#include <GL/glew.h>

#include "shape_renderer.h"
#include "math/math.h"

ShapeRenderer::ShapeRenderer(unsigned int screen_width, unsigned int screen_height) {
  math::ortho_proj(_projection, 0.0f, (float)screen_width, 0.0f, (float)screen_height, -1.0f, 1.0f);

  /* Load shader. */
  _shape_shader = new Shader("assets/shaders/shape.vert",
                             "assets/shaders/shape.frag");
  _shape_shader->use();
  _shape_shader->set_mat4("projection", _projection);

  /* Configure VAO/VBO. */
  glGenVertexArrays(1, &_vao);
  glGenBuffers(1, &_vbo);
  glBindVertexArray(_vao);
  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
  glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 2, NULL, GL_DYNAMIC_DRAW);
  glEnableVertexAttribArray(0);
  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), 0);
  glBindBuffer(GL_ARRAY_BUFFER, 0);
  glBindVertexArray(0);
}

ShapeRenderer::~ShapeRenderer(void) {
  delete _shape_shader;
}

void ShapeRenderer::draw_rect(int x, int y, int width, int height, const Color& color) {
  _shape_shader->use();
  _shape_shader->set_vec3("objectColor", color.r, color.g, color.b);

  float x_f = (float)x;
  float y_f = (float)y;
  float w_f = (float)width;
  float h_f = (float)height;

  /* This is ugly :) */
  float vertices[6][2] = {
    { x_f, y_f + h_f },
    { x_f, y_f },
    { x_f + w_f, y_f },

    { x_f, y_f + h_f },
    { x_f + w_f, y_f },
    {x_f + w_f, y_f + h_f }
  };

  glBindVertexArray(_vao);
  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
  glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
  glDrawArrays(GL_TRIANGLES, 0, 6);
  glBindVertexArray(0);
}

void ShapeRenderer::draw_triangle(int x1, int y1, int x2, int y2, int x3,
                                  int y3, const Color& color) {
  _shape_shader->use();
  _shape_shader->set_vec3("objectColor", color.r, color.g, color.b);

  float vertices[3][2] = {
    {(float)x1, (float)y1},
    {(float)x2, (float)y2},
    {(float)x3, (float)y3},
  };

  glBindVertexArray(_vao);
  glBindBuffer(GL_ARRAY_BUFFER, _vbo);
  /*
   * We're overwriting the buffer content here, this is fine for just one triangle,
   * but don't do it for everything ;)
   */
  glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
  glDrawArrays(GL_TRIANGLES, 0, 3);
  glBindVertexArray(0);
}