@Override
  public List<GraphPath> plan(State origin, Vertex target, int nItineraries) {

    Date targetTime = new Date(origin.getTime() * 1000);
    TraverseOptions options = origin.getOptions();

    if (_graphService.getCalendarService() != null)
      options.setCalendarService(_graphService.getCalendarService());
    options.setTransferTable(_graphService.getGraph().getTransferTable());
    options.setServiceDays(targetTime.getTime() / 1000);
    if (options.getModes().getTransit()
        && !_graphService.getGraph().transitFeedCovers(targetTime)) {
      // user wants a path through the transit network,
      // but the date provided is outside those covered by the transit feed.
      throw new TransitTimesException();
    }
    // decide which A* heuristic to use
    options.remainingWeightHeuristic =
        _remainingWeightHeuristicFactory.getInstanceForSearch(options, target);
    LOG.debug("Applied A* heuristic: {}", options.remainingWeightHeuristic);

    // If transit is not to be used, disable walk limit and only search for one itinerary.
    if (!options.getModes().getTransit()) {
      nItineraries = 1;
      options.setMaxWalkDistance(Double.MAX_VALUE);
    }

    ArrayList<GraphPath> paths = new ArrayList<GraphPath>();

    // The list of options specifying various modes, banned routes, etc to try for multiple
    // itineraries
    Queue<TraverseOptions> optionQueue = new LinkedList<TraverseOptions>();
    optionQueue.add(options);

    /* if the user wants to travel by transit, create a bus-only set of options */
    if (options.getModes().getTrainish() && options.getModes().contains(TraverseMode.BUS)) {
      TraverseOptions busOnly = options.clone();
      busOnly.setModes(options.getModes().clone());
      busOnly.getModes().setTrainish(false);
      // Moved inside block to avoid double insertion in list ? (AMB)
      // optionQueue.add(busOnly);
    }

    double maxWeight = Double.MAX_VALUE;
    long maxTime = options.isArriveBy() ? 0 : Long.MAX_VALUE;
    while (paths.size() < nItineraries) {
      options = optionQueue.poll();
      if (options == null) {
        break;
      }
      StateEditor editor = new StateEditor(origin, null);
      editor.setTraverseOptions(options);
      origin = editor.makeState();

      // options.worstTime = maxTime;
      // options.maxWeight = maxWeight;
      long searchBeginTime = System.currentTimeMillis();
      LOG.debug("BEGIN SEARCH");
      List<GraphPath> somePaths = _routingService.route(origin, target);
      LOG.debug("END SEARCH {} msec", System.currentTimeMillis() - searchBeginTime);
      if (maxWeight == Double.MAX_VALUE) {
        /*
         * the worst trip we are willing to accept is at most twice as bad or twice as long.
         */
        if (somePaths.isEmpty()) {
          // if there is no first path, there won't be any other paths
          return null;
        }
        GraphPath path = somePaths.get(0);
        long duration = path.getDuration();
        LOG.debug("Setting max time and weight for subsequent searches.");
        LOG.debug("First path start time:  {}", path.getStartTime());
        maxTime =
            path.getStartTime() + MAX_TIME_FACTOR * (options.isArriveBy() ? -duration : duration);
        LOG.debug("First path duration:  {}", duration);
        LOG.debug("Max time set to:  {}", maxTime);
        maxWeight = path.getWeight() * MAX_WEIGHT_FACTOR;
        LOG.debug("Max weight set to:  {}", maxWeight);
      }
      if (somePaths.isEmpty()) {
        LOG.debug("NO PATHS FOUND");
        continue;
      }
      for (GraphPath path : somePaths) {
        if (!paths.contains(path)) {
          // DEBUG
          // path.dump();
          paths.add(path);
          // now, create a list of options, one with each trip in this journey banned.

          LOG.debug("New trips: {}", path.getTrips());
          TraverseOptions newOptions = options.clone();
          for (AgencyAndId trip : path.getTrips()) {
            newOptions.bannedTrips.add(trip);
          }

          if (!optionQueue.contains(newOptions)) {
            optionQueue.add(newOptions);
          }
          /*
           * // now, create a list of options, one with each route in this trip banned. //
           * the HashSet banned is not strictly necessary as the optionsQueue will //
           * already remove duplicate options, but it might be slightly faster as //
           * hashing TraverseOptions is slow. LOG.debug("New routespecs: {}",
           * path.getRouteSpecs()); for (RouteSpec spec : path.getRouteSpecs()) {
           * TraverseOptions newOptions = options.clone();
           * newOptions.bannedRoutes.add(spec); if (!optionQueue.contains(newOptions)) {
           * optionQueue.add(newOptions); } }
           */
        }
      }
      LOG.debug("{} / {} itineraries", paths.size(), nItineraries);
    }
    if (paths.size() == 0) {
      return null;
    }
    // We order the list of returned paths by the time of arrival or departure (not path duration)
    Collections.sort(paths, new PathComparator(origin.getOptions().isArriveBy()));
    return paths;
  }
  public void testHalfEdges() {
    // the shortest half-edge from the start vertex takes you down, but the shortest total path
    // is up and over

    TraverseOptions options = new TraverseOptions();

    HashSet<Edge> turns = new HashSet<Edge>(graph.getOutgoing(left));
    turns.addAll(graph.getOutgoing(leftBack));

    StreetLocation start =
        StreetLocation.createStreetLocation(
            "start",
            "start",
            cast(turns, StreetEdge.class),
            new LinearLocation(0, 0.4).getCoordinate(left.getGeometry()));

    HashSet<Edge> endTurns = new HashSet<Edge>(graph.getOutgoing(right));
    endTurns.addAll(graph.getOutgoing(rightBack));

    StreetLocation end =
        StreetLocation.createStreetLocation(
            "end",
            "end",
            cast(endTurns, StreetEdge.class),
            new LinearLocation(0, 0.8).getCoordinate(right.getGeometry()));

    assertTrue(start.getX() < end.getX());
    assertTrue(start.getY() < end.getY());

    List<DirectEdge> extra = end.getExtra();

    assertEquals(12, extra.size());

    GregorianCalendar startTime = new GregorianCalendar(2009, 11, 1, 12, 34, 25);

    ShortestPathTree spt1 =
        AStar.getShortestPathTree(graph, brOut, end, TestUtils.toSeconds(startTime), options);

    GraphPath pathBr = spt1.getPath(end, false);
    assertNotNull("There must be a path from br to end", pathBr);

    ShortestPathTree spt2 =
        AStar.getShortestPathTree(graph, trOut, end, TestUtils.toSeconds(startTime), options);

    GraphPath pathTr = spt2.getPath(end, false);
    assertNotNull("There must be a path from tr to end", pathTr);
    assertTrue(
        "path from bottom to end must be longer than path from top to end",
        pathBr.getWeight() > pathTr.getWeight());

    ShortestPathTree spt =
        AStar.getShortestPathTree(graph, start, end, TestUtils.toSeconds(startTime), options);

    GraphPath path = spt.getPath(end, false);
    assertNotNull("There must be a path from start to end", path);

    // the bottom is not part of the shortest path
    for (State s : path.states) {
      assertNotSame(s.getVertex(), graph.getVertex("bottom"));
      assertNotSame(s.getVertex(), graph.getVertex("bottomBack"));
    }

    startTime = new GregorianCalendar(2009, 11, 1, 12, 34, 25);

    options.setArriveBy(true);
    spt = AStar.getShortestPathTree(graph, start, end, TestUtils.toSeconds(startTime), options);

    path = spt.getPath(start, false);
    assertNotNull("There must be a path from start to end (looking back)", path);

    // the bottom edge is not part of the shortest path
    for (State s : path.states) {
      assertNotSame(s.getVertex(), graph.getVertex("bottom"));
      assertNotSame(s.getVertex(), graph.getVertex("bottomBack"));
    }

    /* Now, the right edge is not bikeable.  But the user can walk their bike.  So here are some tests
     * that prove (a) that walking bikes works, but that (b) it is not preferred to riding a tiny bit longer.
     */

    options = new TraverseOptions(new TraverseModeSet(TraverseMode.BICYCLE));
    start =
        StreetLocation.createStreetLocation(
            "start1",
            "start1",
            cast(turns, StreetEdge.class),
            new LinearLocation(0, 0.95).getCoordinate(top.getGeometry()));
    end =
        StreetLocation.createStreetLocation(
            "end1",
            "end1",
            cast(turns, StreetEdge.class),
            new LinearLocation(0, 0.95).getCoordinate(bottom.getGeometry()));
    spt = AStar.getShortestPathTree(graph, start, end, TestUtils.toSeconds(startTime), options);

    path = spt.getPath(start, false);
    assertNotNull("There must be a path from top to bottom along the right", path);

    // the left edge is not part of the shortest path (even though the bike must be walked along the
    // right)
    for (State s : path.states) {
      assertNotSame(s.getVertex(), graph.getVertex("left"));
      assertNotSame(s.getVertex(), graph.getVertex("leftBack"));
    }

    start =
        StreetLocation.createStreetLocation(
            "start2",
            "start2",
            cast(turns, StreetEdge.class),
            new LinearLocation(0, 0.55).getCoordinate(top.getGeometry()));
    end =
        StreetLocation.createStreetLocation(
            "end2",
            "end2",
            cast(turns, StreetEdge.class),
            new LinearLocation(0, 0.55).getCoordinate(bottom.getGeometry()));
    spt = AStar.getShortestPathTree(graph, start, end, TestUtils.toSeconds(startTime), options);

    path = spt.getPath(start, false);
    assertNotNull("There must be a path from top to bottom", path);

    // the right edge is not part of the shortest path, e
    for (State s : path.states) {
      assertNotSame(s.getVertex(), graph.getVertex("right"));
      assertNotSame(s.getVertex(), graph.getVertex("rightBack"));
    }
  }