001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.tools;
003
004import java.util.Collection;
005import java.util.Collections;
006import java.util.Set;
007
008import org.openstreetmap.josm.data.coor.LatLon;
009import org.openstreetmap.josm.data.osm.OsmPrimitive;
010import org.openstreetmap.josm.data.osm.Relation;
011import org.openstreetmap.josm.data.osm.RelationMember;
012import org.openstreetmap.josm.data.osm.Way;
013
014/**
015 * Look up, if there is right- or left-hand traffic at a certain place.
016 * See <a href="https://en.wikipedia.org/wiki/Left-_and_right-hand_traffic">Left- and right-hand traffic</a>
017 */
018public final class RightAndLefthandTraffic {
019
020    private static final String DRIVING_SIDE = "driving_side";
021    private static final String LEFT = "left";
022    private static final String RIGHT = "right";
023
024    private static volatile GeoPropertyIndex<Boolean> rlCache;
025
026    private RightAndLefthandTraffic() {
027        // Hide implicit public constructor for utility classes
028    }
029
030    /**
031     * Check if there is right-hand traffic at a certain location.
032     *
033     * @param ll the coordinates of the point
034     * @return true if there is right-hand traffic, false if there is left-hand traffic
035     */
036    public static synchronized boolean isRightHandTraffic(LatLon ll) {
037        Boolean value = rlCache.get(ll);
038        return value == null || !value;
039    }
040
041    /**
042     * Initializes Right and lefthand traffic data.
043     * @param geoProperty the property containing the traffic data
044     * TODO: Synchronization can be refined inside the {@link GeoPropertyIndex} as most look-ups are read-only.
045     */
046    static synchronized void initialize(DefaultGeoProperty geoProperty) {
047        rlCache = new GeoPropertyIndex<>(geoProperty, 24);
048    }
049
050    static void appendLeftDrivingBoundaries(OsmPrimitive osm, Collection<Way> ways) {
051        // Find all outer ways of left-driving countries. Many of them are adjacent (African and Asian states)
052        if (LEFT.equals(osm.get(DRIVING_SIDE))) {
053            if (osm instanceof Way) {
054                Way w = (Way) osm;
055                addWayIfNotInner(ways, w);
056            } else if (osm instanceof Relation && osm.isMultipolygon()) {
057                Relation r = (Relation) osm;
058                for (RelationMember rm : r.getMembers()) {
059                    if (rm.isWay() && "outer".equals(rm.getRole()) && !RIGHT.equals(rm.getMember().get(DRIVING_SIDE))) {
060                        addWayIfNotInner(ways, (Way) rm.getMember());
061                    }
062                }
063            }
064        }
065    }
066
067    /**
068     * Adds w to ways, except if it is an inner way of another lefthand driving multipolygon,
069     * as Lesotho in South Africa and Cyprus village in British Cyprus base.
070     * @param ways ways
071     * @param w way
072     */
073    private static void addWayIfNotInner(Collection<Way> ways, Way w) {
074        Set<Way> s = Collections.singleton(w);
075        for (Relation r : OsmPrimitive.getParentRelations(s)) {
076            if (r.isMultipolygon() && LEFT.equals(r.get(DRIVING_SIDE)) &&
077                "inner".equals(r.getMembersFor(s).iterator().next().getRole())) {
078                if (Logging.isDebugEnabled()) {
079                    Logging.debug("Skipping {0} because inner part of {1}", w.get("name:en"), r.get("name:en"));
080                }
081                return;
082            }
083        }
084        ways.add(w);
085    }
086}