/**
 * Stone of Orthanc
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2020 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/

#include "GuiAdapter.h"

#if ORTHANC_ENABLE_OPENGL == 1
#  include "../../Framework/OpenGL/OpenGLIncludes.h"
#endif

#if ORTHANC_ENABLE_SDL == 1
#  include <SDL_video.h>
#  include <SDL_render.h>
#  include <SDL.h>
#endif

#if ORTHANC_ENABLE_THREADS == 1
#  include "../../Framework/Deprecated/Messages/LockingEmitter.h"
#endif

#include <Core/Compatibility.h>

namespace OrthancStone
{
  std::ostream& operator<<(
    std::ostream& os, const GuiAdapterKeyboardEvent& event)
  {
    os << "sym: " << event.sym << " (" << (int)(event.sym[0]) << ") ctrl: " << event.ctrlKey << ", " <<
      "shift: " << event.shiftKey << ", " <<
      "alt: " << event.altKey;
    return os;
  }

  std::ostream& operator<<(
    std::ostream& os, const GuiAdapterMouseEvent& event)
  {
    os << "targetX: " << event.targetX << " targetY: " << event.targetY << " button: " << event.button
      << "ctrlKey: " << event.ctrlKey << "shiftKey: " << event.shiftKey << "altKey: " << event.altKey;
      
    return os;
  }

#if ORTHANC_ENABLE_WASM == 1
  void GuiAdapter::Run(GuiAdapterRunFunc /*func*/, void* /*cookie*/)
  {
  }

  void ConvertFromPlatform(
    GuiAdapterUiEvent& dest,
    int                      eventType,
    const EmscriptenUiEvent& src)
  {
    // no data for now
  }

  void ConvertFromPlatform(
    GuiAdapterMouseEvent& dest,
    int                         eventType,
    const EmscriptenMouseEvent& src)
  {
    memset(&dest, 0, sizeof(GuiAdapterMouseEvent));
    switch (eventType)
    {
    case EMSCRIPTEN_EVENT_CLICK:
      LOG(ERROR) << "Emscripten EMSCRIPTEN_EVENT_CLICK is not supported";
      ORTHANC_ASSERT(false, "Not supported");
      break;
    case EMSCRIPTEN_EVENT_MOUSEDOWN:
      dest.type = GUIADAPTER_EVENT_MOUSEDOWN;
      break;
    case EMSCRIPTEN_EVENT_DBLCLICK:
      dest.type = GUIADAPTER_EVENT_MOUSEDBLCLICK;
      break;
    case EMSCRIPTEN_EVENT_MOUSEMOVE:
      dest.type = GUIADAPTER_EVENT_MOUSEMOVE;
      break;
    case EMSCRIPTEN_EVENT_MOUSEUP:
      dest.type = GUIADAPTER_EVENT_MOUSEUP;
      break;
    case EMSCRIPTEN_EVENT_WHEEL:
      dest.type = GUIADAPTER_EVENT_WHEEL;
      break;

    default:
      LOG(ERROR) << "Emscripten event: " << eventType << " is not supported";
      ORTHANC_ASSERT(false, "Not supported");
    }
    //dest.timestamp = src.timestamp;
    //dest.screenX = src.screenX;
    //dest.screenY = src.screenY;
    //dest.clientX = src.clientX;
    //dest.clientY = src.clientY;
    dest.ctrlKey = src.ctrlKey;
    dest.shiftKey = src.shiftKey;
    dest.altKey = src.altKey;
    //dest.metaKey = src.metaKey;
    dest.button = src.button;
    //dest.buttons = src.buttons;
    //dest.movementX = src.movementX;
    //dest.movementY = src.movementY;
    dest.targetX = src.targetX;
    dest.targetY = src.targetY;
    //dest.canvasX = src.canvasX;
    //dest.canvasY = src.canvasY;
    //dest.padding = src.padding;
  }

  void ConvertFromPlatform( GuiAdapterWheelEvent& dest, int eventType, const EmscriptenWheelEvent& src)
  {
    ConvertFromPlatform(dest.mouse, eventType, src.mouse);
    dest.deltaX = src.deltaX;
    dest.deltaY = src.deltaY;
    switch (src.deltaMode)
    {
    case DOM_DELTA_PIXEL:
      dest.deltaMode = GUIADAPTER_DELTA_PIXEL;
      break;
    case DOM_DELTA_LINE:
      dest.deltaMode = GUIADAPTER_DELTA_LINE;
      break;
    case DOM_DELTA_PAGE:
      dest.deltaMode = GUIADAPTER_DELTA_PAGE;
      break;
    default:
      ORTHANC_ASSERT(false, "Unknown deltaMode: " << src.deltaMode <<
        " in wheel event...");
    }
    dest.deltaMode = src.deltaMode;
  }

  void ConvertFromPlatform(GuiAdapterKeyboardEvent& dest, const EmscriptenKeyboardEvent& src)
  {
    dest.sym[0] = src.key[0];
    dest.sym[1] = 0;
    dest.ctrlKey = src.ctrlKey;
    dest.shiftKey = src.shiftKey;
    dest.altKey = src.altKey;
  }

  template<typename GenericFunc>
  struct FuncAdapterPayload
  {
    std::string canvasCssSelector;
    void* userData;
    GenericFunc callback;
  };

  template<typename GenericFunc,
    typename GuiAdapterEvent,
    typename EmscriptenEvent>
    EM_BOOL OnEventAdapterFunc(
      int eventType, const EmscriptenEvent* emEvent, void* userData)
  {
    // userData is OnMouseWheelFuncAdapterPayload
    FuncAdapterPayload<GenericFunc>* payload =
      reinterpret_cast<FuncAdapterPayload<GenericFunc>*>(userData);
    // LOG(INFO) << "OnEventAdapterFunc";
    // LOG(INFO) << "------------------";
    // LOG(INFO) << "eventType: " << eventType << " wheelEvent: " << 
    //   (int)wheelEvent << " userData: " << userData << 
    //   " payload->userData: " << payload->userData;

    GuiAdapterEvent guiEvent;
    ConvertFromPlatform(guiEvent, eventType, *emEvent);
    bool ret = (*(payload->callback))(payload->canvasCssSelector, &guiEvent, payload->userData);
    return static_cast<EM_BOOL>(ret);
  }

  template<typename GenericFunc,
    typename GuiAdapterEvent,
    typename EmscriptenEvent>
    EM_BOOL OnEventAdapterFunc2(
      int /*eventType*/, const EmscriptenEvent* wheelEvent, void* userData)
  {
    // userData is OnMouseWheelFuncAdapterPayload
    FuncAdapterPayload<GenericFunc>* payload =
      reinterpret_cast<FuncAdapterPayload<GenericFunc>*>(userData);

    GuiAdapterEvent guiEvent;
    ConvertFromPlatform(guiEvent, *wheelEvent);
    bool ret = (*(payload->callback))(payload->canvasCssSelector, &guiEvent, payload->userData);
    return static_cast<EM_BOOL>(ret);
  }

  template<typename GenericFunc>
  EM_BOOL OnEventAdapterFunc3(
    double time, void* userData)
  {
    // userData is OnMouseWheelFuncAdapterPayload
    FuncAdapterPayload<GenericFunc>* payload =
      reinterpret_cast<FuncAdapterPayload<GenericFunc>*>(userData);
    //std::unique_ptr< FuncAdapterPayload<GenericFunc> > deleter(payload);
    bool ret = (*(payload->callback))(time, payload->userData);
    return static_cast<EM_BOOL>(ret);
  }

  /*
  
  Explanation
  ===========

  - in "older" Emscripten, where DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR doesn't exist or is set to 0,
    the following strings need to be used to register events:
    - for canvas, the canvas DOM id. In case of <canvas id="mycanvas1" width='640' ...></canvas>", the string needs 
      to be "mycanvas"
    - for the window (for key events), the string needs to be "#window"
  - in newer Emscripten where DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR==1 (or maybe is not there anymore, in the
    future as of 2020-04-20)
    - for canvas, the canvas DOM id. In case of <canvas id="mycanvas1" width='640' ...></canvas>", the string needs
      to be "#mycanvas"  (notice the "number sign", aka "hash", NOT AKA "sharp", as can be read on https://en.wikipedia.org/wiki/Number_sign)
    - for the window (for key events), the string needs to be EMSCRIPTEN_EVENT_TARGET_WINDOW. I do not mean 
      "EMSCRIPTEN_EVENT_TARGET_WINDOW", but the #define EMSCRIPTEN_EVENT_TARGET_WINDOW         ((const char*)2) that
      can be found in emscripten/html5.h

  The code below converts the input canvasId (as in the old emscripten) to the emscripten-compliant one, with the
  following compile condition : #if DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR == 1

  If the DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR build parameter disappears, you might want to refactor this code
  or continue to pass the DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR compile macro (which is different from the CMake
  variable)     

  What we are doing below:
  - in older Emscripten, the registration functions will receive "mycanvas" and "#window" and the callbacks will receive 
    the same std::string in their payload ("mycanvas" and "#window")

  - in newer Emscripten, the registration functions will receive "#mycanvas" and EMSCRIPTEN_EVENT_TARGET_WINDOW, but 
    the callbacks will receive "#mycanvas" and "#window" (since it is not possible to store the EMSCRIPTEN_EVENT_TARGET_WINDOW
    magic value in an std::string, while we still want the callback to be able to change its behavior according to the
    target element.
  
  */

  void convertElementTarget(const char*& outCanvasCssSelectorSz, std::string& outCanvasCssSelector, const std::string& canvasId)
  {
    // only "#window" can start with a #
    if (canvasId[0] == '#')
    {
      ORTHANC_ASSERT(canvasId == "#window");
    }
#if DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR == 1
    if (canvasId == "#window")
    {
      // we store this in the payload so that the callback can 
      outCanvasCssSelector = "#window";
      outCanvasCssSelectorSz = EMSCRIPTEN_EVENT_TARGET_WINDOW;
    }
    else
    {
      outCanvasCssSelector = "#" + canvasId;
      outCanvasCssSelectorSz = outCanvasCssSelector.c_str();
    }
#else
    if (canvasId == "#window")
    {
      // we store this in the payload so that the callback can 
      outCanvasCssSelector = "#window";
      outCanvasCssSelectorSz = outCanvasCssSelector.c_str();;
    }
    else
    {
      outCanvasCssSelector = canvasId;
      outCanvasCssSelectorSz = outCanvasCssSelector.c_str();;
    }
#endif
  }

  // resize: (const char* target, void* userData, EM_BOOL useCapture, em_ui_callback_func callback)
  template<
    typename GenericFunc,
    typename GuiAdapterEvent,
    typename EmscriptenEvent,
    typename EmscriptenSetCallbackFunc>
    static void SetCallback(
      EmscriptenSetCallbackFunc emFunc,
      std::string canvasId, void* userData, bool capture, GenericFunc func)
  {
    std::string canvasCssSelector;
    const char* canvasCssSelectorSz = NULL;
    convertElementTarget(canvasCssSelectorSz, canvasCssSelector, canvasId);

    // TODO: write RemoveCallback with an int id that gets returned from here

    // create userdata payload
    std::unique_ptr<FuncAdapterPayload<GenericFunc> > payload(new FuncAdapterPayload<GenericFunc>());
    payload->canvasCssSelector = canvasCssSelector;
    payload->callback = func;
    payload->userData = userData;
    void* userDataRaw = reinterpret_cast<void*>(payload.release());

    // call the registration function
    (*emFunc)(
      canvasCssSelectorSz,
      userDataRaw,
      static_cast<EM_BOOL>(capture),
      &OnEventAdapterFunc<GenericFunc, GuiAdapterEvent, EmscriptenEvent>,
      EM_CALLBACK_THREAD_CONTEXT_CALLING_THREAD);
  }

  template<
    typename GenericFunc,
    typename GuiAdapterEvent,
    typename EmscriptenEvent,
    typename EmscriptenSetCallbackFunc>
    static void SetCallback2(
      EmscriptenSetCallbackFunc emFunc,
      std::string canvasId, void* userData, bool capture, GenericFunc func)
  {
    std::string canvasCssSelector;
    const char* canvasCssSelectorSz = NULL;
    convertElementTarget(canvasCssSelectorSz, canvasCssSelector, canvasId);

    // TODO: write RemoveCallback with an int id that gets returned from here

    // create userdata payload
    std::unique_ptr<FuncAdapterPayload<GenericFunc> > payload(new FuncAdapterPayload<GenericFunc>());
    payload->canvasCssSelector = canvasCssSelector;
    payload->callback = func;
    payload->userData = userData;
    void* userDataRaw = reinterpret_cast<void*>(payload.release());

    // call the registration function
    (*emFunc)(
      canvasCssSelectorSz,
      userDataRaw,
      static_cast<EM_BOOL>(capture),
      &OnEventAdapterFunc2<GenericFunc, GuiAdapterEvent, EmscriptenEvent>,
      EM_CALLBACK_THREAD_CONTEXT_CALLING_THREAD);
  }

  template<
    typename GenericFunc,
    typename EmscriptenSetCallbackFunc>
    static void SetAnimationFrameCallback(
      EmscriptenSetCallbackFunc emFunc,
      void* userData, GenericFunc func)
  {
    std::unique_ptr<FuncAdapterPayload<GenericFunc> > payload(
      new FuncAdapterPayload<GenericFunc>()
    );
    payload->canvasCssSelector = "UNDEFINED";
    payload->callback = func;
    payload->userData = userData;
    void* userDataRaw = reinterpret_cast<void*>(payload.release());
    (*emFunc)(
      &OnEventAdapterFunc3<GenericFunc>,
      userDataRaw);
  }

  void GuiAdapter::SetWheelCallback(
    std::string canvasId, void* userData, bool capture, OnMouseWheelFunc func)
  {
    SetCallback<OnMouseWheelFunc, GuiAdapterWheelEvent, EmscriptenWheelEvent>(
      &emscripten_set_wheel_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

  
  void GuiAdapter::SetMouseDblClickCallback(
      std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    SetCallback<OnMouseEventFunc, GuiAdapterMouseEvent, EmscriptenMouseEvent>(
      &emscripten_set_dblclick_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }


  void GuiAdapter::SetMouseDownCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    SetCallback<OnMouseEventFunc, GuiAdapterMouseEvent, EmscriptenMouseEvent>(
      &emscripten_set_mousedown_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

  void GuiAdapter::SetMouseMoveCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    // LOG(INFO) << "SetMouseMoveCallback -- " << "supplied userData: " << 
    //   userData;

    SetCallback<OnMouseEventFunc, GuiAdapterMouseEvent, EmscriptenMouseEvent>(
      &emscripten_set_mousemove_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

  void GuiAdapter::SetMouseUpCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    SetCallback<OnMouseEventFunc, GuiAdapterMouseEvent, EmscriptenMouseEvent>(
      &emscripten_set_mouseup_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

  void GuiAdapter::SetKeyDownCallback(
    std::string canvasId, void* userData, bool capture, OnKeyDownFunc func)
  {
    SetCallback2<OnKeyDownFunc, GuiAdapterKeyboardEvent, EmscriptenKeyboardEvent>(
      &emscripten_set_keydown_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

  void GuiAdapter::SetKeyUpCallback(
    std::string canvasId, void* userData, bool capture, OnKeyUpFunc func)
  {
    SetCallback2<OnKeyUpFunc, GuiAdapterKeyboardEvent, EmscriptenKeyboardEvent>(
      &emscripten_set_keyup_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }

#if 0
  // useless under Wasm where canvas resize is handled automatically
  void GuiAdapter::SetResizeCallback(
    std::string canvasId, void* userData, bool capture, OnWindowResizeFunc func)
  {
    SetCallback<OnWindowResizeFunc, GuiAdapterUiEvent, EmscriptenUiEvent>(
      &emscripten_set_resize_callback_on_thread,
      canvasId,
      userData,
      capture,
      func);
  }
#endif

  void GuiAdapter::RequestAnimationFrame(
    OnAnimationFrameFunc func, void* userData)
  {
    SetAnimationFrameCallback<OnAnimationFrameFunc>(
      &emscripten_request_animation_frame_loop,
      userData,
      func);
  }

#if 0
  void GuiAdapter::SetKeyDownCallback(
    std::string canvasId, void* userData, bool capture, OnKeyDownFunc func)
  {
    emscripten_set_keydown_callback(canvasId.c_str(), userData, static_cast<EM_BOOL>(capture), func);
  }
  void GuiAdapter::SetKeyUpCallback(
    std::string canvasId, void* userData, bool capture, OnKeyUpFunc func)
  {
    emscripten_set_keyup_callback(canvasId.c_str(), userData, static_cast<EM_BOOL>(capture), func);
  }

  // handled from within WebAssemblyViewport
  //void GuiAdapter::SetResizeCallback(std::string canvasId, void* userData, bool capture, OnWindowResizeFunc func)
  //{
  //  emscripten_set_resize_callback(canvasId.c_str(), userData, static_cast<EM_BOOL>(capture), func);
  //}

  void GuiAdapter::RequestAnimationFrame(OnAnimationFrameFunc func, void* userData)
  {
    emscripten_request_animation_frame_loop(func, userData);
  }
#endif


#else

  // SDL ONLY
  void ConvertFromPlatform(GuiAdapterMouseEvent& dest, bool ctrlPressed, bool shiftPressed, bool altPressed, const SDL_Event& source)
  {
    memset(&dest, 0, sizeof(GuiAdapterMouseEvent));
    switch (source.type)
    {
    case SDL_MOUSEBUTTONDOWN:
      if (source.button.clicks == 1) {
        dest.type = GUIADAPTER_EVENT_MOUSEDOWN;
      } else if (source.button.clicks == 2) {
        dest.type = GUIADAPTER_EVENT_MOUSEDBLCLICK;
      } else {
        dest.type = GUIADAPTER_EVENT_MOUSEDBLCLICK;
        LOG(WARNING) << "Multiple-click ignored.";
      }
      break;
    case SDL_MOUSEMOTION:
      dest.type = GUIADAPTER_EVENT_MOUSEMOVE;
      break;
    case SDL_MOUSEBUTTONUP:
      dest.type = GUIADAPTER_EVENT_MOUSEUP;
      break;
    case SDL_MOUSEWHEEL:
      dest.type = GUIADAPTER_EVENT_WHEEL;
      break;
    default:
      LOG(ERROR) << "SDL event: " << source.type << " is not supported";
      ORTHANC_ASSERT(false, "Not supported");
    }
    //dest.timestamp = src.timestamp;
    //dest.screenX = src.screenX;
    //dest.screenY = src.screenY;
    //dest.clientX = src.clientX;
    //dest.clientY = src.clientY;
    dest.ctrlKey = ctrlPressed;
    dest.shiftKey = shiftPressed;
    dest.altKey = altPressed;
    //dest.metaKey = src.metaKey;
    switch (source.button.button)
    {
    case SDL_BUTTON_MIDDLE:
      dest.button =GUIADAPTER_MOUSEBUTTON_MIDDLE;
      break;

    case SDL_BUTTON_RIGHT:
      dest.button = GUIADAPTER_MOUSEBUTTON_RIGHT;
      break;

    case SDL_BUTTON_LEFT:
      dest.button = GUIADAPTER_MOUSEBUTTON_LEFT;
      break;

    default:
      break;
    }
    //dest.buttons = src.buttons;
    //dest.movementX = src.movementX;
    //dest.movementY = src.movementY;
    dest.targetX = source.button.x;
    dest.targetY = source.button.y;
    //dest.canvasX = src.canvasX;
    //dest.canvasY = src.canvasY;
    //dest.padding = src.padding;
  }

  void ConvertFromPlatform(
    GuiAdapterWheelEvent& dest,
    bool ctrlPressed, bool shiftPressed, bool altPressed,
    const SDL_Event& source)
  {
    ConvertFromPlatform(dest.mouse, ctrlPressed, shiftPressed, altPressed, source);
    dest.deltaX = source.wheel.x;
    dest.deltaY = source.wheel.y;
  }

  void ConvertFromPlatform(GuiAdapterKeyboardEvent& dest, const SDL_Event& src)
  {
    memset(&dest, 0, sizeof(GuiAdapterMouseEvent));
    switch (src.type)
    {
    case SDL_KEYDOWN:
      dest.type = GUIADAPTER_EVENT_KEYDOWN;
      break;
    case SDL_KEYUP:
      dest.type = GUIADAPTER_EVENT_KEYUP;
      break;
    default:
      LOG(ERROR) << "SDL event: " << src.type << " is not supported";
      ORTHANC_ASSERT(false, "Not supported");
    }
    dest.sym[0] = src.key.keysym.sym;
    dest.sym[1] = 0;

    if (src.key.keysym.mod & KMOD_CTRL)
      dest.ctrlKey = true;
    else
      dest.ctrlKey = false;

    if (src.key.keysym.mod & KMOD_SHIFT)
      dest.shiftKey = true;
    else
      dest.shiftKey = false;

    if (src.key.keysym.mod & KMOD_ALT)
      dest.altKey = true;
    else
      dest.altKey = false;
  }

  // SDL ONLY
  void GuiAdapter::SetSdlResizeCallback(
    std::string canvasId, void* userData, bool capture, OnSdlWindowResizeFunc func)
  {
    resizeHandlers_.push_back(EventHandlerData<OnSdlWindowResizeFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetMouseDownCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    mouseDownHandlers_.push_back(EventHandlerData<OnMouseEventFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetMouseDblClickCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc func)
  {
    mouseDblCickHandlers_.push_back(EventHandlerData<OnMouseEventFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetMouseMoveCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc  func)
  {
    mouseMoveHandlers_.push_back(EventHandlerData<OnMouseEventFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetMouseUpCallback(
    std::string canvasId, void* userData, bool capture, OnMouseEventFunc  func)
  {
    mouseUpHandlers_.push_back(EventHandlerData<OnMouseEventFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetWheelCallback(
    std::string canvasId, void* userData, bool capture, OnMouseWheelFunc  func)
  {
    mouseWheelHandlers_.push_back(EventHandlerData<OnMouseWheelFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetKeyDownCallback(
    std::string canvasId, void* userData, bool capture, OnKeyDownFunc   func)
  {
    keyDownHandlers_.push_back(EventHandlerData<OnKeyDownFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetKeyUpCallback(
    std::string canvasId, void* userData, bool capture, OnKeyUpFunc    func)
  {
    keyUpHandlers_.push_back(EventHandlerData<OnKeyUpFunc>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::SetGenericSdlEventCallback(
    std::string canvasId, void* userData, bool capture, OnSdlEventCallback func)
  {
    sdlEventHandlers_.push_back(EventHandlerData<OnSdlEventCallback>(canvasId, func, userData));
  }

  // SDL ONLY
  void GuiAdapter::OnAnimationFrame()
  {
    std::vector<size_t> disabledAnimationHandlers;
    for (size_t i = 0; i < animationFrameHandlers_.size(); i++)
    {
      // TODO: fix time 
      bool goOn = (*(animationFrameHandlers_[i].first))(0, animationFrameHandlers_[i].second);

      // If the function returns false, we need to emulate what happens in Web 
      // and remove the function from the handlers...
      if (!goOn)
        disabledAnimationHandlers.push_back(i);
    }
    for (size_t i = 0; i < disabledAnimationHandlers.size(); i++)
    {
      ORTHANC_ASSERT(animationFrameHandlers_.begin() + disabledAnimationHandlers[i] < animationFrameHandlers_.end());
      animationFrameHandlers_.erase(animationFrameHandlers_.begin() + disabledAnimationHandlers[i]);
    }
  }

  // SDL ONLY
  void GuiAdapter::OnResize(unsigned int width, unsigned int height)
  {
    for (size_t i = 0; i < resizeHandlers_.size(); i++)
    {
      (*(resizeHandlers_[i].func))(
        resizeHandlers_[i].canvasName, NULL, width, height, resizeHandlers_[i].userData);
    }
  }



  void GuiAdapter::OnSdlGenericEvent(const SDL_Event& sdlEvent)
  {
    // Events related to a window are only sent to the related canvas
    // User events are sent to everyone (we can't filter them here)
    
    /*
    SDL_WindowEvent    SDL_WINDOWEVENT
    SDL_KeyboardEvent     SDL_KEYDOWN
                          SDL_KEYUP
    SDL_TextEditingEvent  SDL_TEXTEDITING
    SDL_TextInputEvent    SDL_TEXTINPUT
    SDL_MouseMotionEvent  SDL_MOUSEMOTION
    SDL_MouseButtonEvent  SDL_MOUSEBUTTONDOWN 
                          SDL_MOUSEBUTTONUP
    SDL_MouseWheelEvent   SDL_MOUSEWHEEL
    SDL_UserEvent         SDL_USEREVENT through ::SDL_LASTEVENT-1
    */

    // if this string is left empty, it means the message will be sent to
    // all widgets.
    // otherwise, it contains the originating message window title

    std::string windowTitle;
    uint32_t windowId = 0;

    if (sdlEvent.type == SDL_WINDOWEVENT)
      windowId = sdlEvent.window.windowID;
    else if (sdlEvent.type == SDL_KEYDOWN || sdlEvent.type == SDL_KEYUP)
      windowId = sdlEvent.key.windowID;
    else if (sdlEvent.type == SDL_TEXTEDITING)
      windowId = sdlEvent.edit.windowID;
    else if (sdlEvent.type == SDL_TEXTINPUT)
      windowId = sdlEvent.text.windowID;
    else if (sdlEvent.type == SDL_MOUSEMOTION)
      windowId = sdlEvent.motion.windowID;
    else if (sdlEvent.type == SDL_MOUSEBUTTONDOWN || sdlEvent.type == SDL_MOUSEBUTTONUP)
      windowId = sdlEvent.button.windowID;
    else if (sdlEvent.type == SDL_MOUSEWHEEL)
      windowId = sdlEvent.wheel.windowID;
    else if (sdlEvent.type >= SDL_USEREVENT && sdlEvent.type <= (SDL_LASTEVENT-1))
      windowId = sdlEvent.user.windowID;

    if (windowId != 0)
    {
      SDL_Window* sdlWindow = SDL_GetWindowFromID(windowId);
      ORTHANC_ASSERT(sdlWindow != NULL, "Window ID \"" << windowId << "\" is not a valid SDL window ID!");
      const char* windowTitleSz = SDL_GetWindowTitle(sdlWindow);
      ORTHANC_ASSERT(windowTitleSz != NULL, "Window ID \"" << windowId << "\" has a NULL window title!");
      windowTitle = windowTitleSz;
      ORTHANC_ASSERT(windowTitle != "", "Window ID \"" << windowId << "\" has an empty window title!");
    }

    for (size_t i = 0; i < sdlEventHandlers_.size(); i++)
    {
      // normally, the handlers return a bool indicating whether they
      // have handled the event or not, but we don't really care about this
      std::string& canvasName = sdlEventHandlers_[i].canvasName;
      
      bool sendEvent = true;

      if (windowTitle != "" && (canvasName != windowTitle))
        sendEvent = false;

      if (sendEvent)
      {
        OnSdlEventCallback func = sdlEventHandlers_[i].func;
        (*func)(canvasName, sdlEvent, sdlEventHandlers_[i].userData);
      }
    }
  }

  // SDL ONLY
  void GuiAdapter::OnMouseWheelEvent(uint32_t windowID, const GuiAdapterWheelEvent& event)
  {
    // the SDL window name IS the canvas name ("canvas" is used because this lib
    // is designed for Wasm
    SDL_Window* sdlWindow = SDL_GetWindowFromID(windowID);
    ORTHANC_ASSERT(sdlWindow != NULL, "Window ID \"" << windowID << "\" is not a valid SDL window ID!");

    const char* windowTitleSz = SDL_GetWindowTitle(sdlWindow);
    ORTHANC_ASSERT(windowTitleSz != NULL, "Window ID \"" << windowID << "\" has a NULL window title!");

    std::string windowTitle(windowTitleSz);
    ORTHANC_ASSERT(windowTitle != "", "Window ID \"" << windowID << "\" has an empty window title!");

    switch (event.mouse.type)
    {
    case GUIADAPTER_EVENT_WHEEL:
      for (size_t i = 0; i < mouseWheelHandlers_.size(); i++)
      {
        if (mouseWheelHandlers_[i].canvasName == windowTitle)
          (*(mouseWheelHandlers_[i].func))(windowTitle, &event, mouseWheelHandlers_[i].userData);
      }
      break;
    default:
      ORTHANC_ASSERT(false, "Wrong event.type: " << event.mouse.type << " in GuiAdapter::OnMouseWheelEvent(...)");
      break;
    }
  }


  void GuiAdapter::OnKeyboardEvent(uint32_t windowID, const GuiAdapterKeyboardEvent& event)
  {
    // only one-letter (ascii) keyboard events supported for now
    ORTHANC_ASSERT(event.sym[0] != 0);
    ORTHANC_ASSERT(event.sym[1] == 0);

    SDL_Window* sdlWindow = SDL_GetWindowFromID(windowID);
    ORTHANC_ASSERT(sdlWindow != NULL, "Window ID \"" << windowID << "\" is not a valid SDL window ID!");

    const char* windowTitleSz = SDL_GetWindowTitle(sdlWindow);
    ORTHANC_ASSERT(windowTitleSz != NULL, "Window ID \"" << windowID << "\" has a NULL window title!");

    std::string windowTitle(windowTitleSz);
    ORTHANC_ASSERT(windowTitle != "", "Window ID \"" << windowID << "\" has an empty window title!");

    switch (event.type)
    {
    case GUIADAPTER_EVENT_KEYDOWN:
      for (size_t i = 0; i < keyDownHandlers_.size(); i++)
      {
        (*(keyDownHandlers_[i].func))(windowTitle, &event, keyDownHandlers_[i].userData);
      }
      break;
    case GUIADAPTER_EVENT_KEYUP:
      for (size_t i = 0; i < keyUpHandlers_.size(); i++)
      {
        (*(keyUpHandlers_[i].func))(windowTitle, &event, keyUpHandlers_[i].userData);
      }
      break;
    default:
      ORTHANC_ASSERT(false, "Wrong event.type: " << event.type << " in GuiAdapter::OnKeyboardEvent(...)");
      break;
    }
  }

  // SDL ONLY
  void GuiAdapter::OnMouseEvent(uint32_t windowID, const GuiAdapterMouseEvent& event)
  {
    if (windowID == 0)
    {
      LOG(WARNING) << "GuiAdapter::OnMouseEvent -- windowID == 0 and event won't be routed!";
    }
    else
    {
      // the SDL window name IS the canvas name ("canvas" is used because this lib
      // is designed for Wasm
      SDL_Window* sdlWindow = SDL_GetWindowFromID(windowID);

      ORTHANC_ASSERT(sdlWindow != NULL, "Window ID \"" << windowID << "\" is not a valid SDL window ID!");

      const char* windowTitleSz = SDL_GetWindowTitle(sdlWindow);
      ORTHANC_ASSERT(windowTitleSz != NULL, "Window ID \"" << windowID << "\" has a NULL window title!");

      std::string windowTitle(windowTitleSz);
      ORTHANC_ASSERT(windowTitle != "", "Window ID \"" << windowID << "\" has an empty window title!");

      switch (event.type)
      {
      case GUIADAPTER_EVENT_MOUSEDOWN:
        for (size_t i = 0; i < mouseDownHandlers_.size(); i++)
        {
          if (mouseDownHandlers_[i].canvasName == windowTitle)
            (*(mouseDownHandlers_[i].func))(windowTitle, &event, mouseDownHandlers_[i].userData);
        }
        break;
      case GUIADAPTER_EVENT_MOUSEDBLCLICK:
        for (size_t i = 0; i < mouseDblCickHandlers_.size(); i++)
        {
          if (mouseDblCickHandlers_[i].canvasName == windowTitle)
            (*(mouseDblCickHandlers_[i].func))(windowTitle, &event, mouseDblCickHandlers_[i].userData);
        }
        break;
      case GUIADAPTER_EVENT_MOUSEMOVE:
        for (size_t i = 0; i < mouseMoveHandlers_.size(); i++)
        {
          if (mouseMoveHandlers_[i].canvasName == windowTitle)
            (*(mouseMoveHandlers_[i].func))(windowTitle, &event, mouseMoveHandlers_[i].userData);
        }
        break;
      case GUIADAPTER_EVENT_MOUSEUP:
        for (size_t i = 0; i < mouseUpHandlers_.size(); i++)
        {
          if (mouseUpHandlers_[i].canvasName == windowTitle)
            (*(mouseUpHandlers_[i].func))(windowTitle, &event, mouseUpHandlers_[i].userData);
        }
        break;
      default:
        ORTHANC_ASSERT(false, "Wrong event.type: " << event.type << " in GuiAdapter::OnMouseEvent(...)");
        break;
      }
    }
  }


  // extern void Debug_SetContextToBeKilled(std::string title);
  // extern void Debug_SetContextToBeRestored(std::string title);

  // SDL ONLY
  void GuiAdapter::RequestAnimationFrame(OnAnimationFrameFunc func, void* userData)
  {
    animationFrameHandlers_.push_back(std::make_pair(func, userData));
  }

# if ORTHANC_ENABLE_OPENGL == 1 && !defined(__APPLE__)   /* OpenGL debug is not available on OS X */

  // SDL ONLY
  static void GLAPIENTRY
    OpenGLMessageCallback(GLenum source,
      GLenum type,
      GLuint id,
      GLenum severity,
      GLsizei length,
      const GLchar * message,
      const void* userParam)
  {
    if (severity != GL_DEBUG_SEVERITY_NOTIFICATION)
    {
      fprintf(stderr, "GL CALLBACK: %s type = 0x%x, severity = 0x%x, message = %s\n",
        (type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : ""),
        type, severity, message);
    }
  }
# endif

#if 0
  // TODO: remove this when generic sdl event handlers are implemented in 
  // the DoseView
  // SDL ONLY
  bool GuiAdapter::IsSdlViewPortRefreshEvent(const SDL_Event& event) const
  {
    SDL_Window* sdlWindow = SDL_GetWindowFromID(event.window.windowID);

    ORTHANC_ASSERT(sdlWindow != NULL, "Window ID \"" << event.window.windowID << "\" is not a valid SDL window ID!");

    const char* windowTitleSz = SDL_GetWindowTitle(sdlWindow);

    // now we need to find the DoseView from from the canvas name!
    // (and retrieve the SdlViewport)
    boost::shared_ptr<IGuiAdapterWidget> foundWidget;
    VisitWidgets([&foundWidget, windowTitleSz](auto widget)
    {
      if (widget->GetCanvasIdentifier() == std::string(windowTitleSz))
        foundWidget = widget;
    });
    ORTHANC_ASSERT(foundWidget, "The window named: \"" << windowTitleSz << "\" was not found in the registered widgets!");
    return foundWidget->GetSdlViewport().IsRefreshEvent(event);
  }
#endif

  // SDL ONLY
  void GuiAdapter::Run(GuiAdapterRunFunc func, void* cookie)
  {
#if 1
    // TODO: MAKE THIS DYNAMIC !!! See SdlOpenGLViewport vs Cairo in ViewportWrapper
# if ORTHANC_ENABLE_OPENGL == 1 && !defined(__APPLE__)
    glEnable(GL_DEBUG_OUTPUT);
    glDebugMessageCallback(OpenGLMessageCallback, 0);
# endif
#endif

    // Uint32 SDL_GetWindowID(SDL_Window* window)
    // SDL_Window* SDL_GetWindowFromID(Uint32 id)   // may return NULL

    bool stop = false;
    while (!stop)
    {
      {
        // TODO: lock all viewports here! (use a scoped object)
        if(func != NULL)
          (*func)(cookie);
        OnAnimationFrame(); // in SDL we must call it
      }

      while (!stop)
      {
        std::vector<SDL_Event> sdlEvents;
        std::map<Uint32,SDL_Event> userEventsMap;
        
        SDL_Event sdlEvent;

        // FIRST: collect all pending events
        while (SDL_PollEvent(&sdlEvent) != 0)
        {
          if ( (sdlEvent.type >= SDL_USEREVENT) && 
               (sdlEvent.type <= SDL_USEREVENT) )
          {
            // we don't want to have multiple events with the same event.type
            userEventsMap[sdlEvent.type] = sdlEvent;
          }
          else
          {
            sdlEvents.push_back(sdlEvent);
          }
        }

        // SECOND: collect all user events
        for (std::map<Uint32,SDL_Event>::const_iterator it = userEventsMap.begin(); it != userEventsMap.end(); ++it)
          sdlEvents.push_back(it->second);
                
        // now process the events
        for (std::vector<SDL_Event>::const_iterator it = sdlEvents.begin(); it != sdlEvents.end(); ++it)
        {
          const SDL_Event& sdlEvent = *it;
          // TODO: lock all viewports here! (use a scoped object)

          if (sdlEvent.type == SDL_QUIT)
          {
            // TODO: call exit callbacks here
            stop = true;
            break;
          }
          else if ((sdlEvent.type == SDL_MOUSEMOTION) ||
            (sdlEvent.type == SDL_MOUSEBUTTONDOWN) ||
                   (sdlEvent.type == SDL_MOUSEBUTTONUP))
          {
            int scancodeCount = 0;
            const uint8_t* keyboardState = SDL_GetKeyboardState(&scancodeCount);
            bool ctrlPressed(false);
            bool shiftPressed(false);
            bool altPressed(false);

            if (SDL_SCANCODE_LCTRL < scancodeCount && keyboardState[SDL_SCANCODE_LCTRL])
              ctrlPressed = true;
            if (SDL_SCANCODE_RCTRL < scancodeCount && keyboardState[SDL_SCANCODE_RCTRL])
              ctrlPressed = true;
            if (SDL_SCANCODE_LSHIFT < scancodeCount && keyboardState[SDL_SCANCODE_LSHIFT])
              shiftPressed = true;
            if (SDL_SCANCODE_RSHIFT < scancodeCount && keyboardState[SDL_SCANCODE_RSHIFT])
              shiftPressed = true;
            if (SDL_SCANCODE_LALT < scancodeCount && keyboardState[SDL_SCANCODE_LALT])
              altPressed = true;

            GuiAdapterMouseEvent dest;
            ConvertFromPlatform(dest, ctrlPressed, shiftPressed, altPressed, sdlEvent);
            OnMouseEvent(sdlEvent.window.windowID, dest);
  #if 0
            // for reference, how to create trackers
            if (tracker)
            {
              PointerEvent e;
              e.AddPosition(compositor.GetPixelCenterCoordinates(
                sdlEvent.button.x, sdlEvent.button.y));
              tracker->PointerMove(e);
            }
  #endif
          }
          else if (sdlEvent.type == SDL_MOUSEWHEEL)
          {

            int scancodeCount = 0;
            const uint8_t* keyboardState = SDL_GetKeyboardState(&scancodeCount);
            bool ctrlPressed(false);
            bool shiftPressed(false);
            bool altPressed(false);

            if (SDL_SCANCODE_LCTRL < scancodeCount && keyboardState[SDL_SCANCODE_LCTRL])
              ctrlPressed = true;
            if (SDL_SCANCODE_RCTRL < scancodeCount && keyboardState[SDL_SCANCODE_RCTRL])
              ctrlPressed = true;
            if (SDL_SCANCODE_LSHIFT < scancodeCount && keyboardState[SDL_SCANCODE_LSHIFT])
              shiftPressed = true;
            if (SDL_SCANCODE_RSHIFT < scancodeCount && keyboardState[SDL_SCANCODE_RSHIFT])
              shiftPressed = true;
            if (SDL_SCANCODE_LALT < scancodeCount && keyboardState[SDL_SCANCODE_LALT])
              altPressed = true;

            GuiAdapterWheelEvent dest;
            ConvertFromPlatform(dest, ctrlPressed, shiftPressed, altPressed, sdlEvent);
            OnMouseWheelEvent(sdlEvent.window.windowID, dest);

            //KeyboardModifiers modifiers = GetKeyboardModifiers(keyboardState, scancodeCount);

            //int x, y;
            //SDL_GetMouseState(&x, &y);

            //if (sdlEvent.wheel.y > 0)
            //{
            //  locker.GetCentralViewport().MouseWheel(MouseWheelDirection_Up, x, y, modifiers);
            //}
            //else if (sdlEvent.wheel.y < 0)
            //{
            //  locker.GetCentralViewport().MouseWheel(MouseWheelDirection_Down, x, y, modifiers);
            //}
          }
          else if (sdlEvent.type == SDL_WINDOWEVENT &&
            (sdlEvent.window.event == SDL_WINDOWEVENT_RESIZED ||
             sdlEvent.window.event == SDL_WINDOWEVENT_SIZE_CHANGED))
          {
  #if 0
            tracker.reset();
  #endif
            OnResize(sdlEvent.window.data1, sdlEvent.window.data2);
          }
          else if (sdlEvent.type == SDL_KEYDOWN && sdlEvent.key.repeat == 0 /* Ignore key bounce */)
          {
            switch (sdlEvent.key.keysym.sym)
            {
            case SDLK_f:
              // window.GetWindow().ToggleMaximize(); //TODO: move to particular handler
              break;

            // This commented out code was used to debug the context
            // loss/restoring code (2019-08-10)
            // case SDLK_k:
            //   {
            //     SDL_Window* window = SDL_GetWindowFromID(sdlEvent.window.windowID);
            //     std::string windowTitle(SDL_GetWindowTitle(window));
            //     Debug_SetContextToBeKilled(windowTitle);
            //   }
            //   break;
            // case SDLK_l:
            //   {
            //     SDL_Window* window = SDL_GetWindowFromID(sdlEvent.window.windowID);
            //     std::string windowTitle(SDL_GetWindowTitle(window));
            //     Debug_SetContextToBeRestored(windowTitle);
            //   }
            //   break;

            case SDLK_q:
              stop = true;
              break;

            default:
              GuiAdapterKeyboardEvent dest;
              ConvertFromPlatform(dest, sdlEvent);
              OnKeyboardEvent(sdlEvent.window.windowID, dest);
              break;
            }
          }
        
          OnSdlGenericEvent(sdlEvent);
        }
      }

      SDL_Delay(1);
    }
  }
#endif
}