package org.openstreetmap.josm.plugins.routes;

import java.util.BitSet;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

import org.openstreetmap.josm.data.osm.Way;
import org.openstreetmap.josm.plugins.routes.ConvertedWay.WayEnd;

public class PathBuilder {

    private Map<Way, BitSet> wayRoutes = new HashMap<>();
    private Collection<ConvertedWay> convertedWays;

    public void addWay(Way way, RouteDefinition route) {

        if (way.getNodesCount() >= 2) {
            BitSet routes = wayRoutes.get(way);
            if (routes == null) {
                routes = new BitSet();
                wayRoutes.put(way, routes);
            }
            routes.set(route.getIndex());
        }

    }

    public Collection<ConvertedWay> getConvertedWays() {
        if (convertedWays == null) {
            Map<WayEnd, ConvertedWay> ways = new HashMap<>();

            for (Entry<Way, BitSet> wayEntry:wayRoutes.entrySet()) {
                ConvertedWay way = new ConvertedWay(wayEntry.getValue(), wayEntry.getKey());

                ConvertedWay wayBefore = ways.get(way.getStart());
                ConvertedWay wayAfter = ways.get(way.getStop());

                if (wayBefore != null) {
                    removeWay(ways, wayBefore);
                    way.connect(wayBefore);
                }

                if (wayAfter != null) {
                    removeWay(ways, wayAfter);
                    way.connect(wayAfter);
                }

                ways.put(way.getStart(), way);
                ways.put(way.getStop(), way);
            }

            Set<ConvertedWay> uniqueWays = new HashSet<>();
            uniqueWays.addAll(ways.values());
            convertedWays = uniqueWays;
        }
        return convertedWays;
    }

    private void removeWay(Map<WayEnd, ConvertedWay> map, ConvertedWay wayInMap) {
        map.remove(wayInMap.getStart());
        map.remove(wayInMap.getStop());
    }

    public void clear() {
        convertedWays = null;
        wayRoutes.clear();
    }

}
