// Copyright 2015 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.

#ifndef SERVICES_GFX_COMPOSITOR_BACKEND_GPU_RASTERIZER_H_
#define SERVICES_GFX_COMPOSITOR_BACKEND_GPU_RASTERIZER_H_

#include <memory>

#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/task_runner.h"
#include "base/timer/timer.h"
#include "mojo/gpu/gl_context.h"
#include "mojo/public/cpp/bindings/binding.h"
#include "mojo/services/gpu/interfaces/context_provider.mojom.h"
#include "mojo/skia/ganesh_context.h"
#include "mojo/skia/ganesh_framebuffer_surface.h"

namespace compositor {

class RenderFrame;
class VsyncScheduler;

// Ganesh-based rasterizer which runs on a separate thread from the compositor.
// Calls into this object, including its creation, must be posted to the
// correct message loop by the output.
class GpuRasterizer : public mojo::ViewportParameterListener,
                      public mojo::GLContext::Observer {
 public:
  // Callback invoked when a frame completes.
  // |presented| is true if the frame was actually presented, false if
  // the frame was discarded.
  using FrameCallback = base::Callback<void(bool presented)>;

  GpuRasterizer(mojo::ContextProviderPtr context_provider,
                const scoped_refptr<VsyncScheduler>& scheduler,
                const scoped_refptr<base::TaskRunner>& task_runner,
                const base::Closure& error_callback);
  ~GpuRasterizer() override;

  // Submits a frame to be drawn.
  // If the GL context isn't ready yet, the frame will be retained unless
  // superceded by another frame.
  void SubmitFrame(const scoped_refptr<RenderFrame>& frame,
                   const FrameCallback& frame_callback);

 private:
  // |ViewportParameterListener|:
  void OnVSyncParametersUpdated(int64_t timebase, int64_t interval) override;

  // |GLContext::Observer|:
  void OnContextLost() override;

  void CreateContext();
  void InitContext(mojo::InterfaceHandle<mojo::CommandBuffer> command_buffer);
  void AbandonContext();
  void DestroyContext();
  void RecreateContextAfterLoss();
  void OnContextProviderConnectionError();
  void OnViewportParameterTimeout();
  void ApplyViewportParameters();

  void DidEchoCallback(FrameCallback frame_callback);
  void Draw();

  void PostErrorCallback();

  mojo::ContextProviderPtr context_provider_;
  scoped_refptr<VsyncScheduler> scheduler_;
  scoped_refptr<base::TaskRunner> task_runner_;
  base::Closure error_callback_;

  scoped_refptr<mojo::GLContext> gl_context_;
  scoped_refptr<mojo::skia::GaneshContext> ganesh_context_;
  std::unique_ptr<mojo::skia::GaneshFramebufferSurface> ganesh_surface_;

  scoped_refptr<RenderFrame> frame_;
  FrameCallback frame_callback_;

  mojo::Binding<ViewportParameterListener> viewport_parameter_listener_binding_;
  base::Timer viewport_parameter_timeout_;
  bool have_viewport_parameters_ = false;
  int64_t vsync_timebase_ = 0u;
  int64_t vsync_interval_ = 0u;
  uint32_t frames_pending_ = 0u;

  base::WeakPtrFactory<GpuRasterizer> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(GpuRasterizer);
};

}  // namespace compositor

#endif  // SERVICES_GFX_COMPOSITOR_BACKEND_GPU_RASTERIZER_H_