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#ifndef GEOGRAM_DELAUNAY_DELAUNAY_NN
#define GEOGRAM_DELAUNAY_DELAUNAY_NN

#include <geogram/basic/common.h>
#include <geogram/delaunay/delaunay.h>
#include <geogram/points/nn_search.h>
#include <geogram/basic/process.h>

/**
 * \file geogram/delaunay/delaunay_nn.h
 * \brief Implementation of Delaunay using nearest neighbors
 */

namespace GEO {

    /**
     * \brief Delaunay interface for NearestNeighbors search.
     * \details
     * This does not fully implement a Delaunay triangulation,
     * cell-related queries are not implemented. It only
     * implements neighborhood queries, which are the only ones
     * needed by RestrictedVoronoiDiagram with radius of security.
     */
    class GEOGRAM_API Delaunay_NearestNeighbors : public Delaunay {
    public:
        /**
         * \brief Creates a new Delaunay_NearestNeighbors.
         * \param[in] dimension the dimension of the points
         */
        Delaunay_NearestNeighbors(coord_index_t dimension);

        /**
         * \brief Stores nb neighbors with vertex i.
         * \details By default, Delaunay::default_nb_neighbors()
         *  are stored for each vertex. This function changes
         *  the number of stored neighbors for a given vertex.
         * \param[in] i index of the vertex which neighborhood should
         *  be enlarged
         * \param[in] nb new number of vertices in vertex \p i%'s neighborhood.
         */
        virtual void enlarge_neighborhood(index_t i, index_t nb);

        void set_vertices(
            index_t nb_vertices, const double* vertices
        ) override;

        index_t nearest_vertex(const double* p) const override;

        /**
         * \brief Gets the NearestNeighborSearch used internally.
         * \return a pointer to the NearestNeighborSearch.
         */
        NearestNeighborSearch* nn_search() {
            return NN_;
        }

    public:
        /**
         * \brief Used internally for parallel
         *  computation of the neighborhoods
         *  in Delaunay.
         */
        void store_neighbors_CB(index_t i) override;

    protected:
        /**
         * \brief Delaunay_NearestNeighbors destructor
         */
        ~Delaunay_NearestNeighbors() override;

        /**
         * \brief Internal implementation for get_neighbors (with vector).
         * \param[in] v index of the Delaunay vertex
         * \param[in,out] neighbors the computed neighbors of vertex \p v.
         *    Its size is used to determine the number of queried neighbors.
         */
        void get_neighbors_internal(
            index_t v, vector<index_t>& neighbors
        ) const override;

        /**
         * \brief Internal implementation for get_neighbors (with pointers).
         * \param[in] v index of the Delaunay vertex
         * \param[in] nb_neighbors required number of neighbors
         * \param[out] neighbors the computed neighbors of vertex \p v,
         *  allocated and managed by caller
         * \return the obtained number of neighbors (can be
         * smaller than nb_neighbors if duplicate points
         * are encountered)
         */
        virtual index_t get_neighbors_internal(
            index_t v, index_t nb_neighbors, index_t* neighbors
        ) const;

    private:
        NearestNeighborSearch_var NN_;
    };
}

#endif
