// Copyright 2013 The Flutter 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 FLUTTER_SHELL_PLATFORM_WINDOWS_ANGLE_SURFACE_MANAGER_H_
#define FLUTTER_SHELL_PLATFORM_WINDOWS_ANGLE_SURFACE_MANAGER_H_

// OpenGL ES and EGL includes
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <EGL/eglplatform.h>
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>

// Windows platform specific includes
#include <d3d11.h>
#include <windows.h>
#include <wrl/client.h>
#include <memory>

#include "flutter/fml/macros.h"
#include "flutter/shell/platform/windows/window_binding_handler.h"

namespace flutter {

// A manager for initializing ANGLE correctly and using it to create and
// destroy surfaces
class AngleSurfaceManager {
 public:
  static std::unique_ptr<AngleSurfaceManager> Create(bool enable_impeller);

  virtual ~AngleSurfaceManager();

  // Creates an EGLSurface wrapper and backing DirectX 11 SwapChain
  // associated with window, in the appropriate format for display.
  // HWND is the window backing the surface. Width and height represent
  // dimensions surface is created at.
  //
  // After the surface is created, |SetVSyncEnabled| should be called on a
  // thread that can bind the |egl_context_|.
  virtual bool CreateSurface(HWND hwnd, EGLint width, EGLint height);

  // Resizes backing surface from current size to newly requested size
  // based on width and height for the specific case when width and height do
  // not match current surface dimensions. Target represents the visual entity
  // to bind to.
  //
  // This binds |egl_context_| to the current thread.
  virtual void ResizeSurface(HWND hwnd,
                             EGLint width,
                             EGLint height,
                             bool enable_vsync);

  // queries EGL for the dimensions of surface in physical
  // pixels returning width and height as out params.
  void GetSurfaceDimensions(EGLint* width, EGLint* height);

  // Releases the pass-in EGLSurface wrapping and backing resources if not null.
  virtual void DestroySurface();

  // Check if the current thread has a context bound.
  bool HasContextCurrent();

  // Binds |egl_context_| to the current rendering thread and to the draw and
  // read surfaces returning a boolean result reflecting success.
  virtual bool MakeCurrent();

  // Unbinds the current EGL context from the current thread.
  virtual bool ClearCurrent();

  // Clears the |egl_context_| draw and read surfaces.
  bool ClearContext();

  // Binds egl_resource_context_ to the current rendering thread and to the draw
  // and read surfaces returning a boolean result reflecting success.
  bool MakeResourceCurrent();

  // Swaps the front and back buffers of the DX11 swapchain backing surface if
  // not null.
  EGLBoolean SwapBuffers();

  // Creates a |EGLSurface| from the provided handle.
  EGLSurface CreateSurfaceFromHandle(EGLenum handle_type,
                                     EGLClientBuffer handle,
                                     const EGLint* attributes) const;

  // Gets the |EGLDisplay|.
  EGLDisplay egl_display() const { return egl_display_; };

  // If enabled, makes the current surface's buffer swaps block until the
  // v-blank.
  //
  // If disabled, allows one thread to swap multiple buffers per v-blank
  // but can result in screen tearing if the system compositor is disabled.
  //
  // This binds |egl_context_| to the current thread and makes the render
  // surface current.
  virtual void SetVSyncEnabled(bool enabled);

  // Gets the |ID3D11Device| chosen by ANGLE.
  bool GetDevice(ID3D11Device** device);

 protected:
  // Creates a new surface manager retaining reference to the passed-in target
  // for the lifetime of the manager.
  explicit AngleSurfaceManager(bool enable_impeller);

 private:
  bool Initialize(bool enable_impeller);
  void CleanUp();

  // Attempts to initialize EGL using ANGLE.
  bool InitializeEGL(
      PFNEGLGETPLATFORMDISPLAYEXTPROC egl_get_platform_display_EXT,
      const EGLint* config,
      bool should_log);

  // EGL representation of native display.
  EGLDisplay egl_display_;

  // EGL representation of current rendering context.
  EGLContext egl_context_;

  // EGL representation of current rendering context used for async texture
  // uploads.
  EGLContext egl_resource_context_;

  // current frame buffer configuration.
  EGLConfig egl_config_;

  // State representing success or failure of display initialization used when
  // creating surfaces.
  bool initialize_succeeded_;

  // Current render_surface that engine will draw into.
  EGLSurface render_surface_ = EGL_NO_SURFACE;

  // Requested dimensions for current surface
  EGLint surface_width_ = 0;
  EGLint surface_height_ = 0;

  // The current D3D device.
  Microsoft::WRL::ComPtr<ID3D11Device> resolved_device_;

  // Number of active instances of AngleSurfaceManager
  static int instance_count_;

  FML_DISALLOW_COPY_AND_ASSIGN(AngleSurfaceManager);
};

}  // namespace flutter

#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_ANGLE_SURFACE_MANAGER_H_