#include "Angel.h"
#include <fstream>
#include <iostream>
#include <vector>

#define PARAMS_DEBUG_PRINT true

const int texNumTriangles = 64770;
const int cowNumTriangles = 5804;

const int NumTriangles = texNumTriangles + cowNumTriangles;
const int NumVertices = 3 * NumTriangles;
const int TextureWidth = 256;
const int TextureHeight = 128;

typedef Angel::vec4 point4;
typedef Angel::vec4 color4;

// terrain altitude array
float ter_alt[128][256];

// Texture objects and storage for texture image
GLuint textures[1];

GLubyte image[TextureWidth][TextureHeight][3];

// Vertex data arrays
point4 points[NumVertices];
vec2 tex_coords[NumVertices];
vec3 normals[NumVertices];

// plane light params
GLuint plane_light;
GLfloat light_on = 1.0f;

// fog params
GLuint fog; // is_foggy uniform
GLuint eye_pos;
int foggy = 1;

GLuint fog_fac;
float fogFac = 1.0f;

// object (cow) params
GLuint obj_shi;
float objShi = 50.0f;

// Viewing transformation parameters
GLfloat theta = 0.0;
GLfloat phi = 0.0;
GLfloat tau = 0.0;

GLfloat eye_x = 0.0;
GLfloat eye_y = 0.25;
GLfloat eye_z = 0.1;
GLfloat eye_w = 1.0;

GLfloat at_x;
GLfloat at_y;
GLfloat at_z;
GLfloat at_w;

GLuint model_view; // model-view matrix uniform shader variable location

// Projection transformation parameters

GLfloat left = -0.01, right = 0.01;
GLfloat bottom = -0.01, top = 0.01;
GLfloat zNear = 0.1, zFar = 2.0;

GLuint projection; // projection matrix uniform shader variable location

//----------------------------------------------------------------------------

bool hit_check(GLfloat &x, GLfloat &y, GLfloat &z) {
  int x_idx = x * 256;
  int y_idx = y * 256;
  if (x_idx > 255 || x_idx < 0 || y_idx < 0 || y_idx > 127) {
    x = 0.0;
    y = 0.25;
    z = 0.1;
    return false;
  }
  if (PARAMS_DEBUG_PRINT) {
    printf("%f, %f\n", ter_alt[y_idx][x_idx], z);
  }
  if (ter_alt[y_idx][x_idx] >= z) {
    x = 0.0;
    y = 0.25;
    z = 0.1;
    return false;
  }
  return true;
}

void load_model(const std::string &file_name, bool not_tex = false,
                float x_offset = 0.0f, float y_offset = 0.0f,
                float z_offset = 0.0f) {
  std::vector<point4> vertices;
  std::vector<vec2> tex_cods;
  std::fstream s(file_name, std::fstream::in);
  static int index = 0;
  if (!s.is_open()) {
    std::cerr << "failed to open" << file_name << std::endl;
  } else {
    std::string t;
    float x, y, z;
    int a, b, c;
    int num = 0;
    int idx = 0;
    while (s >> t) {
      if (t == "v") { // vertices
        s >> x >> y >> z;
        vertices.emplace_back(x / 50.0f + x_offset, z / 50.0f + z_offset,
                              y / 50.0f + y_offset, 1.0);
        if (!not_tex) {
          *(reinterpret_cast<float *>(ter_alt) + idx) = y / 50.0f;
          idx++;
        }
      } else if (t == "vt") {
        s >> x >> y;
        tex_cods.emplace_back(x, y);
      } else if (t == "f") {
        s >> a >> b >> c;
        a--;
        b--;
        c--;
        vec3 normal = normalize(
            cross(vertices[b] - vertices[a], vertices[c] - vertices[b]));
        points[index] = vertices[a];
        normals[index] = normal;
        if (not_tex) {
          tex_coords[index] = {20.0, 0.0};
        } else {
          tex_coords[index] = tex_cods[a];
        }
        index++;
        points[index] = vertices[b];
        normals[index] = normal;
        if (not_tex) {
          tex_coords[index] = {20.0, 0.0};
        } else {
          tex_coords[index] = tex_cods[b];
        }
        index++;
        points[index] = vertices[c];
        normals[index] = normal;
        if (not_tex) {
          tex_coords[index] = {20.0, 0.0};
        } else {
          tex_coords[index] = tex_cods[c];
        }
        index++;
        num++;
      }
    }
    std::cout << "Load model:" << file_name << std::endl;
    std::cout << "There are " << vertices.size() << "vertice(s)"
              << ", " << tex_cods.size() << "tex cor(s)" << std::endl
              << "There are " << num << "fragment(s)" << std::endl;
    s.close();
  }
}
//----------------------------------------------------------------------------

void load_tex(const std::string &file_name) {
  char cline[1024];
  char p6[10];
  int width;
  int height;
  int depth;
  FILE *fp = fopen(file_name.data(), "rb");
  fgets(cline, sizeof(cline), fp);
  sscanf(cline, "%s %d %d %d", p6, &width, &height, &depth);
  std::cout << p6 << "," << width << "," << height << "," << depth << std::endl;
  fread(image, sizeof(GLubyte), width * height * 3, fp);
  fclose(fp);
}

void init() {
  load_tex("gc_tex.ppm");
  load_model("gc_tex.obj");
  load_model("cow.obj", true, 0.90, 0.05, 0.25); // no tex data in cow obj
  // Initialize texture objects
  glGenTextures(1, textures);

  glBindTexture(GL_TEXTURE_2D, textures[0]);
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TextureWidth, TextureHeight, 0, GL_RGB,
               GL_UNSIGNED_BYTE, image);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D, textures[0]);

  // Create a vertex array object
  GLuint vao;
  glGenVertexArrays(1, &vao);
  glBindVertexArray(vao);

  // Create and initialize a buffer object
  GLuint buffer;
  glGenBuffers(1, &buffer);
  glBindBuffer(GL_ARRAY_BUFFER, buffer);
  glBufferData(GL_ARRAY_BUFFER,
               sizeof(points) + sizeof(tex_coords) + sizeof(normals), NULL,
               GL_STATIC_DRAW);

  // Specify an offset to keep track of where we're placing data in our
  //   vertex array buffer.  We'll use the same technique when we
  //   associate the offsets with vertex attribute pointers.
  GLintptr offset = 0;
  glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(points), points);
  offset += sizeof(points);

  glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(tex_coords), tex_coords);
  offset += sizeof(tex_coords);

  glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(normals), normals);

  // Load shaders and use the resulting shader program
  GLuint program = InitShader("vshader71.glsl", "fshader71.glsl");
  glUseProgram(program);

  // set up vertex arrays
  offset = 0;
  GLuint vPosition = glGetAttribLocation(program, "vPosition");
  glEnableVertexAttribArray(vPosition);
  glVertexAttribPointer(vPosition, 4, GL_FLOAT, GL_FALSE, 0,
                        BUFFER_OFFSET(offset));
  offset += sizeof(points);

  GLuint vTexCoord = glGetAttribLocation(program, "vTexCoord");
  glEnableVertexAttribArray(vTexCoord);
  glVertexAttribPointer(vTexCoord, 2, GL_FLOAT, GL_FALSE, 0,
                        BUFFER_OFFSET(offset));
  offset += sizeof(tex_coords);

  GLuint vNormal = glGetAttribLocation(program, "vNormal");
  glEnableVertexAttribArray(vNormal);
  glVertexAttribPointer(vNormal, 3, GL_FLOAT, GL_FALSE, 0,
                        BUFFER_OFFSET(offset));

  // Set the value of the fragment shader texture sampler variable
  //   ("texture") to the the appropriate texture unit. In this case,
  //   zero, for GL_TEXTURE0 which was previously set by calling
  //   glActiveTexture().
  glUniform1i(glGetUniformLocation(program, "tex"), 0);
  model_view = glGetUniformLocation(program, "model_view");
  projection = glGetUniformLocation(program, "projection");
  fog = glGetUniformLocation(program, "foggy");
  eye_pos = glGetUniformLocation(program, "eye_pos");
  plane_light = glGetUniformLocation(program, "plane_light_on");
  fog_fac = glGetUniformLocation(program, "fog_fac");
  obj_shi = glGetUniformLocation(program, "obj_shi");
  glEnable(GL_DEPTH_TEST);

  glClearColor(1, 1, 1, 1);
}

void display(void) {
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  point4 eye(eye_x, eye_y, eye_z, 1.0);
  at_x = cos(theta) * cos(phi) * 100.0;
  at_y = sin(theta) * cos(phi) * 100.0;
  at_z = sin(phi) * 100.0;
  point4 at(at_x, at_y, at_z, 1.0);
  vec4 up(0.0, 100 * sin(tau), 100 * cos(tau), 0.0);

  mat4 mv = LookAt(eye, at, up);
  glUniformMatrix4fv(model_view, 1, GL_TRUE, mv);

  mat4 p = Frustum(left, right, bottom, top, zNear, zFar);
  glUniformMatrix4fv(projection, 1, GL_TRUE, p);

  glUniform3f(eye_pos, eye_x, eye_y, eye_z);

  glUniform1i(fog, foggy);

  glUniform1f(plane_light, light_on);

  glUniform1f(fog_fac, fogFac);

  glUniform1f(obj_shi, objShi);

  glDrawArrays(GL_TRIANGLES, 0, NumVertices);

  glutSwapBuffers();
}

//----------------------------------------------------------------------------

void mouse(int button, int state, int x, int y) {}

//----------------------------------------------------------------------------

void idle(void) { glutPostRedisplay(); }

//----------------------------------------------------------------------------

void keyboard(unsigned char key, int mousex, int mousey) {
  switch (key) {
  case 033: // Escape Key
    exit(0);
    break;
  case 'l':
    if (light_on > 0.0) {
      light_on = 0.0;
    } else {
      light_on = 1.0;
    }
    break;
  case 'f':
    if (foggy > 0) {
      foggy = 0;
    } else {
      foggy = 1;
    }
    break;
  case 'k':
    objShi -= 1.0f;
    if (objShi < 0.0f) {
      objShi = 0.0f;
    }
    break;
  case 'K':
    objShi += 1.0f;
    break;
  case 'g':
    fogFac -= 0.1;
    if (fogFac < 0) {
      fogFac = 0;
    }
    break;
  case 'G':
    fogFac += 0.1;
    break;
  case '1':
    tau += 0.01;
    break;
  case '3':
    tau -= 0.01;
    break;
  case 'q':
    theta += 0.01;
    break;
  case 'e':
    theta -= 0.01;
    break;
  case 'w':
    eye_x += 0.01;
    break;
  case 's':
    eye_x -= 0.01;
    break;
  case 'd':
    eye_y -= 0.01;
    break;
  case 'a':
    eye_y += 0.01;
    break;
  case '9':
    eye_z -= 0.01;
    break;
  case '6':
    eye_z += 0.01;
    break;
  case '8':
    phi -= 0.01;
    break;
  case '5':
    phi += 0.01;
    break;
  }
  if (PARAMS_DEBUG_PRINT) {
    printf("obj_shi:%f\n", objShi);
    printf("eye_x,y,z:%f, %f, %f, %f\n", eye_x, eye_y, eye_z, eye_w);
    printf("at_x,y,z:%f, %f, %f, %f\n", at_x, at_y, at_z, at_w);
  }
  hit_check(eye_x, eye_y, eye_z);
  glutPostRedisplay();
}

//----------------------------------------------------------------------------

int main(int argc, char **argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
  glutInitWindowSize(512, 512);
  glutInitContextVersion(3, 1);
  glutInitContextProfile(GLUT_CORE_PROFILE);
  glutCreateWindow("flying");

  if (glewInit() != GLEW_OK) {
    std::cerr << "Failed to initialize GLEW ... exiting" << std::endl;
    exit(EXIT_FAILURE);
  }

  init();

  glutDisplayFunc(display);
  glutKeyboardFunc(keyboard);
  glutMouseFunc(mouse);
  // glutIdleFunc(idle);
  glutMainLoop();
  return 0;
}