// Copyright (c) 2012 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 "ui/gl/gl_context.h"

#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/sys_info.h"
#include "ui/gl/gl_bindings.h"
#include "ui/gl/gl_context_egl.h"
#include "ui/gl/gl_context_osmesa.h"
#include "ui/gl/gl_context_stub.h"
#include "ui/gl/gl_implementation.h"
#include "ui/gl/gl_surface.h"

namespace gfx {

namespace {

// Used to render into an already current context+surface,
// that we do not have ownership of (draw callback).
// TODO(boliu): Make this inherit from GLContextEGL.
class GLNonOwnedContext : public GLContextReal {
 public:
  GLNonOwnedContext(GLShareGroup* share_group);

  // Implement GLContext.
  bool Initialize(GLSurface* compatible_surface,
                  GpuPreference gpu_preference) override;
  bool MakeCurrent(GLSurface* surface) override;
  void ReleaseCurrent(GLSurface* surface) override {}
  bool IsCurrent(GLSurface* surface) override { return true; }
  void* GetHandle() override { return nullptr; }
  void OnSetSwapInterval(int interval) override {}
  std::string GetExtensions() override;

 protected:
  ~GLNonOwnedContext() override {}

 private:
  EGLDisplay display_;

  DISALLOW_COPY_AND_ASSIGN(GLNonOwnedContext);
};

GLNonOwnedContext::GLNonOwnedContext(GLShareGroup* share_group)
  : GLContextReal(share_group), display_(nullptr) {}

bool GLNonOwnedContext::Initialize(GLSurface* compatible_surface,
                        GpuPreference gpu_preference) {
  display_ = eglGetDisplay(EGL_DEFAULT_DISPLAY);
  return true;
}

bool GLNonOwnedContext::MakeCurrent(GLSurface* surface) {
  SetCurrent(surface);
  SetRealGLApi();
  return true;
}

std::string GLNonOwnedContext::GetExtensions() {
  const char* extensions = eglQueryString(display_, EGL_EXTENSIONS);
  if (!extensions)
    return GLContext::GetExtensions();

  return GLContext::GetExtensions() + " " + extensions;
}

}  // anonymous namespace

// static
scoped_refptr<GLContext> GLContext::CreateGLContext(
    GLShareGroup* share_group,
    GLSurface* compatible_surface,
    GpuPreference gpu_preference) {
  scoped_refptr<GLContext> context;
  switch (GetGLImplementation()) {
    case kGLImplementationMockGL:
      return scoped_refptr<GLContext>(new GLContextStub());
    case kGLImplementationOSMesaGL:
      context = new GLContextOSMesa(share_group);
      break;
    default:
      if (compatible_surface->GetHandle())
        context = new GLContextEGL(share_group);
      else
        context = new GLNonOwnedContext(share_group);
      break;
  }

  if (!context->Initialize(compatible_surface, gpu_preference))
    return nullptr;

  return context;
}

}