#ifndef UNICODE
#define UNICODE
#endif

#include <windows.h>
#include <new>

using std::nothrow;

class StateInfo{
	//struct members not shown yet
};

inline StateInfo* GetAppState(HWND hwnd){
	LONG_PTR ptr = GetWindowLongPtr(hwnd, GWLP_USERDATA);
	StateInfo* pState = reinterpret_cast<StateInfo*>(ptr);
	return pState;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
	// Register the window class.
	const wchar_t CLASS_NAME[] = L"Sample Window Class";

	StateInfo *pState = new (std::nothrow) StateInfo;
	if (pState == NULL){
		return 0;
	}
	//initialize the struct members

	WNDCLASS wc = {};
	wc.lpfnWndProc = WindowProc;
	wc.hInstance = hInstance;
	wc.lpszClassName = CLASS_NAME;

	RegisterClass(&wc);

	// Create the window.

	HWND hwnd = CreateWindowEx(
		0,                              // Optional window styles.
		CLASS_NAME,                     // Window class
		L"UnlikeSuika's Windows Programming Practice",    // Window text
		WS_OVERLAPPEDWINDOW,            // Window style

		// Size and position
		CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,

		NULL,       // Parent window
		NULL,       // Menu
		hInstance,  // Instance handle
		pState        // Additional application data
		);

	if (hwnd == NULL)
	{
		return 0;
	}

	ShowWindow(hwnd, nCmdShow);

	// Run the message loop.

	MSG msg = {};
	while (GetMessage(&msg, NULL, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	StateInfo* pState;
	if (uMsg == WM_CREATE){
		CREATESTRUCT *pCreate = reinterpret_cast<CREATESTRUCT*>(lParam);
		pState = reinterpret_cast<StateInfo*>(pCreate->lpCreateParams);
		SetWindowLongPtr(hwnd, GWLP_USERDATA, (LONG_PTR)pState);
	}
	else{
		pState = GetAppState(hwnd);
	}
	switch (uMsg){
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;

	case WM_CLOSE:
		if (MessageBox(hwnd, L"Quitting already? Aw", L"Obligatory Prompting Message", MB_YESNO | MB_ICONASTERISK) == IDYES){
			DestroyWindow(hwnd);
		}
		return 0;

	case WM_PAINT:
		PAINTSTRUCT ps;
		HDC hdc = BeginPaint(hwnd, &ps);

		FillRect(hdc, &ps.rcPaint, (HBRUSH)(COLOR_WINDOW + 1));

		EndPaint(hwnd, &ps);
		return 0;
	}
	return DefWindowProc(hwnd, uMsg, wParam, lParam);
}