source the primitive to merge
078     * @param candidates a set of possible candidates for a new primitive
079     */
080    protected void mergePrimitive(OsmPrimitive source, Collection<? extends OsmPrimitive> candidates) {
081        if (!source.isNew()) {
082            // try to merge onto a matching primitive with the same defined id
083            //
084            if (mergeById(source))
085                return;
086        } else {
087            // ignore deleted primitives from source
088            if (source.isDeleted()) return;
089
090            // try to merge onto a primitive  which has no id assigned
091            // yet but which is equal in its semantic attributes
092            //
093            for (OsmPrimitive target : candidates) {
094                if (!target.isNew() || target.isDeleted()) {
095                    continue;
096                }
097                if (target.hasEqualSemanticAttributes(source)) {
098                    mergedMap.put(source.getPrimitiveId(), target.getPrimitiveId());
099                    // copy the technical attributes from other version
100                    target.setVisible(source.isVisible());
101                    target.setUser(source.getUser());
102                    target.setRawTimestamp(source.getRawTimestamp());
103                    target.setModified(source.isModified());
104                    objectsWithChildrenToMerge.add(source.getPrimitiveId());
105                    return;
106                }
107            }
108        }
109
110        // If we get here we didn't find a suitable primitive in
111        // the target dataset. Create a clone and add it to the target dataset.
112        //
113        OsmPrimitive target = null;
114        switch(source.getType()) {
115        case NODE: target = source.isNew() ? new Node() : new Node(source.getId()); break;
116        case WAY: target = source.isNew() ? new Way() : new Way(source.getId()); break;
117        case RELATION: target = source.isNew() ? new Relation() : new Relation(source.getId()); break;
118        default: throw new AssertionError();
119        }
120        target.mergeFrom(source);
121        targetDataSet.addPrimitive(target);
122        mergedMap.put(source.getPrimitiveId(), target.getPrimitiveId());
123        objectsWithChildrenToMerge.add(source.getPrimitiveId());
124    }
125
126    protected OsmPrimitive getMergeTarget(OsmPrimitive mergeSource) {
127        PrimitiveId targetId = mergedMap.get(mergeSource.getPrimitiveId());
128        if (targetId == null)
129            return null;
130        return targetDataSet.getPrimitiveById(targetId);
131    }
132
133    protected void addConflict(Conflict<?> c) {
134        c.setMergedMap(mergedMap);
135        conflicts.add(c);
136    }
137
138    protected void addConflict(OsmPrimitive my, OsmPrimitive their) {
139        addConflict(new Conflict<>(my, their));
140    }
141
142    protected void fixIncomplete(Way other) {
143        Way myWay = (Way) getMergeTarget(other);
144        if (myWay == null)
145            throw new RuntimeException(tr("Missing merge target for way with id {0}", other.getUniqueId()));
146    }
147
148    /**
149     * Postprocess the dataset and fix all merged references to point to the actual
150     * data.
151     */
152    public void fixReferences() {
153        for (Way w : sourceDataSet.getWays()) {
154            if (!conflicts.hasConflictForTheir(w) && objectsWithChildrenToMerge.contains(w.getPrimitiveId())) {
155                mergeNodeList(w);
156                fixIncomplete(w);
157            }
158        }
159        for (Relation r : sourceDataSet.getRelations()) {
160            if (!conflicts.hasConflictForTheir(r) && objectsWithChildrenToMerge.contains(r.getPrimitiveId())) {
161                mergeRelationMembers(r);
162            }
163        }
164
165        deleteMarkedObjects();
166    }
167
168    /**
169     * Deleted objects in objectsToDelete set and create conflicts for objects that cannot
170     * be deleted because they're referenced in the target dataset.
171     */
172    protected void deleteMarkedObjects() {
173        boolean flag;
174        do {
175            flag = false;
176            for (Iterator<OsmPrimitive> it = objectsToDelete.iterator(); it.hasNext();) {
177                OsmPrimitive target = it.next();
178                OsmPrimitive source = sourceDataSet.getPrimitiveById(target.getPrimitiveId());
179                if (source == null)
180                    throw new RuntimeException(
181                            tr("Object of type {0} with id {1} was marked to be deleted, but it''s missing in the source dataset",
182                            target.getType(), target.getUniqueId()));
183
184                List<OsmPrimitive> referrers = target.getReferrers();
185                if (referrers.isEmpty()) {
186                    resetPrimitive(target);
187                    target.mergeFrom(source);
188                    target.setDeleted(true);
189                    it.remove();
190                    flag = true;
191                } else {
192                    for (OsmPrimitive referrer : referrers) {
193                        // If one of object referrers isn't going to be deleted,
194                        // add a conflict and don't delete the object
195                        if (!objectsToDelete.contains(referrer)) {
196                            addConflict(target, source);
197                            it.remove();
198                            flag = true;
199                            break;
200                        }
201                    }
202                }
203
204            }
205        } while (flag);
206
207        if (!objectsToDelete.isEmpty()) {
208            // There are some more objects rest in the objectsToDelete set
209            // This can be because of cross-referenced relations.
210            for (OsmPrimitive osm: objectsToDelete) {
211                resetPrimitive(osm);
212            }
213            for (OsmPrimitive osm: objectsToDelete) {
214                osm.setDeleted(true);
215                osm.mergeFrom(sourceDataSet.getPrimitiveById(osm.getPrimitiveId()));
216            }
217        }
218    }
219
220    private static void resetPrimitive(OsmPrimitive osm) {
221        if (osm instanceof Way) {
222            ((Way) osm).setNodes(null);
223        } else if (osm instanceof Relation) {
224            ((Relation) osm).setMembers(null);
225        }
226    }
227
228    /**
229     * Merges the node list of a source way onto its target way.
230     *
231     * @param source the source way
232     * @throws IllegalStateException if no target way can be found for the source way
233     * @throws IllegalStateException if there isn't a target node for one of the nodes in the source way
234     *
235     */
236    private void mergeNodeList(Way source) {
237        Way target = (Way) getMergeTarget(source);
238        if (target == null)
239            throw new IllegalStateException(tr("Missing merge target for way with id {0}", source.getUniqueId()));
240
241        List<Node> newNodes = new ArrayList<>(source.getNodesCount());
242        for (Node sourceNode : source.getNodes()) {
243            Node targetNode = (Node) getMergeTarget(sourceNode);
244            if (targetNode != null) {
245                newNodes.add(targetNode);
246                if (targetNode.isDeleted() && !conflicts.hasConflictForMy(targetNode)) {
247                    addConflict(new Conflict<OsmPrimitive>(targetNode, sourceNode, true));
248                    targetNode.setDeleted(false);
249                }
250            } else
251                throw new IllegalStateException(tr("Missing merge target for node with id {0}", sourceNode.getUniqueId()));
252        }
253        target.setNodes(newNodes);
254    }
255
256    /**
257     * Merges the relation members of a source relation onto the corresponding target relation.
258     * @param source the source relation
259     * @throws IllegalStateException if there is no corresponding target relation
260     * @throws IllegalStateException if there isn't a corresponding target object for one of the relation
261     * members in source
262     */
263    private void mergeRelationMembers(Relation source) {
264        Relation target = (Relation) getMergeTarget(source);
265        if (target == null)
266            throw new IllegalStateException(tr("Missing merge target for relation with id {0}", source.getUniqueId()));
267        List<RelationMember> newMembers = new LinkedList<>();
268        for (RelationMember sourceMember : source.getMembers()) {
269            OsmPrimitive targetMember = getMergeTarget(sourceMember.getMember());
270            if (targetMember == null)
271                throw new IllegalStateException(tr("Missing merge target of type {0} with id {1}",
272                        sourceMember.getType(), sourceMember.getUniqueId()));
273            RelationMember newMember = new RelationMember(sourceMember.getRole(), targetMember);
274            newMembers.add(newMember);
275            if (targetMember.isDeleted() && !conflicts.hasConflictForMy(targetMember)) {
276                addConflict(new Conflict<>(targetMember, sourceMember.getMember(), true));
277                targetMember.setDeleted(false);
278            }
279        }
280        target.setMembers(newMembers);
281    }
282
283    /**
284     * Tries to merge a primitive <code>source</code> into an existing primitive with the same id.
285     *
286     * @param source  the source primitive which is to be merged into a target primitive
287     * @return true, if this method was able to merge <code>source</code> into a target object; false, otherwise
288     */
289    private boolean mergeById(OsmPrimitive source) {
290        OsmPrimitive target = targetDataSet.getPrimitiveById(source.getId(), source.getType());
291        // merge other into an existing primitive with the same id, if possible
292        //
293        if (target == null)
294            return false;
295        // found a corresponding target, remember it
296        mergedMap.put(source.getPrimitiveId(), target.getPrimitiveId());
297
298        if (target.getVersion() > source.getVersion())
299            // target.version > source.version => keep target version
300            return true;
301
302        if (target.isIncomplete() && !source.isIncomplete()) {
303            // target is incomplete, source completes it
304            // => merge source into target
305            //
306            target.mergeFrom(source);
307            objectsWithChildrenToMerge.add(source.getPrimitiveId());
308        } else if (!target.isIncomplete() && source.isIncomplete()) {
309            // target is complete and source is incomplete
310            // => keep target, it has more information already
311            //
312        } else if (target.isIncomplete() && source.isIncomplete()) {
313            // target and source are incomplete. Doesn't matter which one to
314            // take. We take target.
315            //
316        } else if (!target.isModified() && !source.isModified() && target.isVisible() != source.isVisible()
317                && target.getVersion() == source.getVersion())
318            // Same version, but different "visible" attribute and neither of them are modified.
319            // It indicates a serious problem in datasets.
320            // For example, datasets can be fetched from different OSM servers or badly hand-modified.
321            // We shouldn't merge that datasets.
322            throw new DataIntegrityProblemException(tr("Conflict in ''visible'' attribute for object of type {0} with id {1}",
323                    target.getType(), target.getId()));
324        else if (target.isDeleted() && !source.isDeleted() && target.getVersion() == source.getVersion()) {
325            // same version, but target is deleted. Assume target takes precedence
326            // otherwise too many conflicts when refreshing from the server
327            // but, if source has a referrer that is not in the target dataset there is a conflict
328            // If target dataset refers to the deleted primitive, conflict will be added in fixReferences method
329            for (OsmPrimitive referrer: source.getReferrers()) {
330                if (targetDataSet.getPrimitiveById(referrer.getPrimitiveId()) == null) {
331                    addConflict(new Conflict<>(target, source, true));
332                    target.setDeleted(false);
333                    break;
334                }
335            }
336        } else if (!target.isModified() && source.isDeleted()) {
337            // target not modified. We can assume that source is the most recent version,
338            // so mark it to be deleted.
339            //
340            objectsToDelete.add(target);
341        } else if (!target.isModified() && source.isModified()) {
342            // target not modified. We can assume that source is the most recent version.
343            // clone it into target.
344            target.mergeFrom(source);
345            objectsWithChildrenToMerge.add(source.getPrimitiveId());
346        } else if (!target.isModified() && !source.isModified() && target.getVersion() == source.getVersion()) {
347            // both not modified. Merge nevertheless.
348            // This helps when updating "empty" relations, see #4295
349            target.mergeFrom(source);
350            objectsWithChildrenToMerge.add(source.getPrimitiveId());
351        } else if (!target.isModified() && !source.isModified() && target.getVersion() < source.getVersion()) {
352            // my not modified but other is newer. clone other onto mine.
353            //
354            target.mergeFrom(source);
355            objectsWithChildrenToMerge.add(source.getPrimitiveId());
356        } else if (target.isModified() && !source.isModified() && target.getVersion() == source.getVersion()) {
357            // target is same as source but target is modified
358            // => keep target and reset modified flag if target and source are semantically equal
359            if (target.hasEqualSemanticAttributes(source, false)) {
360                target.setModified(false);
361            }
362        } else if (source.isDeleted() != target.isDeleted()) {
363            // target is modified and deleted state differs.
364            // this have to be resolved manually.
365            //
366            addConflict(target, source);
367        } else if (!target.hasEqualSemanticAttributes(source)) {
368            // target is modified and is not semantically equal with source. Can't automatically
369            // resolve the differences
370            // =>  create a conflict
371            addConflict(target, source);
372        } else {
373            // clone from other. mergeFrom will mainly copy
374            // technical attributes like timestamp or user information. Semantic
375            // attributes should already be equal if we get here.
376            //
377            target.mergeFrom(source);
378            objectsWithChildrenToMerge.add(source.getPrimitiveId());
379        }
380        return true;
381    }
382
383    /**
384     * Runs the merge operation. Successfully merged {@link OsmPrimitive}s are in
385     * {@link #getTargetDataSet()}.
386     *
387     * See {@link #getConflicts()} for a map of conflicts after the merge operation.
388     */
389    public void merge() {
390        merge(null);
391    }
392
393    /**
394     * Runs the merge operation. Successfully merged {@link OsmPrimitive}s are in
395     * {@link #getTargetDataSet()}.
396     *
397     * See {@link #getConflicts()} for a map of conflicts after the merge operation.
398     * @param progressMonitor The progress monitor
399     */
400    public void merge(ProgressMonitor progressMonitor) {
401        if (sourceDataSet == null)
402            return;
403        if (progressMonitor != null) {
404            progressMonitor.beginTask(tr("Merging data..."), sourceDataSet.allPrimitives().size());
405        }
406        targetDataSet.beginUpdate();
407        try {
408            List<? extends OsmPrimitive> candidates = new ArrayList<>(targetDataSet.getNodes());
409            for (Node node: sourceDataSet.getNodes()) {
410                mergePrimitive(node, candidates);
411                if (progressMonitor != null) {
412                    progressMonitor.worked(1);
413                }
414            }
415            candidates.clear();
416            candidates = new ArrayList<>(targetDataSet.getWays());
417            for (Way way: sourceDataSet.getWays()) {
418                mergePrimitive(way, candidates);
419                if (progressMonitor != null) {
420                    progressMonitor.worked(1);
421                }
422            }
423            candidates.clear();
424            candidates = new ArrayList<>(targetDataSet.getRelations());
425            for (Relation relation: sourceDataSet.getRelations()) {
426                mergePrimitive(relation, candidates);
427                if (progressMonitor != null) {
428                    progressMonitor.worked(1);
429                }
430            }
431            candidates.clear();
432            fixReferences();
433        } finally {
434            targetDataSet.endUpdate();
435        }
436        if (progressMonitor != null) {
437            progressMonitor.finishTask();
438        }
439    }
440
441    /**
442     * replies my dataset
443     *
444     * @return the own (target) data set
445     */
446    public DataSet getTargetDataSet() {
447        return targetDataSet;
448    }
449
450    /**
451     * replies the map of conflicts
452     *
453     * @return the map of conflicts
454     */
455    public ConflictCollection getConflicts() {
456        return conflicts;
457    }
458}