#ifndef slic3r_TriangleMesh_hpp_
#define slic3r_TriangleMesh_hpp_

#include "libslic3r.h"
#include <admesh/stl.h>
#include <functional>
#include <vector>
#include "BoundingBox.hpp"
#include "Line.hpp"
#include "Point.hpp"
#include "Polygon.hpp"
#include "ExPolygon.hpp"

namespace Slic3r {

class TriangleMesh;
class TriangleMeshSlicer;

struct RepairedMeshErrors {
    // How many edges were united by merging their end points with some other end points in epsilon neighborhood?
    int           edges_fixed               = 0;
    // How many degenerate faces were removed?
    int           degenerate_facets         = 0;
    // How many faces were removed during fixing? Includes degenerate_faces and disconnected faces.
    int           facets_removed            = 0;
    // New faces could only be created with stl_fill_holes() and we ditched stl_fill_holes(), because mostly it does more harm than good.
    //int          facets_added             = 0;
    // How many facets were revesed? Faces are reversed by admesh while it connects patches of triangles togeter and a flipped triangle is encountered.
    // Also the facets are reversed when a negative volume is corrected by flipping all facets.
    int           facets_reversed           = 0;
    // Edges shared by two triangles, oriented incorrectly.
    int           backwards_edges           = 0;

    void clear() { *this = RepairedMeshErrors(); }

    void merge(const RepairedMeshErrors& rhs) {
        this->edges_fixed         += rhs.edges_fixed;
        this->degenerate_facets   += rhs.degenerate_facets;
        this->facets_removed      += rhs.facets_removed;
        this->facets_reversed     += rhs.facets_reversed;
        this->backwards_edges     += rhs.backwards_edges;
    }

    bool repaired() const { return degenerate_facets > 0 || edges_fixed > 0 || facets_removed > 0 || facets_reversed > 0 || backwards_edges > 0; }
};

struct TriangleMeshStats {
    // Mesh metrics.
    uint32_t      number_of_facets          = 0;
    stl_vertex    max                       = stl_vertex::Zero();
    stl_vertex    min                       = stl_vertex::Zero();
    stl_vertex    size                      = stl_vertex::Zero();
    float         volume                    = -1.f;
    int           number_of_parts           = 0;

    // Mesh errors, remaining.
    int           open_edges                = 0;

    // Mesh errors, fixed.
    RepairedMeshErrors repaired_errors;

    void clear() { *this = TriangleMeshStats(); }

    TriangleMeshStats merge(const TriangleMeshStats &rhs) const {
      if (this->number_of_facets == 0)
        return rhs;
      else if (rhs.number_of_facets == 0)
        return *this;
      else {
        TriangleMeshStats out;
        out.number_of_facets        = this->number_of_facets + rhs.number_of_facets;
        out.min                     = this->min.cwiseMin(rhs.min);
        out.max                     = this->max.cwiseMax(rhs.max);
        out.size                    = out.max - out.min;
        out.number_of_parts         = this->number_of_parts     + rhs.number_of_parts;
        out.open_edges              = this->open_edges          + rhs.open_edges;
        out.volume                  = this->volume              + rhs.volume;
        out.repaired_errors.merge(rhs.repaired_errors);
        return out;
      }
    }

    bool manifold() const { return open_edges == 0; }
    bool repaired() const { return repaired_errors.repaired(); }
};

class TriangleMesh
{
public:
    TriangleMesh() = default;
    TriangleMesh(const std::vector<Vec3f> &vertices, const std::vector<Vec3i> &faces);
    TriangleMesh(std::vector<Vec3f> &&vertices, const std::vector<Vec3i> &&faces);
    explicit TriangleMesh(const indexed_triangle_set &M);
    explicit TriangleMesh(indexed_triangle_set &&M, const RepairedMeshErrors& repaired_errors = RepairedMeshErrors());
    void clear() { this->its.clear(); this->m_stats.clear(); }
    bool ReadSTLFile(const char* input_file, bool repair = true);
    bool write_ascii(const char* output_file);
    bool write_binary(const char* output_file);
    float volume();
    void WriteOBJFile(const char* output_file) const;
    void scale(float factor);
    void scale(const Vec3f &versor);
    void translate(float x, float y, float z);
    void translate(const Vec3f &displacement);
    void rotate(float angle, const Axis &axis);
    void rotate(float angle, const Vec3d& axis);
    void rotate_x(float angle) { this->rotate(angle, X); }
    void rotate_y(float angle) { this->rotate(angle, Y); }
    void rotate_z(float angle) { this->rotate(angle, Z); }
    void mirror(const Axis axis);
    void mirror_x() { this->mirror(X); }
    void mirror_y() { this->mirror(Y); }
    void mirror_z() { this->mirror(Z); }
    void transform(const Transform3d& t, bool fix_left_handed = false);
    void transform(const Matrix3d& t, bool fix_left_handed = false);
    // Flip triangles, negate volume.
    void flip_triangles();
    void align_to_origin();
    void rotate(double angle, Point* center);
    std::vector<TriangleMesh> split() const;
    void merge(const TriangleMesh &mesh);
    ExPolygons horizontal_projection() const;
    // 2D convex hull of a 3D mesh projected into the Z=0 plane.
    Polygon convex_hull();
    BoundingBoxf3 bounding_box() const;
    // Returns the bbox of this TriangleMesh transformed by the given transformation
    BoundingBoxf3 transformed_bounding_box(const Transform3d &trafo) const;
    // Variant returning the bbox of the part of this TriangleMesh above the given world_min_z
    BoundingBoxf3 transformed_bounding_box(const Transform3d& trafo, double world_min_z) const;
    // Return the size of the mesh in coordinates.
    Vec3d size() const { return m_stats.size.cast<double>(); }
    /// Return the center of the related bounding box.
    Vec3d center() const { return this->bounding_box().center(); }
    // Returns the convex hull of this TriangleMesh
    TriangleMesh convex_hull_3d() const;
    // Slice this mesh at the provided Z levels and return the vector
    std::vector<ExPolygons> slice(const std::vector<double>& z) const;
    size_t facets_count() const { assert(m_stats.number_of_facets == this->its.indices.size()); return m_stats.number_of_facets; }
    bool   empty() const { return this->facets_count() == 0; }
    bool   repaired() const;
    bool   is_splittable() const;
    // Estimate of the memory occupied by this structure, important for keeping an eye on the Undo / Redo stack allocation.
    size_t memsize() const;

    // Used by the Undo / Redo stack, legacy interface. As of now there is nothing cached at TriangleMesh,
    // but we may decide to cache some data in the future (for example normals), thus we keep the interface in place.
    // Release optional data from the mesh if the object is on the Undo / Redo stack only. Returns the amount of memory released.
    size_t release_optional() { return 0; }
    // Restore optional data possibly released by release_optional().
    void   restore_optional() {}

    const TriangleMeshStats& stats() const { return m_stats; }
    
    indexed_triangle_set its;

private:
    TriangleMeshStats m_stats;
};

// Index of face indices incident with a vertex index.
struct VertexFaceIndex
{
public:
    using iterator = std::vector<size_t>::const_iterator;

    VertexFaceIndex(const indexed_triangle_set &its) { this->create(its); }
    VertexFaceIndex() {}

    void create(const indexed_triangle_set &its);
    void clear() { m_vertex_to_face_start.clear(); m_vertex_faces_all.clear(); }

    // Iterators of face indices incident with the input vertex_id.
    iterator begin(size_t vertex_id) const throw() { return m_vertex_faces_all.begin() + m_vertex_to_face_start[vertex_id]; }
    iterator end  (size_t vertex_id) const throw() { return m_vertex_faces_all.begin() + m_vertex_to_face_start[vertex_id + 1]; }
    // Vertex incidence.
    size_t   count(size_t vertex_id) const throw() { return m_vertex_to_face_start[vertex_id + 1] - m_vertex_to_face_start[vertex_id]; }

    const Range<iterator> operator[](size_t vertex_id) const { return {begin(vertex_id), end(vertex_id)}; }

private:
    std::vector<size_t>     m_vertex_to_face_start;
    std::vector<size_t>     m_vertex_faces_all;
};

// Map from a face edge to a unique edge identifier or -1 if no neighbor exists.
// Two neighbor faces share a unique edge identifier even if they are flipped.
// Used for chaining slice lines into polygons.
std::vector<Vec3i> its_face_edge_ids(const indexed_triangle_set &its);
std::vector<Vec3i> its_face_edge_ids(const indexed_triangle_set &its, std::function<void()> throw_on_cancel_callback);
std::vector<Vec3i> its_face_edge_ids(const indexed_triangle_set &its, const std::vector<bool> &face_mask);
// Having the face neighbors available, assign unique edge IDs to face edges for chaining of polygons over slices.
std::vector<Vec3i> its_face_edge_ids(const indexed_triangle_set &its, std::vector<Vec3i> &face_neighbors, bool assign_unbound_edges = false, int *num_edges = nullptr);

// Create index that gives neighbor faces for each face. Ignores face orientations.
std::vector<Vec3i> its_face_neighbors(const indexed_triangle_set &its);
std::vector<Vec3i> its_face_neighbors_par(const indexed_triangle_set &its);

// After applying a transformation with negative determinant, flip the faces to keep the transformed mesh volume positive.
void its_flip_triangles(indexed_triangle_set &its);

// Merge duplicate vertices, return number of vertices removed.
// This function will happily create non-manifolds if more than two faces share the same vertex position
// or more than two faces share the same edge position!
int its_merge_vertices(indexed_triangle_set &its, bool shrink_to_fit = true);

// Remove degenerate faces, return number of faces removed.
int its_remove_degenerate_faces(indexed_triangle_set &its, bool shrink_to_fit = true);

// Remove vertices, which none of the faces references. Return number of freed vertices.
int its_compactify_vertices(indexed_triangle_set &its, bool shrink_to_fit = true);

// store part of index triangle set
bool its_store_triangle(const indexed_triangle_set &its, const char *obj_filename, size_t triangle_index);
bool its_store_triangles(const indexed_triangle_set &its, const char *obj_filename, const std::vector<size_t>& triangles);

std::vector<indexed_triangle_set> its_split(const indexed_triangle_set &its);
std::vector<indexed_triangle_set> its_split(const indexed_triangle_set &its, std::vector<Vec3i> &face_neighbors);

// Number of disconnected patches (faces are connected if they share an edge, shared edge defined with 2 shared vertex indices).
size_t its_number_of_patches(const indexed_triangle_set &its);
size_t its_number_of_patches(const indexed_triangle_set &its, const std::vector<Vec3i> &face_neighbors);
// Same as its_number_of_patches(its) > 1, but faster.
bool its_is_splittable(const indexed_triangle_set &its);
bool its_is_splittable(const indexed_triangle_set &its, const std::vector<Vec3i> &face_neighbors);

// Calculate number of unconnected face edges. There should be no unconnected edge in a manifold mesh.
size_t its_num_open_edges(const indexed_triangle_set &its);
size_t its_num_open_edges(const std::vector<Vec3i> &face_neighbors);

// Shrink the vectors of its.vertices and its.faces to a minimum size by reallocating the two vectors.
void its_shrink_to_fit(indexed_triangle_set &its);

// For convex hull calculation: Transform mesh, trim it by the Z plane and collect all vertices. Duplicate vertices will be produced.
void its_collect_mesh_projection_points_above(const indexed_triangle_set &its, const Matrix3f &m, const float z, Points &all_pts);
void its_collect_mesh_projection_points_above(const indexed_triangle_set &its, const Transform3f &t, const float z, Points &all_pts);

// Calculate 2D convex hull of a transformed and clipped mesh. Uses the function above.
Polygon its_convex_hull_2d_above(const indexed_triangle_set &its, const Matrix3f &m, const float z);
Polygon its_convex_hull_2d_above(const indexed_triangle_set &its, const Transform3f &t, const float z);

// Index of a vertex inside triangle_indices.
inline int its_triangle_vertex_index(const stl_triangle_vertex_indices &triangle_indices, int vertex_idx)
{
    return vertex_idx == triangle_indices[0] ? 0 :
           vertex_idx == triangle_indices[1] ? 1 :
           vertex_idx == triangle_indices[2] ? 2 : -1;
}

inline Vec2i its_triangle_edge(const stl_triangle_vertex_indices &triangle_indices, int edge_idx)
{
    int next_edge_idx = (edge_idx == 2) ? 0 : edge_idx + 1;
    return { triangle_indices[edge_idx], triangle_indices[next_edge_idx] };
}

// Index of an edge inside triangle.
inline int its_triangle_edge_index(const stl_triangle_vertex_indices &triangle_indices, const Vec2i &triangle_edge)
{
    return triangle_edge(0) == triangle_indices[0] && triangle_edge(1) == triangle_indices[1] ? 0 :
           triangle_edge(0) == triangle_indices[1] && triangle_edge(1) == triangle_indices[2] ? 1 :
           triangle_edge(0) == triangle_indices[2] && triangle_edge(1) == triangle_indices[0] ? 2 : -1;
}

using its_triangle = std::array<stl_vertex, 3>;

inline its_triangle its_triangle_vertices(const indexed_triangle_set &its,
                                          size_t                      face_id)
{
    return {its.vertices[its.indices[face_id](0)],
            its.vertices[its.indices[face_id](1)],
            its.vertices[its.indices[face_id](2)]};
}

inline stl_normal its_unnormalized_normal(const indexed_triangle_set &its,
                                          size_t                      face_id)
{
    its_triangle tri = its_triangle_vertices(its, face_id);
    return (tri[1] - tri[0]).cross(tri[2] - tri[0]);
}

float its_volume(const indexed_triangle_set &its);
float its_average_edge_length(const indexed_triangle_set &its);

void its_merge(indexed_triangle_set &A, const indexed_triangle_set &B);
void its_merge(indexed_triangle_set &A, const std::vector<Vec3f> &triangles);
void its_merge(indexed_triangle_set &A, const Pointf3s &triangles);

std::vector<Vec3f> its_face_normals(const indexed_triangle_set &its);
inline Vec3f face_normal(const stl_vertex vertex[3]) { return  (vertex[1] - vertex[0]).cross(vertex[2] - vertex[1]).normalized(); }
inline Vec3f face_normal_normalized(const stl_vertex vertex[3]) { return  face_normal(vertex).normalized(); }
inline Vec3f its_face_normal(const indexed_triangle_set &its, const stl_triangle_vertex_indices face)
    { const stl_vertex vertices[3] { its.vertices[face[0]], its.vertices[face[1]], its.vertices[face[2]] }; return face_normal_normalized(vertices); }
inline Vec3f its_face_normal(const indexed_triangle_set &its, const int face_idx)
    { return its_face_normal(its, its.indices[face_idx]); }

indexed_triangle_set    its_make_cube(double x, double y, double z);
indexed_triangle_set    its_make_prism(float width, float length, float height);
indexed_triangle_set    its_make_cylinder(double r, double h, double fa=(2*PI/360));
indexed_triangle_set    its_make_cone(double r, double h, double fa=(2*PI/360));
indexed_triangle_set    its_make_pyramid(float base, float height);
indexed_triangle_set    its_make_sphere(double radius, double fa);

indexed_triangle_set        its_convex_hull(const std::vector<Vec3f> &pts);
inline indexed_triangle_set its_convex_hull(const indexed_triangle_set &its) { return its_convex_hull(its.vertices); }

inline TriangleMesh     make_cube(double x, double y, double z)                 { return TriangleMesh(its_make_cube(x, y, z)); }
inline TriangleMesh     make_prism(float width, float length, float height)     { return TriangleMesh(its_make_prism(width, length, height)); }
inline TriangleMesh     make_cylinder(double r, double h, double fa=(2*PI/360)) { return TriangleMesh{its_make_cylinder(r, h, fa)}; }
inline TriangleMesh     make_cone(double r, double h, double fa=(2*PI/360))     { return TriangleMesh(its_make_cone(r, h, fa)); }
inline TriangleMesh     make_pyramid(float base, float height)                  { return TriangleMesh(its_make_pyramid(base, height)); }
inline TriangleMesh     make_sphere(double rho, double fa=(2*PI/360))           { return TriangleMesh(its_make_sphere(rho, fa)); }

bool        its_write_stl_ascii(const char *file, const char *label, const std::vector<stl_triangle_vertex_indices> &indices, const std::vector<stl_vertex> &vertices);
inline bool its_write_stl_ascii(const char *file, const char *label, const indexed_triangle_set &its) { return its_write_stl_ascii(file, label, its.indices, its.vertices); }
bool        its_write_stl_binary(const char *file, const char *label, const std::vector<stl_triangle_vertex_indices> &indices, const std::vector<stl_vertex> &vertices);
inline bool its_write_stl_binary(const char *file, const char *label, const indexed_triangle_set &its) { return its_write_stl_binary(file, label, its.indices, its.vertices); }

inline BoundingBoxf3 bounding_box(const TriangleMesh &m) { return m.bounding_box(); }
inline BoundingBoxf3 bounding_box(const indexed_triangle_set& its)
{
    if (its.vertices.empty())
        return {};

    Vec3f bmin = its.vertices.front(), bmax = its.vertices.front();

    for (const Vec3f &p : its.vertices) {
        bmin = p.cwiseMin(bmin);
        bmax = p.cwiseMax(bmax);
    }

    return {bmin.cast<double>(), bmax.cast<double>()};
}

}

// Serialization through the Cereal library
#include <cereal/access.hpp>
namespace cereal {
    template <class Archive> struct specialize<Archive, Slic3r::TriangleMesh, cereal::specialization::non_member_load_save> {};
    template<class Archive> void load(Archive &archive, Slic3r::TriangleMesh &mesh) {
        archive.loadBinary(reinterpret_cast<char*>(const_cast<Slic3r::TriangleMeshStats*>(&mesh.stats())), sizeof(Slic3r::TriangleMeshStats));
        archive(mesh.its.indices, mesh.its.vertices);
    }
    template<class Archive> void save(Archive &archive, const Slic3r::TriangleMesh &mesh) {
        archive.saveBinary(reinterpret_cast<const char*>(&mesh.stats()), sizeof(Slic3r::TriangleMeshStats));
        archive(mesh.its.indices, mesh.its.vertices);
    }
}

#endif