#include <catch2/catch.hpp>

#include <libslic3r/Emboss.hpp>
#include <libslic3r/SVG.hpp> // only debug visualization

#include <optional>
#include <libslic3r/AABBTreeIndirect.hpp>
#include <libslic3r/Utils.hpp> // for next_highest_power_of_2()

using namespace Slic3r;

namespace Private{
        
// calculate multiplication of ray dir to intersect - inspired by
// segment_segment_intersection when ray dir is normalized retur distance from
// ray point to intersection No value mean no intersection
std::optional<double> ray_segment_intersection(const Vec2d &r_point,
                                               const Vec2d &r_dir,
                                               const Vec2d &s0,
                                               const Vec2d &s1)
{
    auto denominate = [](const Vec2d &v0, const Vec2d &v1) -> double {
        return v0.x() * v1.y() - v1.x() * v0.y();
    };

    Vec2d  segment_dir = s1 - s0;
    double d           = denominate(segment_dir, r_dir);
    if (std::abs(d) < std::numeric_limits<double>::epsilon())
        // Line and ray are collinear.
        return {};

    Vec2d  s12         = s0 - r_point;
    double s_number    = denominate(r_dir, s12);
    bool   change_sign = false;
    if (d < 0.) {
        change_sign = true;
        d           = -d;
        s_number    = -s_number;
    }

    if (s_number < 0. || s_number > d)
        // Intersection outside of segment.
        return {};

    double r_number = denominate(segment_dir, s12);
    if (change_sign) r_number = -r_number;

    if (r_number < 0.)
        // Intersection before ray start.
        return {};

    return r_number / d;
}

Vec2d get_intersection(const Vec2d &               point,
                       const Vec2d &               dir,
                       const std::array<Vec2d, 3> &triangle)
{
    std::optional<double> t;
    for (size_t i = 0; i < 3; ++i) {
        size_t i2 = i + 1;
        if (i2 == 3) i2 = 0;
        if (!t.has_value()) {
            t = ray_segment_intersection(point, dir, triangle[i],
                                         triangle[i2]);
            continue;
        }

        // small distance could be preccission inconsistance
        std::optional<double> t2 = ray_segment_intersection(point, dir,
                                                            triangle[i],
                                                            triangle[i2]);
        if (t2.has_value() && *t2 > *t) t = t2;
    }
    assert(t.has_value()); // Not found intersection.
    return point + dir * (*t);
}

Vec3d calc_hit_point(const igl::Hit &          h,
                     const Vec3i &             triangle,
                     const std::vector<Vec3f> &vertices)
{
    double c1 = h.u;
    double c2 = h.v;
    double c0 = 1.0 - c1 - c2;
    Vec3d  v0 = vertices[triangle[0]].cast<double>();
    Vec3d  v1 = vertices[triangle[1]].cast<double>();
    Vec3d  v2 = vertices[triangle[2]].cast<double>();
    return v0 * c0 + v1 * c1 + v2 * c2;
}

Vec3d calc_hit_point(const igl::Hit &h, indexed_triangle_set &its)
{
    return calc_hit_point(h, its.indices[h.id], its.vertices);
}
} // namespace Private

#include "imgui/imstb_truetype.h"
TEST_CASE("Emboss text - Times MacOs", "[Emboss]") {

    std::string font_path = "C:/Users/filip/Downloads/Times.ttc";
    //std::string font_path = "//System/Library/Fonts/Times.ttc";
    char  letter   = 'C';
    float flatness = 2.;
    FILE *file = fopen(font_path.c_str(), "rb");
    REQUIRE(file != nullptr);
    // find size of file
    REQUIRE(fseek(file, 0L, SEEK_END) == 0);
    size_t size = ftell(file);
    REQUIRE(size != 0);
    rewind(file);
    std::vector<unsigned char> buffer(size);
    size_t count_loaded_bytes = fread((void *) &buffer.front(), 1, size, file);
    REQUIRE(count_loaded_bytes == size);
    int font_offset = stbtt_GetFontOffsetForIndex(buffer.data(), 0);
    REQUIRE(font_offset >= 0);
    stbtt_fontinfo font_info;
    REQUIRE(stbtt_InitFont(&font_info, buffer.data(), font_offset) != 0);    
    int unicode_letter = (int) letter;
    int glyph_index = stbtt_FindGlyphIndex(&font_info, unicode_letter);
    REQUIRE(glyph_index != 0);
    stbtt_vertex *vertices;
    int num_verts = stbtt_GetGlyphShape(&font_info, glyph_index, &vertices);
    CHECK(num_verts > 0);
}

#include <libslic3r/Utils.hpp>
TEST_CASE("Emboss text", "[Emboss]") 
{
    std::string font_path = std::string(TEST_DATA_DIR) + "/fonts/NotoSans-Regular.ttf";
    char  letter   = '%';
    float flatness = 2.;

    auto font = Emboss::load_font(font_path.c_str());
    REQUIRE(font != nullptr);

    std::optional<Emboss::Glyph> glyph = Emboss::letter2glyph(*font, letter, flatness);
    REQUIRE(glyph.has_value());

    ExPolygons shape = glyph->shape;    
    REQUIRE(!shape.empty());

    float z_depth = 1.f;
    Emboss::ProjectZ projection(z_depth);
    indexed_triangle_set its = Emboss::polygons2model(shape, projection);

    CHECK(!its.indices.empty());    
}

TEST_CASE("Test hit point", "[AABBTreeIndirect]")
{
    indexed_triangle_set its;
    its.vertices = {
        Vec3f(1, 1, 1),
        Vec3f(2, 10, 2),
        Vec3f(10, 0, 2),
    };
    its.indices = {Vec3i(0, 2, 1)};
    auto tree   = AABBTreeIndirect::build_aabb_tree_over_indexed_triangle_set(
        its.vertices, its.indices);

    Vec3d    ray_point(8, 1, 0);
    Vec3d    ray_dir(0, 0, 1);
    igl::Hit hit;
    AABBTreeIndirect::intersect_ray_first_hit(its.vertices, its.indices, tree,
                                              ray_point, ray_dir, hit);
    Vec3d hp = Private::calc_hit_point(hit, its);
    CHECK(abs(hp.x() - ray_point.x()) < .1);
    CHECK(abs(hp.y() - ray_point.y()) < .1);
}

TEST_CASE("ray segment intersection", "[MeshBoolean]")
{
    Vec2d r_point(1, 1);
    Vec2d r_dir(1, 0);

    // colinear
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(0, 0), Vec2d(2, 0)).has_value());
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 0), Vec2d(0, 0)).has_value());

    // before ray
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(0, 0), Vec2d(0, 2)).has_value());
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(0, 2), Vec2d(0, 0)).has_value());

    // above ray
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 2), Vec2d(2, 3)).has_value());
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 3), Vec2d(2, 2)).has_value());

    // belove ray
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 0), Vec2d(2, -1)).has_value());
    CHECK(!Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, -1), Vec2d(2, 0)).has_value());

    // intersection at [2,1] distance 1
    auto t1 = Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 0), Vec2d(2, 2));
    REQUIRE(t1.has_value());
    auto t2 = Private::ray_segment_intersection(r_point, r_dir, Vec2d(2, 2), Vec2d(2, 0));
    REQUIRE(t2.has_value());

    CHECK(abs(*t1 - *t2) < std::numeric_limits<double>::epsilon());
}

TEST_CASE("triangle intersection", "[]")
{
    Vec2d                point(1, 1);
    Vec2d                dir(-1, 0);
    std::array<Vec2d, 3> triangle = {Vec2d(0, 0), Vec2d(5, 0), Vec2d(0, 5)};
    Vec2d                i = Private::get_intersection(point, dir, triangle);
    CHECK(abs(i.x()) < std::numeric_limits<double>::epsilon());
    CHECK(abs(i.y() - 1.) < std::numeric_limits<double>::epsilon());
}

#ifndef __APPLE__
#include <string>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
TEST_CASE("Italic check", "[]") 
{  
    std::queue<std::string> dir_paths;
#ifdef _WIN32
    dir_paths.push("C:/Windows/Fonts");
#elif defined(__linux__)
    dir_paths.push("/usr/share/fonts");
#endif
    bool exist_italic = false;
    bool exist_non_italic = false;
    while (!dir_paths.empty()) {
        std::string dir_path = dir_paths.front();
        dir_paths.pop();
        for (const auto &entry : fs::directory_iterator(dir_path)) {
            const fs::path &act_path = entry.path();
            if (entry.is_directory()) {
                dir_paths.push(act_path.u8string());
                continue;
            }
            std::string ext = act_path.extension().u8string();
            std::transform(ext.begin(), ext.end(), ext.begin(),
                           [](unsigned char c) { return std::tolower(c); });
            if (ext != ".ttf") continue;
            std::string path_str = act_path.u8string();
            auto        font_opt = Emboss::load_font(path_str.c_str());
            if (font_opt == nullptr) continue;
            if (Emboss::is_italic(*font_opt))
                exist_italic = true;
            else
                exist_non_italic = true;
            //std::cout << ((Emboss::is_italic(*font_opt)) ? "[yes] " : "[no ] ") << entry.path() << std::endl;
        }
    }
    CHECK(exist_italic);
    CHECK(exist_non_italic);
}
#endif // not __APPLE__

#include <CGAL/Polygon_mesh_processing/corefinement.h>
#include <CGAL/Exact_integer.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Cartesian_converter.h>

struct GlyphID
{
    int32_t glyph { -1 };
    int32_t expoly { -1 };
    int32_t contour { -1 };
    // vertex or edge ID, where edge ID is the index of the source point.
    int32_t idx { -1 };

    GlyphID& operator++() { ++idx; return *this; }
};

namespace Slic3r::MeshBoolean::cgal2 {

    namespace CGALProc = CGAL::Polygon_mesh_processing;
    namespace CGALParams = CGAL::Polygon_mesh_processing::parameters;

    using EpecKernel = CGAL::Exact_predicates_exact_constructions_kernel;
    using EpicKernel = CGAL::Exact_predicates_inexact_constructions_kernel;
    using _EpicMesh = CGAL::Surface_mesh<EpicKernel::Point_3>;
    using _EpecMesh = CGAL::Surface_mesh<EpecKernel::Point_3>;

    using CGALMesh = _EpicMesh;

    void triangle_mesh_to_cgal(const std::vector<stl_vertex>& V,
        const std::vector<stl_triangle_vertex_indices>& F,
        CGALMesh& out, 
        CGALMesh::Property_map<CGAL::SM_Face_index, int32_t> object_face_source_id)
    {
        if (F.empty()) return;

        size_t vertices_count = V.size();
        size_t edges_count = (F.size() * 3) / 2;
        size_t faces_count = F.size();
        out.reserve(vertices_count, edges_count, faces_count);

        for (auto& v : V)
            out.add_vertex(typename CGALMesh::Point{ v.x(), v.y(), v.z() });

        using VI = typename CGALMesh::Vertex_index;
        for (auto& f : F) {
            auto fid = out.add_face(VI(f(0)), VI(f(1)), VI(f(2)));
            object_face_source_id[fid] = int32_t(&f - &F.front());
        }
    }

    void glyph2model(
        const ExPolygons& glyph,
        int32_t glyph_id,
        const Slic3r::Emboss::IProject& projection, 
        CGALMesh& out,
        typename CGALMesh::Property_map<CGAL::SM_Edge_index, GlyphID> &glyph_id_edge,
        typename CGALMesh::Property_map<CGAL::SM_Face_index, GlyphID> &glyph_id_face)
    {
        std::vector<CGALMesh::Vertex_index> indices;
        auto insert_contour = [&projection, &indices , &out, glyph_id, &glyph_id_edge, &glyph_id_face](const Polygon& polygon, int32_t iexpoly, int32_t id) {
            indices.clear();
            indices.reserve(polygon.points.size() * 2);
            for (const Point& p2 : polygon.points) {
                auto p = projection.project(p2);
                indices.emplace_back(out.add_vertex(typename CGALMesh::Point{ p.first.x(), p.first.y(), p.first.z() }));
                indices.emplace_back(out.add_vertex(typename CGALMesh::Point{ p.second.x(), p.second.y(), p.second.z() }));
            }
            for (int32_t i = 0; i < int32_t(indices.size()); i += 2) {
                int32_t j = (i + 2) % int32_t(indices.size());
                auto find_edge = [&out](CGALMesh::Face_index fi, CGALMesh::Vertex_index from, CGALMesh::Vertex_index to) {
                    CGALMesh::Halfedge_index hi = out.halfedge(fi);
                    for (; out.target(hi) != to; hi = out.next(hi));
                    assert(out.source(hi) == from);
                    assert(out.target(hi) == to);
                    return hi;
                };
                auto fi = out.add_face(indices[i], indices[i + 1], indices[j]);
                GlyphID glid { glyph_id, iexpoly, id, i * 2 };
                glyph_id_edge[out.edge(find_edge(fi, indices[i], indices[i + 1]))] = glid;
                glyph_id_face[fi] = ++ glid;
                glyph_id_edge[out.edge(find_edge(fi, indices[i + 1], indices[j]))] = ++ glid;
                glyph_id_face[out.add_face(indices[j], indices[i + 1], indices[j + 1])] = ++ glid;
            }
        };

        size_t count_point = count_points(glyph);
        out.reserve(out.number_of_vertices() + 2 * count_point, out.number_of_edges() + 4 * count_point, out.number_of_faces() + 2 * count_point);

        for (const ExPolygon &expolygon : glyph) {
            int32_t idx_contour = &expolygon - &glyph.front();
            insert_contour(expolygon.contour, idx_contour, 0);
            for (const Polygon& hole : expolygon.holes)
                insert_contour(hole, idx_contour, 1 + (&hole - &expolygon.holes.front()));
        }
    }
}

bool its_write_obj(const indexed_triangle_set& its, const std::vector<Vec3f> &color, const char* file)
{
    Slic3r::CNumericLocalesSetter locales_setter;
    FILE* fp = fopen(file, "w");
    if (fp == nullptr) {
        return false;
    }

    for (size_t i = 0; i < its.vertices.size(); ++i)
        fprintf(fp, "v %f %f %f %f %f %f\n", 
            its.vertices[i](0), its.vertices[i](1), its.vertices[i](2),
            color[i](0), color[i](1), color[i](2));
    for (size_t i = 0; i < its.indices.size(); ++i)
        fprintf(fp, "f %d %d %d\n", its.indices[i][0] + 1, its.indices[i][1] + 1, its.indices[i][2] + 1);
    fclose(fp);
    return true;
}

TEST_CASE("Emboss extrude cut", "[Emboss-Cut]") 
{
    std::string font_path = std::string(TEST_DATA_DIR) + "/fonts/NotoSans-Regular.ttf";
    char  letter   = '%';
    float flatness = 2.;

    auto font = Emboss::load_font(font_path.c_str());
    REQUIRE(font != nullptr);

    std::optional<Emboss::Glyph> glyph = Emboss::letter2glyph(*font, letter, flatness);
    REQUIRE(glyph.has_value());

    ExPolygons shape = glyph->shape;    
    REQUIRE(!shape.empty());

    float z_depth = 10.f;
    Emboss::ProjectZ projection(z_depth);

#if 0
    indexed_triangle_set text = Emboss::polygons2model(shape, projection);
    BoundingBoxf3 bbox = bounding_box(text);

    CHECK(!text.indices.empty());    
#endif

    auto cube = its_make_cube(782 - 49 + 50, 724 + 10 + 50, 5);
    its_translate(cube, Vec3f(49 - 25, -10 - 25, 2.5));

    MeshBoolean::cgal2::CGALMesh cgalcube, cgaltext;
    auto object_face_source_id = cgalcube.add_property_map<MeshBoolean::cgal2::CGALMesh::Face_index, int32_t>("f:object_face_source_id").first;
    MeshBoolean::cgal2::triangle_mesh_to_cgal(cube.vertices, cube.indices, cgalcube, object_face_source_id);

    auto edge_glyph_id = cgaltext.add_property_map<MeshBoolean::cgal2::CGALMesh::Edge_index, GlyphID>("e:glyph_id").first;
    auto face_glyph_id = cgaltext.add_property_map<MeshBoolean::cgal2::CGALMesh::Face_index, GlyphID>("f:glyph_id").first;
    auto vertex_glyph_id = cgalcube.add_property_map<MeshBoolean::cgal2::CGALMesh::Vertex_index, GlyphID>("v:glyph_id").first;

    MeshBoolean::cgal2::glyph2model(shape, 0, projection, cgaltext, edge_glyph_id, face_glyph_id);

    struct Visitor {
        using TriangleMesh = Slic3r::MeshBoolean::cgal2::CGALMesh;

        const TriangleMesh &object;
        const TriangleMesh &glyphs;
        // Properties of the glyphs mesh:
        TriangleMesh::Property_map<CGAL::SM_Edge_index, GlyphID> glyph_id_edge;
        TriangleMesh::Property_map<CGAL::SM_Face_index, GlyphID> glyph_id_face;
        // Properties of the object mesh.
        TriangleMesh::Property_map<CGAL::SM_Face_index, int32_t> object_face_source_id;
        TriangleMesh::Property_map<CGAL::SM_Vertex_index, GlyphID> object_vertex_glyph_id;

        typedef boost::graph_traits<TriangleMesh> GT;
        typedef typename GT::face_descriptor face_descriptor;
        typedef typename GT::halfedge_descriptor halfedge_descriptor;
        typedef typename GT::vertex_descriptor vertex_descriptor;

        int32_t source_face_id;

        void before_subface_creations(face_descriptor f_old, TriangleMesh& mesh)
        {
            assert(&mesh == &object);
            source_face_id = object_face_source_id[f_old];
        }
        void after_subface_created(face_descriptor f_new, TriangleMesh& mesh) {
            assert(&mesh == &object);
            object_face_source_id[f_new] = source_face_id;
        }

        std::vector<const GlyphID*> intersection_point_glyph;

        // Intersecting an edge hh_edge from tm_edge with a face hh_face of tm_face.
        void intersection_point_detected(
            // ID of the intersection point, starting at 0. Ids are consecutive.
            std::size_t         i_id,
            // Dimension of a simplex part of face(hh_face) that is intersected by hh_edge:
            // 0 for vertex: target(hh_face)
            // 1 for edge: hh_face
            // 2 for the interior of face: face(hh_face)
            int                 simplex_dimension,
            // Edge of tm_edge, see edge_source_coplanar_with_face & edge_target_coplanar_with_face whether any vertex of hh_edge is coplanar with face(hh_face).
            halfedge_descriptor hh_edge,
            // Vertex, halfedge or face of tm_face intersected by hh_edge, see comment at simplex_dimension.
            halfedge_descriptor hh_face,
            // Mesh containing hh_edge
            const TriangleMesh& tm_edge,
            // Mesh containing hh_face
            const TriangleMesh& tm_face,
            // source(hh_edge) is coplanar with face(hh_face).
            bool                edge_source_coplanar_with_face,
            // target(hh_edge) is coplanar with face(hh_face).
            bool                edge_target_coplanar_with_face)
        {
            if (i_id <= intersection_point_glyph.size()) {
                intersection_point_glyph.reserve(Slic3r::next_highest_power_of_2(i_id + 1));
                intersection_point_glyph.resize(i_id + 1);
            }

            const GlyphID* glyph = nullptr;
            if (&tm_face == &glyphs) {
                assert(&tm_edge == &object);
                switch (simplex_dimension) {
                case 1:
                    // edge x edge intersection
                    glyph = &glyph_id_edge[glyphs.edge(hh_face)];
                    break;
                case 2:
                    // edge x face intersection
                    glyph = &glyph_id_face[glyphs.face(hh_face)];
                    break;
                default:
                    assert(false);
                }
                if (edge_source_coplanar_with_face)
                    object_vertex_glyph_id[object.source(hh_edge)] = *glyph;
                if (edge_target_coplanar_with_face)
                    object_vertex_glyph_id[object.target(hh_edge)] = *glyph;
            }
            else {
                assert(&tm_edge == &glyphs && &tm_face == &object);
                assert(!edge_source_coplanar_with_face);
                assert(!edge_target_coplanar_with_face);
                glyph = &glyph_id_edge[glyphs.edge(hh_edge)];
                if (simplex_dimension)
                    object_vertex_glyph_id[object.target(hh_face)] = *glyph;
            }
            intersection_point_glyph[i_id] = glyph;
        }

        void new_vertex_added(std::size_t node_id, vertex_descriptor vh, const TriangleMesh &tm)
        {
            assert(&tm == &object);
            assert(node_id < intersection_point_glyph.size());
            const GlyphID * glyph = intersection_point_glyph[node_id];
            assert(glyph != nullptr);
            assert(glyph->glyph != -1);
            assert(glyph->expoly != -1);
            assert(glyph->contour != -1);
            assert(glyph->idx != -1);
            object_vertex_glyph_id[vh] = glyph ? *glyph : GlyphID{};
        }

        void after_subface_creations(TriangleMesh&) {}
        void before_subface_created(TriangleMesh&) {}
        void before_edge_split(halfedge_descriptor /* h */, TriangleMesh& /* tm */) {}
        void edge_split(halfedge_descriptor /* hnew */, TriangleMesh& /* tm */) {}
        void after_edge_split() {}
        void add_retriangulation_edge(halfedge_descriptor /* h */, TriangleMesh& /* tm */) {}
    }
    visitor { cgalcube, cgaltext, edge_glyph_id, face_glyph_id, object_face_source_id, vertex_glyph_id };

    auto ecm = get(CGAL::dynamic_edge_property_t<bool>(), cgalcube);
    auto ecm2 = get(CGAL::dynamic_edge_property_t<bool>(), cgaltext);
    const auto& p = CGAL::Polygon_mesh_processing::parameters::throw_on_self_intersection(false).visitor(visitor).edge_is_constrained_map(ecm);
    const auto& q = CGAL::Polygon_mesh_processing::parameters::throw_on_self_intersection(false).visitor(visitor).edge_is_constrained_map(ecm2).do_not_modify(true);
    //    CGAL::Polygon_mesh_processing::corefine(cgalcube, cgalcube2, p, p);

    CGAL::Polygon_mesh_processing::corefine(cgalcube, cgaltext, p, q);

    auto vertex_colors = cgalcube.add_property_map<MeshBoolean::cgal2::CGALMesh::Vertex_index, CGAL::Color>("v:color").first;
    auto face_colors = cgalcube.add_property_map<MeshBoolean::cgal2::CGALMesh::Face_index, CGAL::Color>("f:color").first;

    const CGAL::Color marked { 255, 0, 0 };
    for (auto fi : cgalcube.faces()) {
        CGAL::Color color(0, 255, 0);
        auto hi_end = cgalcube.halfedge(fi);
        auto hi = hi_end;
        do {
            if (get(ecm, cgalcube.edge(hi))) {
                // This face has a constrained edge.
                GlyphID g1 = vertex_glyph_id[cgalcube.source(hi)];
                GlyphID g2 = vertex_glyph_id[cgalcube.target(hi)];
                assert(g1.glyph != -1 && g1.glyph == g2.glyph);
                assert(g1.expoly != -1 && g1.expoly == g2.expoly);
                assert(g1.contour != -1 && g1.contour == g2.contour);
                assert(g1.idx != -1);
                assert(g2.idx != -1);
                const auto &expoly  = glyph->shape[g1.expoly];
                const auto &contour = g1.contour == 0 ? expoly.contour : expoly.holes[g1.contour - 1];
                bool ccw = false;
                int32_t i1 = g1.idx / 4;
                int32_t i2 = g2.idx / 4;
                if (g1.idx < g2.idx) {
                    if (i1 == 0 && i2 + 1 == contour.size()) {
                        // cw
                    } else {
                        ccw = true;
                    }
                } else {
                    if (i2 == 0 && i1 + 1 == contour.size()) {
                        ccw = true;
                        std::swap(g1, g2);
                        std::swap(i1, i2);
                    }
                }
                if (ccw) {
                    // Face is left of a constrained edge.
                    // Check whether the face is facing forward or backwards.
                    int type = g1.idx % 4;
                    // The object vertex intersects glyph edge. Take front point of the intersecting glyph edge.
                    const auto& p = cgaltext.point(MeshBoolean::cgal2::CGALMesh::Vertex_index((i1 + (type >= 2)) * 2 + 1));
                    // Is this face oriented towards p or away from p?
                    auto abcp = CGAL::orientation(cgalcube.point(cgalcube.source(hi)), cgalcube.point(cgalcube.target(hi)), cgalcube.point(cgalcube.target(cgalcube.next(hi))), p);
                    assert(abcp != CGAL::COPLANAR);
                    if (abcp == CGAL::POSITIVE)
                        color = marked;
                }
                break;
            }
            hi = cgalcube.next(hi);
        } while (hi != hi_end);
        face_colors[fi] = color;
    }

    // Seed fill the other faces inside the region.
    std::vector<MeshBoolean::cgal2::CGALMesh::Face_index> queue;
    for (auto fi_seed : cgalcube.faces())
        if (face_colors[fi_seed] != marked) {
            // Is this face completely unconstrained?
            auto hi      = cgalcube.halfedge(fi_seed);
            auto hi_prev = cgalcube.prev(hi);
            auto hi_next = cgalcube.next(hi);
            if (! get(ecm, cgalcube.edge(hi)) && ! get(ecm, cgalcube.edge(hi_prev)) && ! get(ecm, cgalcube.edge(hi_next))) {
                queue.emplace_back(fi_seed);
                do {
                    auto fi = queue.back();
                    queue.pop_back();
                    auto hi      = cgalcube.halfedge(fi);
                    auto hi_prev = cgalcube.prev(hi);
                    auto hi_next = cgalcube.next(hi);
                    assert(! get(ecm, cgalcube.edge(hi)) && ! get(ecm, cgalcube.edge(hi_prev)) && ! get(ecm, cgalcube.edge(hi_next)));
                    auto this_opposite = cgalcube.face(cgalcube.opposite(hi));
                    bool this_marked   = face_colors[this_opposite] == marked;
                    auto prev_opposite = cgalcube.face(cgalcube.opposite(hi_prev));
                    bool prev_marked   = face_colors[prev_opposite] == marked;
                    auto next_opposite = cgalcube.face(cgalcube.opposite(hi_next));
                    bool next_marked   = face_colors[next_opposite] == marked;
                    int  num_marked    = this_marked + prev_marked + next_marked;
                    if (num_marked >= 2) {
                        face_colors[fi] = marked;
                        if (num_marked == 2)
                            queue.emplace_back(! this_marked ? this_opposite : ! prev_marked ? prev_opposite : next_opposite);
                    }
                } while (! queue.empty());
            }
        }

    // Mapping of its_extruded faces to source faces.
    enum class FaceType : int32_t {
        Unknown         = -1,
        Unmarked        = -2,
        UnmarkedSplit   = -3,
        Marked          = -4,
        MarkedSplit     = -5,
        UnmarkedEmitted = -6,
    };
    std::vector<int32_t> map_faces(cube.indices.size(), int32_t(FaceType::Unknown));
    for (auto fi_seed : cgalcube.faces()) {
        int32_t &state = map_faces[object_face_source_id[fi_seed]];
        bool     m     = face_colors[fi_seed] == marked;
        switch (state) {
        case int32_t(FaceType::Unknown):
            state = m ? int32_t(FaceType::Marked) : int32_t(FaceType::Unmarked);
            break;
        case int32_t(FaceType::Unmarked):
        case int32_t(FaceType::UnmarkedSplit):
            state = m ? int32_t(FaceType::MarkedSplit) : int32_t(FaceType::UnmarkedSplit);
            break;
        case int32_t(FaceType::Marked):
        case int32_t(FaceType::MarkedSplit):
            state = int32_t(FaceType::MarkedSplit);
            break;
        default:
            assert(false);
        }
    }

    CGAL::IO::write_OFF("c:\\data\\temp\\corefined.off", cgalcube);

    indexed_triangle_set its_extruded;
    its_extruded.indices.reserve(cgalcube.number_of_faces());
    its_extruded.vertices.reserve(cgalcube.number_of_vertices());
    // Mapping of its_extruded vertices (original and offsetted) to cgalcuble's vertices.
    std::vector<std::pair<int32_t, int32_t>> map_vertices(cgalcube.number_of_vertices(), std::pair<int32_t, int32_t>{-1, -1});

    Vec3f extrude_dir { 0, 0, 5.f };
    for (auto fi : cgalcube.faces()) {
        const int32_t source_face_id = object_face_source_id[fi];
        const int32_t state          = map_faces[source_face_id];
        assert(state == int32_t(FaceType::Unmarked) || state == int32_t(FaceType::UnmarkedSplit) || state == int32_t(FaceType::UnmarkedEmitted) ||
               state == int32_t(FaceType::Marked) || state == int32_t(FaceType::MarkedSplit));
        if (state == int32_t(FaceType::UnmarkedEmitted)) {
            // Already emitted.
        } else if (state == int32_t(FaceType::Unmarked) || state == int32_t(FaceType::UnmarkedSplit)) {
            // Just copy the unsplit source face.
            const Vec3i source_vertices = cube.indices[source_face_id];
            Vec3i       target_vertices;
            for (int i = 0; i < 3; ++i) {
                target_vertices(i) = map_vertices[source_vertices(i)].first;
                if (target_vertices(i) == -1) {
                    map_vertices[source_vertices(i)].first = target_vertices(i) = int(its_extruded.vertices.size());
                    its_extruded.vertices.emplace_back(cube.vertices[source_vertices(i)]);
                }
            }
            its_extruded.indices.emplace_back(target_vertices);
            map_faces[source_face_id] = int32_t(FaceType::UnmarkedEmitted);
        } else { 
            auto hi = cgalcube.halfedge(fi);
            auto hi_prev = cgalcube.prev(hi);
            auto hi_next = cgalcube.next(hi);
            const Vec3i source_vertices{ int((std::size_t)cgalcube.target(hi)), int((std::size_t)cgalcube.target(hi_next)), int((std::size_t)cgalcube.target(hi_prev)) };
            Vec3i       target_vertices;
            if (face_colors[fi] == marked) {
                // Extrude the face. Neighbor edges separating extruded face from non-extruded face will be extruded.
                bool boundary_vertex[3] = { false, false, false };
                Vec3i target_vertices_extruded { -1, -1, -1 };
                for (int i = 0; i < 3; ++i) {
                    if (face_colors[cgalcube.face(cgalcube.opposite(hi))] != marked)
                        // Edge separating extruded / non-extruded region.
                        boundary_vertex[i] = boundary_vertex[(i + 2) % 3] = true;
                    hi = cgalcube.next(hi);
                }
                for (int i = 0; i < 3; ++ i) {
                    target_vertices_extruded(i) = map_vertices[source_vertices(i)].second;
                    if (target_vertices_extruded(i) == -1) {
                        map_vertices[source_vertices(i)].second = target_vertices_extruded(i) = int(its_extruded.vertices.size());
                        const auto& p = cgalcube.point(cgalcube.target(hi));
                        its_extruded.vertices.emplace_back(Vec3f{ float(p.x()), float(p.y()), float(p.z()) } + extrude_dir);
                    }
                    if (boundary_vertex[i]) {
                        target_vertices(i) = map_vertices[source_vertices(i)].first;
                        if (target_vertices(i) == -1) {
                            map_vertices[source_vertices(i)].first = target_vertices(i) = int(its_extruded.vertices.size());
                            const auto& p = cgalcube.point(cgalcube.target(hi));
                            its_extruded.vertices.emplace_back(p.x(), p.y(), p.z());
                        }
                    }
                    hi = cgalcube.next(hi);
                }
                its_extruded.indices.emplace_back(target_vertices_extruded);
                // Add the sides.
                for (int i = 0; i < 3; ++ i) {
                    int j = (i + 1) % 3;
                    assert(target_vertices_extruded[i] != -1 && target_vertices_extruded[j] != -1);
                    if (boundary_vertex[i] && boundary_vertex[j]) {
                        assert(target_vertices[i] != -1 && target_vertices[j] != -1);
                        its_extruded.indices.emplace_back(Vec3i{ target_vertices[i], target_vertices[j], target_vertices_extruded[i] });
                        its_extruded.indices.emplace_back(Vec3i{ target_vertices_extruded[i], target_vertices[j], target_vertices_extruded[j] });
                    }
                }
            } else {
                // Copy the face.
                Vec3i target_vertices;
                for (int i = 0; i < 3; ++ i) {
                    target_vertices(i) = map_vertices[source_vertices(i)].first;
                    if (target_vertices(i) == -1) {
                        map_vertices[source_vertices(i)].first = target_vertices(i) = int(its_extruded.vertices.size());
                        const auto &p = cgalcube.point(cgalcube.target(hi));
                        its_extruded.vertices.emplace_back(p.x(), p.y(), p.z());
                    }
                    hi = cgalcube.next(hi);
                }
                its_extruded.indices.emplace_back(target_vertices);
            }
        }
    }

    its_write_obj(its_extruded, "c:\\data\\temp\\text-extruded.obj");

    indexed_triangle_set edges_its;
    std::vector<Vec3f>   edges_its_colors;
    for (auto ei : cgalcube.edges())
        if (cgalcube.is_valid(ei)) {
            const auto &p1 = cgalcube.point(cgalcube.vertex(ei, 0));
            const auto &p2 = cgalcube.point(cgalcube.vertex(ei, 1));
            bool constrained = get(ecm, ei);
            Vec3f color = constrained ? Vec3f{ 1.f, 0, 0 } : Vec3f{ 0, 1., 0 };
            edges_its.indices.emplace_back(Vec3i(edges_its.vertices.size(), edges_its.vertices.size() + 1, edges_its.vertices.size() + 2));
            edges_its.vertices.emplace_back(Vec3f(p1.x(), p1.y(), p1.z()));
            edges_its.vertices.emplace_back(Vec3f(p2.x(), p2.y(), p2.z()));
            edges_its.vertices.emplace_back(Vec3f(p2.x(), p2.y(), p2.z() + 0.001));
            edges_its_colors.emplace_back(color);
            edges_its_colors.emplace_back(color);
            edges_its_colors.emplace_back(color);
        }
    its_write_obj(edges_its, edges_its_colors, "c:\\data\\temp\\corefined-edges.obj");

//    MeshBoolean::cgal::minus(cube, cube2);

//    REQUIRE(!MeshBoolean::cgal::does_self_intersect(cube));
}