#define GLEW_STATIC
#pragma comment( lib, "opengl32.lib" )
#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <array>
#include <cassert>

GLuint create_framebuffer_msaa( GLsizei width, GLsizei height, GLsizei samples );
void   render();

int main( int argc, char * argv[] )
{
  constexpr GLsizei width   = 1800;
  constexpr GLsizei height  = 1600;
  constexpr GLsizei samples = 4;

  ::glfwInit();
  ::glfwWindowHint( GLFW_RESIZABLE, GLFW_FALSE );

  // ::glfwWindowHint( GLFW_SAMPLES, samples );

  GLFWwindow * window = ::glfwCreateWindow( width, height, "ogl.window", {}, {} );
  ::glfwMakeContextCurrent( window );
  ::glewInit();
  ::glfwSwapInterval( 0 );

  GLuint draw_framebuffer    = create_framebuffer_msaa( width, height, samples );
  GLuint default_framebuffer = 0;

  while ( !::glfwWindowShouldClose( window ) )
  {
    ::glfwPollEvents();
    glBindFramebuffer( GL_FRAMEBUFFER, draw_framebuffer );
    render();
    glBlitNamedFramebuffer( draw_framebuffer,
                            default_framebuffer,
                            0,
                            0,
                            width,
                            height,
                            0,
                            0,
                            width,
                            height,
                            GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT,
                            GL_NEAREST );
    glBindFramebuffer( GL_FRAMEBUFFER, 0 );

    ::glfwSwapBuffers( window );
  }
}

GLuint create_framebuffer_msaa( GLsizei width, GLsizei height, GLsizei samples )
{
  GLuint framebuffer = 0;
  glCreateFramebuffers( 1, &framebuffer );

  GLuint color_texture = {};
  glCreateTextures( GL_TEXTURE_2D_MULTISAMPLE, 1, &color_texture );
  glTextureStorage2DMultisample( color_texture, samples, GL_RGBA8 /*GL_RGB8*/, width, height, false );
  glNamedFramebufferTexture( framebuffer, GL_COLOR_ATTACHMENT0, color_texture, 0 );

  GLuint depth_texture = {};
  glCreateTextures( GL_TEXTURE_2D_MULTISAMPLE, 1, &depth_texture );
  glTextureStorage2DMultisample( depth_texture, samples, GL_DEPTH24_STENCIL8, width, height, false );
  glNamedFramebufferTexture( framebuffer, GL_DEPTH_STENCIL_ATTACHMENT, depth_texture, 0 );

  const bool is_complete = glCheckNamedFramebufferStatus( framebuffer, GL_FRAMEBUFFER ) == GL_FRAMEBUFFER_COMPLETE;
  assert( is_complete );

  return framebuffer;
}

void draw_triangle()
{
  glBegin( GL_TRIANGLES );
  glVertex2f( -0.7f, -0.7f );
  glColor3f( 1.f, 0.f, 0.f );
  glVertex2f( 1.f, 0.f );
  glColor3f( 0.f, 1.f, 0.f );
  glVertex2f( 0.f, 1.f );
  glColor3f( 0.f, 0.f, 1.f );
  glEnd();
}

void clear()
{
  std::array color{0.5f, 1.f, 0.7f, 1.f};
  glClearBufferfv( GL_COLOR, 0, std::data( color ) );

  GLfloat depth = 1;
  glClearBufferfv( GL_DEPTH, 0, &depth );
}

void rotate( GLfloat angle )
{
  glRotatef( angle, 1.f, 1.f, 1.f );
}

void render()
{
  clear();
  rotate( 3.14f );
  draw_triangle();
}