#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>

#include <iostream>
#include <string>

#include "util/shaderutil.hpp"

#define WIDTH   800
#define HEIGHT  600

using namespace std;
using namespace glm;

GLuint vao;
GLuint vbo;
GLuint shaderprogram;

static const GLfloat vertices[3 * 3] = {
  0.0, 0.5, 0.0,
  0.5,-0.5, 0.0,
 -0.5,-0.5, 0.0
};

bool found = false;

void check(int line) {
  GLenum e = glGetError();
  if (e != GL_NO_ERROR && !found) {
    cerr << "ERROR FOUND @ LINE " << line << " WITH ERROR CODE " << e << endl;
    found = true;
  }
}

void initialize() {
  glGenVertexArrays(1, &vao);
  glBindVertexArray(vao);

  glGenBuffers(1, &vbo);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);
  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

  string version = (char*) glGetString(GL_VERSION);
  cout << "Using OpenGL Version: " << version << endl << endl;

  glClearColor(0.5, 0.7, 0.9, 1.0);

  string vShaderPath   = "shaders/shader.vert";
  string fShaderPath   = "shaders/shader.frag";
  shaderprogram        = ShaderUtil::createProgram(vShaderPath.c_str(), fShaderPath.c_str());
}

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

  glEnableVertexAttribArray(0);
  glBindBuffer(GL_ARRAY_BUFFER, vbo);

  glUseProgram(shaderprogram);
  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
  glDrawArrays(GL_TRIANGLES, 0, 3);

  glDisableVertexAttribArray(0);
}

void clean() {
  glDeleteProgram(shaderprogram);
}


int main(int argc, char** argv) {
  if (!glfwInit()) {
    cerr << "GLFW ERROR!" << endl;
    return -1;
  }

  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

  GLFWwindow* win = glfwCreateWindow(WIDTH, HEIGHT, "Stuff happening...", NULL, NULL);
  glfwMakeContextCurrent(win);
  glewExperimental = GL_TRUE;

  if (glewInit() != GLEW_OK) {
    cerr << "GLEW ERROR!" << endl;
    return -1;
  } else {
    glGetError();
    //GLEW BUG: SETTING THE ERRORFLAG TO INVALID_ENUM; THEREFORE RESET
  }

  initialize();

  while (!glfwWindowShouldClose(win)) {
    render();

    glfwPollEvents();
    glfwSwapBuffers(win);
  }

  clean();

  glfwDestroyWindow(win);
  glfwTerminate();

  return 0;
}