#ifndef SLACOMMON_HPP
#define SLACOMMON_HPP

#include <memory>
#include <vector>
#include <numeric>
#include <functional>
#include <Eigen/Geometry>

#include "SLASpatIndex.hpp"

#include <libslic3r/ExPolygon.hpp>
#include <libslic3r/TriangleMesh.hpp>

// #define SLIC3R_SLA_NEEDS_WINDTREE

namespace Slic3r {
    
// Typedefs from Point.hpp
typedef Eigen::Matrix<float, 3, 1, Eigen::DontAlign> Vec3f;
typedef Eigen::Matrix<double, 3, 1, Eigen::DontAlign> Vec3d;
typedef Eigen::Matrix<int, 4, 1, Eigen::DontAlign> Vec4i;

namespace sla {
    
// An enum to keep track of where the current points on the ModelObject came from.
enum class PointsStatus {
    NoPoints,           // No points were generated so far.
    Generating,     // The autogeneration algorithm triggered, but not yet finished.
    AutoGenerated,  // Points were autogenerated (i.e. copied from the backend).
    UserModified    // User has done some edits.
};

struct SupportPoint
{
    Vec3f pos;
    float head_front_radius;
    bool  is_new_island;

    SupportPoint()
        : pos(Vec3f::Zero()), head_front_radius(0.f), is_new_island(false)
    {}

    SupportPoint(float pos_x,
                 float pos_y,
                 float pos_z,
                 float head_radius,
                 bool  new_island)
        : pos(pos_x, pos_y, pos_z)
        , head_front_radius(head_radius)
        , is_new_island(new_island)
    {}

    SupportPoint(Vec3f position, float head_radius, bool new_island)
        : pos(position)
        , head_front_radius(head_radius)
        , is_new_island(new_island)
    {}

    SupportPoint(Eigen::Matrix<float, 5, 1, Eigen::DontAlign> data)
        : pos(data(0), data(1), data(2))
        , head_front_radius(data(3))
        , is_new_island(data(4) != 0.f)
    {}

    bool operator==(const SupportPoint &sp) const
    {
        float rdiff = std::abs(head_front_radius - sp.head_front_radius);
        return (pos == sp.pos) && rdiff < float(EPSILON) &&
               is_new_island == sp.is_new_island;
    }
    
    bool operator!=(const SupportPoint &sp) const { return !(sp == (*this)); }

    template<class Archive> void serialize(Archive &ar)
    {
        ar(pos, head_front_radius, is_new_island);
    }
};

using SupportPoints = std::vector<SupportPoint>;

struct Contour3D;

/// An index-triangle structure for libIGL functions. Also serves as an
/// alternative (raw) input format for the SLASupportTree.
//  Implemented in SLASupportTreeIGL.cpp
class EigenMesh3D {
    class AABBImpl;

    Eigen::MatrixXd m_V;
    Eigen::MatrixXi m_F;
    double m_ground_level = 0, m_gnd_offset = 0;

    std::unique_ptr<AABBImpl> m_aabb;
public:

    EigenMesh3D(const TriangleMesh&);
    EigenMesh3D(const EigenMesh3D& other);
    EigenMesh3D(const Contour3D &other);
    EigenMesh3D& operator=(const EigenMesh3D&);

    ~EigenMesh3D();

    inline double ground_level() const { return m_ground_level + m_gnd_offset; }
    inline void ground_level_offset(double o) { m_gnd_offset = o; }
    inline double ground_level_offset() const { return m_gnd_offset; }

    inline const Eigen::MatrixXd& V() const { return m_V; }
    inline const Eigen::MatrixXi& F() const { return m_F; }

    // Result of a raycast
    class hit_result {
        double m_t = std::nan("");
        int m_face_id = -1;
        const EigenMesh3D *m_mesh = nullptr;
        Vec3d m_dir;
        Vec3d m_source;
        friend class EigenMesh3D;

        // A valid object of this class can only be obtained from
        // EigenMesh3D::query_ray_hit method.
        explicit inline hit_result(const EigenMesh3D& em): m_mesh(&em) {}
    public:

        // This can create a placeholder object which is invalid (not created
        // by a query_ray_hit call) but the distance can be preset to
        // a specific value for distinguishing the placeholder.
        inline hit_result(double val = std::nan("")): m_t(val) {}

        inline double distance() const { return m_t; }
        inline const Vec3d& direction() const { return m_dir; }
        inline Vec3d position() const { return m_source + m_dir * m_t; }
        inline int face() const { return m_face_id; }
        inline bool is_valid() const { return m_mesh != nullptr; }

        // Hit_result can decay into a double as the hit distance.
        inline operator double() const { return distance(); }

        inline Vec3d normal() const {
            if(m_face_id < 0 || !is_valid()) return {};
            auto trindex    = m_mesh->m_F.row(m_face_id);
            const Vec3d& p1 = m_mesh->V().row(trindex(0));
            const Vec3d& p2 = m_mesh->V().row(trindex(1));
            const Vec3d& p3 = m_mesh->V().row(trindex(2));
            Eigen::Vector3d U = p2 - p1;
            Eigen::Vector3d V = p3 - p1;
            return U.cross(V).normalized();
        }

        inline bool is_inside() {
            return m_face_id >= 0 && normal().dot(m_dir) > 0;
        }
    };

    // Casting a ray on the mesh, returns the distance where the hit occures.
    hit_result query_ray_hit(const Vec3d &s, const Vec3d &dir) const;

    class si_result {
        double m_value;
        int m_fidx;
        Vec3d m_p;
        si_result(double val, int i, const Vec3d& c):
            m_value(val), m_fidx(i), m_p(c) {}
        friend class EigenMesh3D;
    public:

        si_result() = delete;

        double value() const { return m_value; }
        operator double() const { return m_value; }
        const Vec3d& point_on_mesh() const { return m_p; }
        int F_idx() const { return m_fidx; }
    };

#ifdef SLIC3R_SLA_NEEDS_WINDTREE
    // The signed distance from a point to the mesh. Outputs the distance,
    // the index of the triangle and the closest point in mesh coordinate space.
    si_result signed_distance(const Vec3d& p) const;

    bool inside(const Vec3d& p) const;
#endif /* SLIC3R_SLA_NEEDS_WINDTREE */

    double squared_distance(const Vec3d& p, int& i, Vec3d& c) const;
    inline double squared_distance(const Vec3d &p) const
    {
        int   i;
        Vec3d c;
        return squared_distance(p, i, c);
    }
};

using PointSet = Eigen::MatrixXd;


/// Dumb vertex mesh consisting of triangles (or) quads. Capable of merging with
/// other meshes of this type and converting to and from other mesh formats.
struct Contour3D {
    Pointf3s points;
    std::vector<Vec3i> faces3;
    std::vector<Vec4i> faces4;
    
    Contour3D() = default;
    Contour3D(const TriangleMesh &trmesh);
    Contour3D(TriangleMesh &&trmesh);
    Contour3D(const EigenMesh3D  &emesh);
    
    Contour3D& merge(const Contour3D& ctr);
    Contour3D& merge(const Pointf3s& triangles);
    
    // Write the index triangle structure to OBJ file for debugging purposes.
    void to_obj(std::ostream& stream);
    void from_obj(std::istream &stream);
    
    inline bool empty() const { return points.empty() || (faces4.empty() && faces3.empty()); }
};

using ClusterEl = std::vector<unsigned>;
using ClusteredPoints = std::vector<ClusterEl>;

// Clustering a set of points by the given distance.
ClusteredPoints cluster(const std::vector<unsigned>& indices,
                        std::function<Vec3d(unsigned)> pointfn,
                        double dist,
                        unsigned max_points);

ClusteredPoints cluster(const PointSet& points,
                        double dist,
                        unsigned max_points);

ClusteredPoints cluster(
    const std::vector<unsigned>& indices,
    std::function<Vec3d(unsigned)> pointfn,
    std::function<bool(const PointIndexEl&, const PointIndexEl&)> predicate,
    unsigned max_points);


// Calculate the normals for the selected points (from 'points' set) on the
// mesh. This will call squared distance for each point.
PointSet normals(const PointSet& points,
    const EigenMesh3D& convert_mesh,
    double eps = 0.05,  // min distance from edges
    std::function<void()> throw_on_cancel = [](){},
    const std::vector<unsigned>& selected_points = {});

/// Mesh from an existing contour.
TriangleMesh to_triangle_mesh(const Contour3D& ctour);

/// Mesh from an evaporating 3D contour
TriangleMesh to_triangle_mesh(Contour3D&& ctour);

} // namespace sla
} // namespace Slic3r


#endif // SLASUPPORTTREE_HPP