// Copyright (c) 2006-2010 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.

#include "chrome/gpu/gpu_info_collector.h"

#include <string>
#include <vector>

#include "app/gfx/gl/gl_bindings.h"
#include "app/gfx/gl/gl_context.h"
#include "base/logging.h"
#include "base/string_number_conversions.h"
#include "base/string_piece.h"
#include "base/string_split.h"

namespace {

// This creates an offscreen GL context for gl queries.  Returned GLContext
// should be deleted in FinalizeGLContext.
gfx::GLContext* InitializeGLContext() {
  if (!gfx::GLContext::InitializeOneOff()) {
    LOG(ERROR) << "gfx::GLContext::InitializeOneOff() failed";
    return NULL;
  }
  gfx::GLContext* context = gfx::GLContext::CreateOffscreenGLContext(NULL);
  if (context == NULL) {
    LOG(ERROR) << "gfx::GLContext::CreateOffscreenGLContext(NULL) failed";
    return NULL;
  }
  if (!context->MakeCurrent()) {
    LOG(ERROR) << "gfx::GLContext::MakeCurrent() failed";
    context->Destroy();
    delete context;
    return NULL;
  }
  return context;
}

// This destroy and delete the GL context.
void FinalizeGLContext(gfx::GLContext** context) {
  DCHECK(context);
  if (*context) {
    (*context)->Destroy();
    delete *context;
    *context = NULL;
  }
}

std::string GetGLString(unsigned int pname) {
  const char* gl_string =
      reinterpret_cast<const char*>(glGetString(pname));
  if (gl_string)
    return std::string(gl_string);
  return "";
}

uint32 GetVersionNumberFromString(const std::string& version_string) {
  int major = 0, minor = 0;
  size_t begin = version_string.find_first_of("0123456789");
  if (begin != std::string::npos) {
    size_t end = version_string.find_first_not_of("01234567890.", begin);
    std::string sub_string;
    if (end != std::string::npos)
      sub_string = version_string.substr(begin, end - begin);
    else
      sub_string = version_string.substr(begin);
    std::vector<std::string> pieces;
    base::SplitString(sub_string, '.', &pieces);
    if (pieces.size() >= 2) {
      base::StringToInt(pieces[0], &major);
      base::StringToInt(pieces[1], &minor);
    }
  }
  return ((major << 8) + minor);
}

}  // namespace anonymous

namespace gpu_info_collector {

bool CollectGraphicsInfoGL(GPUInfo* gpu_info) {
  DCHECK(gpu_info);

  gfx::GLContext* context = InitializeGLContext();
  if (context == NULL)
    return false;

  gpu_info->SetGLRenderer(GetGLString(GL_RENDERER));
  gpu_info->SetGLVendor(GetGLString(GL_VENDOR));
  gpu_info->SetGLVersionString(GetGLString(GL_VERSION));
  gpu_info->SetGLExtensions(GetGLString(GL_EXTENSIONS));

  bool validGLVersionInfo = CollectGLVersionInfo(gpu_info);
  bool validVideoCardInfo = CollectVideoCardInfo(gpu_info);
  bool validDriverInfo = CollectDriverInfo(gpu_info);

  FinalizeGLContext(&context);

  return (validGLVersionInfo && validVideoCardInfo && validDriverInfo);
}

bool CollectGLVersionInfo(GPUInfo* gpu_info) {
  DCHECK(gpu_info);

  std::string gl_version_string = gpu_info->gl_version_string();
  std::string glsl_version_string =
      GetGLString(GL_SHADING_LANGUAGE_VERSION);

  uint32 gl_version = GetVersionNumberFromString(gl_version_string);
  gpu_info->SetGLVersion(gl_version);

  uint32 glsl_version = GetVersionNumberFromString(glsl_version_string);
  gpu_info->SetShaderVersion(glsl_version, glsl_version);

  return true;
}

}  // namespace gpu_info_collector