#define TINYOBJ_LOADER_C_IMPLEMENTATION
#include "../../tinyobj_loader_c.h"

#include "glad.h"

#include <float.h>
#include <limits.h>
#include <math.h>

#ifdef _WIN64
#define atoll(S) _atoi64(S)
#include <windows.h>
#else
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <unistd.h>
#endif

#ifdef __APPLE__
#include <OpenGL/glu.h>
#else
#include <GL/glu.h>
#endif

#include <GLFW/glfw3.h>

#include "trackball.h"

typedef struct {
  GLuint vb;
  int numTriangles;
} DrawObject;

static DrawObject gDrawObject;

static int width = 768;
static int height = 768;

static float prevMouseX, prevMouseY;
static int mouseLeftPressed;
static int mouseMiddlePressed;
static int mouseRightPressed;
static float curr_quat[4];
static float prev_quat[4];
static float eye[3], lookat[3], up[3];

static GLFWwindow* gWindow;

static void CheckErrors(const char* desc) {
  GLenum e = glGetError();
  if (e != GL_NO_ERROR) {
    fprintf(stderr, "OpenGL error in \"%s\": %d (%d)\n", desc, e, e);
    exit(20);
  }
}

static void CalcNormal(float N[3], float v0[3], float v1[3], float v2[3]) {
  float v10[3];
  float v20[3];
  float len2;

  v10[0] = v1[0] - v0[0];
  v10[1] = v1[1] - v0[1];
  v10[2] = v1[2] - v0[2];

  v20[0] = v2[0] - v0[0];
  v20[1] = v2[1] - v0[1];
  v20[2] = v2[2] - v0[2];

  N[0] = v20[1] * v10[2] - v20[2] * v10[1];
  N[1] = v20[2] * v10[0] - v20[0] * v10[2];
  N[2] = v20[0] * v10[1] - v20[1] * v10[0];

  len2 = N[0] * N[0] + N[1] * N[1] + N[2] * N[2];
  if (len2 > 0.0f) {
    float len = (float)sqrt((double)len2);

    N[0] /= len;
    N[1] /= len;
  }
}

static const char* mmap_file(size_t* len, const char* filename) {
#ifdef _WIN64
  HANDLE file =
      CreateFileA(filename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING,
                  FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);
  assert(file != INVALID_HANDLE_VALUE);

  HANDLE fileMapping = CreateFileMapping(file, NULL, PAGE_READONLY, 0, 0, NULL);
  assert(fileMapping != INVALID_HANDLE_VALUE);

  LPVOID fileMapView = MapViewOfFile(fileMapping, FILE_MAP_READ, 0, 0, 0);
  auto fileMapViewChar = (const char*)fileMapView;
  assert(fileMapView != NULL);
#else

  FILE* f;
  long file_size;
  struct stat sb;
  char* p;
  int fd;

  (*len) = 0;

  f = fopen(filename, "r");
  fseek(f, 0, SEEK_END);
  file_size = ftell(f);
  fclose(f);

  fd = open(filename, O_RDONLY);
  if (fd == -1) {
    perror("open");
    return NULL;
  }

  if (fstat(fd, &sb) == -1) {
    perror("fstat");
    return NULL;
  }

  if (!S_ISREG(sb.st_mode)) {
    fprintf(stderr, "%s is not a file\n", "lineitem.tbl");
    return NULL;
  }

  p = (char*)mmap(0, (size_t)file_size, PROT_READ, MAP_SHARED, fd, 0);

  if (p == MAP_FAILED) {
    perror("mmap");
    return NULL;
  }

  if (close(fd) == -1) {
    perror("close");
    return NULL;
  }

  (*len) = (size_t)file_size;

  return p;

#endif
}

static const char* get_file_data(size_t* len, const char* filename) {
  const char* ext = strrchr(filename, '.');

  size_t data_len = 0;
  const char* data = NULL;

  if (strcmp(ext, ".gz") == 0) {
    assert(0); /* todo */

  } else {
    data = mmap_file(&data_len, filename);
  }

  (*len) = data_len;
  return data;
}

static int LoadObjAndConvert(float bmin[3], float bmax[3],
                             const char* filename) {
  tinyobj_attrib_t attrib;
  tinyobj_shape_t* shapes = NULL;
  size_t num_shapes;
  tinyobj_material_t* materials = NULL;
  size_t num_materials;

  size_t data_len = 0;
  const char* data = get_file_data(&data_len, filename);
  if (data == NULL) {
    exit(-1);
    /* return 0; */
  }
  printf("filesize: %d\n", (int)data_len);

  {
    unsigned int flags = TINYOBJ_FLAG_TRIANGULATE;
    int ret = tinyobj_parse_obj(&attrib, &shapes, &num_shapes, &materials,
                                &num_materials, data, data_len, flags);
    if (ret != TINYOBJ_SUCCESS) {
      return 0;
    }

    printf("# of shapes    = %d\n", (int)num_shapes);
    printf("# of materials = %d\n", (int)num_materials);

    /*
    {
      int i;
      for (i = 0; i < num_shapes; i++) {
        printf("shape[%d] name = %s\n", i, shapes[i].name);
      }
    }
    */
  }

  bmin[0] = bmin[1] = bmin[2] = FLT_MAX;
  bmax[0] = bmax[1] = bmax[2] = -FLT_MAX;

  {
    DrawObject o;
    float* vb;
    /* std::vector<float> vb; //  */
    size_t face_offset = 0;
    size_t i;

    /* Assume triangulated face. */
    size_t num_triangles = attrib.num_face_num_verts;
    size_t stride = 9; /* 9 = pos(3float), normal(3float), color(3float) */

    vb = (float*)malloc(sizeof(float) * stride * num_triangles * 3);

    for (i = 0; i < attrib.num_face_num_verts; i++) {
      size_t f;
      assert(attrib.face_num_verts[i] % 3 ==
             0); /* assume all triangle faces. */
      for (f = 0; f < (size_t)attrib.face_num_verts[i] / 3; f++) {
        size_t k;
        float v[3][3];
        float n[3][3];
        float c[3];
        float len2;

        tinyobj_vertex_index_t idx0 = attrib.faces[face_offset + 3 * f + 0];
        tinyobj_vertex_index_t idx1 = attrib.faces[face_offset + 3 * f + 1];
        tinyobj_vertex_index_t idx2 = attrib.faces[face_offset + 3 * f + 2];

        for (k = 0; k < 3; k++) {
          int f0 = idx0.v_idx;
          int f1 = idx1.v_idx;
          int f2 = idx2.v_idx;
          assert(f0 >= 0);
          assert(f1 >= 0);
          assert(f2 >= 0);

          v[0][k] = attrib.vertices[3 * (size_t)f0 + k];
          v[1][k] = attrib.vertices[3 * (size_t)f1 + k];
          v[2][k] = attrib.vertices[3 * (size_t)f2 + k];
          bmin[k] = (v[0][k] < bmin[k]) ? v[0][k] : bmin[k];
          bmin[k] = (v[1][k] < bmin[k]) ? v[1][k] : bmin[k];
          bmin[k] = (v[2][k] < bmin[k]) ? v[2][k] : bmin[k];
          bmax[k] = (v[0][k] > bmax[k]) ? v[0][k] : bmax[k];
          bmax[k] = (v[1][k] > bmax[k]) ? v[1][k] : bmax[k];
          bmax[k] = (v[2][k] > bmax[k]) ? v[2][k] : bmax[k];
        }

        if (attrib.num_normals > 0) {
          int f0 = idx0.vn_idx;
          int f1 = idx1.vn_idx;
          int f2 = idx2.vn_idx;
          if (f0 >= 0 && f1 >= 0 && f2 >= 0) {
            assert(f0 < (int)attrib.num_normals);
            assert(f1 < (int)attrib.num_normals);
            assert(f2 < (int)attrib.num_normals);
            for (k = 0; k < 3; k++) {
              n[0][k] = attrib.normals[3 * (size_t)f0 + k];
              n[1][k] = attrib.normals[3 * (size_t)f1 + k];
              n[2][k] = attrib.normals[3 * (size_t)f2 + k];
            }
          } else { /* normal index is not defined for this face */
            /* compute geometric normal */
            CalcNormal(n[0], v[0], v[1], v[2]);
            n[1][0] = n[0][0];
            n[1][1] = n[0][1];
            n[1][2] = n[0][2];
            n[2][0] = n[0][0];
            n[2][1] = n[0][1];
            n[2][2] = n[0][2];
          }
        } else {
          /* compute geometric normal */
          CalcNormal(n[0], v[0], v[1], v[2]);
          n[1][0] = n[0][0];
          n[1][1] = n[0][1];
          n[1][2] = n[0][2];
          n[2][0] = n[0][0];
          n[2][1] = n[0][1];
          n[2][2] = n[0][2];
        }

        for (k = 0; k < 3; k++) {
          vb[(3 * i + k) * stride + 0] = v[k][0];
          vb[(3 * i + k) * stride + 1] = v[k][1];
          vb[(3 * i + k) * stride + 2] = v[k][2];
          vb[(3 * i + k) * stride + 3] = n[k][0];
          vb[(3 * i + k) * stride + 4] = n[k][1];
          vb[(3 * i + k) * stride + 5] = n[k][2];

          /* Use normal as color. */
          c[0] = n[k][0];
          c[1] = n[k][1];
          c[2] = n[k][2];
          len2 = c[0] * c[0] + c[1] * c[1] + c[2] * c[2];
          if (len2 > 0.0f) {
            float len = (float)sqrt((double)len2);

            c[0] /= len;
            c[1] /= len;
            c[2] /= len;
          }

          vb[(3 * i + k) * stride + 6] = (c[0] * 0.5f + 0.5f);
          vb[(3 * i + k) * stride + 7] = (c[1] * 0.5f + 0.5f);
          vb[(3 * i + k) * stride + 8] = (c[2] * 0.5f + 0.5f);
        }
      }
      face_offset += (size_t)attrib.face_num_verts[i];
    }

    o.vb = 0;
    o.numTriangles = 0;
    if (num_triangles > 0) {
      glGenBuffers(1, &o.vb);
      glBindBuffer(GL_ARRAY_BUFFER, o.vb);
      glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)(num_triangles * 3 * stride * sizeof(float)),
                   vb, GL_STATIC_DRAW);
      o.numTriangles = (int)num_triangles;
    }

    free(vb);

    gDrawObject = o;
  }

  printf("bmin = %f, %f, %f\n", (double)bmin[0], (double)bmin[1],
         (double)bmin[2]);
  printf("bmax = %f, %f, %f\n", (double)bmax[0], (double)bmax[1],
         (double)bmax[2]);

  tinyobj_attrib_free(&attrib);
  tinyobj_shapes_free(shapes, num_shapes);
  tinyobj_materials_free(materials, num_materials);

  return 1;
}

static void reshapeFunc(GLFWwindow* window, int w, int h) {
  int fb_w, fb_h;
  glfwGetFramebufferSize(window, &fb_w, &fb_h);

  glViewport(0, 0, fb_w, fb_h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(45.0, (GLdouble)w / (GLdouble)h, (GLdouble)0.01f,
                 (GLdouble)100.0f);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  width = w;
  height = h;
}

static void keyboardFunc(GLFWwindow* window, int key, int scancode, int action,
                         int mods) {
  (void)window;
  (void)scancode;
  (void)mods;
  if (action == GLFW_PRESS || action == GLFW_REPEAT) {
    /* Move camera */
    float mv_x = 0, mv_y = 0, mv_z = 0;
    if (key == GLFW_KEY_K)
      mv_x += 1;
    else if (key == GLFW_KEY_J)
      mv_x += -1;
    else if (key == GLFW_KEY_L)
      mv_y += 1;
    else if (key == GLFW_KEY_H)
      mv_y += -1;
    else if (key == GLFW_KEY_P)
      mv_z += 1;
    else if (key == GLFW_KEY_N)
      mv_z += -1;

    if (key == GLFW_KEY_Q || key == GLFW_KEY_ESCAPE)
      glfwSetWindowShouldClose(window, GL_TRUE);
  }
}

static void clickFunc(GLFWwindow* window, int button, int action, int mods) {
  (void)window;
  (void)mods;
  if (button == GLFW_MOUSE_BUTTON_LEFT) {
    if (action == GLFW_PRESS) {
      mouseLeftPressed = 1;
      trackball(prev_quat, 0.0, 0.0, 0.0, 0.0);
    } else if (action == GLFW_RELEASE) {
      mouseLeftPressed = 0;
    }
  }
  if (button == GLFW_MOUSE_BUTTON_RIGHT) {
    if (action == GLFW_PRESS) {
      mouseRightPressed = 1;
    } else if (action == GLFW_RELEASE) {
      mouseRightPressed = 0;
    }
  }
  if (button == GLFW_MOUSE_BUTTON_MIDDLE) {
    if (action == GLFW_PRESS) {
      mouseMiddlePressed = 1;
    } else if (action == GLFW_RELEASE) {
      mouseMiddlePressed = 0;
    }
  }
}

static void motionFunc(GLFWwindow* window, double mouse_x, double mouse_y) {
  float rotScale = 1.0f;
  float transScale = 2.0f;

  (void)window;

  if (mouseLeftPressed) {
    trackball(prev_quat, rotScale * (2.0f * prevMouseX - width) / (float)width,
              rotScale * (height - 2.0f * prevMouseY) / (float)height,
              rotScale * (2.0f * (float)mouse_x - width) / (float)width,
              rotScale * (height - 2.0f * (float)mouse_y) / (float)height);

    add_quats(prev_quat, curr_quat, curr_quat);
  } else if (mouseMiddlePressed) {
    eye[0] -= transScale * ((float)mouse_x - prevMouseX) / (float)width;
    lookat[0] -= transScale * ((float)mouse_x - prevMouseX) / (float)width;
    eye[1] += transScale * ((float)mouse_y - prevMouseY) / (float)height;
    lookat[1] += transScale * ((float)mouse_y - prevMouseY) / (float)height;
  } else if (mouseRightPressed) {
    eye[2] += transScale * ((float)mouse_y - prevMouseY) / (float)height;
    lookat[2] += transScale * ((float)mouse_y - prevMouseY) / (float)height;
  }

  prevMouseX = (float)mouse_x;
  prevMouseY = (float)mouse_y;
}

static void Draw(const DrawObject* draw_object) {
  glPolygonMode(GL_FRONT, GL_FILL);
  glPolygonMode(GL_BACK, GL_FILL);

  glEnable(GL_POLYGON_OFFSET_FILL);
  glPolygonOffset(1.0, 1.0);
  glColor3f(1.0f, 1.0f, 1.0f);
  if (draw_object->vb >= 1) {
    glBindBuffer(GL_ARRAY_BUFFER, draw_object->vb);
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_NORMAL_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glVertexPointer(3, GL_FLOAT, 36, (const void*)0);
    glNormalPointer(GL_FLOAT, 36, (const void*)(sizeof(float) * 3));
    glColorPointer(3, GL_FLOAT, 36, (const void*)(sizeof(float) * 6));

    glDrawArrays(GL_TRIANGLES, 0, 3 * draw_object->numTriangles);
    CheckErrors("drawarrays");
  }

  /* draw wireframe */
  glDisable(GL_POLYGON_OFFSET_FILL);
  glPolygonMode(GL_FRONT, GL_LINE);
  glPolygonMode(GL_BACK, GL_LINE);

  glColor3f(0.0f, 0.0f, 0.4f);

  if (draw_object->vb >= 1) {
    glBindBuffer(GL_ARRAY_BUFFER, draw_object->vb);
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);
    glVertexPointer(3, GL_FLOAT, 36, (const void*)0);
    glNormalPointer(GL_FLOAT, 36, (const void*)(sizeof(float) * 3));

    glDrawArrays(GL_TRIANGLES, 0, 3 * draw_object->numTriangles);
    CheckErrors("drawarrays");
  }
}

static void Init() {
  trackball(curr_quat, 0, 0, 0, 0);

  eye[0] = 0.0f;
  eye[1] = 0.0f;
  eye[2] = 3.0f;

  lookat[0] = 0.0f;
  lookat[1] = 0.0f;
  lookat[2] = 0.0f;

  up[0] = 0.0f;
  up[1] = 1.0f;
  up[2] = 0.0f;
}

int main(int argc, char** argv) {
  if (argc < 2) {
    fprintf(stderr, "Needs input.obj\n");
    return 0;
  }

  Init();

  printf("Initialize GLFW...\n");

  if (!glfwInit()) {
    fprintf(stderr, "Failed to initialize GLFW.\n");
    return -1;
  }

  gWindow = glfwCreateWindow(width, height, "Obj viewer", NULL, NULL);
  if (gWindow == NULL) {
    fprintf(stderr, "Failed to open GLFW window.\n");
    glfwTerminate();
    return 1;
  }

  glfwSwapInterval(1);

  glfwSetWindowSizeCallback(gWindow, reshapeFunc);
  glfwSetKeyCallback(gWindow, keyboardFunc);
  glfwSetMouseButtonCallback(gWindow, clickFunc);
  glfwSetCursorPosCallback(gWindow, motionFunc);

  glfwMakeContextCurrent(gWindow);

  if (!gladLoadGLLoader((GLADloadproc) glfwGetProcAddress)) {
    fprintf(stderr, "Failed to initialize GLAD.\n");
	return -1;
    }


  reshapeFunc(gWindow, width, height);

  {
    float bmin[3], bmax[3];
    float maxExtent;
    if (0 == LoadObjAndConvert(bmin, bmax, argv[1])) {
      printf("failed to load & conv\n");
      return -1;
    }

    maxExtent = 0.5f * (bmax[0] - bmin[0]);
    if (maxExtent < 0.5f * (bmax[1] - bmin[1])) {
      maxExtent = 0.5f * (bmax[1] - bmin[1]);
    }
    if (maxExtent < 0.5f * (bmax[2] - bmin[2])) {
      maxExtent = 0.5f * (bmax[2] - bmin[2]);
    }

    while (glfwWindowShouldClose(gWindow) == GL_FALSE) {
      GLfloat mat[4][4];

      glfwPollEvents();
      glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

      glEnable(GL_DEPTH_TEST);

      glMatrixMode(GL_MODELVIEW);
      glLoadIdentity();
      gluLookAt((GLdouble)eye[0], (GLdouble)eye[1], (GLdouble)eye[2],
                (GLdouble)lookat[0], (GLdouble)lookat[1], (GLdouble)lookat[2],
                (GLdouble)up[0], (GLdouble)up[1], (GLdouble)up[2]);
      build_rotmatrix(mat, curr_quat);
      glMultMatrixf(&mat[0][0]);

      /* Fit to -1, 1 */
      glScalef(1.0f / maxExtent, 1.0f / maxExtent, 1.0f / maxExtent);

      /* Centerize object. */
      glTranslatef(-0.5f * (bmax[0] + bmin[0]), -0.5f * (bmax[1] + bmin[1]),
                   -0.5f * (bmax[2] + bmin[2]));

      Draw(&gDrawObject);

      glfwSwapBuffers(gWindow);
    }
  }

  glfwTerminate();
  return 0;
}