// Created by: Kirill Gavrilov
// Copyright (c) 2021 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _Wasm_Window_HeaderFile
#define _Wasm_Window_HeaderFile

#include <Aspect_Window.hxx>

#include <Aspect_VKey.hxx>
#include <NCollection_Vec2.hxx>
#include <Standard_TypeDef.hxx>

class Aspect_WindowInputListener;

struct EmscriptenMouseEvent;
struct EmscriptenWheelEvent;
struct EmscriptenTouchEvent;
struct EmscriptenKeyboardEvent;
struct EmscriptenUiEvent;
struct EmscriptenFocusEvent;

//! This class defines WebAssembly window (HTML5 canvas) intended for creation of OpenGL (WebGL)
//! context.
//!
//! Note that canvas may define an independent dimensions for backing store (WebGL buffer to render)
//! and for CSS (logical units to present buffer onto screen).
//! These dimensions differ when browser is dragged into a high pixel density screen (HiDPI),
//! or when user scales page in the browser (in both cases window.devicePixelRatio JavaScript
//! property becomes not equal to 1.0).
//!
//! By default, Wasm_Window::DoResize() will scale backing store of a canvas basing on
//! DevicePixelRatio() scale factor to ensure canvas content being rendered with the native
//! resolution and not stretched by browser. This, however, might have side effects:
//! - a slow GPU might experience performance issues on drawing into larger buffer (e.g. HiDPI);
//! - user interface displayed in 3D Viewer (e.g. AIS presentations) should be scaled proportionally
//! to be accessible,
//!   which might require extra processing at application level.
//! Consider changing ToScaleBacking flag passed to Wasm_Window constructor in case of issues.
class Wasm_Window : public Aspect_Window
{
  DEFINE_STANDARD_RTTIEXT(Wasm_Window, Aspect_Window)
public:
  //! Convert Emscripten mouse buttons into Aspect_VKeyMouse.
  Standard_EXPORT static Aspect_VKeyMouse MouseButtonsFromNative(unsigned short theButtons);

  //! Convert DOM virtual key into Aspect_VKey.
  Standard_EXPORT static Aspect_VKey VirtualKeyFromNative(int theKey);

public:
  //! Wraps existing HTML5 canvas into window.
  //! @param[in] theCanvasId target HTML element id defined in a querySelector() syntax
  //! @param[in] theToScaleBacking when TRUE, window will automatically scale backing store of
  //! canvas
  //!                              basing on DevicePixelRatio() scale factor within DoResize()
  Standard_EXPORT Wasm_Window(const TCollection_AsciiString& theCanvasId,
                              const bool                     theToScaleBacking = true);

  //! Destroys the window.
  Standard_EXPORT ~Wasm_Window() override;

  //! Return true if window is not hidden.
  bool IsMapped() const override { return myIsMapped; }

  //! Change window mapped flag to TRUE.
  void Map() const override { myIsMapped = true; }

  //! Change window mapped flag to FALSE.
  void Unmap() const override { myIsMapped = false; }

  //! Resize window.
  //! In case of ToScaleBacking flag, this method will resize the backing store of canvas
  //! basing on DevicePixelRatio() scale factor and CSS canvas size.
  Standard_EXPORT Aspect_TypeOfResize DoResize() override;

  //! Apply the mapping change to the window.
  bool DoMapping() const override { return true; }

  //! Returns window ratio equal to the physical width/height dimensions.
  Standard_EXPORT double Ratio() const override;

  //! Returns The Window POSITION in PIXEL
  Standard_EXPORT void Position(int& theX1, int& theY1, int& theX2, int& theY2) const override;

  //! Return the window size in pixels.
  Standard_EXPORT void Size(int& theWidth, int& theHeight) const override;

  //! Set new window size in logical (density-independent units).
  //! Backing store will be resized basing on DevicePixelRatio().
  Standard_EXPORT void SetSizeLogical(const NCollection_Vec2<double>& theSize);

  //! Set new window size in pixels.
  //! Logical size of the element will be resized basing on DevicePixelRatio().
  Standard_EXPORT void SetSizeBacking(const NCollection_Vec2<int>& theSize);

  //! Returns canvas id.
  const TCollection_AsciiString& CanvasId() const { return myCanvasId; }

  //! Current EGL implementation in Emscripten accepts only 0 for native window id.
  Aspect_Drawable NativeHandle() const override { return 0; }

  //! Always returns 0 for this class.
  Aspect_Drawable NativeParentHandle() const override { return 0; }

  //! Always returns 0 for this class.
  Aspect_FBConfig NativeFBConfig() const override { return nullptr; }

  //! Return device pixel ratio (logical to backing store scale factor).
  double DevicePixelRatio() const override { return myDevicePixelRatio; }

  //! Sets device pixel ratio for a window with IsVirtual() flag.
  void SetDevicePixelRatio(double theDevicePixelRatio) { myDevicePixelRatio = theDevicePixelRatio; }

  //! Invalidate entire window content through generation of Expose event.
  Standard_EXPORT void InvalidateContent(
    const occ::handle<Aspect_DisplayConnection>& theDisp) override;

public:
  //! Process a single window message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessMessage(Aspect_WindowInputListener& theListener,
                                              int                         theEventType,
                                              const void*                 theEvent);

  //! Process a mouse input message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessMouseEvent(Aspect_WindowInputListener& theListener,
                                                 int                         theEventType,
                                                 const EmscriptenMouseEvent* theEvent);

  //! Process a (mouse) wheel input message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessWheelEvent(Aspect_WindowInputListener& theListener,
                                                 int                         theEventType,
                                                 const EmscriptenWheelEvent* theEvent);

  //! Process a mouse input message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessTouchEvent(Aspect_WindowInputListener& theListener,
                                                 int                         theEventType,
                                                 const EmscriptenTouchEvent* theEvent);

  //! Process a keyboard input message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessKeyEvent(Aspect_WindowInputListener&    theListener,
                                               int                            theEventType,
                                               const EmscriptenKeyboardEvent* theEvent);

  //! Process a UI input message (like window resize).
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessUiEvent(Aspect_WindowInputListener& theListener,
                                              int                         theEventType,
                                              const EmscriptenUiEvent*    theEvent);

  //! Process a focus input change message.
  //! @param[in,out] theListener listener to redirect message
  //! @param[in] theEventType message type to process
  //! @param[in] theEvent message to process
  //! @return TRUE if message has been processed
  Standard_EXPORT virtual bool ProcessFocusEvent(Aspect_WindowInputListener& theListener,
                                                 int                         theEventType,
                                                 const EmscriptenFocusEvent* theEvent);

protected:
  TCollection_AsciiString myCanvasId;
  NCollection_Vec2<int>   mySize;
  double                  myDevicePixelRatio;
  bool                    myToScaleBacking;
  mutable bool            myIsMapped;
};

#endif // _Wasm_Window_HeaderFile
