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.JsonValue;
020import javax.json.stream.JsonParser;
021import javax.json.stream.JsonParser.Event;
022import javax.json.stream.JsonParsingException;
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.UploadPolicy;
032import org.openstreetmap.josm.data.osm.Way;
033import org.openstreetmap.josm.data.projection.Projection;
034import org.openstreetmap.josm.data.projection.Projections;
035import org.openstreetmap.josm.gui.progress.NullProgressMonitor;
036import org.openstreetmap.josm.gui.progress.ProgressMonitor;
037import org.openstreetmap.josm.tools.Logging;
038
039/**
040 * Reader that reads GeoJSON files. See <a href="https://tools.ietf.org/html/rfc7946">RFC7946</a> for more information.
041 * @since 15424
042 */
043public class GeoJSONReader extends AbstractReader {
044
045    private static final String CRS = "crs";
046    private static final String NAME = "name";
047    private static final String LINK = "link";
048    private static final String COORDINATES = "coordinates";
049    private static final String FEATURES = "features";
050    private static final String PROPERTIES = "properties";
051    private static final String GEOMETRY = "geometry";
052    private static final String TYPE = "type";
053    private JsonParser parser;
054    private Projection projection = Projections.getProjectionByCode("EPSG:4326"); // WGS 84
055
056    GeoJSONReader() {
057        // Restricts visibility
058    }
059
060    private void setParser(final JsonParser parser) {
061        this.parser = parser;
062    }
063
064    private void parse() throws IllegalDataException {
065        while (parser.hasNext()) {
066            Event event = parser.next();
067            if (event == Event.START_OBJECT) {
068                parseRoot(parser.getObject());
069            }
070        }
071        parser.close();
072    }
073
074    private void parseRoot(final JsonObject object) throws IllegalDataException {
075        parseCrs(object.getJsonObject(CRS));
076        switch (object.getString(TYPE)) {
077            case "FeatureCollection":
078                parseFeatureCollection(object.getJsonArray(FEATURES));
079                break;
080            case "Feature":
081                parseFeature(object);
082                break;
083            case "GeometryCollection":
084                parseGeometryCollection(null, object);
085                break;
086            default:
087                parseGeometry(null, object);
088        }
089    }
090
091    /**
092     * Parse CRS as per https://geojson.org/geojson-spec.html#coordinate-reference-system-objects.
093     * CRS are obsolete in RFC7946 but still allowed for interoperability with older applications.
094     * Only named CRS are supported.
095     *
096     * @param crs CRS JSON object
097     * @throws IllegalDataException in case of error
098     */
099    private void parseCrs(final JsonObject crs) throws IllegalDataException {
100        if (crs != null) {
101            // Inspired by https://github.com/JOSM/geojson/commit/f13ceed4645244612a63581c96e20da802779c56
102            JsonObject properties = crs.getJsonObject("properties");
103            if (properties != null) {
104                switch (crs.getString(TYPE)) {
105                    case NAME:
106                        String crsName = properties.getString(NAME);
107                        if ("urn:ogc:def:crs:OGC:1.3:CRS84".equals(crsName)) {
108                            // https://osgeo-org.atlassian.net/browse/GEOT-1710
109                            crsName = "EPSG:4326";
110                        } else if (crsName.startsWith("urn:ogc:def:crs:EPSG:")) {
111                            crsName = crsName.replace("urn:ogc:def:crs:", "");
112                        }
113                        projection = Optional.ofNullable(Projections.getProjectionByCode(crsName))
114                                .orElse(Projections.getProjectionByCode("EPSG:4326")); // WGS84
115                        break;
116                    case LINK: // Not supported (security risk)
117                    default:
118                        throw new IllegalDataException(crs.toString());
119                }
120            }
121        }
122    }
123
124    private void parseFeatureCollection(final JsonArray features) {
125        for (JsonValue feature : features) {
126            if (feature instanceof JsonObject) {
127                parseFeature((JsonObject) feature);
128            }
129        }
130    }
131
132    private void parseFeature(final JsonObject feature) {
133        JsonValue geometry = feature.get(GEOMETRY);
134        if (geometry != null && geometry.getValueType() == JsonValue.ValueType.OBJECT) {
135            parseGeometry(feature, geometry.asJsonObject());
136        } else {
137            JsonValue properties = feature.get(PROPERTIES);
138            if (properties != null && properties.getValueType() == JsonValue.ValueType.OBJECT) {
139                parseNonGeometryFeature(feature, properties.asJsonObject());
140            } else {
141                Logging.warn(tr("Relation/non-geometry feature without properties found: {0}", feature));
142            }
143        }
144    }
145
146    private void parseNonGeometryFeature(final JsonObject feature, final JsonObject properties) {
147        // get relation type
148        JsonValue type = properties.get(TYPE);
149        if (type == null || properties.getValueType() == JsonValue.ValueType.STRING) {
150            Logging.warn(tr("Relation/non-geometry feature without type found: {0}", feature));
151            return;
152        }
153
154        // create misc. non-geometry feature
155        final Relation relation = new Relation();
156        relation.put(TYPE, type.toString());
157        fillTagsFromFeature(feature, relation);
158        getDataSet().addPrimitive(relation);
159    }
160
161    private void parseGeometryCollection(final JsonObject feature, final JsonObject geometry) {
162        for (JsonValue jsonValue : geometry.getJsonArray("geometries")) {
163            parseGeometry(feature, jsonValue.asJsonObject());
164        }
165    }
166
167    private void parseGeometry(final JsonObject feature, final JsonObject geometry) {
168        if (geometry == null) {
169            parseNullGeometry(feature);
170            return;
171        }
172
173        switch (geometry.getString(TYPE)) {
174            case "Point":
175                parsePoint(feature, geometry.getJsonArray(COORDINATES));
176                break;
177            case "MultiPoint":
178                parseMultiPoint(feature, geometry);
179                break;
180            case "LineString":
181                parseLineString(feature, geometry.getJsonArray(COORDINATES));
182                break;
183            case "MultiLineString":
184                parseMultiLineString(feature, geometry);
185                break;
186            case "Polygon":
187                parsePolygon(feature, geometry.getJsonArray(COORDINATES));
188                break;
189            case "MultiPolygon":
190                parseMultiPolygon(feature, geometry);
191                break;
192            case "GeometryCollection":
193                parseGeometryCollection(feature, geometry);
194                break;
195            default:
196                parseUnknown(geometry);
197        }
198    }
199
200    private LatLon getLatLon(final JsonArray coordinates) {
201        return projection.eastNorth2latlon(new EastNorth(
202                parseCoordinate(coordinates.get(0)),
203                parseCoordinate(coordinates.get(1))));
204    }
205
206    private static double parseCoordinate(JsonValue coordinate) {
207        if (coordinate instanceof JsonString) {
208            return Double.parseDouble(((JsonString) coordinate).getString());
209        } else if (coordinate instanceof JsonNumber) {
210            return ((JsonNumber) coordinate).doubleValue();
211        } else {
212            throw new IllegalArgumentException(Objects.toString(coordinate));
213        }
214    }
215
216    private void parsePoint(final JsonObject feature, final JsonArray coordinates) {
217        fillTagsFromFeature(feature, createNode(getLatLon(coordinates)));
218    }
219
220    private void parseMultiPoint(final JsonObject feature, final JsonObject geometry) {
221        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
222            parsePoint(feature, coordinate.asJsonArray());
223        }
224    }
225
226    private void parseLineString(final JsonObject feature, final JsonArray coordinates) {
227        if (!coordinates.isEmpty()) {
228            createWay(coordinates, false)
229                .ifPresent(way -> fillTagsFromFeature(feature, way));
230        }
231    }
232
233    private void parseMultiLineString(final JsonObject feature, final JsonObject geometry) {
234        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
235            parseLineString(feature, coordinate.asJsonArray());
236        }
237    }
238
239    private void parsePolygon(final JsonObject feature, final JsonArray coordinates) {
240        final int size = coordinates.size();
241        if (size == 1) {
242            createWay(coordinates.getJsonArray(0), true)
243                .ifPresent(way -> fillTagsFromFeature(feature, way));
244        } else if (size > 1) {
245            // create multipolygon
246            final Relation multipolygon = new Relation();
247            multipolygon.put(TYPE, "multipolygon");
248            createWay(coordinates.getJsonArray(0), true)
249                .ifPresent(way -> multipolygon.addMember(new RelationMember("outer", way)));
250
251            for (JsonValue interiorRing : coordinates.subList(1, size)) {
252                createWay(interiorRing.asJsonArray(), true)
253                    .ifPresent(way -> multipolygon.addMember(new RelationMember("inner", way)));
254            }
255
256            fillTagsFromFeature(feature, multipolygon);
257            getDataSet().addPrimitive(multipolygon);
258        }
259    }
260
261    private void parseMultiPolygon(final JsonObject feature, final JsonObject geometry) {
262        for (JsonValue coordinate : geometry.getJsonArray(COORDINATES)) {
263            parsePolygon(feature, coordinate.asJsonArray());
264        }
265    }
266
267    private Node createNode(final LatLon latlon) {
268        final Node node = new Node(latlon);
269        getDataSet().addPrimitive(node);
270        return node;
271    }
272
273    private Optional<Way> createWay(final JsonArray coordinates, final boolean autoClose) {
274        if (coordinates.isEmpty()) {
275            return Optional.empty();
276        }
277
278        final List<LatLon> latlons = coordinates.stream().map(
279                coordinate -> getLatLon(coordinate.asJsonArray())).collect(Collectors.toList());
280
281        final int size = latlons.size();
282        final boolean doAutoclose;
283        if (size > 1) {
284            if (latlons.get(0).equals(latlons.get(size - 1))) {
285                // Remove last coordinate, but later add first node to the end
286                latlons.remove(size - 1);
287                doAutoclose = true;
288            } else {
289                doAutoclose = autoClose;
290            }
291        } else {
292            doAutoclose = false;
293        }
294
295        final Way way = new Way();
296        way.setNodes(latlons.stream().map(Node::new).collect(Collectors.toList()));
297        if (doAutoclose) {
298            way.addNode(way.getNode(0));
299        }
300
301        way.getNodes().stream().distinct().forEach(it -> getDataSet().addPrimitive(it));
302        getDataSet().addPrimitive(way);
303
304        return Optional.of(way);
305    }
306
307    private static void fillTagsFromFeature(final JsonObject feature, final OsmPrimitive primitive) {
308        if (feature != null) {
309            primitive.setKeys(getTags(feature));
310        }
311    }
312
313    private static void parseUnknown(final JsonObject object) {
314        Logging.warn(tr("Unknown json object found {0}", object));
315    }
316
317    private static void parseNullGeometry(JsonObject feature) {
318        Logging.warn(tr("Geometry of feature {0} is null", feature));
319    }
320
321    private static Map<String, String> getTags(final JsonObject feature) {
322        final Map<String, String> tags = new TreeMap<>();
323
324        if (feature.containsKey(PROPERTIES) && !feature.isNull(PROPERTIES)) {
325            JsonValue properties = feature.get(PROPERTIES);
326            if (properties != null && properties.getValueType() == JsonValue.ValueType.OBJECT) {
327                for (Map.Entry<String, JsonValue> stringJsonValueEntry : properties.asJsonObject().entrySet()) {
328                    final JsonValue value = stringJsonValueEntry.getValue();
329
330                    if (value instanceof JsonString) {
331                        tags.put(stringJsonValueEntry.getKey(), ((JsonString) value).getString());
332                    } else if (value instanceof JsonObject) {
333                        Logging.warn(
334                            "The GeoJSON contains an object with property '" + stringJsonValueEntry.getKey()
335                                + "' whose value has the unsupported type '" + value.getClass().getSimpleName()
336                                + "'. That key-value pair is ignored!"
337                        );
338                    } else if (value.getValueType() != JsonValue.ValueType.NULL) {
339                        tags.put(stringJsonValueEntry.getKey(), value.toString());
340                    }
341                }
342            }
343        }
344        return tags;
345    }
346
347    @Override
348    protected DataSet doParseDataSet(InputStream source, ProgressMonitor progressMonitor) throws IllegalDataException {
349        setParser(Json.createParser(source));
350        ds.setUploadPolicy(UploadPolicy.DISCOURAGED);
351        try {
352            parse();
353        } catch (JsonParsingException e) {
354            throw new IllegalDataException(e);
355        }
356        return getDataSet();
357    }
358
359    /**
360     * Parse the given input source and return the dataset.
361     *
362     * @param source          the source input stream. Must not be null.
363     * @param progressMonitor the progress monitor. If null, {@link NullProgressMonitor#INSTANCE} is assumed
364     * @return the dataset with the parsed data
365     * @throws IllegalDataException     if an error was found while parsing the data from the source
366     * @throws IllegalArgumentException if source is null
367     */
368    public static DataSet parseDataSet(InputStream source, ProgressMonitor progressMonitor) throws IllegalDataException {
369        return new GeoJSONReader().doParseDataSet(source, progressMonitor);
370    }
371}