osrm-backend/src/extractor/guidance/sliproad_handler.cpp

#include "extractor/guidance/sliproad_handler.hpp"
#include "extractor/guidance/constants.hpp"
#include "util/bearing.hpp"
#include "util/coordinate_calculation.hpp"
#include "util/guidance/name_announcements.hpp"

#include <algorithm>
#include <cmath>
#include <iterator>
#include <limits>

#include <boost/assert.hpp>

using osrm::extractor::guidance::getTurnDirection;
using osrm::util::angularDeviation;

namespace osrm
{
namespace extractor
{
namespace guidance
{

SliproadHandler::SliproadHandler(const IntersectionGenerator &intersection_generator,
                                 const util::NodeBasedDynamicGraph &node_based_graph,
                                 const std::vector<QueryNode> &node_info_list,
                                 const util::NameTable &name_table,
                                 const SuffixTable &street_name_suffix_table)
    : IntersectionHandler(node_based_graph,
                          node_info_list,
                          name_table,
                          street_name_suffix_table,
                          intersection_generator)
{
}

// The intersection has to connect a Sliproad, see the example scenario below:
// Intersection at `d`: Sliproad `bd` connecting `cd` and the road starting at `d`.
bool SliproadHandler::canProcess(const NodeID /*nid*/,
                                 const EdgeID /*via_eid*/,
                                 const Intersection &intersection) const
{
    return intersection.size() > 2;
}

// Detect sliproad b-d in the following example:
//
//       .
//       e
//       .
//       .
// a ... b .... c .
//       `      .
//         `    .
//           `  .
//              d
//              .
//
// ^ a nid
//    ^ ab source_edge_id
//       ^ b intersection
Intersection SliproadHandler::
operator()(const NodeID /*nid*/, const EdgeID source_edge_id, Intersection intersection) const
{
    BOOST_ASSERT(intersection.size() > 2);

    // Potential splitting / start of a Sliproad (b)
    auto intersection_node_id = node_based_graph.GetTarget(source_edge_id);

    // Road index prefering non-sliproads (bc)
    auto obvious = getObviousIndexWithSliproads(source_edge_id, intersection, intersection_node_id);

    if (!obvious)
    {
        return intersection;
    }

    // Potential non-sliproad road (bc), leading to the intersection (c) the Sliproad (bd) shortcuts
    const auto &main_road = intersection[*obvious];

    // The road leading to the intersection (bc) has to continue from our source
    if (!roadContinues(source_edge_id, main_road.eid))
    {
        return intersection;
    }

    // Link-check for (bc) and later on (cd) which both are getting shortcutted by Sliproad
    const auto is_potential_link = [this, main_road](const ConnectedRoad &road) {
        if (!road.entry_allowed)
        {
            return false;
        }

        // Prevent from starting in or going onto a roundabout
        auto onto_roundabout = hasRoundaboutType(road.instruction);

        if (onto_roundabout)
        {
            return false;
        }

        // Narrow turn angle for road (bd) and guard against data issues (overlapping roads)
        auto is_narrow = angularDeviation(road.angle, STRAIGHT_ANGLE) <= 2 * NARROW_TURN_ANGLE;
        auto same_angle = angularDeviation(main_road.angle, road.angle) //
                          <= std::numeric_limits<double>::epsilon();

        if (!is_narrow || same_angle)
        {
            return false;
        }

        const auto &road_data = node_based_graph.GetEdgeData(road.eid);

        auto is_roundabout = road_data.roundabout;

        if (is_roundabout)
        {
            return false;
        }

        return true;
    };

    if (!std::any_of(begin(intersection), end(intersection), is_potential_link))
    {
        return intersection;
    }

    // If the intersection is too far away, don't bother continuing
    if (nextIntersectionIsTooFarAway(intersection_node_id, main_road.eid))
    {
        return intersection;
    }

    // Try to find the intersection at (c) which the Sliproad shortcuts
    const auto main_road_intersection = getNextIntersection(intersection_node_id, main_road.eid);

    if (!main_road_intersection)
    {
        return intersection;
    }

    if (main_road_intersection->intersection.isDeadEnd())
    {
        return intersection;
    }

    // If we are at a traffic loop at the end of a road, don't consider it a sliproad
    if (intersection_node_id == main_road_intersection->node)
    {
        return intersection;
    }

    std::vector<NameID> target_road_name_ids;
    target_road_name_ids.reserve(main_road_intersection->intersection.size());

    for (const auto &road : main_road_intersection->intersection)
    {
        const auto &target_data = node_based_graph.GetEdgeData(road.eid);
        target_road_name_ids.push_back(target_data.name_id);
    }

    auto sliproad_found = false;

    // For all roads at the main intersection except the UTurn road: check Sliproad scenarios.
    for (std::size_t road_index = 1, last = intersection.size(); road_index < last; ++road_index)
    {
        const auto index_left_of_main_road = (*obvious - 1) % intersection.size();
        const auto index_right_of_main_road = (*obvious + 1) % intersection.size();

        // Be strict and require the Sliproad to be either left or right of the main road.
        if (road_index != index_left_of_main_road && road_index != index_right_of_main_road)
            continue;

        auto &sliproad = intersection[road_index]; // this is what we're checking and assigning to
        const auto &sliproad_data = node_based_graph.GetEdgeData(sliproad.eid);

        // Intersection is orderd: 0 is UTurn, then from sharp right to sharp left.
        // We already have an obvious index (bc) for going straight-ish.
        const auto is_right_sliproad_turn = road_index < *obvious;
        const auto is_left_sliproad_turn = road_index > *obvious;

        // Road at the intersection the main road leads onto which the sliproad arrives onto
        const auto crossing_road = [&] {
            if (is_left_sliproad_turn)
                return main_road_intersection->intersection.getLeftmostRoad();

            BOOST_ASSERT_MSG(is_right_sliproad_turn,
                             "Sliproad is neither a left nor right of obvious main road");
            return main_road_intersection->intersection.getRightmostRoad();
        }();

        const auto &crossing_road_data = node_based_graph.GetEdgeData(crossing_road.eid);

        // The crossing road at the main road's intersection must not be incoming-only
        if (crossing_road_data.reversed)
        {
            continue;
        }

        // Discard service and other low priority roads - never Sliproad candidate
        if (sliproad_data.road_classification.IsLowPriorityRoadClass())
        {
            continue;
        }

        // Incoming-only can never be a Sliproad
        if (sliproad_data.reversed)
        {
            continue;
        }

        // This is what we know so far:
        //
        //       .
        //       e
        //       .
        //       .
        // a ... b .... c .   < `main_road_intersection` is intersection at `c`
        //       `      .
        //         `    .
        //           `  .
        //              d     < `target_intersection` is intersection at `d`
        //              .       `sliproad_edge_target` is node `d`
        //              e
        //
        //
        //          ^ `sliproad` is `bd`
        //       ^ `intersection` is intersection at `b`

        if (!is_potential_link(sliproad))
        {
            continue;
        }

        // The Sliproad graph edge - in the following we use the graph walker to
        // adjust this edge forward jumping over artificial intersections.
        auto sliproad_edge = sliproad.eid;

        // Starting out at the intersection and going onto the Sliproad we skip artificial
        // degree two intersections and limit the max hop count in doing so.
        IntersectionFinderAccumulator intersection_finder{10, intersection_generator};
        const SkipTrafficSignalBarrierRoadSelector road_selector{};
        (void)graph_walker.TraverseRoad(intersection_node_id, // start node
                                        sliproad_edge,        // onto edge
                                        intersection_finder,  // accumulator
                                        road_selector);       // selector

        sliproad_edge = intersection_finder.via_edge_id;
        const auto target_intersection = intersection_finder.intersection;

        // Constrain the Sliproad's target to sliproad, outgoing, incoming from main intersection
        if (target_intersection.size() != 3)
        {
            continue;
        }

        const NodeID sliproad_edge_target = node_based_graph.GetTarget(sliproad_edge);

        // Distinct triangle nodes `bcd`
        if (intersection_node_id == main_road_intersection->node ||
            intersection_node_id == sliproad_edge_target ||
            main_road_intersection->node == sliproad_edge_target)
        {
            continue;
        }

        // If the sliproad candidate is a through street, we cannot handle it as a sliproad.
        if (isThroughStreet(sliproad_edge, target_intersection))
        {
            continue;
        }

        // The turn off of the Sliproad has to be obvious and a narrow turn and must not be a
        // roundabout
        {
            const auto index = findObviousTurn(sliproad_edge, target_intersection);

            if (index == 0)
            {
                continue;
            }

            const auto onto = target_intersection[index];
            const auto angle_deviation = angularDeviation(onto.angle, STRAIGHT_ANGLE);
            const auto is_narrow_turn = angle_deviation <= 2 * NARROW_TURN_ANGLE;

            if (!is_narrow_turn)
            {
                continue;
            }

            const auto &onto_data = node_based_graph.GetEdgeData(onto.eid);

            if (onto_data.roundabout)
            {
                continue;
            }
        }

        // Check for curvature. Depending on the turn's direction at `c`. Scenario for right turn:
        //
        // a ... b .... c .   a ... b .... c .   a ... b .... c .
        //       `      .           `  .   .             .    .
        //         `    .                . .           .      .
        //           `  .                 ..             .    .
        //              d                  d                . d
        //
        //                    Sliproad           Not a Sliproad
        {
            const auto &coordinate_extractor = intersection_generator.GetCoordinateExtractor();

            const NodeID start = intersection_node_id; // b
            const EdgeID edge = sliproad_edge;         // bd

            const auto coords = coordinate_extractor.GetForwardCoordinatesAlongRoad(start, edge);

            // due to filtering of duplicated coordinates, we can end up with empty segments.
            // this can only happen as long as
            // https://github.com/Project-OSRM/osrm-backend/issues/3470 persists
            if (coords.size() < 2)
                continue;
            BOOST_ASSERT(coords.size() >= 2);

            // Now keep start and end coordinate fix and check for curvature
            const auto start_coord = coords.front();
            const auto end_coord = coords.back();

            const auto first = std::begin(coords) + 1;
            const auto last = std::end(coords) - 1;

            auto snuggles = false;

            using namespace util::coordinate_calculation;

            // In addition, if it's a right/left turn we expect the rightmost/leftmost
            // turn at `c` to be more or less ~90 degree for a Sliproad scenario.
            double deviation_from_straight = 0;

            if (is_right_sliproad_turn)
            {
                snuggles = std::all_of(first, last, [=](auto each) { //
                    return !isCCW(start_coord, each, end_coord);
                });

                const auto rightmost = main_road_intersection->intersection.getRightmostRoad();
                deviation_from_straight = angularDeviation(rightmost.angle, STRAIGHT_ANGLE);
            }
            else if (is_left_sliproad_turn)
            {
                snuggles = std::all_of(first, last, [=](auto each) { //
                    return isCCW(start_coord, each, end_coord);
                });

                const auto leftmost = main_road_intersection->intersection.getLeftmostRoad();
                deviation_from_straight = angularDeviation(leftmost.angle, STRAIGHT_ANGLE);
            }

            // The data modelling for small Sliproads is not reliable enough.
            // Only check for curvature and ~90 degree when it makes sense to do so.
            const constexpr auto MIN_LENGTH = 3.;

            const auto length = haversineDistance(node_info_list[intersection_node_id],
                                                  node_info_list[main_road_intersection->node]);

            const double perpendicular_angle = 90 + FUZZY_ANGLE_DIFFERENCE;

            if (length >= MIN_LENGTH)
            {
                if (!snuggles)
                {
                    continue;
                }

                if (deviation_from_straight > perpendicular_angle)
                {
                    continue;
                }
            }
        }

        // Check for area under triangle `bdc`.
        //
        // a ... b .... c .
        //       `      .
        //         `    .
        //           `  .
        //              d
        //
        const auto area_threshold = std::pow(
            scaledThresholdByRoadClass(MAX_SLIPROAD_THRESHOLD, sliproad_data.road_classification),
            2.);

        if (!isValidSliproadArea(area_threshold,
                                 intersection_node_id,
                                 main_road_intersection->node,
                                 sliproad_edge_target))
        {
            continue;
        }

        // Check all roads at `d` if one is connected to `c`, is so `bd` is Sliproad.
        for (const auto &candidate_road : target_intersection)
        {
            const auto &candidate_data = node_based_graph.GetEdgeData(candidate_road.eid);

            // Name mismatch: check roads at `c` and `d` for same name
            const auto name_mismatch = [&](const NameID road_name_id) {
                const auto unnamed = road_name_id == EMPTY_NAMEID;

                return unnamed ||
                       util::guidance::requiresNameAnnounced(road_name_id,              //
                                                             candidate_data.name_id,    //
                                                             name_table,                //
                                                             street_name_suffix_table); //

            };

            const auto candidate_road_name_mismatch = std::all_of(begin(target_road_name_ids), //
                                                                  end(target_road_name_ids),   //
                                                                  name_mismatch);              //

            if (candidate_road_name_mismatch)
            {
                continue;
            }

            // If the Sliproad `bd` is a link, `bc` and `cd` must not be links.
            if (!isValidSliproadLink(sliproad, main_road, candidate_road))
            {
                continue;
            }

            if (node_based_graph.GetTarget(candidate_road.eid) == main_road_intersection->node)
            {
                sliproad.instruction.type = TurnType::Sliproad;
                sliproad_found = true;
                break;
            }
            else
            {
                const auto skip_traffic_light_intersection = intersection_generator(
                    node_based_graph.GetTarget(sliproad_edge), candidate_road.eid);
                if (skip_traffic_light_intersection.isTrafficSignalOrBarrier() &&
                    node_based_graph.GetTarget(skip_traffic_light_intersection[1].eid) ==
                        main_road_intersection->node)
                {

                    sliproad.instruction.type = TurnType::Sliproad;
                    sliproad_found = true;
                    break;
                }
            }
        }
    }

    // Now in case we found a Sliproad and assigned the corresponding type to the road,
    // it could be that the intersection from which the Sliproad splits off was a Fork before.
    // In those cases the obvious non-Sliproad is now obvious and we discard the Fork turn type.
    if (sliproad_found && main_road.instruction.type == TurnType::Fork)
    {
        const auto &source_edge_data = node_based_graph.GetEdgeData(source_edge_id);
        const auto &main_road_data = node_based_graph.GetEdgeData(main_road.eid);

        const auto same_name = source_edge_data.name_id != EMPTY_NAMEID && //
                               main_road_data.name_id != EMPTY_NAMEID &&   //
                               !util::guidance::requiresNameAnnounced(source_edge_data.name_id,
                                                                      main_road_data.name_id,
                                                                      name_table,
                                                                      street_name_suffix_table); //

        if (same_name)
        {
            if (angularDeviation(main_road.angle, STRAIGHT_ANGLE) < 5)
                intersection[*obvious].instruction.type = TurnType::Suppressed;
            else
                intersection[*obvious].instruction.type = TurnType::Continue;
            intersection[*obvious].instruction.direction_modifier =
                getTurnDirection(intersection[*obvious].angle);
        }
        else if (main_road_data.name_id != EMPTY_NAMEID)
        {
            intersection[*obvious].instruction.type = TurnType::NewName;
            intersection[*obvious].instruction.direction_modifier =
                getTurnDirection(intersection[*obvious].angle);
        }
        else
        {
            intersection[*obvious].instruction.type = TurnType::Suppressed;
        }
    }

    return intersection;
}

// Implementation details

boost::optional<std::size_t> SliproadHandler::getObviousIndexWithSliproads(
    const EdgeID from, const Intersection &intersection, const NodeID at) const
{
    BOOST_ASSERT(from != SPECIAL_EDGEID);
    BOOST_ASSERT(at != SPECIAL_NODEID);

    // If a turn is obvious without taking Sliproads into account use this
    const auto index = findObviousTurn(from, intersection);

    if (index != 0)
    {
        return boost::make_optional(index);
    }

    // Otherwise check if the road is forking into two and one of them is a Sliproad;
    // then the non-Sliproad is the obvious one.
    if (intersection.size() != 3)
    {
        return boost::none;
    }

    const auto forking = intersection[1].instruction.type == TurnType::Fork &&
                         intersection[2].instruction.type == TurnType::Fork;

    if (!forking)
    {
        return boost::none;
    }

    const auto first = getNextIntersection(at, intersection.getRightmostRoad().eid);
    const auto second = getNextIntersection(at, intersection.getLeftmostRoad().eid);

    if (!first || !second)
    {
        return boost::none;
    }

    if (first->intersection.isDeadEnd() || second->intersection.isDeadEnd())
    {
        return boost::none;
    }

    // In case of loops at the end of the road, we will arrive back at the intersection
    // itself. If that is the case, the road is obviously not a sliproad.
    if (canBeTargetOfSliproad(first->intersection) && at != second->node)
    {
        return boost::make_optional(std::size_t{2});
    }

    if (canBeTargetOfSliproad(second->intersection) && at != first->node)
    {
        return boost::make_optional(std::size_t{1});
    }

    return boost::none;
}

bool SliproadHandler::nextIntersectionIsTooFarAway(const NodeID start, const EdgeID onto) const
{
    BOOST_ASSERT(start != SPECIAL_NODEID);
    BOOST_ASSERT(onto != SPECIAL_EDGEID);

    const auto &coordinate_extractor = intersection_generator.GetCoordinateExtractor();

    // Base max distance threshold on the current road class we're on
    const auto &data = node_based_graph.GetEdgeData(onto);
    const auto threshold = scaledThresholdByRoadClass(MAX_SLIPROAD_THRESHOLD, // <- scales down
                                                      data.road_classification);

    DistanceToNextIntersectionAccumulator accumulator{
        coordinate_extractor, node_based_graph, threshold};
    const SkipTrafficSignalBarrierRoadSelector selector{};

    (void)graph_walker.TraverseRoad(start, onto, accumulator, selector);

    return accumulator.too_far_away;
}

bool SliproadHandler::isThroughStreet(const EdgeID from, const IntersectionView &intersection) const
{
    BOOST_ASSERT(from != SPECIAL_EDGEID);
    BOOST_ASSERT(!intersection.empty());

    const auto &edge_name_id = node_based_graph.GetEdgeData(from).name_id;

    auto first = begin(intersection) + 1; // Skip UTurn road
    auto last = end(intersection);

    auto same_name = [&](const auto &road) {
        const auto &road_name_id = node_based_graph.GetEdgeData(road.eid).name_id;

        return edge_name_id != EMPTY_NAMEID && //
               road_name_id != EMPTY_NAMEID && //
               !util::guidance::requiresNameAnnounced(edge_name_id,
                                                      road_name_id,
                                                      name_table,
                                                      street_name_suffix_table); //
    };

    return std::find_if(first, last, same_name) != last;
}

bool SliproadHandler::roadContinues(const EdgeID current, const EdgeID next) const
{
    const auto &current_data = node_based_graph.GetEdgeData(current);
    const auto &next_data = node_based_graph.GetEdgeData(next);

    auto same_road_category = current_data.road_classification == next_data.road_classification;
    auto same_travel_mode = current_data.travel_mode == next_data.travel_mode;

    auto same_name = current_data.name_id != EMPTY_NAMEID && //
                     next_data.name_id != EMPTY_NAMEID &&    //
                     !util::guidance::requiresNameAnnounced(current_data.name_id,
                                                            next_data.name_id,
                                                            name_table,
                                                            street_name_suffix_table); //

    const auto continues = same_road_category && same_travel_mode && same_name;
    return continues;
}

bool SliproadHandler::isValidSliproadArea(const double max_area,
                                          const NodeID a,
                                          const NodeID b,
                                          const NodeID c) const

{
    using namespace util::coordinate_calculation;

    const auto first = node_info_list[a];
    const auto second = node_info_list[b];
    const auto third = node_info_list[c];

    const auto length = haversineDistance(first, second);
    const auto heigth = haversineDistance(second, third);

    const auto area = (length * heigth) / 2.;

    // Everything below is data issue - there are some weird situations where
    // nodes are really close to each other and / or tagging ist just plain off.
    const constexpr auto MIN_SLIPROAD_AREA = 3.;

    if (area < MIN_SLIPROAD_AREA || area > max_area)
    {
        return false;
    }

    return true;
}

bool SliproadHandler::isValidSliproadLink(const IntersectionViewData &sliproad,
                                          const IntersectionViewData &first,
                                          const IntersectionViewData &second) const
{
    // If the Sliproad is not a link we don't care
    const auto &sliproad_data = node_based_graph.GetEdgeData(sliproad.eid);
    if (!sliproad_data.road_classification.IsLinkClass())
    {
        return true;
    }

    // otherwise neither the first road leading to the intersection we shortcut
    const auto &first_road_data = node_based_graph.GetEdgeData(first.eid);
    if (first_road_data.road_classification.IsLinkClass())
    {
        return false;
    }

    // nor the second road coming from the intersection we shotcut must be links
    const auto &second_road_data = node_based_graph.GetEdgeData(second.eid);
    if (second_road_data.road_classification.IsLinkClass())
    {
        return false;
    }

    return true;
}

bool SliproadHandler::canBeTargetOfSliproad(const IntersectionView &intersection)
{
    // Example to handle:
    //       .
    // a . . b .
    //  `    .
    //    `  .
    //       c    < intersection
    //       .
    //

    // One outgoing two incoming
    if (intersection.size() != 3)
    {
        return false;
    }

    const auto backwards = intersection[0].entry_allowed;
    const auto multiple_allowed = intersection[1].entry_allowed && intersection[2].entry_allowed;

    if (backwards || multiple_allowed)
    {
        return false;
    }

    return true;
}

double SliproadHandler::scaledThresholdByRoadClass(const double max_threshold,
                                                   const RoadClassification &classification)
{
    double factor = 1.0;

    switch (classification.GetPriority())
    {
    case RoadPriorityClass::MOTORWAY:
        factor = 1.0;
        break;
    case RoadPriorityClass::TRUNK:
        factor = 0.8;
        break;
    case RoadPriorityClass::PRIMARY:
        factor = 0.8;
        break;
    case RoadPriorityClass::SECONDARY:
        factor = 0.6;
        break;
    case RoadPriorityClass::TERTIARY:
        factor = 0.5;
        break;
    case RoadPriorityClass::MAIN_RESIDENTIAL:
        factor = 0.4;
        break;
    case RoadPriorityClass::SIDE_RESIDENTIAL:
        factor = 0.3;
        break;
    case RoadPriorityClass::LINK_ROAD:
        factor = 0.3;
        break;
    case RoadPriorityClass::CONNECTIVITY:
        factor = 0.1;
        break;

    // What
    case RoadPriorityClass::BIKE_PATH:
    case RoadPriorityClass::FOOT_PATH:
    default:
        factor = 0.1;
    }

    const auto scaled = max_threshold * factor;

    BOOST_ASSERT(scaled <= max_threshold);
    return scaled;
}

} // namespace guidance
} // namespace extractor
} // namespace osrm