// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file implements the ViewGLContext and PbufferGLContext classes.

#if !defined(UNIT_TEST)
#include <dlfcn.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#endif

#include "gpu/command_buffer/service/gl_context.h"
#include "base/scoped_ptr.h"
#include "gpu/command_buffer/service/gl_utils.h"
#include "gpu/command_buffer/common/logging.h"

namespace gpu {

#if !defined(UNIT_TEST)

// scoped_ptr functor for XFree(). Use as follows:
//   scoped_ptr_malloc<XVisualInfo, ScopedPtrXFree> foo(...);
// where "XVisualInfo" is any X type that is freed with XFree.
class ScopedPtrXFree {
 public:
  void operator()(void* x) const {
    ::XFree(x);
  }
};

// Some versions of NVIDIA's GL libGL.so include a broken version of
// dlopen/dlsym, and so linking it into chrome breaks it. So we dynamically
// load it, and use glew to dynamically resolve symbols.
// See http://code.google.com/p/chromium/issues/detail?id=16800

static bool InitializeGLXEW(Display* display) {
  static bool glxew_initialized = false;
  if (!glxew_initialized) {
    void* handle = dlopen("libGL.so.1", RTLD_LAZY | RTLD_GLOBAL);
    if (!handle) {
      LOG(ERROR) << "Could not find libGL.so.1";
      return false;
    }

    // Initializes context-independent parts of GLEW
    if (glxewInit() != GLEW_OK) {
      LOG(ERROR) << "glxewInit failed";
      return false;
    }
    // glxewContextInit really only needs a display connection to
    // complete, and we don't want to have to create an OpenGL context
    // just to get access to GLX 1.3 entry points to create pbuffers.
    // We therefore added a glxewContextInitWithDisplay entry point.
    if (glxewContextInitWithDisplay(display) != GLEW_OK) {
      LOG(ERROR) << "glxewContextInit failed";
      return false;
    }
    glxew_initialized = true;
  }

  return true;
}

#endif  // UNIT_TEST

bool ViewGLContext::Initialize(bool multisampled) {
#if !defined(UNIT_TEST)
  if (multisampled) {
    DLOG(WARNING) << "Multisampling not implemented.";
  }

  if (!InitializeGLXEW(display_))
    return false;

  XWindowAttributes attributes;
  XGetWindowAttributes(display_, window_, &attributes);
  XVisualInfo visual_info_template;
  visual_info_template.visualid = XVisualIDFromVisual(attributes.visual);
  int visual_info_count = 0;
  scoped_ptr_malloc<XVisualInfo, ScopedPtrXFree> visual_info_list(
      XGetVisualInfo(display_, VisualIDMask,
                     &visual_info_template,
                     &visual_info_count));
  DCHECK(visual_info_list.get());
  DCHECK_GT(visual_info_count, 0);
  context_ = NULL;
  for (int i = 0; i < visual_info_count; ++i) {
    context_ = glXCreateContext(display_, visual_info_list.get() + i, 0, True);
    if (context_)
      break;
  }
  if (!context_) {
    DLOG(ERROR) << "Couldn't create GL context.";
    return false;
  }

  if (!MakeCurrent()) {
    Destroy();
    DLOG(ERROR) << "Couldn't make context current for initialization.";
    return false;
  }

  if (!InitializeGLEW()) {
    Destroy();
    return false;
  }
#endif  // UNIT_TEST

  return true;
}

void ViewGLContext::Destroy() {
  #if !defined(UNIT_TEST)
Bool result = glXMakeCurrent(display_, 0, 0);
  // glXMakeCurrent isn't supposed to fail when unsetting the context, unless
  // we have pending draws on an invalid window - which shouldn't be the case
  // here.
  DCHECK(result);
  if (context_) {
    glXDestroyContext(display_, context_);
    context_ = NULL;
  }
#endif  // UNIT_TEST
}

bool ViewGLContext::MakeCurrent() {
#if !defined(UNIT_TEST)
  if (glXGetCurrentDrawable() == window_ &&
      glXGetCurrentContext() == context_) {
    return true;
  }
  if (glXMakeCurrent(display_, window_, context_) != True) {
    glXDestroyContext(display_, context_);
    context_ = 0;
    DLOG(ERROR) << "Couldn't make context current.";
    return false;
  }
#endif  // UNIT_TEST

  return true;
}

bool ViewGLContext::IsOffscreen() {
  return false;
}

void ViewGLContext::SwapBuffers() {
#if !defined(UNIT_TEST)
  glXSwapBuffers(display_, window_);
#endif  // UNIT_TEST
}

gfx::Size ViewGLContext::GetSize() {
#if !defined(UNIT_TEST)
  XWindowAttributes attributes;
  XGetWindowAttributes(display_, window_, &attributes);
  return gfx::Size(attributes.width, attributes.height);
#else
  return gfx::Size();
#endif  // UNIT_TEST
}

GLContextHandle ViewGLContext::GetHandle() {
#if !defined(UNIT_TEST)
  return context_;
#else
  return NULL;
#endif  // UNIT_TEST
}

bool PbufferGLContext::Initialize(GLContext* shared_context) {
#if !defined(UNIT_TEST)
  if (!InitializeGLXEW(display_))
    return false;

  if (!glXChooseFBConfig ||
      !glXCreateNewContext ||
      !glXCreatePbuffer ||
      !glXDestroyPbuffer) {
    DLOG(ERROR) << "Pbuffer support not available.";
    return false;
  }

  // Get the shared context handle.
  GLContextHandle shared_handle = NULL;
  if (shared_context)
    shared_handle = shared_context->GetHandle();

  static const int config_attributes[] = {
    GLX_DRAWABLE_TYPE,
    GLX_PBUFFER_BIT,
    GLX_RENDER_TYPE,
    GLX_RGBA_BIT,
    GLX_DOUBLEBUFFER,
    0,
    0
  };

  int nelements = 0;
  // TODO(kbr): figure out whether hardcoding screen to 0 is sufficient.
  scoped_ptr_malloc<GLXFBConfig, ScopedPtrXFree> config(
      glXChooseFBConfig(display_, 0, config_attributes, &nelements));
  if (!config.get()) {
    DLOG(ERROR) << "glXChooseFBConfig failed.";
    return false;
  }
  if (!nelements) {
    DLOG(ERROR) << "glXChooseFBConfig returned 0 elements.";
    return false;
  }
  context_ = glXCreateNewContext(display_,
                                 config.get()[0],
                                 GLX_RGBA_TYPE,
                                 shared_handle,
                                 True);
  if (!context_) {
    DLOG(ERROR) << "glXCreateNewContext failed.";
    return false;
  }
  static const int pbuffer_attributes[] = {
    GLX_PBUFFER_WIDTH,
    1,
    GLX_PBUFFER_HEIGHT,
    1,
    0
  };
  pbuffer_ = glXCreatePbuffer(display_,
                              config.get()[0], pbuffer_attributes);
  if (!pbuffer_) {
    Destroy();
    DLOG(ERROR) << "glXCreatePbuffer failed.";
    return false;
  }

  if (!MakeCurrent()) {
    Destroy();
    DLOG(ERROR) << "Couldn't make context current for initialization.";
    return false;
  }

  if (!InitializeGLEW()) {
    Destroy();
    return false;
  }
#endif  // UNIT_TEST

  return true;
}

void PbufferGLContext::Destroy() {
#if !defined(UNIT_TEST)
  Bool result = glXMakeCurrent(display_, 0, 0);
  // glXMakeCurrent isn't supposed to fail when unsetting the context, unless
  // we have pending draws on an invalid window - which shouldn't be the case
  // here.
  DCHECK(result);
  if (context_) {
    glXDestroyContext(display_, context_);
    context_ = NULL;
  }

  if (pbuffer_) {
    glXDestroyPbuffer(display_, pbuffer_);
    pbuffer_ = NULL;
  }
#endif  // UNIT_TEST
}

bool PbufferGLContext::MakeCurrent() {
#if !defined(UNIT_TEST)
  if (glXGetCurrentDrawable() == pbuffer_ &&
      glXGetCurrentContext() == context_) {
    return true;
  }
  if (glXMakeCurrent(display_, pbuffer_, context_) != True) {
    glXDestroyContext(display_, context_);
    context_ = NULL;
    DLOG(ERROR) << "Couldn't make context current.";
    return false;
  }
#endif  // UNIT_TEST

  return true;
}

bool PbufferGLContext::IsOffscreen() {
  return true;
}

void PbufferGLContext::SwapBuffers() {
  NOTREACHED() << "Attempted to call SwapBuffers on a pbuffer.";
}

gfx::Size PbufferGLContext::GetSize() {
  NOTREACHED() << "Should not be requesting size of this pbuffer.";
  return gfx::Size(1, 1);
}

GLContextHandle PbufferGLContext::GetHandle() {
#if !defined(UNIT_TEST)
  return context_;
#else
  return NULL;
#endif  // UNIT_TEST
}

}  // namespace gpu