#include <windows.h>
#include "resource.h" // for icon only
#define MENUCOLOR 0xD8E9EC

int x, y, b = 0;
UINT iNumber = 0, Binary = 0, binmask = 0x80000000;
BOOL replaying = FALSE, syskey = FALSE;
char Buf[1024];
HINSTANCE hInstance;
HWND hwnd, hwndHelp, hwndCopy, hwndClear;
HBRUSH hBrush;
HGLOBAL hGlobal;
LPVOID pGlobal;

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

DWORD CalcIt (UINT iFirstNum, int iOperation, UINT iNum)
{
	switch (iOperation)
	{
	case '=': return iNum;
	case '+': return iFirstNum +  iNum;
	case '-': return iFirstNum -  iNum;
	case '*': return iFirstNum *  iNum;
	case '&': return iFirstNum &  iNum;
	case '|': return iFirstNum |  iNum;
	case '^': return iFirstNum ^  iNum;
	case '<': return iFirstNum << iNum;
	case '>': return iFirstNum >> iNum;
	case '/': return iNum ? iFirstNum / iNum: MAXDWORD;
	case '%': return iNum ? iFirstNum % iNum: MAXDWORD;
	default : return 0;
	}
}

BOOL IsOperator(num)
{
	switch(num)
	{
	case '=': return TRUE;
	case '+': return TRUE;
	case '-': return TRUE;
	case '*': return TRUE;
	case '&': return TRUE;
	case '|': return TRUE;
	case '^': return TRUE;
	case '<': return TRUE;
	case '>': return TRUE;
	case '/': return TRUE;
	case '%': return TRUE;
	default : return FALSE;
	}
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
	static char szAppName[] = "Programmer's Calc";
	MSG		msg;
	WNDCLASS	wndclass;

	hBrush = CreateSolidBrush(MENUCOLOR);

	wndclass.style			= CS_HREDRAW | CS_VREDRAW;
	wndclass.lpfnWndProc	= WndProc;
	wndclass.cbClsExtra	= 0;
	wndclass.cbWndExtra	= 0;
	wndclass.hInstance	= hInstance;
	wndclass.hIcon			= LoadIcon (NULL, IDI_APPLICATION);
	wndclass.hCursor		= LoadCursor (NULL, IDC_ARROW);
	wndclass.hbrBackground = hBrush;
	wndclass.lpszMenuName = NULL;
	wndclass.lpszClassName = szAppName;

	if (!RegisterClass(&wndclass))
		return 0;

	hwnd = CreateWindow (szAppName, szAppName,
		WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX,
		450,350,370,170,
		NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, iCmdShow);
	UpdateWindow(hwnd);

	while (GetMessage (&msg, NULL, 0, 0))
	{
		TranslateMessage (&msg);
		DispatchMessage (&msg);
	}
	return msg.wParam;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	TCHAR szBuffer[36];
	static TCHAR cBinary[] = "00000000 00000000 00000000 00000000";
	static TCHAR temp[] = "00000000 00000000 00000000 00000000";
	int bufSize;
	HDC hdc;
	PAINTSTRUCT ps;
	RECT rect;
	static BOOL  bNewNumber = TRUE;
	static int   iOperation = '=';
	static iFirstNum;
	static int Input = 0;	//0 for Dec, 1 for Hex, 2 for Char, 3 for Bin
	UINT bitmask;
	static DWORD ThisThreadID;

	switch (message)
	{
	case WM_CREATE:
		memset(Buf, ' ', 1024);
		hwndHelp = CreateWindow(TEXT("BUTTON"), TEXT("H&elp"),
			WS_CHILD | WS_VISIBLE,
			190, 10, 60, 20,
			hwnd, (HMENU)192, hInstance, NULL);
		hwndCopy = CreateWindow(TEXT("BUTTON"), TEXT("C&opy"),
			WS_CHILD | WS_VISIBLE,
			244, 40, 60, 20,
			hwnd, (HMENU)192, hInstance, NULL);
		hwndClear = CreateWindow(TEXT("BUTTON"), TEXT("C&lear"),
			WS_CHILD | WS_VISIBLE,
			300, 70, 60, 20,
			hwnd, (HMENU)192, hInstance, NULL);
		SetFocus(hwnd);
		break;

	case WM_ACTIVATEAPP:
		if (wParam == FALSE)//being deactivated
		{
			SetWindowPos(hwnd, HWND_TOPMOST, 450,350,370,170, SWP_NOMOVE|SWP_NOACTIVATE);
			BringWindowToTop(hwnd);//new Mar 28, 2005
		}
		else//being activated
			ThisThreadID = GetWindowThreadProcessId(hwnd, NULL);
		break;
	
	case WM_COMMAND:
		if ((HWND)(LPARAM)lParam == hwndHelp)
			SendMessage(hwnd, WM_SYSKEYDOWN, (WPARAM)0x45, 0); // E
		else if ((HWND)(LPARAM)lParam == hwndCopy)
			SendMessage(hwnd, WM_SYSKEYDOWN, (WPARAM)0x4F, 0); // O
		else if ((HWND)(LPARAM)lParam == hwndClear)
			SendMessage(hwnd, WM_SYSKEYDOWN, (WPARAM)0x4C, 0); // L
		break;

	case WM_SYSKEYDOWN: // buttons
		syskey = TRUE;
		//fall thru
	case WM_KEYDOWN:
		if (syskey) {
			if (wParam == 0x45) { // &HELP
				MessageBox(hwnd, "Use Up/Down Arrow keys\nOperators: + - * / % & | ^ < > =\nPress Backspace to remove last number\n", "Help", MB_OK);
				syskey = FALSE;
			}
			else if (wParam == 0x4C) { // C&LEAR
				replaying = FALSE;
				iOperation = '=';
				iNumber = 0;
				for (x = 0; x <= 34; x++)
					cBinary[x] = temp[x];
				binmask = 0x80000000;
				Binary = 0;
				for (x = 0; (x < 1024) && (Buf[x] != ' '); x++)
					Buf[x] = ' ';
				b = 0;
				syskey = FALSE;
				SetFocus(hwnd);
				InvalidateRect(hwnd, NULL, FALSE);
			}
			else if (wParam == 0x4F) { // C&OPY
				if (Input == 0)
					bufSize = wsprintf(szBuffer, TEXT ("%u"), iNumber);
				else if (Input == 1)
					bufSize = wsprintf(szBuffer, TEXT ("%X"), iNumber);
				else if (Input == 2)
					bufSize = wsprintf(szBuffer, TEXT ("%1C"), iNumber);
				else if (Input == 3) {
					strcpy(szBuffer, cBinary);
					bufSize = 35;
				}
				hGlobal = GlobalAlloc(GMEM_MOVEABLE, (bufSize + 1) * sizeof(TCHAR));
 				pGlobal = (char*)GlobalLock(hGlobal);
				lstrcpy(pGlobal, szBuffer);
				GlobalUnlock(hGlobal);
				OpenClipboard(NULL);
				EmptyClipboard();
				SetClipboardData(CF_TEXT, hGlobal);
				CloseClipboard();
				syskey = FALSE;
				SetFocus(hwnd);
			}
		}
		if ((wParam == VK_DOWN) && (Input != 3))
			Input += 1;
		else if ((wParam == VK_UP) && (Input != 0))
			Input -= 1;
		if (wParam == VK_BACK) {
			if(!IsOperator(Buf[b-1])) {
				if (Input == 1)//hex
					iNumber /= 16;
				else if (Input == 0) // dec
					iNumber /= 10;
				else if (Input == 2) // char
					iNumber = 0;
			}
			if (b) 
				b--;
			Buf[b] = ' '; // remove last entered digit
		}
		InvalidateRect(hwnd, NULL, FALSE);
		if (wParam == VK_ESCAPE)
			SendMessage(hwnd, WM_CLOSE, 0, 0);
		return 0;

	case WM_CHAR:
		if (wParam == VK_RETURN)
			wParam = '=';
		else if (Input == 1)
			wParam = (WPARAM)CharUpper((TCHAR*)wParam); // need to do this here

		if ((Input == 0) && (isdigit(LOWORD(wParam)))) { // decimal digit
			if (bNewNumber) {
				iFirstNum = iNumber;
				iNumber = 0;
			}
			bNewNumber = FALSE;
//add new digit
			if (iNumber <= (MAXDWORD >> 4)) {
				iNumber = (10 * iNumber) + (wParam - '0');
				if ((!replaying) && (b < 1024))
					Buf[b] = wParam;
				if (b < 1024)
					b++;
			}
		}

		else if ((Input == 1) && (isxdigit (LOWORD (wParam)))) { // hex digit
			if (bNewNumber) {
				iFirstNum = iNumber;
				iNumber = 0;
			}
			bNewNumber = FALSE;
//add new digit
			if (iNumber <= (MAXDWORD >> 4)) {
				iNumber = (16 * iNumber) + (wParam - (isdigit (wParam) ? '0': 'A' - 10));
				if ((!replaying) && (b < 1024))
					Buf[b] = wParam;
				if (b < 1024)
					b++;
			}
		}

		else if (Input == 2) { // ASCII char
			iNumber = wParam;
			bNewNumber = TRUE;
		}

		else if (Input == 3) { // binary 1 or 0
			if ((wParam == '1') || (wParam == '0')) {
				for (x = 0, y = 1; x < 34; x++, y++) {
					if ((x == 8) || (x == 17) || (x == 26))
						x++;
					if ((y == 8) || (y == 17) || (y == 26))
						y++;
					cBinary[x] = cBinary[y];
					
				}
				cBinary[34] = wParam;
				binmask = 0x80000000;
				Binary = 0;
				for (x = 0; x <= 34; x++) {
					if ((x == 8) || (x == 17) || (x == 26))
						x++;
					if (cBinary[x] == '1')
						Binary |= binmask;
					binmask >>= 1;
				}
				iNumber = Binary;
			}
		}

		else { // operator
			if (IsOperator(wParam) == FALSE) {
				MessageBeep(0);
				break;
			}
			else if (!bNewNumber)
				iNumber = CalcIt(iFirstNum, iOperation, iNumber);
			bNewNumber = TRUE;
			iOperation = LOWORD (wParam);
			if ((!replaying) && (b < 1024) && (wParam != '=') && (Input < 2))
				Buf[b] = wParam;
			if (b < 1024)
				b++;
		}

		if (Input != 3) {
			for (x = 0; x < 35; x++)
				cBinary[x] = temp[x];
			bitmask = 1 << 31;
			for (x = 0; x < 35; x++) {
				if ((x == 8) || (x == 17) || (x == 26))
					x++;
				if (iNumber & bitmask)
					cBinary[x] = '1';
				bitmask >>= 1;
			}
		}
		InvalidateRect(hwnd, NULL, FALSE);
		return 0;

	case WM_PAINT:
		hdc = BeginPaint (hwnd, &ps);
		GetClientRect(hwnd, &rect);
		SetBkColor(hdc, MENUCOLOR);
		MoveToEx(hdc, 185, 0, NULL);
		LineTo(hdc, 185, 95);
		LineTo(hdc, rect.right, 95);
		TextOut(hdc, 10, 10, TEXT("Dec           "), 14);
		TextOut(hdc, 10, 40, TEXT("Hex           "), 14);
		TextOut(hdc, 10, 70, TEXT("Char          "), 14);
		TextOut(hdc, 10, 100, TEXT("Bin            "), 15);
		TextOut(hdc, 10, 120, Buf, 90); // 90 spaces show
		szBuffer[0] = iOperation;
		TextOut(hdc, 68, (10 + (30 * Input)), szBuffer, 1);
		SelectObject(hdc, GetStockObject(SYSTEM_FIXED_FONT));
		SetTextAlign(hdc, TA_RIGHT);
		bufSize = wsprintf(szBuffer, TEXT ("%10u"), iNumber);
		TextOut(hdc, 180, 10, szBuffer, bufSize);
		bufSize = wsprintf(szBuffer, TEXT ("%8X"), iNumber);
		TextOut(hdc, 180, 40, szBuffer, bufSize);
		if ((iNumber > 0x20) && (iNumber < 0xFF)) {
			szBuffer[0] = iNumber;
			TextOut(hdc, 180, 70, szBuffer, 1);
		}
		else
			TextOut(hdc, 180, 70, " ", 1);
		TextOut(hdc, 360, 100, cBinary, 35);
		SelectObject(hdc, GetStockObject(SYSTEM_FONT));
		SetTextAlign(hdc, TA_LEFT);
		SetBkColor(hdc, 0xFFFFFF);
		EndPaint (hwnd, &ps);
		return 0;

	case WM_DESTROY:
		DestroyWindow(hwndHelp);
		DestroyWindow(hwndCopy);
		DestroyWindow(hwndClear);
		PostQuitMessage(0);
		return 0;
	}
	return DefWindowProc (hwnd, message, wParam, lParam);
}