/*
 * Copyright 2022 Frederico de Oliveira Linhares
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mesh.hpp"

#include <array>
#include <fstream>

#include "../command.hpp"
#include "../core.hpp"
#include "vertex_3d.hpp"

namespace
{

// Data that is only needed for the command chain but not for the Mesh goes
// here.
struct MeshBuilder
{
  std::string mesh_path;
  VK::Mesh *mesh;

  MeshBuilder(VK::Mesh *m, std::string mp);
  MeshBuilder(VK::Mesh *m, const char* mp);
};

MeshBuilder::MeshBuilder(VK::Mesh *m, std::string mp):
  mesh{m},
  mesh_path{mp}
{
}

MeshBuilder::MeshBuilder(VK::Mesh *m, const char *mp):
  MeshBuilder{m, std::string(mp)}
{
}

uint32_t read_uint32_from_file(std::ifstream &input_file)
{
  uint32_t data{};
  input_file.read((char*)&data, sizeof(uint32_t));
  return data;
}

glm::vec2 read_vec2_from_file(std::ifstream &input_file)
{
  glm::vec2 data{};
  input_file.read((char*)&data.x, sizeof(glm::vec2::value_type));
  input_file.read((char*)&data.y, sizeof(glm::vec2::value_type));
  return data;
}

glm::vec3 read_vec3_from_file(std::ifstream &input_file)
{
  glm::vec3 data{};
  input_file.read((char*)&data.x, sizeof(glm::vec3::value_type));
  input_file.read((char*)&data.y, sizeof(glm::vec3::value_type));
  input_file.read((char*)&data.z, sizeof(glm::vec3::value_type));
  return data;
}

void
load_mesh(void *obj)
{
  auto self = static_cast<MeshBuilder*>(obj);

  std::ifstream input_file{self->mesh_path};
  if(!input_file.is_open()) throw CommandError{"Failed to open file."};

  self->mesh->queue_family =
    cg_core.vk_device_with_swapchain->get_queue_family_with_graphics();

  // Load vertexes.
  {
    auto vertex_count{read_uint32_from_file(input_file)};
    std::vector<VK::Vertex3D> vertexes{vertex_count};

    for(auto i{0}; i < vertex_count; i++)
    {
      vertexes[i].position = read_vec3_from_file(input_file);
      vertexes[i].normal = read_vec3_from_file(input_file);
      vertexes[i].texture_coord = read_vec2_from_file(input_file);
    }

    void *vertexes_data{vertexes.data()};
    size_t vertexes_size = sizeof(vertexes[0]) * vertexes.size();
    self->mesh->source_vertex_buffer = new VK::SourceBuffer{
      self->mesh->queue_family->device, vertexes_data, vertexes_size};
    self->mesh->vertex_buffer = new VK::DestinationBuffer{
      self->mesh->queue_family, self->mesh->source_vertex_buffer,
      VK_BUFFER_USAGE_VERTEX_BUFFER_BIT};
  }

  // Load indexes.
  {
    self->mesh->index_count = read_uint32_from_file(input_file);
    std::vector<uint32_t> indexes(self->mesh->index_count);

    for(auto i{0}; i < self->mesh->index_count; i++)
      indexes[i] = read_uint32_from_file(input_file);

    void *indexes_data{indexes.data()};
    size_t indexes_size{sizeof(indexes[0]) * indexes.size()};
    VK::SourceBuffer source_index_buffer{
      self->mesh->queue_family->device, indexes_data, indexes_size};
    self->mesh->index_buffer = new VK::DestinationBuffer{
      self->mesh->queue_family, &source_index_buffer,
      VK_BUFFER_USAGE_INDEX_BUFFER_BIT};
  }
}

void
unload_mesh(void *obj)
{
  auto self = static_cast<MeshBuilder*>(obj);

  delete self->mesh->index_buffer;
  delete self->mesh->vertex_buffer;
  delete self->mesh->source_vertex_buffer;
}

static const CommandChain loader{
  {&load_mesh, &unload_mesh}
};

}

namespace VK
{

Mesh::Mesh(std::string mesh_path)
{
  MeshBuilder mesh_builder(this, mesh_path);
  loader.execute(&mesh_builder);
}

Mesh::Mesh(const char* mesh_path):
  Mesh{std::string(mesh_path)}
{
}

Mesh::~Mesh()
{
  MeshBuilder mesh_builder(this, "");
  loader.revert(&mesh_builder);
}

}