#include "win32_window.h"

#include <flutter_windows.h>
#include <shellapi.h> //for systray
#include <strsafe.h> //for systray text
#include <tchar.h> //for systray menu
#include <iostream>
#include <string>

#include "resource.h"

namespace {

constexpr const wchar_t kWindowClassName[] = L"FLUTTER_RUNNER_WIN32_WINDOW";

// The number of Win32Window objects that currently exist.
static int g_active_window_count = 0;

//For systray:
HINSTANCE hInst;                    // current instance
NOTIFYICONDATA nidApp;
HMENU hPopMenu;
BOOL bDisable = FALSE;              // keep application state
#define WM_USER_SHELLICON WM_USER + 1
#define IDM_SHOW 104
#define IDM_EXIT 105

using EnableNonClientDpiScaling = BOOL __stdcall(HWND hwnd);

// Scale helper to convert logical scaler values to physical using passed in
// scale factor
int Scale(int source, double scale_factor) {
  return static_cast<int>(source * scale_factor);
}

// Dynamically loads the |EnableNonClientDpiScaling| from the User32 module.
// This API is only needed for PerMonitor V1 awareness mode.
void EnableFullDpiSupportIfAvailable(HWND hwnd) {
  HMODULE user32_module = LoadLibraryA("User32.dll");
  if (!user32_module) {
    return;
  }
  auto enable_non_client_dpi_scaling =
      reinterpret_cast<EnableNonClientDpiScaling*>(
          GetProcAddress(user32_module, "EnableNonClientDpiScaling"));
  if (enable_non_client_dpi_scaling != nullptr) {
    enable_non_client_dpi_scaling(hwnd);
    FreeLibrary(user32_module);
  }
}

}  // namespace

// Manages the Win32Window's window class registration.
class WindowClassRegistrar {
 public:
  ~WindowClassRegistrar() = default;

  // Returns the singleton registar instance.
  static WindowClassRegistrar* GetInstance() {
    if (!instance_) {
      instance_ = new WindowClassRegistrar();
    }
    return instance_;
  }

  // Returns the name of the window class, registering the class if it hasn't
  // previously been registered.
  const wchar_t* GetWindowClass();

  // Unregisters the window class. Should only be called if there are no
  // instances of the window.
  void UnregisterWindowClass();

 private:
  WindowClassRegistrar() = default;

  static WindowClassRegistrar* instance_;

  bool class_registered_ = false;
};

WindowClassRegistrar* WindowClassRegistrar::instance_ = nullptr;

const wchar_t* WindowClassRegistrar::GetWindowClass() {
  if (!class_registered_) {
    WNDCLASS window_class{};
    window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
    window_class.lpszClassName = kWindowClassName;
    window_class.style = CS_HREDRAW | CS_VREDRAW;
    window_class.cbClsExtra = 0;
    window_class.cbWndExtra = 0;
    window_class.hInstance = GetModuleHandle(nullptr);
    window_class.hIcon =
        LoadIcon(window_class.hInstance, MAKEINTRESOURCE(IDI_APP_ICON));
    window_class.hbrBackground = 0;
    window_class.lpszMenuName = nullptr;
    window_class.lpfnWndProc = Win32Window::WndProc;
    RegisterClass(&window_class);
    class_registered_ = true;

    //For systray:
    hInst = window_class.hInstance;
  }
  return kWindowClassName;
}

void WindowClassRegistrar::UnregisterWindowClass() {
  UnregisterClass(kWindowClassName, nullptr);
  class_registered_ = false;
}

Win32Window::Win32Window() {
  ++g_active_window_count;
}

Win32Window::~Win32Window() {
  --g_active_window_count;
  Destroy();
}

bool Win32Window::CreateAndShow(const std::wstring& title,
                                const Point& origin,
                                const Size& size) {
  Destroy();

  const wchar_t* window_class =
      WindowClassRegistrar::GetInstance()->GetWindowClass();

  const POINT target_point = {static_cast<LONG>(origin.x),
                              static_cast<LONG>(origin.y)};
  HMONITOR monitor = MonitorFromPoint(target_point, MONITOR_DEFAULTTONEAREST);
  UINT dpi = FlutterDesktopGetDpiForMonitor(monitor);
  double scale_factor = dpi / 96.0;

  //New code, create dwStyle and modify to make non-resizable:
  DWORD dwStyle = WS_OVERLAPPEDWINDOW | WS_VISIBLE;
  dwStyle &= ~WS_SIZEBOX; //applies NOT operator to WS_SIZEBOX bit to disable dragging to resize
  dwStyle &= ~WS_MAXIMIZEBOX; //disables maximise button
  HWND window = CreateWindow(
      window_class, title.c_str(), dwStyle,
      Scale(origin.x, scale_factor), Scale(origin.y, scale_factor),
      Scale(size.width, scale_factor), Scale(size.height, scale_factor),
      nullptr, nullptr, GetModuleHandle(nullptr), this);

  if (!window) {
    return false;
  }

  //Systray:
  HICON hMainIcon;
  hMainIcon = LoadIcon(hInst, MAKEINTRESOURCE(IDI_APP_ICON));
  nidApp.cbSize = sizeof(NOTIFYICONDATA); // sizeof the struct in bytes
  nidApp.hWnd = (HWND) window;              //handle of the window which will process this app. messages
  nidApp.uFlags = NIF_ICON | NIF_MESSAGE | NIF_TIP; //ORing of all the flags
  nidApp.hIcon = hMainIcon; // handle of the Icon to be displayed, obtained from LoadIcon
  nidApp.uCallbackMessage = WM_USER_SHELLICON;
  StringCchCopy(nidApp.szTip, ARRAYSIZE(nidApp.szTip), L"All Platforms Test");
  Shell_NotifyIcon(NIM_ADD, &nidApp);

  return OnCreate();
}

// static
LRESULT CALLBACK Win32Window::WndProc(HWND const window,
                                      UINT const message,
                                      WPARAM const wparam,
                                      LPARAM const lparam) noexcept {
  if (message == WM_NCCREATE) {
    auto window_struct = reinterpret_cast<CREATESTRUCT*>(lparam);
    SetWindowLongPtr(window, GWLP_USERDATA,
                     reinterpret_cast<LONG_PTR>(window_struct->lpCreateParams));

    auto that = static_cast<Win32Window*>(window_struct->lpCreateParams);
    EnableFullDpiSupportIfAvailable(window);
    that->window_handle_ = window;
  }
  else if (message == WM_USER_SHELLICON) { //interacting with systray icon
    if (LOWORD(lparam) == WM_RBUTTONDOWN) { //right clicked
        POINT lpClickPoint;
        GetCursorPos(&lpClickPoint);
        hPopMenu = CreatePopupMenu();
        InsertMenu(hPopMenu,0xFFFFFFFF,MF_BYPOSITION|MF_STRING,IDM_SHOW,_T("Show"));
        InsertMenu(hPopMenu,0xFFFFFFFF,MF_BYPOSITION|MF_STRING,IDM_EXIT,_T("Quit"));
        SetForegroundWindow(window);
        TrackPopupMenu(hPopMenu,TPM_LEFTALIGN|TPM_LEFTBUTTON|TPM_BOTTOMALIGN,lpClickPoint.x, lpClickPoint.y,0,window,NULL);
    }
    else if (LOWORD(lparam) == WM_LBUTTONDOWN) { //left clicked
        ShowWindow(window, SW_NORMAL);
        //LOOK: works but shows blank screen until is interacted with (mouse enters or key is pressed etc)
    }
  }
  else if (message == WM_COMMAND) { //if message is a command event such as a click on the exit menu option
      int wmId;
      wmId = LOWORD(wparam);

      if (wmId == IDM_EXIT) { //if quit has been pressed
          Shell_NotifyIcon(NIM_DELETE,&nidApp);
          DestroyWindow(window);
      }
      else if (wmId == IDM_SHOW) {
          ShowWindow(window, SW_NORMAL);
          //LOOK: works but shows blank screen until is interacted with (mouse enters or key is pressed etc)
      }
  }
  else if (Win32Window* that = GetThisFromHandle(window)) {
    return that->MessageHandler(window, message, wparam, lparam);
  }

  return DefWindowProc(window, message, wparam, lparam);
}

LRESULT
Win32Window::MessageHandler(HWND hwnd,
                            UINT const message,
                            WPARAM const wparam,
                            LPARAM const lparam) noexcept {
  switch (message) {
    case WM_DESTROY:
      window_handle_ = nullptr;
      Destroy();
      if (quit_on_close_) {
        PostQuitMessage(0);
      }
      return 0;

    case WM_DPICHANGED: {
      auto newRectSize = reinterpret_cast<RECT*>(lparam);
      LONG newWidth = newRectSize->right - newRectSize->left;
      LONG newHeight = newRectSize->bottom - newRectSize->top;

      SetWindowPos(hwnd, nullptr, newRectSize->left, newRectSize->top, newWidth,
                   newHeight, SWP_NOZORDER | SWP_NOACTIVATE);

      return 0;
    }
    case WM_SIZE: {
      RECT rect = GetClientArea();
      if (child_content_ != nullptr) {
        // Size and position the child window.
        MoveWindow(child_content_, rect.left, rect.top, rect.right - rect.left,
                   rect.bottom - rect.top, TRUE);
      }
      return 0;
    }

    case WM_ACTIVATE:
      if (child_content_ != nullptr) {
        SetFocus(child_content_);
      }
      return 0;

    case WM_CLOSE: //stop window from closing normally, can only be closed when DestroyWindow() is run from systray
      //Hide window and continue running in background.
      ShowWindow(hwnd, SW_HIDE);
      return 0;
  }

  return DefWindowProc(window_handle_, message, wparam, lparam);
}

void Win32Window::Destroy() {
  //Remove systray icon:
  Shell_NotifyIcon(NIM_DELETE,&nidApp);

  OnDestroy();

  if (window_handle_) {
    DestroyWindow(window_handle_);
    window_handle_ = nullptr;
  }
  if (g_active_window_count == 0) {
    WindowClassRegistrar::GetInstance()->UnregisterWindowClass();
  }
}

Win32Window* Win32Window::GetThisFromHandle(HWND const window) noexcept {
  return reinterpret_cast<Win32Window*>(
      GetWindowLongPtr(window, GWLP_USERDATA));
}

void Win32Window::SetChildContent(HWND content) {
  child_content_ = content;
  SetParent(content, window_handle_);
  RECT frame = GetClientArea();

  MoveWindow(content, frame.left, frame.top, frame.right - frame.left,
             frame.bottom - frame.top, true);

  SetFocus(child_content_);
}

RECT Win32Window::GetClientArea() {
  RECT frame;
  GetClientRect(window_handle_, &frame);
  return frame;
}

HWND Win32Window::GetHandle() {
  return window_handle_;
}

void Win32Window::SetQuitOnClose(bool quit_on_close) {
  quit_on_close_ = quit_on_close;
}

bool Win32Window::OnCreate() {
  // No-op; provided for subclasses.
  return true;
}

void Win32Window::OnDestroy() {
  // No-op; provided for subclasses.
}