/*
 * Copyright 2009, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


// This file implements the GAPIGL class.

#include <build/build_config.h>
#include "command_buffer/service/gapi_gl.h"

#ifdef OS_LINUX
#include "command_buffer/service/linux/x_utils.h"
#endif  // OS_LINUX

namespace command_buffer {
namespace o3d {

GAPIGL::GAPIGL()
    : cg_context_(NULL),
#ifdef OS_LINUX
      window_(NULL),
#endif
#ifdef OS_WIN
      hwnd_(NULL),
      device_context_(NULL),
      gl_context_(NULL),
#endif
      anti_aliased_(false),
      current_vertex_struct_(kInvalidResource),
      validate_streams_(true),
      max_vertices_(0),
      current_effect_id_(kInvalidResource),
      validate_effect_(true),
      current_effect_(NULL) {
}

GAPIGL::~GAPIGL() {
}

bool GAPIGL::Initialize() {
  if (!InitPlatformSpecific())
    return false;
  if (!InitCommon())
    return false;
  CHECK_GL_ERROR();
  return true;
}

#if defined(OS_WIN)
static const PIXELFORMATDESCRIPTOR kPixelFormatDescriptor = {
  sizeof(kPixelFormatDescriptor),    // Size of structure.
  1,                       // Default version.
  PFD_DRAW_TO_WINDOW |     // Window drawing support.
  PFD_SUPPORT_OPENGL |     // OpenGL support.
  PFD_DOUBLEBUFFER,        // Double buffering support (not stereo).
  PFD_TYPE_RGBA,           // RGBA color mode (not indexed).
  24,                      // 24 bit color mode.
  0, 0, 0, 0, 0, 0,        // Don't set RGB bits & shifts.
  8, 0,                    // 8 bit alpha
  0,                       // No accumulation buffer.
  0, 0, 0, 0,              // Ignore accumulation bits.
  24,                      // 24 bit z-buffer size.
  8,                       // 8-bit stencil buffer.
  0,                       // No aux buffer.
  PFD_MAIN_PLANE,          // Main drawing plane (not overlay).
  0,                       // Reserved.
  0, 0, 0,                 // Layer masks ignored.
};

LRESULT CALLBACK IntermediateWindowProc(HWND window,
                                        UINT message,
                                        WPARAM w_param,
                                        LPARAM l_param) {
  return ::DefWindowProc(window, message, w_param, l_param);
}

// Helper routine that returns the highest quality pixel format supported on
// the current platform.  Returns true upon success.
static bool GetWindowsPixelFormat(HWND window,
                                  bool anti_aliased,
                                  int* pixel_format) {
  // We must initialize a GL context before we can determine the multi-sampling
  // supported on the current hardware, so we create an intermediate window
  // and context here.
  HINSTANCE module_handle;
  if (!::GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT |
                           GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
                           reinterpret_cast<wchar_t*>(IntermediateWindowProc),
                           &module_handle)) {
    return false;
  }

  WNDCLASS intermediate_class;
  intermediate_class.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
  intermediate_class.lpfnWndProc = IntermediateWindowProc;
  intermediate_class.cbClsExtra = 0;
  intermediate_class.cbWndExtra = 0;
  intermediate_class.hInstance = module_handle;
  intermediate_class.hIcon = LoadIcon(NULL, IDI_APPLICATION);
  intermediate_class.hCursor = LoadCursor(NULL, IDC_ARROW);
  intermediate_class.hbrBackground = NULL;
  intermediate_class.lpszMenuName = NULL;
  intermediate_class.lpszClassName = L"Intermediate GL Window";

  ATOM class_registration = ::RegisterClass(&intermediate_class);
  if (!class_registration) {
    return false;
  }

  HWND intermediate_window = ::CreateWindow(
      reinterpret_cast<wchar_t*>(class_registration),
      L"",
      WS_OVERLAPPEDWINDOW,
      0, 0,
      CW_USEDEFAULT, CW_USEDEFAULT,
      NULL,
      NULL,
      NULL,
      NULL);

  if (!intermediate_window) {
    ::UnregisterClass(reinterpret_cast<wchar_t*>(class_registration),
                      module_handle);
    return false;
  }

  HDC intermediate_dc = ::GetDC(intermediate_window);
  int format_index = ::ChoosePixelFormat(intermediate_dc,
                                         &kPixelFormatDescriptor);
  if (format_index == 0) {
    DLOG(ERROR) << "Unable to get the pixel format for GL context.";
    ::ReleaseDC(intermediate_window, intermediate_dc);
    ::DestroyWindow(intermediate_window);
    ::UnregisterClass(reinterpret_cast<wchar_t*>(class_registration),
                      module_handle);
    return false;
  }
  if (!::SetPixelFormat(intermediate_dc, format_index,
                        &kPixelFormatDescriptor)) {
    DLOG(ERROR) << "Unable to set the pixel format for GL context.";
    ::ReleaseDC(intermediate_window, intermediate_dc);
    ::DestroyWindow(intermediate_window);
    ::UnregisterClass(reinterpret_cast<wchar_t*>(class_registration),
                      module_handle);
    return false;
  }

  // Store the pixel format without multisampling.
  *pixel_format = format_index;
  HGLRC gl_context = ::wglCreateContext(intermediate_dc);
  if (::wglMakeCurrent(intermediate_dc, gl_context)) {
    // GL context was successfully created and applied to the window's DC.
    // Startup GLEW, the GL extensions wrangler.
    GLenum glew_error = ::glewInit();
    if (glew_error == GLEW_OK) {
      DLOG(INFO) << "Initialized GLEW " << ::glewGetString(GLEW_VERSION);
    } else {
      DLOG(ERROR) << "Unable to initialise GLEW : "
                  << ::glewGetErrorString(glew_error);
      ::wglMakeCurrent(intermediate_dc, NULL);
      ::wglDeleteContext(gl_context);
      ::ReleaseDC(intermediate_window, intermediate_dc);
      ::DestroyWindow(intermediate_window);
      ::UnregisterClass(reinterpret_cast<wchar_t*>(class_registration),
                        module_handle);
      return false;
    }

    // If the multi-sample extensions are present, query the api to determine
    // the pixel format.
    if (anti_aliased && WGLEW_ARB_pixel_format && WGLEW_ARB_multisample) {
      int pixel_attributes[] = {
        WGL_SAMPLES_ARB, 4,
        WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
        WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
        WGL_ACCELERATION_ARB, WGL_FULL_ACCELERATION_ARB,
        WGL_COLOR_BITS_ARB, 24,
        WGL_ALPHA_BITS_ARB, 8,
        WGL_DEPTH_BITS_ARB, 24,
        WGL_STENCIL_BITS_ARB, 8,
        WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
        WGL_SAMPLE_BUFFERS_ARB, GL_TRUE,
        0, 0};

      float pixel_attributes_f[] = {0, 0};
      int msaa_pixel_format;
      unsigned int num_formats;

      // Query for the highest sampling rate supported, starting at 4x.
      static const int kSampleCount[] = {4, 2};
      static const int kNumSamples = 2;
      for (int sample = 0; sample < kNumSamples; ++sample) {
        pixel_attributes[1] = kSampleCount[sample];
        if (GL_TRUE == ::wglChoosePixelFormatARB(intermediate_dc,
                                                 pixel_attributes,
                                                 pixel_attributes_f,
                                                 1,
                                                 &msaa_pixel_format,
                                                 &num_formats)) {
          *pixel_format = msaa_pixel_format;
          break;
        }
      }
    }
  }

  ::wglMakeCurrent(intermediate_dc, NULL);
  ::wglDeleteContext(gl_context);
  ::ReleaseDC(intermediate_window, intermediate_dc);
  ::DestroyWindow(intermediate_window);
  ::UnregisterClass(reinterpret_cast<wchar_t*>(class_registration),
                    module_handle);
  return true;
}
#endif

bool GAPIGL::InitPlatformSpecific() {
#if defined(OS_WIN)
  device_context_ = ::GetDC(hwnd_);

  int pixel_format;

  if (!GetWindowsPixelFormat(hwnd_,
                             anti_aliased(),
                             &pixel_format)) {
      DLOG(ERROR) << "Unable to determine optimal pixel format for GL context.";
      return false;
  }

  if (!::SetPixelFormat(device_context_, pixel_format,
                        &kPixelFormatDescriptor)) {
    DLOG(ERROR) << "Unable to set the pixel format for GL context.";
    return false;
  }

  gl_context_ = ::wglCreateContext(device_context_);
  if (!gl_context_) {
    DLOG(ERROR) << "Failed to create GL context.";
    return false;
  }

  if (!::wglMakeCurrent(device_context_, gl_context_)) {
    DLOG(ERROR) << "Unable to make gl context current.";
    return false;
  }
#elif defined(OS_LINUX)
  DCHECK(window_);
  if (!window_->Initialize())
    return false;
  if (!window_->MakeCurrent())
    return false;
#endif

  return true;
}

bool GAPIGL::InitCommon() {
  if (!InitGlew())
    return false;
  InitCG();

  // Initialize global GL settings.
  // Tell GL that texture buffers can be single-byte aligned.
  glPixelStorei(GL_PACK_ALIGNMENT, 1);
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
  glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
  // Get the initial viewport (set to the window size) to set up the helper
  // constant.
  GLint viewport[4];
  glGetIntegerv(GL_VIEWPORT, viewport);
  SetViewport(viewport[0], viewport[1], viewport[2], viewport[3], 0.f, 1.f);
  CHECK_GL_ERROR();

  ::glGenFramebuffersEXT(1, &render_surface_framebuffer_);
  CHECK_GL_ERROR();
  return true;
}

void GAPIGL::InitCG() {
  cg_context_ = cgCreateContext();
  // Set up all Cg State Assignments for OpenGL.
  cgGLRegisterStates(cg_context_);
  cgGLSetDebugMode(CG_FALSE);
  // Enable the profiles we use.
  cgGLEnableProfile(CG_PROFILE_ARBVP1);
  cgGLEnableProfile(CG_PROFILE_ARBFP1);
}

bool GAPIGL::InitGlew() {
  DLOG(INFO) << "Initializing GL and GLEW for GAPI.";

  GLenum glew_error = glewInit();
  if (glew_error != GLEW_OK) {
    DLOG(ERROR) << "Unable to initialise GLEW : "
                << ::glewGetErrorString(glew_error);
    return false;
  }

  // Check to see that we can use the OpenGL vertex attribute APIs
  // TODO(petersont):  Return false if this check fails, but because some
  // Intel hardware does not support OpenGL 2.0, yet does support all of the
  // extensions we require, we only log an error.  A future CL should change
  // this check to ensure that all of the extension strings we require are
  // present.
  if (!GLEW_VERSION_2_0) {
    DLOG(ERROR) << "GL drivers do not have OpenGL 2.0 functionality.";
  }

  bool extensions_found = true;
  if (!GLEW_ARB_vertex_buffer_object) {
    // NOTE: Linux NVidia drivers claim to support OpenGL 2.0 when using
    // indirect rendering (e.g. remote X), but it is actually lying. The
    // ARB_vertex_buffer_object functions silently no-op (!) when using
    // indirect rendering, leading to crashes. Fortunately, in that case, the
    // driver claims to not support ARB_vertex_buffer_object, so fail in that
    // case.
    DLOG(ERROR) << "GL drivers do not support vertex buffer objects.";
    extensions_found = false;
  }
  if (!GLEW_EXT_framebuffer_object) {
    DLOG(ERROR) << "GL drivers do not support framebuffer objects.";
    extensions_found = false;
  }
  // Check for necessary extensions
  if (!GLEW_VERSION_2_0 && !GLEW_EXT_stencil_two_side) {
    DLOG(ERROR) << "Two sided stencil extension missing.";
    extensions_found = false;
  }
  if (!GLEW_VERSION_1_4 && !GLEW_EXT_blend_func_separate) {
    DLOG(ERROR) <<"Separate blend func extension missing.";
    extensions_found = false;
  }
  if (!GLEW_VERSION_2_0 && !GLEW_EXT_blend_equation_separate) {
    DLOG(ERROR) << "Separate blend function extension missing.";
    extensions_found = false;
  }
  if (!extensions_found)
    return false;

  return true;
}

void GAPIGL::Destroy() {
  vertex_buffers_.DestroyAllResources();
  index_buffers_.DestroyAllResources();
  vertex_structs_.DestroyAllResources();
  effects_.DestroyAllResources();
  effect_params_.DestroyAllResources();
  // textures_.DestroyAllResources();
  // samplers_.DestroyAllResources();
  cgDestroyContext(cg_context_);
  cg_context_ = NULL;
#ifdef OS_LINUX
  DCHECK(window_);
  window_->Destroy();
#endif
}

void GAPIGL::BeginFrame() {
}

void GAPIGL::EndFrame() {
#ifdef OS_WIN
  ::SwapBuffers(device_context_);
#endif

#ifdef OS_LINUX
  DCHECK(window_);
  window_->SwapBuffers();
#endif

  CHECK_GL_ERROR();
}

void GAPIGL::Clear(unsigned int buffers,
                   const RGBA &color,
                   float depth,
                   unsigned int stencil) {
  glClearColor(color.red, color.green, color.blue, color.alpha);
  glClearDepth(depth);
  glClearStencil(stencil);
  glClear((buffers & kColor ? GL_COLOR_BUFFER_BIT : 0) |
          (buffers & kDepth ? GL_DEPTH_BUFFER_BIT : 0) |
          (buffers & kStencil ? GL_STENCIL_BUFFER_BIT : 0));
  CHECK_GL_ERROR();
}

}  // namespace o3d
}  // namespace command_buffer