osrm-backend/include/engine/api/match_api.hpp

#ifndef ENGINE_API_MATCH_HPP
#define ENGINE_API_MATCH_HPP

#include "engine/api/match_parameters.hpp"
#include "engine/api/match_parameters_tidy.hpp"
#include "engine/api/route_api.hpp"

#include "engine/datafacade/datafacade_base.hpp"

#include "engine/internal_route_result.hpp"
#include "engine/map_matching/sub_matching.hpp"

#include "util/integer_range.hpp"

namespace osrm
{
namespace engine
{
namespace api
{

class MatchAPI final : public RouteAPI
{
  public:
    MatchAPI(const datafacade::BaseDataFacade &facade_,
             const MatchParameters &parameters_,
             const tidy::Result &tidy_result_)
        : RouteAPI(facade_, parameters_), parameters(parameters_), tidy_result(tidy_result_)
    {
    }

    void MakeResponse(const std::vector<map_matching::SubMatching> &sub_matchings,
                      const std::vector<InternalRouteResult> &sub_routes,
                      util::json::Object &response) const
    {
        auto number_of_routes = sub_matchings.size();
        util::json::Array routes;
        routes.values.reserve(number_of_routes);
        BOOST_ASSERT(sub_matchings.size() == sub_routes.size());
        for (auto index : util::irange<std::size_t>(0UL, sub_matchings.size()))
        {
            auto route = MakeRoute(sub_routes[index].segment_end_coordinates,
                                   sub_routes[index].unpacked_path_segments,
                                   sub_routes[index].source_traversed_in_reverse,
                                   sub_routes[index].target_traversed_in_reverse);
            route.values["confidence"] = sub_matchings[index].confidence;
            routes.values.push_back(std::move(route));
        }
        response.values["tracepoints"] = MakeTracepoints(sub_matchings);
        response.values["matchings"] = std::move(routes);
        response.values["code"] = "Ok";
    }

  protected:
    // FIXME this logic is a little backwards. We should change the output format of the
    // map_matching
    // routing algorithm to be easier to consume here.
    util::json::Array
    MakeTracepoints(const std::vector<map_matching::SubMatching> &sub_matchings) const
    {
        util::json::Array waypoints;
        waypoints.values.reserve(parameters.coordinates.size());

        struct MatchingIndex
        {
            MatchingIndex() = default;
            MatchingIndex(unsigned sub_matching_index_, unsigned point_index_)
                : sub_matching_index(sub_matching_index_), point_index(point_index_)
            {
            }

            unsigned sub_matching_index = std::numeric_limits<unsigned>::max();
            unsigned point_index = std::numeric_limits<unsigned>::max();

            bool NotMatched()
            {
                return sub_matching_index == std::numeric_limits<unsigned>::max() &&
                       point_index == std::numeric_limits<unsigned>::max();
            }
        };

        std::vector<MatchingIndex> trace_idx_to_matching_idx(parameters.coordinates.size());
        for (auto sub_matching_index :
             util::irange(0u, static_cast<unsigned>(sub_matchings.size())))
        {
            for (auto point_index : util::irange(
                     0u, static_cast<unsigned>(sub_matchings[sub_matching_index].indices.size())))
            {
                // tidied_to_original: index of the input coordinate that a tidied coordinate
                // corresponds to.
                // sub_matching indices: index of the coordinate passed to map matching plugin that
                // a matched node corresponds to.
                trace_idx_to_matching_idx[tidy_result
                                              .tidied_to_original[sub_matchings[sub_matching_index]
                                                                      .indices[point_index]]] =
                    MatchingIndex{sub_matching_index, point_index};
            }
        }

        BOOST_ASSERT(parameters.waypoints.empty() || sub_matchings.size() == 1);

        std::size_t was_waypoint_idx = 0;
        for (auto trace_index : util::irange<std::size_t>(0UL, parameters.coordinates.size()))
        {
            if (tidy_result.can_be_removed[trace_index])
            {
                waypoints.values.push_back(util::json::Null());
                continue;
            }
            auto matching_index = trace_idx_to_matching_idx[trace_index];
            if (matching_index.NotMatched())
            {
                waypoints.values.push_back(util::json::Null());
                continue;
            }
            const auto &phantom =
                sub_matchings[matching_index.sub_matching_index].nodes[matching_index.point_index];
            auto waypoint = BaseAPI::MakeWaypoint(phantom);
            waypoint.values["matchings_index"] = matching_index.sub_matching_index;
            waypoint.values["waypoint_index"] = matching_index.point_index;
            waypoint.values["alternatives_count"] =
                sub_matchings[matching_index.sub_matching_index]
                    .alternatives_count[matching_index.point_index];
            // waypoint indices need to be adjusted if route legs were collapsed
            // waypoint parameter assumes there is only one match object
            if (!parameters.waypoints.empty())
            {
                if (tidy_result.was_waypoint[trace_index])
                {
                    waypoint.values["waypoint_index"] = was_waypoint_idx;
                    was_waypoint_idx++;
                }
                else
                {
                    waypoint.values["waypoint_index"] = util::json::Null();
                }
            }
            waypoints.values.push_back(std::move(waypoint));
        }

        return waypoints;
    }

    const MatchParameters &parameters;
    const tidy::Result &tidy_result;
};

} // ns api
} // ns engine
} // ns osrm

#endif