001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.tools;
003
004import java.awt.geom.Area;
005import java.io.IOException;
006import java.io.InputStream;
007import java.util.ArrayList;
008import java.util.Collection;
009import org.openstreetmap.josm.data.coor.LatLon;
010import org.openstreetmap.josm.data.osm.BBox;
011import org.openstreetmap.josm.data.osm.DataSet;
012import org.openstreetmap.josm.data.osm.Way;
013import org.openstreetmap.josm.io.CachedFile;
014import org.openstreetmap.josm.io.IllegalDataException;
015import org.openstreetmap.josm.io.OsmReader;
016import org.openstreetmap.josm.tools.GeoPropertyIndex.GeoProperty;
017import org.openstreetmap.josm.tools.Geometry.PolygonIntersection;
018
019/**
020 * Look up, if there is right- or left-hand traffic at a certain place.
021 */
022public class RightAndLefthandTraffic {
023    
024    private static class RLTrafficGeoProperty implements GeoProperty<Boolean> {
025
026        @Override
027        public Boolean get(LatLon ll) {
028            for (Area a : leftHandTrafficPolygons) {
029                if (a.contains(ll.lon(), ll.lat()))
030                    return true;
031            }
032            return false;
033        }
034
035        @Override
036        public Boolean get(BBox box) {
037            Area abox = new Area(box.toRectangle());
038            for (Area a : leftHandTrafficPolygons) {
039                PolygonIntersection is = Geometry.polygonIntersection(abox, a, 1e-10 /* using deg and not meters */);
040                if (is == PolygonIntersection.FIRST_INSIDE_SECOND)
041                    return true;
042                if (is != PolygonIntersection.OUTSIDE)
043                    return null;
044            }
045            return false;
046        }
047    }
048    
049    private static Collection<Area> leftHandTrafficPolygons;
050    private static GeoPropertyIndex<Boolean> rlCache;
051
052    /**
053     * Check if there is right-hand traffic at a certain location.
054     * 
055     * TODO: Synchronization can be refined inside the {@link GeoPropertyIndex}
056     *       as most look-ups are read-only. 
057     * @param ll the coordinates of the point
058     * @return true if there is right-hand traffic, false if there is left-hand traffic
059     */
060    public static synchronized boolean isRightHandTraffic(LatLon ll) {
061        if (leftHandTrafficPolygons == null) {
062            initialize();
063        }
064        return !rlCache.get(ll);
065    }
066
067    private static void initialize() {
068        leftHandTrafficPolygons = new ArrayList<>();
069        try (InputStream is = new CachedFile("resource://data/left-right-hand-traffic.osm").getInputStream()) {
070            DataSet data = OsmReader.parseDataSet(is, null);
071            for (Way w : data.getWays()) {
072                leftHandTrafficPolygons.add(Geometry.getAreaLatLon(w.getNodes()));
073            }
074        } catch (IOException | IllegalDataException ex) {
075            throw new RuntimeException(ex);
076        }
077        rlCache = new GeoPropertyIndex<Boolean>(new RLTrafficGeoProperty(), 24);
078    }
079    
080}