/*===========================================================================*\
 *                                                                           *
 *                            OpenVolumeMesh                                 *
 *        Copyright (C) 2011 by Computer Graphics Group, RWTH Aachen         *
 *                        www.openvolumemesh.org                             *
 *                                                                           *
 *---------------------------------------------------------------------------*
 *  This file is part of OpenVolumeMesh.                                     *
 *                                                                           *
 *  OpenVolumeMesh is free software: you can redistribute it and/or modify   *
 *  it under the terms of the GNU Lesser General Public License as           *
 *  published by the Free Software Foundation, either version 3 of           *
 *  the License, or (at your option) any later version with the              *
 *  following exceptions:                                                    *
 *                                                                           *
 *  If other files instantiate templates or use macros                       *
 *  or inline functions from this file, or you compile this file and         *
 *  link it with other files to produce an executable, this file does        *
 *  not by itself cause the resulting executable to be covered by the        *
 *  GNU Lesser General Public License. This exception does not however       *
 *  invalidate any other reasons why the executable file might be            *
 *  covered by the GNU Lesser General Public License.                        *
 *                                                                           *
 *  OpenVolumeMesh is distributed in the hope that it will be useful,        *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            *
 *  GNU Lesser General Public License for more details.                      *
 *                                                                           *
 *  You should have received a copy of the GNU LesserGeneral Public          *
 *  License along with OpenVolumeMesh.  If not,                              *
 *  see <http://www.gnu.org/licenses/>.                                      *
 *                                                                           *
\*===========================================================================*/

/*===========================================================================*\
 *                                                                           *
 *   $Revision$                                                         *
 *   $Date$                    *
 *   $LastChangedBy$                                                *
 *                                                                           *
\*===========================================================================*/

#ifndef TOPOLOGYKERNEL_HH_
#define TOPOLOGYKERNEL_HH_

#include <cassert>
#include <set>
#include <vector>

#include "BaseEntities.hh"
#include "OpenVolumeMeshHandle.hh"
#include "ResourceManager.hh"
#include "Iterators.hh"

namespace OpenVolumeMesh {

class TopologyKernel : public ResourceManager {
public:

    TopologyKernel();
    virtual ~TopologyKernel();

    /*
     * Defines and constants
     */

    static const VertexHandle   InvalidVertexHandle;
    static const EdgeHandle     InvalidEdgeHandle;
    static const FaceHandle     InvalidFaceHandle;
    static const CellHandle     InvalidCellHandle;
    static const HalfEdgeHandle InvalidHalfEdgeHandle;
    static const HalfFaceHandle InvalidHalfFaceHandle;

    typedef OpenVolumeMeshEdge Edge;
    typedef OpenVolumeMeshFace Face;
    typedef OpenVolumeMeshCell Cell;

    // Add StatusAttrib to list of friend classes
    // since it provides a garbage collection
    // that needs access to some protected methods
    friend class StatusAttrib;

    //=====================================================================
    // Iterators
    //=====================================================================

    friend class VertexOHalfEdgeIter;
    friend class HalfEdgeHalfFaceIter;
    friend class VertexCellIter;
    friend class HalfEdgeCellIter;
    friend class CellVertexIter;
    friend class CellCellIter;
    friend class HalfFaceVertexIter;
    friend class BoundaryHalfFaceHalfFaceIter;
    friend class BoundaryFaceIter;
    friend class VertexIter;
    friend class EdgeIter;
    friend class HalfEdgeIter;
    friend class FaceIter;
    friend class HalfFaceIter;
    friend class CellIter;

    /*
     * Circulators
     */

protected:
    template <class Circulator>
    static Circulator make_end_circulator(const Circulator& _circ)
    {
        Circulator end = _circ;
        if (end.valid()) {
            end.lap(_circ.max_laps());
            end.valid(false);
        }
        return end;
    }

public:

    VertexOHalfEdgeIter voh_iter(const VertexHandle& _h, int _max_laps = 1) const {
        return VertexOHalfEdgeIter(_h, this, _max_laps);
    }

    std::pair<VertexOHalfEdgeIter, VertexOHalfEdgeIter> outgoing_halfedges(const VertexHandle& _h, int _max_laps = 1) const {
        VertexOHalfEdgeIter begin = voh_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    HalfEdgeHalfFaceIter hehf_iter(const HalfEdgeHandle& _h, int _max_laps = 1) const {
        return HalfEdgeHalfFaceIter(_h, this, _max_laps);
    }

    std::pair<HalfEdgeHalfFaceIter, HalfEdgeHalfFaceIter> halfedge_halffaces(const HalfEdgeHandle& _h, int _max_laps = 1) const {
        HalfEdgeHalfFaceIter begin = hehf_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    VertexCellIter vc_iter(const VertexHandle& _h, int _max_laps = 1) const {
        return VertexCellIter(_h, this, _max_laps);
    }

    std::pair<VertexCellIter, VertexCellIter> vertex_cells(const VertexHandle& _h, int _max_laps = 1){
        VertexCellIter begin = vc_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    HalfEdgeCellIter hec_iter(const HalfEdgeHandle& _h, int _max_laps = 1) const {
        return HalfEdgeCellIter(_h, this, _max_laps);
    }

    std::pair<HalfEdgeCellIter, HalfEdgeCellIter> halfedge_cells(const HalfEdgeHandle& _h, int _max_laps = 1){
        HalfEdgeCellIter begin = hec_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    CellVertexIter cv_iter(const CellHandle& _h, int _max_laps = 1) const {
        return CellVertexIter(_h, this, _max_laps);
    }

    std::pair<CellVertexIter, CellVertexIter> cell_vertices(const CellHandle& _h, int _max_laps = 1) const {
        CellVertexIter begin = cv_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    CellCellIter cc_iter(const CellHandle& _h, int _max_laps = 1) const {
        return CellCellIter(_h, this, _max_laps);
    }

    std::pair<CellCellIter, CellCellIter> cell_cells(const CellHandle& _h, int _max_laps = 1) const {
        CellCellIter begin = cc_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    HalfFaceVertexIter hfv_iter(const HalfFaceHandle& _h, int _max_laps = 1) const {
        return HalfFaceVertexIter(_h, this, _max_laps);
    }

    std::pair<HalfFaceVertexIter, HalfFaceVertexIter> halfface_vertices(const HalfFaceHandle& _h, int _max_laps = 1) const {
        HalfFaceVertexIter begin = hfv_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    BoundaryHalfFaceHalfFaceIter bhfhf_iter(const HalfFaceHandle& _ref_h, int _max_laps = 1) const {
        return BoundaryHalfFaceHalfFaceIter(_ref_h, this, _max_laps);
    }

    std::pair<BoundaryHalfFaceHalfFaceIter, BoundaryHalfFaceHalfFaceIter> boundary_halfface_halffaces(const HalfFaceHandle& _h, int _max_laps = 1) const {
        BoundaryHalfFaceHalfFaceIter begin = bhfhf_iter(_h, _max_laps);
        return std::make_pair(begin, make_end_circulator(begin));
    }

    /*
     * Iterators
     */

    BoundaryFaceIter bf_iter() const {
        return BoundaryFaceIter(this);
    }

    VertexIter v_iter() const {
        return VertexIter(this);
    }

    VertexIter vertices_begin() const {
        return VertexIter(this, VertexHandle(0));
    }

    VertexIter vertices_end() const {
        return VertexIter(this, VertexHandle(n_vertices()));
    }

    std::pair<VertexIter, VertexIter> vertices() const {
        return std::make_pair(vertices_begin(), vertices_end());
    }

    EdgeIter e_iter() const {
        return EdgeIter(this);
    }

    EdgeIter edges_begin() const {
        return EdgeIter(this, EdgeHandle(0));
    }

    EdgeIter edges_end() const {
        return EdgeIter(this, EdgeHandle(edges_.size()));
    }

    std::pair<EdgeIter, EdgeIter> edges() const {
        return std::make_pair(edges_begin(), edges_end());
    }

    HalfEdgeIter he_iter() const {
        return HalfEdgeIter(this);
    }

    HalfEdgeIter halfedges_begin() const {
        return HalfEdgeIter(this, HalfEdgeHandle(0));
    }

    HalfEdgeIter halfedges_end() const {
        return HalfEdgeIter(this, HalfEdgeHandle(edges_.size() * 2));
    }

    std::pair<HalfEdgeIter, HalfEdgeIter> halfedges() const {
        return std::make_pair(halfedges_begin(), halfedges_end());
    }

    FaceIter f_iter() const {
        return FaceIter(this);
    }

    FaceIter faces_begin() const {
        return FaceIter(this, FaceHandle(0));
    }

    FaceIter faces_end() const {
        return FaceIter(this, FaceHandle(faces_.size()));
    }

    std::pair<FaceIter, FaceIter> faces() const {
        return std::make_pair(faces_begin(), faces_end());
    }

    HalfFaceIter hf_iter() const {
        return HalfFaceIter(this);
    }

    HalfFaceIter halffaces_begin() const {
        return HalfFaceIter(this, HalfFaceHandle(0));
    }

    HalfFaceIter halffaces_end() const {
        return HalfFaceIter(this, HalfFaceHandle(faces_.size() * 2));
    }

    std::pair<HalfFaceIter, HalfFaceIter> halffaces() const {
        return std::make_pair(halffaces_begin(), halffaces_end());
    }

    CellIter c_iter() const {
        return CellIter(this);
    }

    CellIter cells_begin() const {
        return CellIter(this, CellHandle(0));
    }

    CellIter cells_end() const {
        return CellIter(this, CellHandle(cells_.size()));
    }

    std::pair<CellIter, CellIter> cells() const {
        return std::make_pair(cells_begin(), cells_end());
    }

    /*
     * Virtual functions with implementation
     */

    /// Get number of vertices in mesh
    virtual size_t n_vertices()   const { return n_vertices_; }
    /// Get number of edges in mesh
    virtual size_t n_edges()      const { return edges_.size(); }
    /// Get number of halfedges in mesh
    virtual size_t n_halfedges()  const { return edges_.size() * 2u; }
    /// Get number of faces in mesh
    virtual size_t n_faces()      const { return faces_.size(); }
    /// Get number of halffaces in mesh
    virtual size_t n_halffaces()  const { return faces_.size() * 2u; }
    /// Get number of cells in mesh
    virtual size_t n_cells()      const { return cells_.size(); }

    int genus() const {

        int g = (1 - (n_vertices() -
                      n_edges() +
                      n_faces() -
                      n_cells()));

        if(g % 2 == 0) return (g / 2);

        // An error occured
        // The mesh might not be manifold
        return  -1;
    }

private:

    // Cache total vertex number
    size_t n_vertices_;

public:

    /// Add abstract vertex
    virtual VertexHandle add_vertex();

    //=======================================================================

    /// Add edge
    virtual EdgeHandle add_edge(const VertexHandle& _fromVertex, const VertexHandle& _toHandle, bool _allowDuplicates = false);

    /// Add face via incident edges
    ///
    /// \return Handle of the new face, InvalidFaceHandle if \a _halfedges
    ///         are not connected and \a _topologyCheck is \a true.
    ///
    /// \warning If _halfedges are not connected and \a _topologyCheck is \a false,
    ///          the behavior is undefined.
    virtual FaceHandle add_face(const std::vector<HalfEdgeHandle>& _halfedges, bool _topologyCheck = false);

    /// Add face via incident vertices
    virtual FaceHandle add_face(const std::vector<VertexHandle>& _vertices);

    /// Add cell via incident halffaces
    ///
    /// \return Handle of the new cell, InvalidCellHandle if \a _topologyCheck is \a true and
    ///         \a _halffaces are not connected.
    ///
    /// \warning If _halffaces are not connected and \a _topologyCheck is \a false,
    ///          the behavior is undefined.
    virtual CellHandle add_cell(const std::vector<HalfFaceHandle>& _halffaces, bool _topologyCheck = false);

    /// Set the vertices of an edge
    void set_edge(const EdgeHandle& _eh, const VertexHandle& _fromVertex, const VertexHandle& _toVertex);

    /// Set the half-edges of a face
    void set_face(const FaceHandle& _fh, const std::vector<HalfEdgeHandle>& _hes);

    /// Set the half-faces of a cell
    void set_cell(const CellHandle& _ch, const std::vector<HalfFaceHandle>& _hfs);

    /*
     * Non-virtual functions
     */

    /// Get edge with handle _edgeHandle
    const Edge& edge(const EdgeHandle& _edgeHandle) const;

    /// Get face with handle _faceHandle
    const Face& face(const FaceHandle& _faceHandle) const;

    /// Get cell with handle _cellHandle
    const Cell& cell(const CellHandle& _cellHandle) const;

    /// Get edge with handle _edgeHandle
    Edge& edge(const EdgeHandle& _edgeHandle);

    /// Get face with handle _faceHandle
    Face& face(const FaceHandle& _faceHandle);

    /// Get cell with handle _cellHandle
    Cell& cell(const CellHandle& _cellHandle);

    /// Get edge that corresponds to halfedge with handle _halfEdgeHandle
    Edge halfedge(const HalfEdgeHandle& _halfEdgeHandle) const;

    /// Get face that corresponds to halfface with handle _halfFaceHandle
    Face halfface(const HalfFaceHandle& _halfFaceHandle) const;

    /// Get opposite halfedge that corresponds to halfedge with handle _halfEdgeHandle
    Edge opposite_halfedge(const HalfEdgeHandle& _halfEdgeHandle) const;

    /// Get opposite halfface that corresponds to halfface with handle _halfFaceHandle
    Face opposite_halfface(const HalfFaceHandle& _halfFaceHandle) const;

    /// Get halfedge from vertex _vh1 to _vh2
    HalfEdgeHandle halfedge(const VertexHandle& _vh1, const VertexHandle& _vh2) const;

    /// Get half-face from list of incident vertices (in connected order)
    ///
    /// \note Only the first three vertices are checked
    HalfFaceHandle halfface(const std::vector<VertexHandle>& _vs) const;

    /// Get half-face from list of incident vertices (in connected order)
    ///
    /// \note All vertices are checked
    HalfFaceHandle halfface_extensive(const std::vector<VertexHandle>& _vs) const;

    /// Get half-face from list of incident half-edges
    ///
    /// \note Only the first two half-edges are checked
    HalfFaceHandle halfface(const std::vector<HalfEdgeHandle>& _hes) const;

    /// Get next halfedge within a halfface
    HalfEdgeHandle next_halfedge_in_halfface(const HalfEdgeHandle& _heh, const HalfFaceHandle& _hfh) const;

    /// Get previous halfedge within a halfface
    HalfEdgeHandle prev_halfedge_in_halfface(const HalfEdgeHandle& _heh, const HalfFaceHandle& _hfh) const;

    /// Get valence of vertex (number of incident edges)
    inline size_t valence(const VertexHandle& _vh) const {
        assert(has_vertex_bottom_up_incidences());
        assert(_vh.is_valid() && (size_t)_vh.idx() < outgoing_hes_per_vertex_.size());

        return outgoing_hes_per_vertex_[_vh.idx()].size();
    }

    /// Get valence of edge (number of incident faces)
    inline size_t valence(const EdgeHandle& _eh) const {
        assert(has_edge_bottom_up_incidences());
        assert(_eh.is_valid() && (size_t)_eh.idx() < edges_.size());
        assert((size_t)halfedge_handle(_eh, 0).idx() < incident_hfs_per_he_.size());

        return incident_hfs_per_he_[halfedge_handle(_eh, 0).idx()].size();
    }

    /// Get valence of face (number of incident edges)
    inline size_t valence(const FaceHandle& _fh) const {
        assert(_fh.is_valid() && (size_t)_fh.idx() < faces_.size());

        return face(_fh).halfedges().size();
    }

    /// Get valence of cell (number of incident faces)
    inline size_t valence(const CellHandle& _ch) const {
        assert(_ch.is_valid() && (size_t)_ch.idx() < cells_.size());

        return cell(_ch).halffaces().size();
    }

    //=====================================================================
    // Delete entities
    //=====================================================================

public:

    virtual VertexIter delete_vertex(const VertexHandle& _h);

    virtual EdgeIter delete_edge(const EdgeHandle& _h);

    virtual FaceIter delete_face(const FaceHandle& _h);

    virtual CellIter delete_cell(const CellHandle& _h);

    virtual void collect_garbage();


    virtual bool is_deleted(const VertexHandle& _h)   const { return vertex_deleted_[_h.idx()]; }
    virtual bool is_deleted(const EdgeHandle& _h)     const { return edge_deleted_[_h.idx()];   }
    virtual bool is_deleted(const HalfEdgeHandle& _h) const { return edge_deleted_[_h.idx()/2]; }
    virtual bool is_deleted(const FaceHandle& _h)     const { return face_deleted_[_h.idx()];   }
    virtual bool is_deleted(const HalfFaceHandle& _h) const { return face_deleted_[_h.idx()/2]; }
    virtual bool is_deleted(const CellHandle& _h)     const { return cell_deleted_[_h.idx()];   }

private:

    template <class ContainerT>
    void get_incident_edges(const ContainerT& _vs, std::set<EdgeHandle>& _es) const;

    template <class ContainerT>
    void get_incident_faces(const ContainerT& _es, std::set<FaceHandle>& _fs) const;

    template <class ContainerT>
    void get_incident_cells(const ContainerT& _fs, std::set<CellHandle>& _cs) const;

    VertexIter delete_vertex_core(const VertexHandle& _h);

    EdgeIter delete_edge_core(const EdgeHandle& _h);

    FaceIter delete_face_core(const FaceHandle& _h);

    CellIter delete_cell_core(const CellHandle& _h);

protected:

    virtual void swap_cells(CellHandle _h1, CellHandle _h2);

    virtual void swap_faces(FaceHandle _h1, FaceHandle _h2);

    virtual void swap_edges(EdgeHandle _h1, EdgeHandle _h2);

    virtual void swap_vertices(VertexHandle _h1, VertexHandle _h2);

    virtual void delete_multiple_vertices(const std::vector<bool>& _tag);

    virtual void delete_multiple_edges(const std::vector<bool>& _tag);

    virtual void delete_multiple_faces(const std::vector<bool>& _tag);

    virtual void delete_multiple_cells(const std::vector<bool>& _tag);

    class EdgeCorrector {
    public:
        EdgeCorrector(const std::vector<int>& _newIndices) :
            newIndices_(_newIndices) {}

        void operator()(Edge& _edge) {
            _edge.set_from_vertex(VertexHandle(newIndices_[_edge.from_vertex().idx()]));
            _edge.set_to_vertex(VertexHandle(newIndices_[_edge.to_vertex().idx()]));
        }
    private:
        const std::vector<int>& newIndices_;
    };

    class FaceCorrector {
    public:
        FaceCorrector(const std::vector<int>& _newIndices) :
            newIndices_(_newIndices) {}

        void operator()(Face& _face) {
            std::vector<HalfEdgeHandle> hes = _face.halfedges();
            for(std::vector<HalfEdgeHandle>::iterator he_it = hes.begin(),
                    he_end = hes.end(); he_it != he_end; ++he_it) {

                EdgeHandle eh = edge_handle(*he_it);
                unsigned char opp = (he_it->idx() - halfedge_handle(eh, 0).idx());
                *he_it = halfedge_handle(newIndices_[eh.idx()], opp);
            }
            _face.set_halfedges(hes);
        }
    private:
        const std::vector<int>& newIndices_;
    };

    class CellCorrector {
    public:
        CellCorrector(const std::vector<int>& _newIndices) :
            newIndices_(_newIndices) {}

        void operator()(Cell& _cell) {
            std::vector<HalfFaceHandle> hfs = _cell.halffaces();
            for(std::vector<HalfFaceHandle>::iterator hf_it = hfs.begin(),
                    hf_end = hfs.end(); hf_it != hf_end; ++hf_it) {

                FaceHandle fh = face_handle(*hf_it);
                unsigned char opp = (hf_it->idx() - halfface_handle(fh, 0).idx());
                *hf_it = halfface_handle(newIndices_[fh.idx()], opp);
            }
            _cell.set_halffaces(hfs);
        }
    private:
        const std::vector<int>& newIndices_;
    };

public:

    /** \brief Delete range of cells
     *
     * Deletes all cells in range [_first, _last].
     *
     * @param _first Iterator to first cell that is to be deleted
     * @param _last Iterator to last cell that is to be deleted
     * @return An iterator to the first cell after the deleted range
     */
    CellIter delete_cell_range(const CellIter& _first, const CellIter& _last);

public:

    /// Clear whole mesh
    virtual void clear(bool _clearProps = true) {

        edges_.clear();
        faces_.clear();
        cells_.clear();
        vertex_deleted_.clear();
        edge_deleted_.clear();
        face_deleted_.clear();
        cell_deleted_.clear();
        outgoing_hes_per_vertex_.clear();
        incident_hfs_per_he_.clear();
        incident_cell_per_hf_.clear();
        n_vertices_ = 0;

        if(_clearProps) {

            // Delete all property data
            clear_vertex_props();
            clear_edge_props();
            clear_halfedge_props();
            clear_face_props();
            clear_halfface_props();
            clear_cell_props();
            clear_mesh_props();

        } else {
            // Resize props
            resize_vprops(0u);
            resize_eprops(0u);
            resize_fprops(0u);
            resize_cprops(0u);
        }
    }

    //=====================================================================
    // Bottom-up Incidences
    //=====================================================================

public:

    void enable_bottom_up_incidences(bool _enable = true) {

        enable_vertex_bottom_up_incidences(_enable);
        enable_edge_bottom_up_incidences(_enable);
        enable_face_bottom_up_incidences(_enable);
    }

    void enable_vertex_bottom_up_incidences(bool _enable = true) {

        if(_enable && !v_bottom_up_) {
            // Vertex bottom-up incidences have to be
            // recomputed for the whole mesh
            compute_vertex_bottom_up_incidences();
        }

        if(!_enable) {
            outgoing_hes_per_vertex_.clear();
        }

        v_bottom_up_ = _enable;
    }

    void enable_edge_bottom_up_incidences(bool _enable = true) {

        if(_enable && !e_bottom_up_) {
            // Edge bottom-up incidences have to be
            // recomputed for the whole mesh
            compute_edge_bottom_up_incidences();

            if(f_bottom_up_) {
#if defined(__clang_major__) && (__clang_major__ >= 5)
                for(EdgeIter e_it = edges_begin(), e_end = edges_end();
                    e_it != e_end; ++e_it) {
                    reorder_incident_halffaces(*e_it);
                }
#else
                std::for_each(edges_begin(), edges_end(),
                              fun::bind(&TopologyKernel::reorder_incident_halffaces, this, fun::placeholders::_1));
#endif
            }
        }

        if(!_enable) {
            incident_hfs_per_he_.clear();
        }

        e_bottom_up_ = _enable;
    }

    void enable_face_bottom_up_incidences(bool _enable = true) {

        bool updateOrder = false;
        if(_enable && !f_bottom_up_) {
            // Face bottom-up incidences have to be
            // recomputed for the whole mesh
            compute_face_bottom_up_incidences();

            updateOrder = true;
        }

        if(!_enable) {
            incident_cell_per_hf_.clear();
        }

        f_bottom_up_ = _enable;

        if(updateOrder) {
            if(e_bottom_up_) {
#if defined(__clang_major__) && (__clang_major__ >= 5)
                for(EdgeIter e_it = edges_begin(), e_end = edges_end();
                    e_it != e_end; ++e_it) {
                    reorder_incident_halffaces(*e_it);
                }
#else
                std::for_each(edges_begin(), edges_end(),
                              fun::bind(&TopologyKernel::reorder_incident_halffaces, this, fun::placeholders::_1));
#endif
            }
        }
    }

    bool has_full_bottom_up_incidences() const {
        return (has_vertex_bottom_up_incidences() &&
                has_edge_bottom_up_incidences() &&
                has_face_bottom_up_incidences());
    }

    bool has_vertex_bottom_up_incidences() const { return v_bottom_up_; }

    bool has_edge_bottom_up_incidences() const { return e_bottom_up_; }

    bool has_face_bottom_up_incidences() const { return f_bottom_up_; }


    void enable_deferred_deletion(bool _enable = true);
    bool deferred_deletion_enabled() const { return deferred_deletion; }


    void enable_fast_deletion(bool _enable = true) { fast_deletion = _enable; }
    bool fast_deletion_enabled() const { return fast_deletion; }


protected:

    void compute_vertex_bottom_up_incidences();

    void compute_edge_bottom_up_incidences();

    void compute_face_bottom_up_incidences();

    void reorder_incident_halffaces(const EdgeHandle& _eh);

    // Outgoing halfedges per vertex
    std::vector<std::vector<HalfEdgeHandle> > outgoing_hes_per_vertex_;

    // Incident halffaces per (directed) halfedge
    std::vector<std::vector<HalfFaceHandle> > incident_hfs_per_he_;

    // Incident cell (at most one) per halfface
    std::vector<CellHandle> incident_cell_per_hf_;

private:
    bool v_bottom_up_;

    bool e_bottom_up_;

    bool f_bottom_up_;

    bool deferred_deletion;

    bool fast_deletion;

    //=====================================================================
    // Connectivity
    //=====================================================================

public:

    /// \brief Get halfface that is adjacent (w.r.t. a common halfedge) within the same cell
    ///
    /// \return Handle of the adjacent half-face if \a _halfFaceHandle is not
    ///         at a boundary, \a InvalidHalfFaceHandle otherwise.
    ///
    /// \warning The mesh must have face bottom-up incidences.
    HalfFaceHandle adjacent_halfface_in_cell(const HalfFaceHandle& _halfFaceHandle, const HalfEdgeHandle& _halfEdgeHandle) const;

    /// Get cell that is incident to the given halfface
    CellHandle incident_cell(const HalfFaceHandle& _halfFaceHandle) const;

    bool is_boundary(const HalfFaceHandle& _halfFaceHandle) const {

        assert(_halfFaceHandle.is_valid() && (size_t)_halfFaceHandle.idx() < faces_.size() * 2u);
        assert(has_face_bottom_up_incidences());
        assert((size_t)_halfFaceHandle.idx() < incident_cell_per_hf_.size());
        return incident_cell_per_hf_[_halfFaceHandle.idx()] == InvalidCellHandle;
    }

    bool is_boundary(const FaceHandle& _faceHandle) const {
        assert(_faceHandle.is_valid() && (size_t)_faceHandle.idx() < faces_.size());
        assert(has_face_bottom_up_incidences());
        return  is_boundary(halfface_handle(_faceHandle, 0)) ||
                is_boundary(halfface_handle(_faceHandle, 1));
    }

    bool is_boundary(const EdgeHandle& _edgeHandle) const {
        assert(has_edge_bottom_up_incidences());
        assert(_edgeHandle.is_valid() && (size_t)_edgeHandle.idx() < edges_.size());

        for(HalfEdgeHalfFaceIter hehf_it = hehf_iter(halfedge_handle(_edgeHandle, 0));
                hehf_it.valid(); ++hehf_it) {
            if(is_boundary(face_handle(*hehf_it))) {
                return true;
            }
        }
        return false;
    }

    bool is_boundary(const HalfEdgeHandle& _halfedgeHandle) const {
        assert(has_edge_bottom_up_incidences());
        assert(_halfedgeHandle.is_valid() && (size_t)_halfedgeHandle.idx() < edges_.size() * 2u);

        for(HalfEdgeHalfFaceIter hehf_it = hehf_iter(_halfedgeHandle);
                hehf_it.valid(); ++hehf_it) {
            if(is_boundary(face_handle(*hehf_it))) {
                return true;
            }
        }
        return false;
    }

    bool is_boundary(const VertexHandle& _vertexHandle) const {
        assert(has_vertex_bottom_up_incidences());
        assert(_vertexHandle.is_valid() && (size_t)_vertexHandle.idx() < n_vertices());

        for(VertexOHalfEdgeIter voh_it = voh_iter(_vertexHandle); voh_it.valid(); ++voh_it) {
            if(is_boundary(*voh_it)) return true;
        }
        return false;
    }

    size_t n_vertices_in_cell(const CellHandle& _ch) const {
        assert(_ch.is_valid() && (size_t)_ch.idx() < cells_.size());

        std::set<VertexHandle> vertices;
        std::vector<HalfFaceHandle> hfs = cell(_ch).halffaces();
        for(std::vector<HalfFaceHandle>::const_iterator hf_it = hfs.begin();
                hf_it != hfs.end(); ++hf_it) {
            std::vector<HalfEdgeHandle> hes = halfface(*hf_it).halfedges();
            for(std::vector<HalfEdgeHandle>::const_iterator he_it = hes.begin();
                he_it != hes.end(); ++he_it) {
                vertices.insert(halfedge(*he_it).to_vertex());
            }
        }
        return vertices.size();
    }

    //=========================================================================

    /*
     * Non-virtual functions
     */

    Edge opposite_halfedge(const Edge& _edge) const {
        return Edge(_edge.to_vertex(), _edge.from_vertex());
    }

    Face opposite_halfface(const Face& _face) const {
        std::vector<HalfEdgeHandle> opp_halfedges;
        for(std::vector<HalfEdgeHandle>::const_iterator it = _face.halfedges().begin(); it
                != _face.halfedges().end(); ++it) {
            opp_halfedges.insert(opp_halfedges.begin(), opposite_halfedge_handle(*it));
        }

        return Face(opp_halfedges);
    }

    /*
     * Static functions
     */

    /// Conversion function
    static inline HalfEdgeHandle halfedge_handle(const EdgeHandle& _h, const unsigned char _subIdx) {
        // Is handle in range?
        assert(_h.is_valid());
        assert(_subIdx < 2);
        // if(_h.idx() < 0 || _subIdx > 1) return InvalidHalfEdgeHandle;
        return HalfEdgeHandle((2 * _h.idx()) + (_subIdx ? 1 : 0));
    }

    /// Conversion function
    static inline HalfFaceHandle halfface_handle(const FaceHandle& _h, const unsigned char _subIdx) {
        // Is handle in range?
        assert(_h.is_valid());
        assert(_subIdx < 2);
        // if(_h.idx() < 0 || _subIdx > 1) return InvalidHalfFaceHandle;
        return HalfFaceHandle((2 * _h.idx()) + (_subIdx ? 1 : 0));
    }

    /// Handle conversion
    static inline EdgeHandle edge_handle(const HalfEdgeHandle& _h) {
        // Is handle in range?
        assert(_h.is_valid());
        // if(_h.idx() < 0) return InvalidEdgeHandle;
        return EdgeHandle((int)(_h.idx() / 2));
    }

    static inline FaceHandle face_handle(const HalfFaceHandle& _h) {
        // Is handle in range?
        assert(_h.is_valid());
        // if(_h.idx() < 0) return InvalidFaceHandle;
        return FaceHandle((int)(_h.idx() / 2));
    }

    static inline HalfEdgeHandle opposite_halfedge_handle(const HalfEdgeHandle& _h) {
        // Is handle in range?
        assert(_h.is_valid());
        // if(_h.idx() < 0) return InvalidHalfEdgeHandle;

        // Is handle even?
        if(_h.idx() % 2 == 0) {
            return HalfEdgeHandle(_h.idx() + 1);
        }
        return HalfEdgeHandle(_h.idx() - 1);
    }

    static inline HalfFaceHandle opposite_halfface_handle(const HalfFaceHandle& _h) {
        // Is handle in range?
        assert(_h.is_valid());
        // if(_h.idx() < 0) return InvalidHalfFaceHandle;

        // Is handle even?
        if(_h.idx() % 2 == 0) {
            return HalfFaceHandle(_h.idx() + 1);
        }
        return HalfFaceHandle(_h.idx() - 1);
    }

    bool inline needs_garbage_collection() const {
        return needs_garbage_collection_;
    }

protected:

    // List of edges
    std::vector<Edge> edges_;

    // List of faces
    std::vector<Face> faces_;

    // List of cells
    std::vector<Cell> cells_;

    std::vector<bool> vertex_deleted_;
    std::vector<bool> edge_deleted_;
    std::vector<bool> face_deleted_;
    std::vector<bool> cell_deleted_;
    bool needs_garbage_collection_;

};

}

#endif /* TOPOLOGYKERNEL_HH_ */