/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup stl
 */

#include <cstdint>
#include <cstdio>

#include "BKE_main.h"
#include "BKE_mesh.h"

#include "BLI_array.hh"
#include "BLI_memory_utils.hh"

#include "DNA_mesh_types.h"

#include "stl_import_binary_reader.hh"
#include "stl_import_mesh.hh"

namespace blender::io::stl {

#pragma pack(push, 1)
struct STLBinaryTriangle {
  float normal[3];
  float v1[3], v2[3], v3[3];
  uint16_t attribute_byte_count;
};
#pragma pack(pop)

Mesh *read_stl_binary(FILE *file, Main *bmain, char *mesh_name, bool use_custom_normals)
{
  const int chunk_size = 1024;
  uint32_t num_tris = 0;
  fseek(file, BINARY_HEADER_SIZE, SEEK_SET);
  fread(&num_tris, sizeof(uint32_t), 1, file);
  if (num_tris == 0) {
    return BKE_mesh_add(bmain, mesh_name);
  }

  Array<STLBinaryTriangle> tris_buf(chunk_size);
  STLMeshHelper stl_mesh(num_tris, use_custom_normals);
  size_t num_read_tris;
  while ((num_read_tris = fread(tris_buf.data(), sizeof(STLBinaryTriangle), chunk_size, file))) {
    for (size_t i = 0; i < num_read_tris; i++) {
      if (use_custom_normals) {
        stl_mesh.add_triangle(tris_buf[i].v1, tris_buf[i].v2, tris_buf[i].v3, tris_buf[i].normal);
      }
      else {
        stl_mesh.add_triangle(tris_buf[i].v1, tris_buf[i].v2, tris_buf[i].v3);
      }
    }
  }

  return stl_mesh.to_mesh(bmain, mesh_name);
}

}  // namespace blender::io::stl