#ifndef slic3r_MeshUtils_hpp_
#define slic3r_MeshUtils_hpp_

#include "libslic3r/Point.hpp"
#include "libslic3r/Geometry.hpp"
#include "libslic3r/TriangleMesh.hpp"
#include "libslic3r/AABBMesh.hpp"
#include "libslic3r/CSGMesh/TriangleMeshAdapter.hpp"
#include "libslic3r/CSGMesh/CSGMeshCopy.hpp"
#include "admesh/stl.h"

#include "slic3r/GUI/GLModel.hpp"

#include <cfloat>
#include <optional>
#include <memory>

namespace Slic3r {
namespace GUI {

struct Camera;


// lm_FIXME: Following class might possibly be replaced by Eigen::Hyperplane
class ClippingPlane
{
    std::array<double, 4> m_data;

public:
    ClippingPlane() {
        *this = ClipsNothing();
    }

    ClippingPlane(const Vec3d& direction, double offset) {
        set_normal(direction);
        set_offset(offset);
    }

    bool operator==(const ClippingPlane& cp) const {
        return m_data[0]==cp.m_data[0] && m_data[1]==cp.m_data[1] && m_data[2]==cp.m_data[2] && m_data[3]==cp.m_data[3];
    }
    bool operator!=(const ClippingPlane& cp) const { return ! (*this==cp); }

    double distance(const Vec3d& pt) const {
        // FIXME: this fails: assert(is_approx(get_normal().norm(), 1.));
        return (-get_normal().dot(pt) + m_data[3]);
    }

    bool is_point_clipped(const Vec3d& point) const { return distance(point) < 0.; }
    void set_normal(const Vec3d& normal) {
        const Vec3d norm_dir = normal.normalized();
        m_data[0] = norm_dir.x();
        m_data[1] = norm_dir.y();
        m_data[2] = norm_dir.z();
    }
    void set_offset(double offset) { m_data[3] = offset; }
    double get_offset() const { return m_data[3]; }
    Vec3d get_normal() const { return Vec3d(m_data[0], m_data[1], m_data[2]); }
    void invert_normal() { m_data[0] *= -1.0; m_data[1] *= -1.0; m_data[2] *= -1.0; }
    ClippingPlane inverted_normal() const { return ClippingPlane(-get_normal(), get_offset()); }
    bool is_active() const { return m_data[3] != DBL_MAX; }
    static ClippingPlane ClipsNothing() { return ClippingPlane(Vec3d(0., 0., 1.), DBL_MAX); }
    const std::array<double, 4>& get_data() const { return m_data; }

    // Serialization through cereal library
    template <class Archive>
    void serialize( Archive & ar ) {
        ar( m_data[0], m_data[1], m_data[2], m_data[3] );
    }
};


// MeshClipper class cuts a mesh and is able to return a triangulated cut.
class MeshClipper
{
public:
    // Set whether the cut should be triangulated and whether a cut
    // contour should be calculated and shown.
    void set_behaviour(bool fill_cut, double contour_width);
    
    // Inform MeshClipper about which plane we want to use to cut the mesh
    // This is supposed to be in world coordinates.
    void set_plane(const ClippingPlane& plane);

    // In case the object is clipped by two planes (e.g. in case of sinking
    // objects), this will be used to clip the triagnulated cut.
    // Pass ClippingPlane::ClipsNothing to turn this off.
    void set_limiting_plane(const ClippingPlane& plane);

    // Which mesh to cut. MeshClipper remembers const * to it, caller
    // must make sure that it stays valid.
    void set_mesh(const indexed_triangle_set& mesh);
    void set_mesh(AnyPtr<const indexed_triangle_set> &&ptr);

    void set_negative_mesh(const indexed_triangle_set &mesh);
    void set_negative_mesh(AnyPtr<const indexed_triangle_set> &&ptr);

    template<class It>
    void set_mesh(const Range<It> &csgrange, bool copy_meshes = false)
    {
        if (! csg::is_same(range(m_csgmesh), csgrange)) {
            m_csgmesh.clear();
            if (copy_meshes)
                csg::copy_csgrange_deep(csgrange, std::back_inserter(m_csgmesh));
            else
                csg::copy_csgrange_shallow(csgrange, std::back_inserter(m_csgmesh));

            m_result.reset();
        }
    }

    // Inform the MeshClipper about the transformation that transforms the mesh
    // into world coordinates.
    void set_transformation(const Geometry::Transformation& trafo);

    // Render the triangulated cut. Transformation matrices should
    // be set in world coords.
    void render_cut(const ColorRGBA& color);
    void render_contour(const ColorRGBA& color);

    void pass_mouse_click(const Vec3d& pt);

    bool is_projection_inside_cut(const Vec3d& point) const;
    bool has_valid_contour() const;

private:
    void recalculate_triangles();

    Geometry::Transformation m_trafo;
    AnyPtr<const indexed_triangle_set> m_mesh;
    AnyPtr<const indexed_triangle_set> m_negative_mesh;
    std::vector<csg::CSGPart> m_csgmesh;

    ClippingPlane m_plane;
    ClippingPlane m_limiting_plane = ClippingPlane::ClipsNothing();

    struct CutIsland {
        GLModel model;
        GLModel model_expanded;
        ExPolygon expoly;
        BoundingBox expoly_bb;
        bool disabled = false;
    };
    struct ClipResult {
        std::vector<CutIsland> cut_islands;
        Transform3d trafo; // this rotates the cut into world coords
    };
    std::optional<ClipResult> m_result;
    bool m_fill_cut = true;
    double m_contour_width = 0.;
};



// MeshRaycaster class answers queries such as where on the mesh someone clicked,
// whether certain points are visible or obscured by the mesh etc.
class MeshRaycaster {
public:
    explicit MeshRaycaster(std::shared_ptr<const TriangleMesh> mesh)
        : m_mesh(std::move(mesh))
        , m_emesh(*m_mesh, true) // calculate epsilon for triangle-ray intersection from an average edge length
        , m_normals(its_face_normals(m_mesh->its))
    {
        assert(m_mesh);
    }

    explicit MeshRaycaster(const TriangleMesh &mesh)
        : MeshRaycaster(std::make_unique<TriangleMesh>(mesh))
    {}

    // DEPRICATED - use CameraUtils::ray_from_screen_pos
    static void line_from_mouse_pos(const Vec2d& mouse_pos, const Transform3d& trafo, const Camera& camera,
        Vec3d& point, Vec3d& direction);

    // Given a mouse position, this returns true in case it is on the mesh.
    bool unproject_on_mesh(
        const Vec2d& mouse_pos,
        const Transform3d& trafo, // how to get the mesh into world coords
        const Camera& camera, // current camera position
        Vec3f& position, // where to save the positibon of the hit (mesh coords)
        Vec3f& normal, // normal of the triangle that was hit
        const ClippingPlane* clipping_plane = nullptr, // clipping plane (if active)
        size_t* facet_idx = nullptr // index of the facet hit
    ) const;
    
    const AABBMesh &get_aabb_mesh() const { return m_emesh; }

    bool is_valid_intersection(Vec3d point, Vec3d direction, const Transform3d& trafo) const;

    // Given a vector of points in woorld coordinates, this returns vector
    // of indices of points that are visible (i.e. not cut by clipping plane
    // or obscured by part of the mesh.
    std::vector<unsigned> get_unobscured_idxs(
        const Geometry::Transformation& trafo,  // how to get the mesh into world coords
        const Camera& camera,                   // current camera position
        const std::vector<Vec3f>& points,       // points in world coords
        const ClippingPlane* clipping_plane = nullptr // clipping plane (if active)
    ) const;

    // Returns true if the ray, built from mouse position and camera direction, intersects the mesh.
    // In this case, position and normal contain the position and normal, in model coordinates, of the intersection closest to the camera,
    // depending on the position/orientation of the clipping_plane, if specified 
    bool closest_hit(
        const Vec2d& mouse_pos,
        const Transform3d& trafo, // how to get the mesh into world coords
        const Camera& camera, // current camera position
        Vec3f& position, // where to save the positibon of the hit (mesh coords)
        Vec3f& normal, // normal of the triangle that was hit
        const ClippingPlane* clipping_plane = nullptr, // clipping plane (if active)
        size_t* facet_idx = nullptr // index of the facet hit
    ) const;

    // Given a point in world coords, the method returns closest point on the mesh.
    // The output is in mesh coords.
    // normal* can be used to also get normal of the respective triangle.
    Vec3f get_closest_point(const Vec3f& point, Vec3f* normal = nullptr) const;

    // Given a point in mesh coords, the method returns the closest facet from mesh.
    int get_closest_facet(const Vec3f &point) const;

    Vec3f get_triangle_normal(size_t facet_idx) const;

private:
    std::shared_ptr<const TriangleMesh> m_mesh;
    AABBMesh m_emesh;
    std::vector<stl_normal> m_normals;
};

struct PickingModel
{
    GLModel model;
    std::unique_ptr<MeshRaycaster> mesh_raycaster;

    void reset() {
        model.reset();
        mesh_raycaster.reset();
    }
};

} // namespace GUI
} // namespace Slic3r


#endif // slic3r_MeshUtils_hpp_