001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.io;
003
004import static org.openstreetmap.josm.tools.I18n.tr;
005
006import java.io.InputStream;
007import java.util.List;
008import java.util.Map;
009import java.util.Objects;
010import java.util.Optional;
011import java.util.TreeMap;
012import java.util.stream.Collectors;
013
014import javax.json.Json;
015import javax.json.JsonArray;
016import javax.json.JsonNumber;
017import javax.json.JsonObject;
018import javax.json.JsonString;
019import javax.json.JsonStructure;
020import javax.json.JsonValue;
021import javax.json.stream.JsonParser;
022import javax.json.stream.JsonParser.Event;
023
024import org.openstreetmap.josm.data.coor.EastNorth;
025import org.openstreetmap.josm.data.coor.LatLon;
026import org.openstreetmap.josm.data.osm.DataSet;
027import org.openstreetmap.josm.data.osm.Node;
028import org.openstreetmap.josm.data.osm.OsmPrimitive;
029import org.openstreetmap.josm.data.osm.Relation;
030import org.openstreetmap.josm.data.osm.RelationMember;
031import org.openstreetmap.josm.data.osm.Way;
032import org.openstreetmap.josm.data.projection.Projection;
033import org.openstreetmap.josm.data.projection.Projections;
034import org.openstreetmap.josm.gui.progress.NullProgressMonitor;
035import org.openstreetmap.josm.gui.progress.ProgressMonitor;
036import org.openstreetmap.josm.tools.Logging;
037
038/**
039 * Reader that reads GeoJSON files. See <a href="https://tools.ietf.org/html/rfc7946">RFC7946</a> for more information.
040 * @since 15424
041 */
042public class GeoJSONReader extends AbstractReader {
043
044    private static final String CRS = "crs";
045    private static final String NAME = "name";
046    private static final String LINK = "link";
047    private static final String COORDINATES = "coordinates";
048    private static final String FEATURES = "features";
049    private static final String PROPERTIES = "properties";
050    private static final String GEOMETRY = "geometry";
051    private static final String TYPE = "type";
052    private JsonParser parser;
053    private Projection projection = Projections.getProjectionByCode("EPSG:4326"); // WGS 84
054
055    GeoJSONReader() {
056        // Restricts visibility
057    }
058
059    private void setParser(final JsonParser parser) {
060        this.parser = parser;
061    }
062
063    private void parse() throws IllegalDataException {
064        while (parser.hasNext()) {
065            Event event = parser.next();
066            if (event == Event.START_OBJECT) {
067                parseRoot(parser.getObject());
068            }
069        }
070        parser.close();
071    }
072
073    private void parseRoot(final JsonObject object) throws IllegalDataException {
074        parseCrs(object.getJsonObject(CRS));
075        switch (object.getString(TYPE)) {
076            case "FeatureCollection":
077                parseFeatureCollection(object.getJsonArray(FEATURES));
078                break;
079            case "Feature":
080                parseFeature(object);
081                break;
082            case "GeometryCollection":
083                parseGeometryCollection(null, object);
084                break;
085            default:
086                parseGeometry(null, object);
087        }
088    }
089
090    /**
091     * Parse CRS as per https://geojson.org/geojson-spec.html#coordinate-reference-system-objects.
092     * CRS are obsolete in RFC7946 but still allowed for interoperability with older applications.
093     * Only named CRS are supported.
094     *
095     * @param crs CRS JSON object
096     * @throws IllegalDataException in case of error
097     */
098    private void parseCrs(final JsonObject crs) throws IllegalDataException {
099        if (crs != null) {
100            // Inspired by https://github.com/JOSM/geojson/commit/f13ceed4645244612a63581c96e20da802779c56
101            JsonObject properties = crs.getJsonObject("properties");
102            if (properties != null) {
103                switch (crs.getString(TYPE)) {
104                    case NAME:
105                        String crsName = properties.getString(NAME);
106                        if ("urn:ogc:def:crs:OGC:1.3:CRS84".equals(crsName)) {
107                            // https://osgeo-org.atlassian.net/browse/GEOT-1710
108                            crsName = "EPSG:4326";
109                        } else if (crsName.startsWith("urn:ogc:def:crs:EPSG:")) {
110                            crsName = crsName.replace("urn:ogc:def:crs:", "");
111                        }
112                        projection = Optional.ofNullable(Projections.getProjectionByCode(crsName))
113                                .orElse(Projections.getProjectionByCode("EPSG:4326")); // WGS84
114                        break;
115                    case LINK: // Not supported (security risk)
116                    default:
117                        throw new IllegalDataException(crs.toString());
118                }
119            }
120        }
121    }
122
123    private void parseFeatureCollection(final JsonArray features) {
124        for (JsonValue feature : features) {
125            if (feature instanceof JsonObject) {
126                parseFeature((JsonObject) feature);
127            }
128        }
129    }
130
131    private void parseFeature(final JsonObject feature) {
132        JsonValue geometry = feature.get(GEOMETRY);
133        if (geometry != null && geometry.getValueType() == JsonValue.ValueType.OBJECT) {
134            parseGeometry(feature, geometry.asJsonObject());
135        } else {
136            JsonValue properties = feature.get(PROPERTIES);
137            if (properties != null && properties.getValueType() == JsonValue.ValueType.OBJECT) {
138                parseNonGeometryFeature(feature, properties.asJsonObject());
139            } else {
140                Logging.warn(tr("Relation/non-geometry feature without properties found: {0}", feature));
141            }
142        }
143    }
144
145    private void parseNonGeometryFeature(final JsonObject feature, final JsonObject properties) {
146        // get relation type
147        JsonValue type = properties.get(TYPE);
148        if (type == null || properties.getValueType() == JsonValue.ValueType.STRING) {
149            Logging.warn(tr("Relation/non-geometry feature without type found: {0}", feature));
150            return;
151        }
152
153        // create misc. non-geometry feature
154        final Relation relation = new Relation();
155        relation.put(TYPE, type.toString());
156        fillTagsFromFeature(feature, relation);
157        getDataSet().addPrimitive(relation);
158    }
159
160    private void parseGeometryCollection(final JsonObject feature, final JsonObject geometry) {
161        for (JsonValue jsonValue : geometry.getJsonArray("geometries")) {
162            parseGeometry(feature, jsonValue.asJsonObject());
163        }
164    }
165
166    private void parseGeometry(final JsonObject feature, final JsonObject geometry) {
167        if (geometry == null) {
168            parseNullGeometry(feature);
169            return;
170        }
171
172        switch (geometry.getString(TYPE)) {
173            case "Point":
174                parsePoint(feature, geometry.getJsonArray(COORDINATES));
175                break;
176            case "MultiPoint":
177                parseMultiPoint(feature, geometry);
178                break;
179            case "LineString":
180                parseLineString(feature, geometry.getJsonArray(COORDINATES));
181                break;
182            case "MultiLineString":
183                parseMultiLineString(feature, geometry);
184                break;
185            case "Polygon":
186                parsePolygon(feature, geometry.getJsonArray(COORDINATES));
187                break;
188            case "MultiPolygon":
189                parseMultiPolygon(feature, geometry);
190                break;
191            case "GeometryCollection":
192                parseGeometryCollection(feature, geometry);
193                break;
194            default:
195                parseUnknown(geometry);
196        }
197    }
198
199    private LatLon getLatLon(final JsonArray coordinates) {
200        return projection.eastNorth2latlon(new EastNorth(
201                parseCoordinate(coordinates.get(0)),
202                parseCoordinate(coordinates.get(1))));
203    }
204
205    private static double parseCoordinate(JsonValue coordinate) {
206        if (coordinate instanceof JsonString) {
207            return Double.parseDouble(((JsonString) coordinate).getString());
208        } else if (coordinate instanceof JsonNumber) {
209            return ((JsonNumber) coordinate).doubleValue();
210        } else {
211            throw new IllegalArgumentException(Objects.toString(coordinate));
212        }
213    }
214
215    private void parsePoint(final JsonObject feature, final JsonArray coordinates) {
216        fillTagsFromFeature(feature, createNode(getLatLon(coordinates)));
217    }
218
219    private void parseMultiPoint(final JsonObject feature, final JsonObject geometry) {
220        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
221            parsePoint(feature, coordinate.asJsonArray());
222        }
223    }
224
225    private void parseLineString(final JsonObject feature, final JsonArray coordinates) {
226        if (!coordinates.isEmpty()) {
227            createWay(coordinates, false)
228                .ifPresent(way -> fillTagsFromFeature(feature, way));
229        }
230    }
231
232    private void parseMultiLineString(final JsonObject feature, final JsonObject geometry) {
233        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
234            parseLineString(feature, coordinate.asJsonArray());
235        }
236    }
237
238    private void parsePolygon(final JsonObject feature, final JsonArray coordinates) {
239        final int size = coordinates.size();
240        if (size == 1) {
241            createWay(coordinates.getJsonArray(0), true)
242                .ifPresent(way -> fillTagsFromFeature(feature, way));
243        } else if (size > 1) {
244            // create multipolygon
245            final Relation multipolygon = new Relation();
246            multipolygon.put(TYPE, "multipolygon");
247            createWay(coordinates.getJsonArray(0), true)
248                .ifPresent(way -> multipolygon.addMember(new RelationMember("outer", way)));
249
250            for (JsonValue interiorRing : coordinates.subList(1, size)) {
251                createWay(interiorRing.asJsonArray(), true)
252                    .ifPresent(way -> multipolygon.addMember(new RelationMember("inner", way)));
253            }
254
255            fillTagsFromFeature(feature, multipolygon);
256            getDataSet().addPrimitive(multipolygon);
257        }
258    }
259
260    private void parseMultiPolygon(final JsonObject feature, final JsonObject geometry) {
261        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
262            parsePolygon(feature, coordinate.asJsonArray());
263        }
264    }
265
266    private Node createNode(final LatLon latlon) {
267        final Node node = new Node(latlon);
268        getDataSet().addPrimitive(node);
269        return node;
270    }
271
272    private Optional<Way> createWay(final JsonArray coordinates, final boolean autoClose) {
273        if (coordinates.isEmpty()) {
274            return Optional.empty();
275        }
276
277        final List<LatLon> latlons = coordinates.stream().map(
278                coordinate -> getLatLon(coordinate.asJsonArray())).collect(Collectors.toList());
279
280        final int size = latlons.size();
281        final boolean doAutoclose;
282        if (size > 1) {
283            if (latlons.get(0).equals(latlons.get(size - 1))) {
284                // Remove last coordinate, but later add first node to the end
285                latlons.remove(size - 1);
286                doAutoclose = true;
287            } else {
288                doAutoclose = autoClose;
289            }
290        } else {
291            doAutoclose = false;
292        }
293
294        final Way way = new Way();
295        way.setNodes(latlons.stream().map(Node::new).collect(Collectors.toList()));
296        if (doAutoclose) {
297            way.addNode(way.getNode(0));
298        }
299
300        way.getNodes().stream().distinct().forEach(it -> getDataSet().addPrimitive(it));
301        getDataSet().addPrimitive(way);
302
303        return Optional.of(way);
304    }
305
306    private static void fillTagsFromFeature(final JsonObject feature, final OsmPrimitive primitive) {
307        if (feature != null) {
308            primitive.setKeys(getTags(feature));
309        }
310    }
311
312    private static void parseUnknown(final JsonObject object) {
313        Logging.warn(tr("Unknown json object found {0}", object));
314    }
315
316    private static void parseNullGeometry(JsonObject feature) {
317        Logging.warn(tr("Geometry of feature {0} is null", feature));
318    }
319
320    private static Map<String, String> getTags(final JsonObject feature) {
321        final Map<String, String> tags = new TreeMap<>();
322
323        if (feature.containsKey(PROPERTIES) && !feature.isNull(PROPERTIES)) {
324            JsonValue properties = feature.get(PROPERTIES);
325            if (properties != null && properties.getValueType() == JsonValue.ValueType.OBJECT) {
326                for (Map.Entry<String, JsonValue> stringJsonValueEntry : properties.asJsonObject().entrySet()) {
327                    final JsonValue value = stringJsonValueEntry.getValue();
328
329                    if (value instanceof JsonString) {
330                        tags.put(stringJsonValueEntry.getKey(), ((JsonString) value).getString());
331                    } else if (value instanceof JsonStructure) {
332                        Logging.warn(
333                            "The GeoJSON contains an object with property '" + stringJsonValueEntry.getKey()
334                                + "' whose value has the unsupported type '" + value.getClass().getSimpleName()
335                                + "'. That key-value pair is ignored!"
336                        );
337                    } else if (value.getValueType() != JsonValue.ValueType.NULL) {
338                        tags.put(stringJsonValueEntry.getKey(), value.toString());
339                    }
340                }
341            }
342        }
343        return tags;
344    }
345
346    @Override
347    protected DataSet doParseDataSet(InputStream source, ProgressMonitor progressMonitor) throws IllegalDataException {
348        setParser(Json.createParser(source));
349        parse();
350        return getDataSet();
351    }
352
353    /**
354     * Parse the given input source and return the dataset.
355     *
356     * @param source          the source input stream. Must not be null.
357     * @param progressMonitor the progress monitor. If null, {@link NullProgressMonitor#INSTANCE} is assumed
358     * @return the dataset with the parsed data
359     * @throws IllegalDataException     if an error was found while parsing the data from the source
360     * @throws IllegalArgumentException if source is null
361     */
362    public static DataSet parseDataSet(InputStream source, ProgressMonitor progressMonitor) throws IllegalDataException {
363        return new GeoJSONReader().doParseDataSet(source, progressMonitor);
364    }
365}