#include "glview/fbo.h"
#include "glview/system-gl.h"
#include <cstdio>
#include <iostream>
using namespace std;

fbo_t *fbo_new()
{
  auto fbo = new fbo_t;
  fbo->fbo_id = 0;
  fbo->old_fbo_id = 0;
  fbo->renderbuf_id = 0;
  fbo->depthbuf_id = 0;

  return fbo;
}

bool use_ext()
{
  // do we need to use the EXT or ARB version?
  if (!hasGLExtension(ARB_framebuffer_object) && hasGLExtension(EXT_framebuffer_object)) {
    return true;
  } else {
    return false;
  }
}

bool check_fbo_status()
{
  /* This code is based on user V-man code from
     http://www.opengl.org/wiki/GL_EXT_framebuffer_multisample
     See also: http://www.songho.ca/opengl/gl_fbo.html */
  GLenum status;
  auto result = false;
  if (use_ext()) {
    IF_GL_CHECK(status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT)) return false;
  } else {
    IF_GL_CHECK(status = glCheckFramebufferStatus(GL_FRAMEBUFFER)) return false;
  }

  if (status == GL_FRAMEBUFFER_COMPLETE) {
    result = true;
  } else if (status == GL_FRAMEBUFFER_UNSUPPORTED) {
    cerr << "GL_FRAMEBUFFER_UNSUPPORTED\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT\n";
  } else if (status == GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT) {
    cerr << "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT\n";
  } else {
    cerr << "Unknown Code: glCheckFramebufferStatusEXT returned:" << status << "\n";
  }
  return result;
}

bool fbo_ext_init(fbo_t *fbo, size_t width, size_t height)
{
  // Generate and bind FBO
  IF_GL_CHECK(glGenFramebuffersEXT(1, &fbo->fbo_id)) return false;
  IF_GL_CHECK(glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo_id)) return false;

  // Generate depth and render buffers
  glGenRenderbuffersEXT(1, &fbo->depthbuf_id);
  glGenRenderbuffersEXT(1, &fbo->renderbuf_id);

  // Create buffers with correct size
  if (!fbo_resize(fbo, width, height)) return false;

  // Attach render and depth buffers
  IF_GL_CHECK(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
                                           GL_RENDERBUFFER_EXT, fbo->renderbuf_id)) {
    return false;
  }

  if (!check_fbo_status()) {
    cerr << "Problem with OpenGL EXT framebuffer after specifying color render buffer.\n";
    return false;
  }

  if (hasGLExtension(EXT_packed_depth_stencil)) {
    IF_GL_CHECK(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
                                             GL_RENDERBUFFER_EXT, fbo->depthbuf_id)) {
      return false;
    }

    IF_GL_CHECK(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
                                             GL_RENDERBUFFER_EXT, fbo->depthbuf_id)) {
      return false;
    }

    if (!check_fbo_status()) {
      cerr << "Problem with OpenGL EXT framebuffer after specifying depth render buffer.\n";
      return false;
    }
  } else {
    cerr << "Warning: Cannot create stencil buffer (GL_EXT_packed_depth_stencil not supported)\n";
    IF_GL_CHECK(glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
                                             GL_RENDERBUFFER_EXT, fbo->depthbuf_id)) {
      return false;
    }

    if (!check_fbo_status()) {
      cerr << "Problem with OpenGL EXT framebuffer after specifying depth stencil render buffer.\n";
      return false;
    }
  }

  return true;
}

bool fbo_arb_init(fbo_t *fbo, size_t width, size_t height)
{
  // Generate and bind FBO
  IF_GL_CHECK(glGenFramebuffers(1, &fbo->fbo_id)) return false;
  IF_GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, fbo->fbo_id)) return false;

  // Generate depth and render buffers
  glGenRenderbuffers(1, &fbo->depthbuf_id);
  glGenRenderbuffers(1, &fbo->renderbuf_id);

  // Create buffers with correct size
  if (!fbo_resize(fbo, width, height)) return false;

  // Attach render and depth buffers
  IF_GL_CHECK(glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                        GL_RENDERBUFFER, fbo->renderbuf_id)) {
    return false;
  }

  if (!check_fbo_status()) {
    cerr << "Problem with OpenGL framebuffer after specifying color render buffer.\n";
    return false;
  }

  //glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
  // to prevent Mesa's software renderer from crashing, do this in two stages.
  // ie. instead of using GL_DEPTH_STENCIL_ATTACHMENT, do DEPTH then STENCIL.
  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
                            GL_RENDERBUFFER, fbo->depthbuf_id);
  IF_GL_CHECK(glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
                                        GL_RENDERBUFFER, fbo->depthbuf_id)) {
    return false;
  }

  if (!check_fbo_status()) {
    cerr << "Problem with OpenGL framebuffer after specifying depth render buffer.\n";
    return false;
  }

  return true;
}


bool fbo_init(fbo_t *fbo, size_t width, size_t height)
{
  /*
     Some OpenGL drivers include the framebuffer functions but not with
     core or ARB names, only with the EXT name. This has been worked-around
     by deciding at runtime, using GLEW, which version needs to be used. See also:

     http://www.opengl.org/wiki/Framebuffer_Object
     http://stackoverflow.com/questions/6912988/glgenframebuffers-or-glgenframebuffersex
     http://www.devmaster.net/forums/showthread.php?t=10967
   */

  auto result = false;
  if (hasGLExtension(ARB_framebuffer_object)) {
    result = fbo_arb_init(fbo, width, height);
  } else if (use_ext()) {
    result = fbo_ext_init(fbo, width, height);
  } else {
    cerr << "Framebuffer Object extension not found\n";
  }
  return result;
}

bool fbo_resize(fbo_t *fbo, size_t width, size_t height)
{
  if (use_ext()) {
    glBindRenderbufferEXT(GL_RENDERBUFFER, fbo->depthbuf_id);
    if (hasGLExtension(EXT_packed_depth_stencil)) {
      IF_GL_CHECK(glRenderbufferStorageEXT(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height)) {
        return false;
      }
    } else {
      IF_GL_CHECK(glRenderbufferStorageEXT(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height)) {
        return false;
      }
    }

    glBindRenderbufferEXT(GL_RENDERBUFFER, fbo->renderbuf_id);
    IF_GL_CHECK(glRenderbufferStorageEXT(GL_RENDERBUFFER, GL_RGBA8, width, height)) {
      return false;
    }
  } else {
    glBindRenderbuffer(GL_RENDERBUFFER, fbo->renderbuf_id);
    IF_GL_CHECK(glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height)) {
      return false;
    }

    glBindRenderbuffer(GL_RENDERBUFFER, fbo->depthbuf_id);
    IF_GL_CHECK(glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height)) {
      return false;
    }
  }

  return true;
}

void fbo_delete(fbo_t *fbo)
{
  delete fbo;
}

GLuint fbo_bind(fbo_t *fbo)
{
  glGetIntegerv(GL_FRAMEBUFFER_BINDING, reinterpret_cast<GLint *>(&fbo->old_fbo_id));
  if (use_ext()) {
    glBindFramebufferEXT(GL_FRAMEBUFFER, fbo->fbo_id);
  } else {
    glBindFramebuffer(GL_FRAMEBUFFER, fbo->fbo_id);
  }
  return fbo->old_fbo_id;
}

void fbo_unbind(fbo_t *fbo)
{
  if (use_ext()) {
    glBindFramebufferEXT(GL_FRAMEBUFFER, fbo->old_fbo_id);
  } else {
    glBindFramebuffer(GL_FRAMEBUFFER, fbo->old_fbo_id);
  }
}
