#include "Mesh.hpp"
#include <stdio.h> // fscanf
#include <string.h> // strcmp
#include <stdlib.h> // atof

Mesh::Mesh() {
  vbo = vao = tex = 0;
  flags = 0;
  mode = GL_STATIC_DRAW;
}
Mesh::Mesh(Vec3 *in_vertices, int v_count, Vec2 *in_uvs, int uv_count, Vec3 *in_normals, int n_count) {
  loadArrays(in_vertices, v_count, in_uvs, uv_count, in_normals, n_count);
}

Mesh::~Mesh() {
  if (flags & MESH_BUILT) destroyMesh();
}

int Mesh::loadObj(const char *filename) {
  std::vector <Vec3> temp_vertices;
  std::vector <Vec2> temp_uvs;
  std::vector <Vec3> temp_normals;
  std::vector <unsigned int> vertex_indices;
  std::vector <unsigned int> uv_indices;
  std::vector <unsigned int> normal_indices;
  int ret;
#ifdef _WIN32
  FILE *file;
  fopen_s(&file, filename, "r");
#else
  FILE *file = fopen(filename, "r");
#endif
  if (file == NULL) {
    // TODO: error report
    return 1;
  }
  char word[32];
#ifdef _WIN32
  while ((ret = fscanf_s(file, "%s ", word)) != EOF) {
#else
  while ((ret = fscanf(file, "%s ", word)) != EOF) {
#endif
    if (strcmp(word, "v") == 0) { // vertices
      // "x y z w" as floats, with "w" being optional
      Vec3 vec; // our vertex
      char word[32];
      char ch;
      int pos = 0, w_i = 0;
      while ((ch = fgetc(file)) != EOF) {
        if (ch == ' ' || ch == '\n') {
          if (pos == 0) { // x
            word[w_i] = '\0';
            vec.x = (float)atof(word);
          } else if (pos == 1) { // y
            word[w_i] = '\0';
            vec.y = (float)atof(word);
          } else if (pos == 2) { // z
            word[w_i] = '\0';
            vec.z = (float)atof(word);
          /*} else if (pos == 3) { // w
            word[w_i] = '\0';
            vec.w = atof(word);*/
          }
          pos++;
          w_i = 0;
        }
        if (ch == '\n') break;
        word[w_i++] = ch;
      }
      temp_vertices.push_back(vec);
    } else if (strcmp(word, "vt") == 0) { // texture coordinates
      // "u v [w]" as floats, with "w" being optional
      Vec2 vec; // our texture coord
      char word[32];
      char ch;
      int pos = 0, w_i = 0;
      while ((ch = fgetc(file)) != EOF) {
        if (ch == ' ' || ch == '\n') {
          if (pos == 0) { // x
            word[w_i] = '\0';
            vec.x = (float)atof(word);
          } else if (pos == 1) { // y
            word[w_i] = '\0';
            vec.y = (float)atof(word);
          /*} else if (pos == 3) { // w
            word[w_i] = '\0';
            vec.w = atof(word);*/
          }
          pos++;
          w_i = 0;
        }
        if (ch == '\n') break;
        word[w_i++] = ch;
      }
      temp_uvs.push_back(vec);
    } else if (strcmp(word, "vn") == 0) { // normals
      // "x y z" as floats
      Vec3 vec; // our normal
      char word[32];
      char ch;
      int pos = 0, w_i = 0;
      while ((ch = fgetc(file)) != EOF) {
        if (ch == ' ' || ch == '\n') {
          if (pos == 0) { // x
            word[w_i] = '\0';
            vec.x = (float)atof(word);
          } else if (pos == 1) { // y
            word[w_i] = '\0';
            vec.y = (float)atof(word);
          } else if (pos == 2) { // z
            word[w_i] = '\0';
            vec.z = (float)atof(word);
          /*} else if (pos == 3) { // w
            word[w_i] = '\0';
            vec.w = atof(word);*/
          }
          pos++;
          w_i = 0;
        }
        if (ch == '\n') break;
        word[w_i++] = ch;
      }
      temp_normals.push_back(vec);
    /*} else if (strcmp(word, "vp") == 0) { // parameter space vertices
      // "u v w", with 'v' and 'w' being optional*/
    } else if (strcmp(word, "f") == 0) { // face definitions
      // "v1 v2 v3" for plain vertex indices
      // "v1/vt1 v2/vt2 v3/vt3" for vertex/texture-coordinate indices
      // "v1/vt1/vn1 v2/vt2/vn2 v3/vt3/vn3" for vertex/texture-coordinate/normal indices
      // "v1//vn1 v2//vn2 v3//vn3" for vertex/normal indices
      char word[32];
      char ch;
      int w_i = 0, mode = 0;
      // read in our faces into our index vectors
      while ((ch = fgetc(file)) != EOF) {
        if (ch == ' ' || ch == '\n') {
          word[w_i] = '\0';
          if (mode == 0) { // was in vertex, now in texture-coords
            vertex_indices.push_back(atoi(word));
          } else if (mode == 1) { // was in texture-coords, now in normal
            uv_indices.push_back(atoi(word));
          } else if (mode == 2) { // was in normal, write it out
            normal_indices.push_back(atoi(word));
          }
          w_i = 0;
          mode = 0; // reset our mode
        } else if (ch == '/') {
          word[w_i] = '\0';
          if (mode == 0) { // was in vertex, now in texture-coords
            vertex_indices.push_back(atoi(word));
          } else if (mode == 1) { // was in texture-coords, now in normal
            if (w_i > 0) uv_indices.push_back(atoi(word));
          }
          mode++;
          w_i = 0;
        } else {
          word[w_i++] = ch;
        }
        if (ch == '\n') break;
      }
    //} else if (strcmp(word, "#") == 0) { // comment
    //} else if (strcmp(word, "o") == 0) { // object name
    //} else if (strcmp(word, "g") == 0) { // group name
    //} else if (Strmcpmp(word, "s") == 0) { // smooth
      // "s 1" or "s off"
    } else { // ergo, newline noms
      char ch;
      while ((ch = fgetc(file)) != EOF) {
        if (ch == '\n') break;
      }
    }
  }
  fclose(file);
  // we're done, let's convert our face-derived indices to our actual mesh
  int i;
  int indices = vertex_indices.size();
  // TODO: vertex index access should be checked for validity (>= 0 < temp_vertices.size())
  for (i = 0; i < indices; i++) {
    Vec3 vertex = temp_vertices[vertex_indices[i]-1];
    vertices.push_back(vertex);
  }
  indices = uv_indices.size();
  for (i = 0; i < indices; i++) {
    printf("%d/%d\n", i, indices);
    printf("%d\n", uv_indices[i]);
    Vec2 uv = temp_uvs[uv_indices[i]-1];
    uvs.push_back(uv);
  }
  indices = normal_indices.size();
  for (i = 0; i < indices; i++) {
    Vec3 normal = temp_normals[normal_indices[i]-1];
    normals.push_back(normal);
  }
  flags |= MESH_LOADED;
  return 0;
}
int Mesh::loadArrays(Vec3 *in_vertices, int v_count, Vec2 *in_uvs, int uv_count, Vec3 *in_normals, int n_count) {
  if (v_count > 0) {
    vertices.assign(in_vertices, in_vertices + v_count);
    flags |= MESH_LOADED;
  }
  if (uv_count > 0) {
    uvs.assign(in_uvs, in_uvs + uv_count);
  }
  if (n_count > 0) {
    normals.assign(in_normals, in_normals + n_count);
  }
  return 0;
}

int Mesh::buildMesh() {
  if (!(flags & MESH_LOADED)) return 1;
  if (flags & MESH_BUILT) destroyMesh();
  // generate our vertex buffer object from our given points
  glGenBuffers(1, &vbo);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);
  glBufferData(GL_ARRAY_BUFFER, vertices.size()*sizeof(Vec3), &vertices[0], mode);
  flags |= MESH_BUILT;
  return 0;
}
int Mesh::destroyMesh() {
  glDeleteBuffers(1, &vbo);
  //glDeleteVertexArrays(1, &vao);
  flags &= ~MESH_BUILT;
  return 0;
}